a I B RARY OF THE U N I VERSITY OF ILLINOIS .7 NOTICE: Return or renew all Library Materials! The Minimum Fee for each Lost Book is $50.00. The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for discipli- nary action and may result in dismissal from the University. To renew call Telephone Center, 333-8400 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN L161 O-1096 YIELD OF SWEET CORN In Relation to Distance and Rate of Planting By W. A. Huelsen UNIVERSITY OF ILLINOIS AGRICULTURAL EXPERIMENT STATION Bulletin 48? CONTENTS PAGE PREVIOUS WORK WITH SPACING EXPERIMENTS 35 METHODS AND PROCEDURE 36 Preliminary Experiments 37 1932-1936 Experiments 37 Statistical Methods 42 CLIMATOLOGICAL DATA 44 EXPERIMENTAL RESULTS, CHECKED PLANTINGS 44 Weights of Sorted Unhusked Ears 44 Weights of Prime Husked Ears 47 Number of Sorted Unhusked Ears 50 Weight per Prime Husked Ear 53 Percent Recovery of Prime Husked Ears 53 Weights of Green Fodder 54 EXPERIMENTAL RESULTS, DRILLED PLANTINGS 67 Weights of Sorted Unhusked Ears 67 Weights of Prime Husked Ears 68 Number of Sorted Unhusked Ears 68 Weight per Prime Husked Ear 69 Percent Recovery of Prime Husked Ears 69 Weights of Green Fodder 69 SOME OTHER EFFECTS OF RATE AND DISTANCE OF PLANTING 70 Height of Plants 70 Number of Suckers 70 Time of Reaching Maturity 73 GENERAL DISCUSSION OF RESULTS 73 Space Occupied by Each Plant as a Criterion 75 Optimum Planting Rates and Distances 83 Comparative Effects of Increasing Rates and Decreasing Distances of Planting 90 SUMMARY AND CONCLUSIONS 102 RECOMMENDATIONS 103 UTKRATURE CITED.. ..104 t'rhana, Illinois May, 1942 Publications in the Bulletin series report the results of investigation.-; made or sponsored by the Experiment Station Yield of Sweet Corn in Relation to Distance and Rate of Planting W. A. HUELSEN, Chief in Vegetable Crops PRACTICALLY ALL the sweet corn raised in Illinois is planted in cross-checked rows at distances ranging from 42 x 42 inches down to 36 x 36 inches. The number of plants per hill is equally variable, ranging from 2 to 5, without any apparent regard to the planting distance. Until about 1925, 42 x 42 inches was the most common planting distance for sweet corn, the stands averaging about 3 plants per hill, but at present 38 x 38 inches with 3 to 4 plants per hill seems to be more popular than the wider distances. This trend toward closer spac- ing seems to arise largely from the use of improved farm machinery rather than from any demonstrated superiority in yield or quality from the corn so planted. By 1932 the tendency toward closer planting reached the point where a spacing of 36 x 36 inches with 5 plants per hill was often used. In some instances even, fields were planted 32 x 32 inches with 4 plants per hill. It is self-evident that overplanting is poor farm practice, and that it may be even more disastrous to good yields than underplanting. As this trend toward closer planting coincided with the drouth cycle of 1930-1936, many growers were greatly disappointed in their yields, and consequently in the last few years planting distances have tended to be more conservative. This general confusion in rates and distances of planting sweet corn reflects the lack of definite knowledge on the subject. The experi- ments reported here were started in 1930 for the purpose of determin- ing the optimum distances and rates for planting sweet corn, par- ticularly the two varieties Country Gentleman and Narrow Grain Evergreen. PREVIOUS WORK WITH SPACING EXPERIMENTS A great many spacing studies have been made with various crops, but only a few are of direct interest so far as the spacing of sweet corn is concerned. McCluer 8 * made some very interesting studies, including both sweet and field corn, in Illinois half a century ago. Three sweet- *These numbers refer to literature citations on page 104. 35 36 BULLETIN* No. 487 corn varieties were tested ; namely Cory, an early type 4 feet tall, Burlington, a second early type 5 to 6 feet tall, and Roslyn Hybrid, a late type 7 to 8 feet tall. The spacing between rows was 44 inches, and the hills were 12, 18, 24, 30, and 36 inches apart in the row. For the largest variety, McCluer added plots with hills 42 inches apart. All the plantings were made with 4 kernels per hill. Unfortunately the plant- ings were badly infected by what seems to have been bacterial blight, and the early varieties were very severely damaged. Because of this damage, all ears and nubbins were counted and weighed, a fact which makes it difficult now to interpret the results. Cory, the earliest and smallest type, seems to have done best on a 24- to 30-inch spacing. Burlington, the next largest variety, required a 36-inch spacing. Roslyn Hybrid, the tallest variety, yielded increasingly more and larger ears as the spacing was increased from 18 to 42 inches. In general, and in accordance with expectation, McCluer's results indi- cated that small varieties require less space than large ones. Morrow and Gardner 9 * in 1893 observed that field corn in central Illinois produced smaller ears and stalks and more stover when planted thickly. In five years of their trials they found no difference in yield between corn planted in checked rows and that planted in drilled rows when the same number of kernels was planted per acre. Davenport and Fraser 1 * reported in 1895 on another rate-of -plant- ing experiment with field corn, the most interesting point of which seemed to be that date of planting had no particular effect on the relationships among the plantings made at the various rates, except at the latest planting (June 3), when the difference between yield on plots planted at the rate of 2 kernels per hill and those at the rate of 5 kernels per hill was less than on the plots planted at other dates. In 1908 Hume, Center, and Hegnauer 6 * reported on a rate-of- planting experiment with field corn showing that in general corn could be spaced closer in northern Illinois than in central Illinois. This work is of particular significance to the sweet-corn grower because the pres- ent practice is to plant closer in northern than in central Illinois. Also in these experiments fewer stalks per hill with the hills closer together yielded more grain than more stalks per hill in hills farther apart. The work of Watson, 10 * Watson and Davis, 11 * Haber, 4 * and Magruder 7 * will be discussed later, so far as it bears upon the findings of the present experiments. METHODS AND PROCEDURE The experimental work reported here consisted of two series of tests. The first, conducted in 1930 and 1931, was preliminary; the second, running from 1932 to 1936, was the main test. 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 37 Preliminary Experiments The 1930-1931 experiments involved 90 rates and spacings, with- out replications, as follows: Checked Rows Drilled Rows Inches between Inches between rows Rate rows Rate Single plants 4, 5, 6, 7, 8, 10, 12, 14, 16, and 18 inches apart in the row 1, 2, 3, 4, and 5 plants per hill at each distance 42x421 42x40 42x38 42x36 40x40 40x38 40x36 38x38 38x36 36x36. The plan of the 1930-1931 tests is shown in Fig. 1. It should be understood, however, that the four blocks of plots were not planted precisely as shown, altho the plot arrangement within each block is correctly indicated. In 1930 one series of 90 plots was planted with the Country Gentleman variety, but in 1931 two series were planted, Narrow Grain Evergreen being added. (The results of these tests are discussed on page 75.) 1932-1936 Experiments Layout. In view of the results of the preliminary experiments, the layout for the 1932-1936 experiments (Fig. 2) was changed, the dis- tances and rates used being as follows: Checked Rows Drilled Rows Inches between Inches between rows Rate rows Rate 42 x 42"] 421 40 x 40 1 2, 3, 4, and 5 plants per hill 40 1 Single plants 8, 14, and 20 38 x 38 [ at each distance 38 [ inches apart in the row 36 x 36j 36J (In the drilled rows, a spacing of 20 inches was used even tho 18 inches had been the widest in the preliminary experiments; data from the preliminary experiments had suggested that the widest spacing might lie outside the range of those experiments.) Thus in the main tests there were only four checked-row spacings and four rates, a total of 16 variations. The spacings between drill rows were likewise limited to four, with only three distances between plants, a total of 12 variations. There were accordingly only 28 varia- tions all told, but as each was replicated four times, 112 plots were needed for each variety, Country Gentleman and Narrow Grain Evergreen. The plot detail, which was uniform thruout the work, is shown in Fig. 3. Each plot was entirely surrounded by a single border row and 38 BULLETIN No. 487 [May, 42'X42' XI 42*X4CT X 1 42'X 38" XI 42*X 36" XI 42\4" 42*X5" 42*X42* X 2 42'X 40' X2 42'X36' X2 42*X36* X2 42*"X 6' 42*X 7* 42*X42* X 3 4 2*X 40* X 3 42'X38* X 3 42*X36' X 3 42*X 8' 42*X 10" 4 2*X 42'- X4 42"X 40' X4 42*X38* X4 42*X36' X4 42'X 16" 42"XI2' 42*X42* X 5 42'X 40" X 5 42"X38" X5 4 2*X 36' X5 4 2*X 1 8' 42\I4 1 ' 40*X40* X 1 4dV38" XI 40"X36* XI 40*X4" 40\5" \ \ 40"!X40" X2 40'X38" X2 40*X36" X2 40^6" 40*X7" ' I 40^40" X3 40X38 X3 40"X36" X3 4o"xe' 40'XIO* ( 40"X40" X4 40X38" X4 40\36" X4 40"XI6* 40'XI2' / 40"X40" X5 40"X38" X5 40"X36" X 5 40'XI8' 40*XI4" / 38\38" X 1 38"X36" XI 38*X4' 38'X5" 38"X38" X2 38"X36" X2 38X6 38"X7' 38"X38" X3 38V36" X3 38"X8' srfx io* 38"X38" X4 38X36" X4 38*XI6* 38"XI2* 38'X38* X5 38*X36" XS 38"XI8" 38\I4' se'xse" X 1 36~X4* 36'X5" \ I 36"k 36" X2 36"X6' 36\7' 36*X36" X3 36X8" 36"XIO* ( \ 36"X36* X4 36'XI6* 36X12 1 / 36"X36" X5 1 1 36"XI8" 36"XI4' / '^BORDER FIG. 1. PLOT LAYOUT OF THE 1930-1931 SPACING EXPERIMENTS In 1930 one series was planted with Country Gentleman, and in 1931 there were two such series, one for Country Gentleman and one for Narrow Grain Evergreen. The blocks were planted at random and not in the triangle shown. 1942} PLANTING RATES AND DISTANCES FOR SWEET CORN 39 the outside plots by two border rows. These borders were all cut out by hand the day before harvesting. Records were kept on forty hills. The drilled plots were not exactly the same size, but varied from 35 to 36 feet in length. They were surrounded by one border row on each side, by a 3-foot extension on the inside, and by a 5- foot extension on the outside. Thus on each drilled plot the rows extended at least 3 feet beyond the plot boundaries on each end. The layout in Fig. 2 is on the Latin-square basis, so far as the checked plantings are concerned; but this method could not be ex- tended to the entire block because the drilled plantings would have prevented cross cultivation. Could it have been used thruout, the Latin- square method would have simplified the computations enormously. Soil. The experiments were conducted at Urbana, and the plots were moved each year. The soil was of average fertility and was given no fertilizer treatments except such as were needed to maintain the fertility level. Planting and Cultivation. Each year the blocks were laid out with a horse-drawn marker, and the correct distances in the drilled-rows were marked with a hand marker. The plantings were made with hand planters. The checked plantings were seeded at twice the indicated rate per hill, and in the drilled plantings two seeds were dropped at each place. When the plants were 4 inches high, the checked plantings 3 5 2 4 3 5 2 4 2 4 3 5 2 4 3 5 5 2 4 3 5 2 4 3 A 3 5 2 A 3 5 2 8* 14" 20* 8' 14' 20* 8* 14* 20' 8' 14" 20" a" 14" 20" a" 14" 20" B" 14" 20" s" 14" 20" FIG. 2. PLOT ARRANGEMENT IN ONE OF THE BLOCKS OF THE 1932-1936 SPACING EXPERIMENTS There were four such blocks, one each for the 36-, 38-, 40-, and 42-inch rows. Tiers A, C, E, and G were planted with Country Gentleman and B, D, F, and H with Narrow Grain Evergreen. 40 BULLETIN No. 487 [May, were thinned to the correct rates per hill and the extra plants were removed from the drilled plantings. It should be noted that the drilled plantings were not "blocked" during thinning, the two seeds being dropped in the right place to begin with. Cultivation, given when needed, seldom exceeded two plowings each way for the checked rows. Owing to the plot layout, the drilled rows were cultivated only half as many times as the checked rows. Some hoeing was therefore necessary in the drilled plots. Harvesting. The plots were harvested at identical stages of ma- turity as determined by silk counts, following the method described by Huelsen and Michaels. 5 * In 1930 only the yields of unhusked ears were recorded, but in all subsequent years the weights of husked ears also were recorded. The yields of fodder were measured 1 to 3 days after the ears were snapped. The stalks were cut by hand as close to the ground as prac- ticable and weighed immediately. Varieties. The varieties used in all the experiments were open- xxxxxxxxxxxxxxxxx x x _ x _2 < _ x _ x . x x X-X-X_x. x x x_x_x x xjx xx x!x xfx xxxixxfx x x xjx x x x!x xjx x x xjx xjx x x xjx x x x[x xjx x x xix xjx x x ! x x x xix xjx x x x'x x'x 'I ' I X XIX X X XIX XiX X X XIX XiX X x xix x x xjx x!x x x xjx xjx x X|X x x x'x x!x x x xjx xjx x X XJX X X XiX X|X X X XiX XIX X x x'x x x xjx x|x x x xjx xjx x X X|X X X XJX XJX X X XJX XJX X X xxx^cxxxxxxxxx x x x x XXXXXXXXXXXXXXXXX X X X X X X /v X X X X I X X|^w .A, ys <* i ^ At*. x x xjx xjx x x xjx xjx x x'x xjx x x xjx xjx x x x'x x x x i*x xix x XiX X X X XJX X XX 'X FIG. 3. DETAILS OF STANDARD PLOTS AND BORDERS IN ALL SERIES The yields were measured from four 10-hill rows in the checked plots. In the drill rows also four rows were harvested, each row being 36 feet long in the 8-inch series (54 plants), and 35 feet long in the 14- and 20-inch series (30 and 21 plants respectively). X X X x !x x !x x X xjx X I X A x X X X X !x i X x'x *! x X X N^ X N." X ^ x'x V I \S x'x x NX ' \S \S X xX 1 x'x \s . \s x; x w x X 1942~\ PLANTING RATES AND DISTANCES FOR SWEET CORN 41 pollinated strains selected by ear-row methods at the Illinois Station, and tested by individual ears for germination and freedom from dis- ease. The same strains were used thruout the experiments. Number of Replications. The data in Tables 3 to 14 consist of averages of 21 replications for the checked plantings and 17 for the drilled plantings. The odd replication, 21 instead of 20 and 17 instead of 16, is due to the fact that the 1931 yields were included in the means. Only 17 replications are reported for the drilled plantings because the four replications in 1933 were severely damaged by chinch bugs and the yields for that year were consequently omitted. The replications for fodder yields were 17 for the checked plantings and 13 for the drilled plantings. Yields for 1934 were omitted from the data on checked plantings and those for 1933 and 1934 from the data on drilled plantings because severe drouth and chinch-bug infes- tation caused such excessive dehydration of the stalks that they could scarcely be termed green fodder. As ear yields were relatively good in spite of the conditions, these were included except in the drilled plantings of 1933, as explained above. Some of the mean yields were computed from an odd number of replications, resulting from the omission of one plot or more, generally where the stand was defective because of cutworms, gophers, or other natural hazards. The fact that yields for the unfavorable year 1933 were omitted from the drilled-row plantings and, of course, from the corresponding checked-ro\v planting with which each drilled-row planting was paired, might lead to some question of the conclusions being based on unequal comparisons. In the checked-row plantings the four replications for 1933 were included in all the averages. The question is, would it be better to omit the 1933 replications from the checked-row averages? The effect of omitting the 1933 yields from the means of two of the principal yield components weights of prime husked ears and of green fodder is summarized in Table 1. Since the yields were analyzed on the basis of pairs (that is, the 3-, 4-, and 5-per-hill rates are paired with the 2-per-hill rate for the cor- responding distance ; and the 40"x 40", 38"x 38", and 36"x 36" plant- ing distances are paired with the 42"x 42" for the corresponding rates per hill), similar comparisons must be made of the percentages in Table 1. If the yields of prime husked ears are compared according to dis- tance between rows, rate per hill being held constant, the closer plant- ings would have a slight advantage if data for 1933 were omitted. These increases are, however, within the limits of the standard errors, and it is very doubtful whether any advantage gained by omitting the 1933 data would not be counterbalanced by the corresponding loss in degrees of freedom. So far as green fodder is concerned, the differ- 42 TABLE 1. BULLETIN No. 487 [.May, -PERCENTAGE INCREASES IN AVERAGE YIELDS OF PRIME HUSKED EARS AND OF GREEN FODDER, 1932-1936, WHEN DATA FOR UNFAVORABLE YEAR 1933 ARE OMITTED Planting distance Plants per hill Increases for Country Gentleman in Increases for Narrow Grain Evergreen in Prime husked ears Green fodder Prime husked ears Green fodder inches 42 x 42 2 perct. 1.53 1.58 .94 3.40 -.94 1.81 .91 4.97 -1.57 1.99 4.49 5.13 1.13 3.49 3.54 4.27 perct. 3.58 2.40 6.55 6.32 4.40 -2.02 5.91 7.33 3.91 2.73 6.31 7.68 5.01 4.14 6.72 6.51 perct. .60 .52 -1.67 2.27 1.98 -2.21 2.73 -.23 2.23 2.42 4.81 1.03 .74 -.67 3.60 perct. 4.20 3.38 6.66 6.01 2.78 4.20 4.05 6.73 2.49 2.53 6.21 7.62 1.64 2.70 3.39 6.73 40 x 40 2 38 x 38 2 36 x 36 2 42 x 42 ... 3 40x40 3 38 x 38 3 36 x 36 3 42 x 42 4 40 x 40 4 38 x 38 . 4 36 x 36 . . 4 42 x 42 ... . 5 40 x 40 5 38 x 38 5 36 x 36 5 ences arising from including or excluding the 1933 data are negligible. Likewise, when the comparisons are made on the basis of rate, with distance between rows being held constant, the differences due to including or leaving out the 1933 data are negligible so far as green fodder is concerned and very slight so far as prime husked ears are concerned. Statistical Methods The experimental results could have been analyzed by any one of a number of methods. The method finally adopted seemed the least cumbersome. As mentioned briefly above, it consisted of a definite series of comparisons as follows: 1. Yields from the plots planted at the rate of 3, 4, and 5 plants per hill respectively were paired with yields from the 2-per-hill plant- ing. There were thus four groups of pairs in the data on checked rows, one for each of the distances 42"x 42", 40"x 40", 38"x 38", and 36"x 36". 2. Yields from the plantings at the three drilled-row rates (20, 14, and 8 inches between plants) were paired with yields from the checked rows planted 2 plants per hill for each of the four distances between rows for example, the yields from the 42"x 42"x 2 checked-row planting were paired with the yields from the drilled rows at distances of 42"x 8", 42"x 14", and 42"x 20" respectively ; and the same for the other distances between rows. PLANTING RATES AND DISTANCES FOR SWEET CORN 45 advisable, according to the preceding discussion, it is evident that nothing is gained by planting closer than 42"x42", none of the increases obtained by planting at narrower distances at the 4-per-hill rate being significant. At the 2-per-hill rate significant increases in yield were obtained at the 40"x40" distance, 10.67 percent, and at the 38"x 38" distance, 13.11 percent. Likewise at the 36"x 36" distance a significant increase of 13.13 percent was obtained at the 3-per-hill rate, but a planting as close as this is not advisable in view of the effect on yields of husked ears (Fig. 7). Apparently a planting of 38"x 38" x 2 is the closest advisable for Narrow Grain Evergreen. 3 4 PLANTS PER HILL 20 14 8 INCHES BETWEEN PLANTS FIG. 4. WEIGHTS OF SORTED UNHUSKED EARS, SHOWN AS PERCENT INCREASE OVER THE Two-PER-HiLL RATE FOR EACH DISTANCE BETWEEN Rows (BASED ON TABLE 3) (Single star (*) indicates significant increase; double star (**) shows highly significant increase) [May, 40 38 INCHES BETWEEN ROWS 40 38 INCHES BETWEEN ROWS FIG. 5. WEIGHTS OF SORTED UNHUSKED EARS, SHOWN AS PERCENT INCREASE OVER THE 42-lNCH DISTANCE BETWEEN Rows (BASED ON TABLE 4) (Single star (*) indicates significant increase; double star (**) shows highly significant increase) 1942] PLANTIXC. RATES AND DISTANCES FOR SWEET CORN 47 When the distances of planting Country Gentleman were reduced below 42"x 42" no significant increases in weights of sorted unhusked ears were obtained at either the 3- or the 4-per-hill rate (Table 4 and Fig. 5). However, the yield was slightly higher at each rate of planting when the distance was reduced from 42"x42" to 40"x 40". The 40"x 40"x 3 planting gave the largest increase, tho it was not significant. In view of the probable superiority of the 3-per-hill rate, the 40"x 40" x 3 planting is most likely the heaviest planting advisable. Weights of Prime Husked Ears Xutnbcr of Plants per Hill. The weights of prime husked ears of Narrow Grain Evergreen were significantly increased in a number of instances as the rate of planting was increased above 2 plants per hill (Table 5 and Fig. 6). Planting at the* rate of 3 per hill gave significant increases over all but one of the plantings in the 2-per-hill group. In the 40"x 40" series, 4 plants per hill resulted in the highest increase, and in the 42"x 42" series, 5 plants per hill returned yields very slightly higher than 4 plants per hill. The trends for weights of prime husked ears shown by the curves in Fig. 6 resemble those for weights of sorted unhusked ears (Fig. 4) very closely and the same conclusions may therefore be drawn: namely, that 4 plants per hill is the heaviest rate of planting advisable for Narrow Grain Evergreen. The trends in weights of unhusked and husked ears of Country Gentleman (Tables 3 and 5, and Figs. 4 and 6) also are very similar, and it is therefore certain that rates of planting heavier than 3 plants per hill are not advisable for this variety. Distance Between Rows. The trend in weights of prime husked ears of Narrow Grain Evergreen when the distances between rows were narrowed below 42"x 42" was exactly the same as that in the weights of sorted unhusked ears (Tables 4 and 6, and Figs. 5 and 7), but the only significant increases obtained were those where the rate of planting was 2 plants per hill. The 40"x40"x2 planting gave a significant increase of 7.43 percent and the 38"x 38"x 2 planting a highly significant increase of 12.13 percent. With respect to distances, the 38"x 38"x 2 planting would perhaps seem to be the optimum on the basis both of weights of unhusked ears and of husked ears; but with respect to rate of planting, as discussed above, the 40"x 40"x 4 or 42"x 42"x 4 plantings would seem to be the most favorable. Further comparisons may be made on the basis of mean weights, as follows: Unhusked ears Husked ears Distance Plants per hill (Table 3) (Table 7) Ib. Ib. 38*x38" 2 7542 4622 40*x40* 4 8137 5031 42'x42*. . ..4.. 7 812 4 859 3 4 PLANTS PER HILL 20 14 6 INCHES BETWEEN PLANTS FIG. 6. WEIGHTS OF PRIME HUSKED EARS, SHOWN AS PERCENT INCREASE OVER THE TWG-PER-HlLL RATE FOR EACH DISTANCE BETWEEN ROWS (BASED ON TABLE 5) (Single star (*) indicates significant increase; double star (**) shows highly significant increase) PLANTING RATES AND DISTANCES FOR SWEET CORN 20 40 38 INCHES BETWEEN ROWS 40 38 INCHES BETWEEN ROWS Fu;. 7. WEIGHTS OF PRIME HUSKED EARS, SHOWN AS PERCENT INCREASE OVER THE 42-lNCH DISTANCE BETWEEN Rows (BASED ON TABLE 6) (Single star (*) indicates significant increase; double star (**) shows highly significant increase) 50 BULLETIN No. 487 {.May, Thus the 40-inch and the 42-inch plantings resulted in higher mean weights both of unhusked and of husked ears than the 38-inch plant- ing; and since in analyzing an experiment of this type the widest distances between the rows must obviously be given the preference, it may be assumed that a 40"x 40"x 4 or a 42"x 42"x 4 planting is pref- erable to a 38"x 38"x 2 planting. In the Country Gentleman variety (Table 6 and Fig. 7) the superiority of the 40"x 40" and 42"x42" planting distances was evi- dent, since there were practically no significant increases over the plantings at the 42"x42" distance. The conclusion reached on the basis of weights of unhusked ears, that 40"x 40"x 3 is probably the optimum planting, is valid also with respect to weights of husked ears. Number of Sorted Unhusked Ears Number of Plants per Hill. Increasing the number of plants per hill beyond 2 resulted in large significant increases in number of sorted unhusked ears for both Narrow Grain Evergreen and Country Gentle- man (Table 7 and Fig. 8). Eliminating the less desirable rates and distances of planting would be difficult on the basis of the data in Table 7 alone but becomes rela- tively simple when additional data are taken into account. Thus all the 5-per-hill plantings may be eliminated, as the total unhusked weights (Table 3 and Fig. 4) failed to keep pace with the total number of unhusked ears, indicating an undesirable decrease in weight per ear. Similarly the entire 36"x 36" series need not be considered (Table 3). The 3-per-hill plantings all had smaller increases (Table 7) than the 4-per-hill plantings. This leaves only the 4-per-hill rates planted 42"x42", 40"x 40", and 38"x38". However the 42"x42"x4 plantings had a definitely smaller total yield than the 40"x40"x4 and 38"x38"x4. Accord- ingly the 38"x 38"x 4 and the 40"x 40"x 4 plantings remain as the most nearly optimum plantings where number of sorted unhusked ears per acre is the important yield factor. As to Country Gentleman (Table 7 and Fig. 8), only the 40"x40" and 42"x42" planting distances need be considered. Plantings at the rate of 4 plants per hill gave the maximum increases over the 2-per- hill rate. The 40"x40"x4 planting resulted in both the largest total yield and the largest increase over the 2-per-hill rate. Distance Between Rows. The closer planting distances gave the largest increases over the 42"x42" distance in number of sorted unhusked ears of Narrow Grain Evergreen, according to Table 8 and Fig. 9. As planting distance was narrowed, the largest and most PLANTING RATES AND DISTANCES FOR SWEET CORN 32 51 PLANTS PER HILL 20 14 8 INCHES BETWEEN PLANTS FIG. 8. NUMBER OF SORTED UNHUSKED EARS, SHOWN AS PERCENT INCREASE OVER THE Two-PER-HiLL RATE FOR EACH DISTANCE BETWEEN Rows (BASED ON TABLE 7) (Single star (*) indicates significant increase; double star (**) shows highly significant increase) 52 BULLETIN No. 487 [May, consistent increases in number of ears were obtained with the 3- and the 4-per-hill rates. However, it is doubtful from the previous dis- cussion (Table 7) whether anything is gained by plantings heavier than 38"x 38"x 4. The 36"x 36"x 4 planting gave a larger number of ears, according to Table 8, and a significant increase over the corresponding 42"x 42"x 4 planting, but the equivalent increase in weight of unhusked ears was not significant (Table 4). The 38"x38"x4 planting behaves in a similar fashion to the 36"x36"x4. Since nothing is gained by 24 40 38 INCHES BETWEEN ROWS 40 38 INCHES BETWEEN ROWS FIG. 9. NUMBER OF SORTED UNHUSKED EARS, SHOWN AS PERCENT INCREASE OVER THE 42-lNCH DISTANCE BETWEEN Rows (BASED ON TABLE 8) (Single star (*) indicates significant increase; double star (**) shows highly significant increase) 1942} PLANTING RATES AND DISTANCES FOR SWEET CORN 53 planting closer, the 38"x 38"x 4 is the heaviest planting advisable where number of ears is the primary consideration. Country Gentleman showed a tendency toward an increased num- ber of sorted unhusked ears as the distance between hills was reduced, but only two of the increases were significant (Table 8 and Fig. 9). Since both of these significant increases seem to have occurred at random, it appears that 40" x 40"x 4 is the heaviest planting which need be considered, especially as it produced the largest number of ears per acre. Weight per Prime Husked Ear Data showing yields in terms of number of prime husked ears have been omitted, but the ratios between the weights and the corresponding numbers of prime husked ears, which give the weight per prime husked ear, have been included. Similar ratios for sorted unhusked ears were also computed but are not reported here. The effect of rate and distance of planting on weight per prime husked ear is shown in Tables 9 and 10. In both varieties, increasing the number of plants per hill reduced the weight per ear. This is a mat- ter of great importance to the grower. If ears are sold on the basis of count, a planting somewhat heavier than usual is advisable, as more ears will be produced per acre. In addition the weight per ear in naturally large-eared types such as Narrow Grain Evergreen and Country Gentleman can be reduced somewhat without resulting in any noticeable difference in appearance. On the other hand, for the can- nery grower, whose sweet corn is weighed in, the size of the ear is an important factor in the expense per ton for snapping the heavier the ears the less the expense. According to Tables 9 and 10, rates heavier than 3 plants per hill result in a considerable reduction in the size of the Narrow Grain Evergreen ear. A 40"x 40"x 3 planting seems to be the most desirable planting consistent with the previous discussion regarding weight, and a 40"x 40"x 4 planting the most desirable, so far as number of ears is concerned. The weight per prime husked ear of Country Gentleman was also reduced when the rate was increased. The 40"x 40"x 3 planting is the most desirable planting when corn is to be sold on the basis of weight, and 40"x 40"x 4 when it is sold by number. Percent Recovery of Prime Husked Ears Increasing the number of plants per hill above 2 and reducing the distance between rows below 42"x 42" had only a very slight effect on the recovery of prime husked ears of Narrow Grain Evergreen (Tables 11 and 12), but in Country Gentleman large significant reduc- tions occurred at the closer planting distances. So far as Country 54 BULLETIN No. 487 [May. Gentleman is concerned, the 40"x40"x3 and 40"x40"x4 plantings, previously recommended, gave as good recovery as those planted at a 42-inch spacing or at a 2-per-hill rate. Weights of Green Fodder Number of Plants per Hill. Weights of green fodder of both varieties tended to increase as number of plants was increased above 2 per hill (Table 13). Significant increases in Narrow Grain Ever- green occurred at the 5-per-hill rate in the 42"x42" and 38"x 38" plantings and at all rates in 36"x 36" distance of planting. Total yields varied surprisingly little. Of the plantings previously considered, the 40"x40"x4 planting gave a relatively high total yield. Nothing was gained by using a heavier planting. In Country Gentleman (Table 13) increasing the rate above 2 plants per hill had a much greater effect on weights of green fodder, resulting in large significant increases. The 40"x 40"x 4 planting had the highest total yield and a large significant increase. Distance Between Rows. The largest increases in weights of green fodder for Narrow Grain Evergreen were associated with the 4- and the 5-per-hill rate (Table 14). The previous conclusion that 40"x40"x4 is the heaviest planting of Narrow Grain Evergreen that should be made is confirmed by these comparisons, this planting giving the largest increase over the 42"x 42"x 4 planting. Similarly for Country Gentleman (Table 14) the 40"x40"x4 planting gave both the largest total yield and the largest increase over the 42"x 42"x 4 planting. (Tables 3 to 14 follow.) PLANTING RATES AND DISTANCES FOR SWEET CORN 55 TABLE 3. WEIGHT OF SORTED UNHUSKED EARS: EFFECT OF INCREASING NUMBER OF PLANTS PER HILL IN CHECKED Rows AND REDUCING DISTANCE BETWEEN PLANTS IN DRILLED Rows Planting distance (inches) Plants per hill Pounds per acre Increase over 2-per-hill rate Number of repli- Pounds Percent cations Narrow Grain Evergreen Checked rows 42x42 3 7479 872t 13.20 21 4 7 812 1 205f 18.24 21 5 7 887 1 280f 19.38 21 40x40 3 7832 520* 7.11 21 4 8 137 825t 11.29 21 5 7 577 265 3.62 21 38x38 3 7724 292 3.94 20 4 7 912 370 4.91 21 5 7 626 84 1.12 21 36x36 . 3 8461 1082t 14.66 21 4 8 350 971f 13.16 21 _ ... , 57 490 111 1.50 21 Drilled rows 42x20 1 6377 -156 -2.39 17 42x14 1 6652 119 1.83 17 42 x 8 : 1 7049 516* 7.90 17 40x20 1 7 579 272 3.73 17 40x14 1 8034 727t 9.95 17 40x 8 1 7818 511 6.99 17 38x20 1 7332 -201 -2.67 17 38x14 1 7903 370 4.91 17 38 x 8 1 8183 650* 8.62 17 36x20 1 7376 126 1.74 16 36x14 1 7733 483f 6.66 16 36 x 8 1 7647 397 5.48 16 Country Gentleman Checked rows 42x42 3 5668 126 2.27 21 4 5 900 358* 6.47 21 5 5 518 -24 -.42 21 40x40 .3 6301 560 9.76 21 4 6 287 546 9.52 21 5 5 939 198 3.45 21 38x38 3 6142 54 .89 21 4 5 721 -367 -6.03 21 5 5 501 -587f -9.63 21 36x36 3 6100 243 4.14 21 4 5 767 -90 -1.54 21 Drilled rows 5 OS1 - 806 t -".76 21 42x20 1 5210 -3 -.05 17 42x14 1 5493 280 5.38 17 42 x 8 1 5429 216 4.15 17 40x20 1 5965 98 1.67 17 40x14 1 6536 669* 11.40 17 40 x 8 1 6254 387 6.59 17 38x20 1 5978 -124 -2.03 17 38x14 1 6248 146 2.38 17 38 x 8 1 6106 4 .06 17 36x20 1 6144 330 5.69 16 36x14 1 6334 520* 8.95 16 36x 8 1 5736 -216 -3.64 17 Significant difference, P equals .05. fHighly significant difference, P less than .05. Note. In this and the following tables the fractions of pounds were dropped after the percentages were calculated. 56 BULLETIN No. 487 [May, TABLE 4 WEIGHT OF SORTED UNHUSKED EARS: EFFECT OF REDUCING DISTANCE BETWEEN HILLS IN CHECKED Rows AND REDUCING DISTANCE BETWEEN Rows IN DRILLED Rows Planting distance (inches) Plants per hill Pounds per acre Increase over 42* spacing Pounds Percent Number of repli- cations Narrow Grain Evergreen Checked rows 40x40 2 7312 705f 10.67 21 38x38 2 7432 862' 13.11 20 36x36 2 7379 772* 11.69 21 40x40 3 7832 353 4.72 21 38x38 3 7724 350 4.75 20 36x36 3 8461 982* 13.13 21 40x40 4 8137 325 4.17 21 38x38 4 7912 100 1.29 21 36x36 4 8350 538 6.89 21 40x40 .5 7577 -310 -3.94 21 38x38 5 7626 -261 -3.30 21 36x36 5 7490 -397 -5.03 21 Drilled rows 40x20 1 7579 1202t '18.85 17 38x20 1 7332 955f 14.98 17 36x20 1 7377 1177f 18.97 16 40x14 1 8034 1 382f 20.76 17 38x14 1 7903 1251f 18.80 17 36x14 1 7733 1302* 20.25 16 40 x 8 1 7818 769* 10.91 17 38 x 8 1 8 183 1 134f 16.09 17 36 x 8 1 7647 794 11.59 16 Country Gentleman Checked rows 40x40 2 5741 199 3.60 21 38x38 2 6088 546t 9.86 21 36x36 2 5857 315 5.69 21 40x40.. .3 6301 633 11.18 21 38x38 3 6142 474 8.37 21 36x36 3 6100 432 7.62 21 40x40 .4 6288 388 6.57 21 38x38 4 5721 -179 -3.04 21 36x36 4 5767 -133 -2.26 21 40x40 .5 5939 421 7.62 21 38x38 5 5501 -17 -.31 21 36x36 5 5051 -467 -8.47 21 Drilled rows 40x20 1 5965 755 14.49 17 38x20 1 5979 769t 14.75 17 36x20 1 6144 1 076f - 21.25 16 40x14 1 6536 1 043t 18.98 17 38x14 1 6248 755t 13.74 17 36x14 1 6334 1 091f 20.80 16 40 x 8 1 6254 825f 15.19 17 38x 8 1 6105 677f 12.46 17 36 x 8 1 5 736 307 5.64 17 Significant difference, P equals .05. tHighly significant difference. P less than .05. 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 57 TABLE 5 WEIGHT OF PRIME HUSKED EARS: EFFECT OF INCREASING NUMBER OF PLANTS PER HILL IN CHECKED Rows AND REDUCING DISTANCE BETWEEN PLANTS IN DRILLED Rows Plants Pounds Increase over 2-per-hill rate Number Planting distance (inches) per per of repli- hill acre Pounds Percent cations Narrow Grain Evergreen Checked rows 42x42 3 4664 S42f 13.15 21 4 4 859 737t 17.90 21 5 4 950 828f 20.09 21 40x40 3 4894 466f 10.52 21 4 5 031 603f 13.62 21 5 4 712 284 6.42 21 38x38 3 4843 297 6.53 20 4 4 834 212 4.59 21 5 4 606 -16 -.34 21 36x36 3 5084 592f 13.17 21 4 5 027 535f 11.90 21 5 4 411 -81 -1.80 21 Drilled rows 42x20 1 4111 -38 -.93 17 42x14 1 4203 54 1.28 17 42 x 8 1 4400 251 6.03 17 40x20 1 4664 213 4.79 17 40x14 1 5019 568f 12.75 17 40 x 8 1 4774 323 7.25 17 38x20 1 4572 -27 -.60 17 38x14 1 4958 359 7.80 17 38 x 8 1 5001 402 8.72 17 36x20 1 4481 -195 -4.17 16 36x14 1 4690 14 .31 16 36 x 8 1 4502 -174 -3.73 16 Country Gentleman Checked rows 42x42 3 3821 136 3.68 20 4 3 683 119 3.33 20 5 3 624 -76 -2.05 20 40x40.. .3 3981 508* 14.63 21 4 3 969 496* 14.31 21 5 3 696 223 6.42 21 38x38 .3 3709 -29 -.76 21 4 3 388 -350f -9.36 21 5 3 216 -522t -13.96 21 36x36 .3 3 901 93 2.44 21 4 3 473 -336* -8.82 21 5 2 833 -975f -25.60 21 Drilled Rows 42x20 1 3318 -74 -2.17 17 42x14 1 3523 131 385 17 42 x 8 1 3459 67 1.97 17 40x20 1 3859 331 9.40 17 40x14 1 4223 695f 19.71 17 40 x 8 1 3857 329 9.34 17 38x20 1 3662 -111 -2.94 17 38x14 1 3969 196 5.22 17 38 x 8 1 3775 2 .06 17 36 x 20 1 3 909 68 1 . 78 16 36x14 1 4101 260f 6.77 16 36 x 8 1 3589 -349* -8.87 17 'Significant difference, P equals .05. fHighly significant difference, P less than .05. 58 BULLETIN No. 487 [May, TABLE 6. WEIGHT OF PRIME HUSKED EARS: EFFECT OF REDUCING DISTANCE BETWEEN HILLS IN CHECKED Rows AND REDUCING DISTANCE BETWEEN Rows IN DRILLED Rows Plants Pounds Increase over 42* spacing Number Planting distance (inches) per per of repli- hill acre Pounds Percent cations Narrow Grain Evergreen Checked rows 40x40 2 4428 306* 7.43 21 38 38 2 4622 SOOf 12.13 21 36 36 2 4492 370 8.98 21 40 40 3 4894 230 4.93 21 38 38 3 4843 240 5.22 20 36 36 3 5.084 420 9.00 21 40x40 4 5031 171 3.53 21 38x38 4 4834 -26 -.53 21 36x36 4 5027 167 343 21 40x40 5 4712 -238 -4.81 21 38x38 5 4606 -344 -6.95 21 36x36 5 4411 -539* -10.89 21 Drilled rows 40x20 1 4664 553* 13.47 17 38x20 1 4572 461* 11.22 17 36x20 1 4481 488 12.22 16 40x14 1 5019 816t 19.41 17 38x14 1 4958 755f 17.98 17 36 x 14 1 4 690 636f 15 68 16 40 x 8 1 4773 373 8.50 17 38 x 8 1 5001 601 13.66 17 36 x 8 1 4502 249 5.84 16 Country Gentleman Checked rows 40x40 2 3473 -54 -1.54 21 38x38 2 3738 211 5.98 21 36x36 2 3808 281 7.99 21 40x40 3 4149 328 8.59 20 38 x 38 3 3 845 24 .62 20 36x36 3 4035 214 5.61 20 40x40 . 4 4076 393* 10.68 20 38x38 4 3493 -190 -5.17 20 36x36 4 3613 -70 -1.90 20 40x40 5 3810 186 5.15 20 38x38 5 3340 -284 -7.83 20 36x36 5 2918 -706t -19.48 20 Drilled rows 40x20 1 3859 541 16.31 17 38x20 1 3662 344 10.35 17 36x20 1 3910 710f 22.17 16 40x14 1 4223 700f 19.89 17 38x14 1 3969 446t 12.69 17 36x14 1 4101 768f 23.07 16 40 x 8. . 1 3 857 398f 11.52 17 38x 8 1 3775 316* 9.14 17 36 x 8 1 3589 130 3.77 17 'Significant difference, P equals .05. fHighly significant difference, P less than .05. 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 59 TABLE 7. NUMBER OF SORTED UNHUSKED EARS: EFFECT OF IN- CREASING NUMBER OF PLANTS PER HILL IN CHECKED Rows AND REDUCING DISTANCE BETWEEN PLANTS IN DRILLED Rows Planting distance (inches) Plants per hill Ears per acre Increase over 2-per-hiIl rate Number Percent Number of repli- cations Narrow Grain Evergreen Checked rows 42x42 3 10686 1202t 12.67 21 4 11 784 2 300f 24.25 21 5 12 489 3 OOSt 31.68 21 40x40 3 11398 1190f 11.66 21 4 12 548 2 340J 22.92 21 5 12 929 2 721t 26.66 21 38x38 3 11869 1046f 9.66 20 4 13 094 2 ISOf 19.64 21 5 13 146 2 202f 20.12 21 36x36 3 12567 1 815f 16.88 21 4 13 867 3 115t 28.97 21 5 13 636 2 884f 26.82 21 Drilled rows 42x20 1 9032 -275 -2.95 17 42x14 1 9648 341 3.66 17 42x 8 1 11485 2 178f 23.40 17 40x20 1 10878 714 7.02 17 40x14 1 11646 1 482f 14.58 17 40 x 8 1 13196 3 032f 29.83 17 38x20 1 10368 -568 -5.19 17 38x14 1 11588 652 5.96 17 38 x 8 1 13964 3 028f 27.69 17 36x20 1 10812 90 .84 17 36x14 1 11652 930* 8.67 17 36 x 8 1 13490 2768f 25.82 17 Country Gentleman Checked rows . 42x42 3 9508 708f 8.04 21 4 10 314 1 514t 17.20 21 5 10 061 1 26lf 14.33 21 40x40 3 10346 974* 10.39 21 4 11 064 1 692f 18.05 21 5 11 016 1 644f 17.54 21 38x38 3 10737 628 6.21 21 4 10 952 843 8.34 21 5 10 816 707 6.99 21 36x36 3 10570 688 6.96 21 4 11 049 1 167* 11.81 21 5 10 641 759 7.6 21 Drilled rows 42x20 8308 56 .68 17 42x14 9172 920* 11.15 17 42 x 8 10169 1 917t 23.23 17 40x20 9824 227 2.36 17 40x14 10734 1 137f 11.85 17 40x 8 11824 2 227f 23.20 17 38x20 9779 -308 -3.05 17 38x14 10878 791 7.84 17 38 x 8 11817 1 730f 17.15 17 36x20 10072 121 1.22 17 36x14 10820 869t 8.73 17 36x 8 11584 1 633f 16.41 17 Significant difference, P equals .05. fHighly significant difference, P less than .05. 60 BULLETIN No. 487 [May, TABLE 8. NUMBER OF SORTED UNHUSKED EARS: EFFECT OF REDUCING DISTANCE BETWEEN HILLS IN CHECKED Rows AND REDUCING DISTANCE BETWEEN Rows IN DRILLED Rows Planting distance (inches) Plants per hill Ears per Increase over 42* spacing Number Percent Number of repli- cations Narrow Grain Evergreen Checked rows 40x40 2 10208 724f 7.63 21 38x38 2 10944 1460f 15.39 21 36x36.. 2 10752 1268* 13.37 21 40x40 3 " 11398 712 6.66 21 38x38 3 11869 1306t 12.36 20 36x36 3 12567 1881f 17.60 21 40x40 4 12548 764* 6.48 21 38x38 4 13094 1310* 11.12 21 36x3o 4 13867 2 083f 17.68 40x40 5 12929 440 3.52 21 38 x 38 5 13 146 657 5 . 26 21 36x36 5 13636 1147 9.18 21 Drilled rows 40x20 1 10878 1846t 20.44 17 38x20 1 10368 1336t 14.79 17 36x20 1 10812 1 78Ot 19.71 17 40x14 11646 1 998t 20.71 17 38x14 11588 1 940t 20.11 17 36x14 11652 2 004f 20.77 17 40x 8 13196 1 711t 14.90 17 38 x 8 13964 2 479f 21.58 17 36 x 8 13490 2005* 17.49 17 Country Gentleman Checked rows 40x40 2 9372 572 6.50 21 38x38 2 10109 1309 14.88 21 36x36 2 9882 1082 12.30 21 40x40 .3 10346 838 8.81 21 38x38 3 10737 I229t 12.92 21 36x36 3 10570 1062 11.17 21 40x40 . 4 11064 750 7.27 21 38x38 4 10952 638 6.18 21 36x36 4 11049 735 7.13 21 40x40 . 5 11016 955* 9.49 21 38x38 5 10816 755 7.50 21 36x36 5 10641 580 5.76 21 Drilled rows 40x20 1 9824 1 516t 18.25 17 38x20 1 9779 1471t 17.70 17 36x20 1 10072 1764f 21.23 17 40x14 1 10734 1 562f 17.03 17 38x14 1 10878 1706f 18.60 17 36x14 1 10820 1 648f 17.97 17 40 x 8... 1 11 824 1 655f 16.27 17 38 x 8 1 11817 1 648f 16.21 17 36 x 8 1 11 584 1 415 13.91 17 Significant difference, P equals .05. tHighly significant difference. P less than .05. 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 61 TABLE 9 WEIGHT PER PRIME HUSKED EAR: EFFECT OF INCREASING NUMBER OF PLANTS PER HILL IN CHECKED Rows AND REDUCING DISTANCE BETWEEN PLANTS IN DRILLED Rows Plants Planting distance (inches) per hill Pounds Increase over 2-per-hill rate Number ear Pounds Percent cations Narrow Grain Evergreen Checked rows 42 x 42 . 3 .49 .46 .45 .49 .46 .43 .47 .44 .41 .47 .43 .40 .51 .49 .44 .51 .50 .43 .50 .50 .42 .50 .49 .42 -.01 -.04 -.05 -.01 -.04 -.07 -.01 -.04 -.07 -.02 -.06 -.09 -.02 -.07 -.01 -.08 .01 .01 -.07 -.01 -.02 -.09 -2.00 -8.00 -10.00 -2.00 -8.00 -14.00 -2.08 -8.33 -14.58 -4.08 -12.24 -18.37 -3.92 -13.72 -1.96 -15.69 2.04 2.04 -14.29 -1.96 -3.92 -17.65 21 21 21 21 21 21 21 21 21 21 21 21 17 17 17 17 17 17 17 17 17 16 16 16 40 x 40 . 4 5 3 38 x 38 4 5 . 3 36 x 36 4 5 . 3 Drilled rows 42 20 4 5 1 42 14 1 42 8 1 40 20 1 40 14 1 40x 8 1 38 x 20 1 38 x 14 1 38 x 8 1 36 x 20 ... 1 36 x 14 1 36 x 8 1 Country Gentleman Checked rows 42 x 42 . 3 .42 .40 .38 .42 .40 .39 .41 .38 .36 .42 .38 .33 .45 .43 .38 .45 .45 .38 .45 .44 .38 .46 .44 .37 -.02 -.04 -.06 -.02 -.03 -.02 -.05 -.07 -.01 -.05 -.10 -.01 -.03 -.08 .02 .02 -.05 .01 -.06 .01 -.01 -.08 -4.54 -9.09 -13.64 -4.76 -7.14 -4.65 -11.63 -16.28 -2.33 -11.63 -23.26 -2.17 -6.52 -17.39 -4.65 -4.65 -11.63 2.27 -13.64 2.22 2.22 -17.78 20 20 20 21 21 21 21 21 21 21 21 21 17 17 17 17 17 17 17 17 17 16 16 16 40 x 40 4 5 . 3 38 x 38 4 5 . 3 36 x 36 4 5 . 3 Drilled rows 42 x 20 4 5 1 42 x 14 1 42 x 8 1 40 x 20. . . 1 40 x 14 1 40 x 8 1 38 x 20 ... 1 38 x 14 1 38 x 8 1 36 x 20 ... 1 36 x 14. . 1 36 x 8. . 1 62 BULLETIN No. 487 [May, TABLE 10. WEIGHT PER PRIME HUSKED EAR: EFFECT OF REDUCING DISTANCE BETWEEN HILLS IN CHECKED Rows AND REDUCING DISTANCE BETWEEN Rows IN DRILLED Rows Planting distance (inches) Plants per hill Pounds per ear Increase over 42" spacing Pounds Percent Number of repli- cations Narrow Grain Evergreen Checked rows 40x40 2 .50 21 38x38 2 .48 -.02 -4.00 21 36x36 2 .49 -.01 -2.00 21 40x40 3 .49 21 38x38 3 .47 -.02 -4.08 21 36x36 3 .47 -.02 -4.08 21 40x40 4 .46 21 38x38 4 .44 -.02 -4.35 21 36x36 4 .43 -.03 -6.52 21 40x40 5 .43 -.02 -4.44 21 38x38 5 .41 -.04 -8.88 21 36x36 5 .40 -.05 -11.11 21 Drilled rows 40x20 1 .51 17 38x20 1 .50 -.01 -1.96 17 36x20 1 .50 -.01 -1.96 16 40x14 1 .50 .01 2.04 17 38x14 .50 .01 2.04 17 36x14 .49 16 40 x 8 .43 -.01 -2.27 17 38 x 8 .42 -.02 -4.54 17 36 x 8 .42 -.02 -4.54 16 Country Gentleman Checked rows 40x40 2 .42 -.02 -4.54 21 38x38 2 .43 -.01 -2.27 21 36x36 2 .43 .01 -2.27 21 40x40 .3 .42 21 38x38 3 .41 -.01 -2.38 21 36x36 3 .42 40x40.. .4 .40 -.03 -6.98 21 38x38 4 .38 -.05 -11.63 21 36x36 4 .38 -.05 -11.63 21 40x40.. .5 .39 -.04 -9.30 21 38x38 5 .36 -.07 -16.28 21 36x36 5 .33 -.10 -23.26 21* Drilled rows 40x20 1 .45 17 38x20 1 .45 17 36x20 1 .46 .01 2.22 16b 40x14.. 1 .45 .02 4.65 17 38x14 1 .44 .01 2.33 17 36x14 1 .44 .01 2.33 16*> 40x 8. . 1 .38 17 38 x 8 1 .38 17 36 x 8 1 .37 -.01 -2.63 16>> Twenty replications for the 42* distance. b Seventeen replications for the 42* distance. 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 63 TABLE 11 RECOVERY OF PRIME HUSKED EARS: EFFECT OF INCREASING NUMBER OF PLANTS PER HILL IN CHECKED Rows AND REDUCING DISTANCE BETWEEN PLANTS IN DRILLED Rows Planting distance (inches) Plants per hill Pounds per 100 pounds of sorted unhusked ears Increase over 2-per-hill rate Pounds Percent Number of repli- cations Narrow Grain Evergreen Checked rows 42x42 3 59.47 .21 .35 . 21 4 59.53 .27 .46 21 5 59.70 .44 .74 21 40x40... 3 60.73 1.86 3.16 21 4 59.86 .99 1.68 21 5 60.06 1.19 2.02 21 38x38.. .3 61.12 1.41 2.36 20 4 60.00 .14 .23 21 5 58.99 -.87 -1.45 21 36x36.. .3 58.55 -1.05 -1.76 21 4 58.89 -.71 -1.19 21 5 57.76 -1.84 -3.09 21 Drilled rows 42x20 6183 2.20 3.69 17 42x14 59.82 .19 .32 17 42x 8 58.79 -.84 -1.41 17 40x20 59.89 1.06 1.80 17 40x14 60.50 1.67 2.84 17 40x 8 57.89 -.94 -1.60 17 38x20.. 1 60.17 .66 1.11 17 38x14 1 59.75 .24 .40 17 38 x 8 1 58.92 -.59 -.99 17 36x20 1 58.85 -1.28 -2.13 16 36x14 1 58.48 -1.65 -2.74 16 36 x 8 1 56.53 -3.60f -5.99 16 Country Gentleman Checked rows 42x42 3 61.14 1.79 3.02 20 4 58.49 -.83 -1.40 19 5 60.82 -.91 -1.47 19 40x40.. . 3 58.40 1.85 3.27 21 4 58.90 2.35 4.16 21 5 57.23 .68 1.20 21 38x38.. .3 56.61 -1.75 -3.00 21 4 56.15 -2.21 -3.79 21 5 55.84 -2.52 -4.32 21 36x36.. .3 59.33 -4.23f -6.66 21 4 57.59 -5.97f -9.39 21 5 55.23 -8.33f -13.11 21 Drilled rows 42x20 1 60.96 1.53 2.57 16 42 14 1 61.44 2.01 3.38 16 42 8 1 59.04 -.39 -.66 16 40 20 1 60.39 5.13f 9.28 17 40 14 1 61.24 5.98* 10.82 17 40 8 1 56.30 1.04 1.88 17 38 20.. 1 57.05 -1.15 -1.98 17 38 14 1 58.18 -.02 -.03 17 38x 8 1 57.30 -.90 -1.55 17 36x20 1 59.21 -5.12 -7.96 16 36x14 1 61.13 -3.20 -4.97 16 36 x 8 1 59.98 -4.52 -7.01 17 Significant difference, P equals .05. fHighly significant difference, P less than .05. 64 BULLETIN No. 487 [May, TABLE 12. RECOVERY OF PRIME HUSKED EARS: EFFECT OF REDUCING DISTANCE BETWEEN HILLS IN CHECKED Rows AND REDUCING DISTANCE BETWEEN Rows IN DRILLED Rows Planting distance (inches) Plants per hill Pounds per 100 pounds of sorted unhuskedears Increase over 42* spacing Pounds Percent Number of repli- cations Narrow Grain Evergreen Checked rows 40x40 2 58.87 -.39 -.66 21 38x38 2 59.86 .60 1.01 21 36x36 2 59.59 .33 .56 21 40x40... . 3 60.73 1.25 2.10 21 38x38 3 61.12 1.74 2.93 20 36x36 3 58.55 -.93 -1.56 21 40x40.. 4 59.86 .33 .55 21 38x38 4 60.00 .47 .79 21 36x36 4 58.89 -.64 -1.08 21 40x40 5 60.07 .36 .60 21 38x38 5 58.99 -.72 -1.21 21 36x36 5 57.76 -1.95 -3.27 21 Drilled rows 40x20 1 59.89 -1.94 -3.14 17 38x20 1 60.17 -1.66 -2.68 17 36x20 1 58.84 -2.78 -4.51 16 40x14.. 60.51 .69 1.15 17 38x14 59.76 -.06 -.10 17 36x14 58.48 -1.06 -1.78 16 40x 8.. 57.89 -.90 -1.53 17 38 x 8 58.92 .13 .22 17 36 x 8 1 56.53 -1.79 -3.07 16 Country Gentleman Checked rows 40x40 2 56.85 -2.50 -4.21 20 38x38 2 59.66 .31 .52 20 36x36 2 62.56 3.21 5.41 20 40x40.. . 3 59.59 -1.55 -2.54 20 38x38 3 57.46 -3.68f -6.02 20 36x36 3 60.66 -.48 -.78 20 40x40... .4 59.35 2.20 3.85 20 38x38 4 56.48 -.67f -1.17 20 36x36 4 58.30 1.15 2.01 20 40x40 5 57.87 -1.82 -3.05 20 38x38 5 56.92 -2.77t -4.64 20 36x36 5 56.70 -2.99t -5.01 20 Drilled rows 40x20 60.39 1.08 1.82 17 38x20 57.04 -2.27 -3.83 17 36x20 59.21 .54 .92 16 40x14 61.25 1.12 1.86 17 38x14 58.17 -1.96 -3.26 17 36x14 61.13 1.56 2.62 16 40x 8 56.30 -1.98 -3.40 17 38x 8 57.29 -.99 -1.70 17 36 x 8 59.98 1.70 2.92 17 tHighly significant difference, P less than .05. PLANTING RATES AND DISTANCES FOR SWEET CORN 65 TABLE 13. WEIGHT OF GREEN FODDER: EFFECT OF INCREASING NUMBER OF PLANTS PER HILL IN CHECKED Rows AND REDUCING DISTANCE BETWEEN PLANTS IN DRILLED Rows Planting distance (inches) Plants per hill Pounds per acre Increase over 2-per-hill rate Pounds Percent Number of repli- cations Narrow Grain Evergreen Checked rows 42x42 3 13868 144 1.05 4 13 883 159 1.16 5 14 910 1 186f 8.64 40x40 . ... 3 14852 -227 -1.51 4 15 726 647 4.29 5 15 714 635 4.21 38x38 . 3 14 419 -6 -.04 4 15 373 682 4.64 5 16 492 1 801t 12.26 36x36.. .3 15475 1453* 10.36 4 15 677 1 655f 11.81 5 16 591 2 569t 18.33 Drilled rows 42x20 1 14032 -269 -1.88 42x14 1 14061 -240 -1.68 42 x 8 1 15723 1422f 9.95 40x20 1 16 489 900 5.77 40x14 1 16993 1404 9.01 40x 8 1 17808 2 219f 14.24 38x20.. 1 17361 1 975f 12.84 38x14 1 17365 1 979f 12.86 38 x 8 1 18329 2 943f 19.13 36x20. . 1 15 614 882 5.99 36x14 1 15439 707 4.80 36 x 8 1 15924 1192 8.09 Country Gentleman Checked rows 42x42 3 11695 -95 -.81 4 12 310 520 4.41 5 12 665 875 7.42 40x40. . .3 13 658 763 5.92 4 14 414 1 519f 11.78 5 14 336 1 441f 11.18 38 x 38 . .3 13 284 940 7.61 4 13 219 875t 7.08 5 13 981 1 637f 13.26 36x36. . .3 12 339 747* 6.44 4 12 698 1 106t 9.54 5 13 861 2 269f 19.58 Drilled rows 42x20 1 12409 197 1.61 42x14 1 12291 79 .65 42 x 8 1 13999 1787f 14.64 40x20.. 1 15405 2 200f 16.66 40x14 1 15076 1871* 14.17 40 x 8 1 15434 2 229t 16.88 38x20. . 1 14 421 1 268 9.64 38x14 1 15670 2 517t 19.14 38 x 8 1 16471 3 318t 25.22 36x20 1 13462 1360f 11.24 36x14 1 13867 1766t 14.59 36 x 8 1 15210 2 885t 23.41 17 17 17 17 17 17 16 17 17 17 17 17 13 13 13 13 13 13 13 13 13 12 12 12 17 17 17 17 17 17 17 17 17 17 17 17 13 13 13 13 13 13 13 13 13 12 12 13 Significant difference, P equals .05. fHighly significant difference, P less than .05. 66 BULLETIN No. 487 [May, TABLE 14. WEIGHT OF GREEN FODDER: EFFECT OF REDUCING DIS- TANCE BETWEEN HILLS IN CHECKED Rows AND REDUCING DISTANCE BETWEEN Rows IN DRILLED Rows Planting distance (inches) Plants per hill Pounds per acre Increase over 42" spacing Pounds Percent Number of repli- cations Narrow Grain Evergreen Checked rows 40x40 2 15079 1355f 9.87 17 38x38 2 14691 967 7.05 17 36x36 2 14022 298 2.17 17 40x40 .3 14852 984 7.10 17 38x38 3 14419 539 3.88 16 36x36 3 15474 1606 11.58 17 40x40 4 15726 1 843t 13.28 17 38x38 4 15373 1490f 10.73 17 36x36 4 15677 1794* 12.92 17 40x40.. .5 15715 805* 5.40 17 38x38 5 16492 1582f 10.61 17 36x36 5 16591 1681* 11.27 17 Drilled rows 40x20 1 16489 2 457f 17.51 13 38x20 1 17361 3 329t 23.72 13 36x20 1 15615 1628 16.39 12 40x14 1 16994 2 933f 20.86 13 38x14 1 17365 3 304J 23.50 13 36x14 1 15439 1591* 11.49 12 40 x 8 ... 1 17808 2 085f 13.26 13 38 x 8 1 18329 2 606f 16.57 13 36 x 8 1 15924 335 2.15 12 Country Gentleman Checked rows 40x40 2 12894 1104 9.36 17 38x38 2 12344 554 4.70 17 36x36 2 11591 -199 -1.69 17 40x40 .3 13658 1 963f 16.78 17 38x38 3 13284 1589* 13.59 17 36x36 3 12338 643 5.50 17 40x40 4 14415 2104f 17.09 17 38x38 4 13218 908 7.37 17 36x36 4 12698 387 3.14 17 40x40.., . 5 14336 1 671f 13.19 17 38x38 5 13981 1316* 10.39 17 36x36 5 13862 1197* 9.45 17 Drilled rows 40x20 1 15405 2 997t 24.15 13 38x20 1 14420 2 012f 16.22 13 36x20 1 13462 1086* 8.78 12 40x14 1 15077 2 785t 22.65 13 38x14 1 15670 3 378f 27.48 13 36x14 1 13868 1776f 14.69 12 40 x 8.. 1 15 434 1 435* 10.25 13 38 x 8 1 16471 2 472f 17.66 13 36 x 8 '. 1 15210 1 211t 8.65 13 'Significant difference, P equals .05. fHighly significant difference, P less than .05. 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 67 EXPERIMENTAL RESULTS, DRILLED PLANTINGS The discussion of the results from the drilled-row plantings is given separately in order to avoid confusion. Growing sweet corn in drilled rows is usually limited to the early market types raised by truck growers, practically no canning corn being grown by this method in Illinois. From the standpoint of culture of the crop, however, there is no real reason why canning corn should not be so grown, as recent improvements in cultivating tools should enable the grower to keep drilled rows relatively free from weeds without hand hoeing. Large acreages of silage corn are grown in drilled rows without the weed problem proving to be unduly serious. The question of the comparative value of drilled-row and checked- row plantings has never been satisfactorily answered so far as sweet corn is concerned. Planting in drilled rows gives a much evener dis- tribution of plants over a given area, and therefore, theoretically at least, there is much less competition between the plants than in checked rows, where several plants are crowded together in a hill. Weights of Sorted Unhusked Ears Distance Between Plants in Row. The drilled plantings of Narrow Grain Evergreen (Table 3 and Fig. 4) tended to yield greater weights of sorted unhusked ears than the respective checked rows having 2 plants per hill, some of the differences being significant. Two plantings seemed to give outstanding results, 40"x 14" and 38"x 8" ; but as the total yields of the two were almost the same, the thinner planting, 40"x 14", is to be recommended. The total yield of the 40"x 14" plant- ing (8,034 pounds) was nearly the same as that of the best of the recommended checked-row plantings. Of the Country Gentleman drilled-row plantings only two yielded significantly heavier weights of sorted unhusked ears than the cor- responding checked rows having 2 plants per hill. Of these two drilled plantings the 40"x 14" was considerably superior. The mean total yield of this planting, 6,536 pounds of sorted unhusked ears per acre, was as high as that of the best checked-row plot. Distance Between Rows. Nearly all the drilled plantings at dis- tances narrower than 42 inches showed significant yield increases over those at the 42-inch distance, an indication that closer planting is essen- tial for the heaviest yields of sorted unhusked ears from drilled rows (Table 4 and Fig. 5). For the Narrow Grain Evergreen variety the 40-inch distance seemed to be most nearly the optimum, the 40"x 14" planting predominating. The trend in Country Gentleman was similar, but there was little choice between the 36"x 20", 40"x 14", and 36"x 14" plantings. Since, however, the widest rows are the easiest to cultivate, 68 BULLETIN No. 487 [May, 40"x 14" is the preferable drilled planting for Country Gentleman. Average yields from the drilled plots were not substantially different from those of the checked plots. Weights of Prime Husked Ears Distance Between Plants in Row. In weight of prime husked ears the 40"x 14" drilled-row planting gave the largest significant increase over the 2-per-hill checked-row planting at the corresponding distance (Table 5 and Fig. 6). This was true of both Narrow Grain Evergreen and Country Gentleman. The better drilled plantings returned about the same mean total yields of prime husked ears as the corresponding checked-row plots. Distance Between Rows. Significant increases in weights of prime husked ears of Narrow Grain Evergreen appeared in the 40"x 14", 40"x 20", 36"xl4", 38"x20", and 38"x 14" plantings (Table 6, Fig. 7). The 40"x 14" planting gave the largest significant increase and also the largest mean yield of prime husked ears. Similarly three plantings of Country Gentleman 36"x 20", 40"x 14", and 36"x 14" gave almost equally large significant increases in weights of prime husked ears over those of the corresponding 42-inch rows. Since, however, the 40"x 14" planting gave the highest mean yield it is probably prefer- able to either of the others. Number of Sorted Unhusked Ears Distance Between Plants. Increases in number of sorted un- husked ears produced on the drilled plots over those produced on the corresponding checked-row plots having 2 plants per hill were very large for both varieties, many of the differences being significant (Table 7 and Fig. 8). The 8-inch spacing in the row gave the highest yields, and from the standpoint of number of unhusked ears, 8 inches is the best distance between plants in the row. In the Narrow Grain Evergreen variety there is little to choose between the 40"x 8", 38"x 8", and 36"x 8" plantings. Since the 40"x 8" planting is the easiest to cultivate, it should be given preference. The 42"x 8" and 40"x 8" plantings are outstanding in the Country Gentle- man variety (Table 7), but since the 40"x 8" produces the larger mean yields, it is the one to be preferred. Distance Between Rows. In both varieties the highest total num- ber of sorted unhusked ears was obtained from rows closer than 42 inches (Table 8 and Fig. 9). However, reducing the distance between rows below 40 inches did not have a great deal of effect either on mean total yields or percentages of increase. The 8-inch plantings produced the highest mean yields of both varieties; and within that series the 38"x 8" plot produced the maximum yield of Narrow Grain 1942} PLANTING RATES AND DISTANCES FOR SWEET CORN 69 Evergreen (tho there was little to choose between the 40-, 38-, and 36-inch plantings) and the 40"x 8" plot produced the maximum yield of Country Gentleman. In general, the number of sorted unhusked ears produced on the drilled plantings was comparable to that produced on the checked-row plantings. Weight per Prime Husked Ear Weight per prime husked ear produced on the drilled plots was reduced as the distance between plants in the row was reduced (Table 9), as was true also on the checked-row plantings. It should be noted that the ears in the plantings drilled 20 inches apart in the row were just as heavy as those from the corresponding 2-per-hill checked plantings. The closest planting consistent with maximum weight per prime husked ear is 14 inches between plants. Reductions in weight per prime husked ear as the distance between rows was reduced were very slight (Table 10) for both varieties. The distance at which the plants were spaced in the row evidently had a much more important effect on weight per ear than the distance between the rows. Percent Recovery of Prime Husked Ears The effect of decreasing the distance between plants in the drilled rows was negligible so far as the recovery of prime husked ears of Narrow Grain Evergreen was concerned (Table 11) ; but for Country Gentleman the trends were rather diverse, the 40"x 20" and 40"x 14" plantings giving significant increases over the 40"x 40"x 2 checked- row planting. Apparently Country Gentleman should be planted in 42- or 40-inch rows with the plants spaced no closer than 14 inches in the row. Decreasing the distance between rows had a negligible effect upon the recovery of prime husked ears of both varieties (Table 12). Weights of Green Fodder Distance Between Plants in Row. Yields of fodder in drilled rows were about the same as in checked rows. Fodder weights of Narrow Grain Evergreen in the drilled rows (Table 13) increased as the distance between plants in the row was reduced, the 8-inch spacing yielding the most. The 38-inch series produced heavier weights of fodder than any of the three others, and within this series the 38"x 8" planting was especially high. Closer spacing between plants of the Country Gentleman variety (Table 13) tended to increase fodder yields, but there was not very much increase unless the rows were 36 or 38 inches apart. The largest mean yield of fodder was produced by the 38"x 8" planting. 70 BULLETIN No. 487 [May, Distance Between Rows. Decreasing the distance between rows had a somewhat unexpected effect upon yields of green fodder from the drilled rows (Table 14), the 38-inch distance proving to be for both varieties the narrowest planting consistent with maximum weights, except for the 40"x 20" spacing for Country Gentleman. Moreover, it should be noted that in general the superiority of the 38-inch over the 40-inch plantings was very slight, and that when the plants in the row were spaced 20 inches apart, the 40-inch rows of Country Gentle- man were better than the 38-inch rows. SOME OTHER EFFECTS OF RATE AND DISTANCE OF PLANTING In addition to the effects of rate and distance of planting sweet corn on the various yield components discussed in the foregoing sec- tions, there were certain effects on the growth habits of the plants not directly measured by the yields. Those on which records were kept were the height of the plants, the number of suckers produced, and the time at which the plants reached maturity. Height of Plants Heights of the plants on plots planted at different rates and dis- tances were carefully measured in three of the years. The yearly averages are listed in Table 15. In 1933 and 1936, when soil moisture was a limiting factor, reducing the distance between hills in the checked-row plantings below 40 inches tended to reduce the height of the plant. Such reductions were not generally observable in 1935, when the amount of soil moisture was much more nearly normal. The effect of increasing the number of plants in the hill was some- what different from that of reducing the distance between hills. Increasing the number of plants per hill had either a very slight effect on height of plant or tended to increase it certainly no tendency to reduce the height. Data on height of plants in the drilled-row plantings were kept only two years, but those are sufficient to show that when soil moisture is normal, as in 1935, reducing the distance between rows tended to increase the height of the plants. When moisture was abnormally low, as in 1936, the reverse tended to be true. Similar effects were observed when the distance between plants in the row was reduced. Number of Suckers The number of suckers per plant varied considerably from year to year, but there was a general tendency in the checked-row plantings for the suckers to increase as distance between hills was increased 1942~\ PLANTING RATES AND DISTANCES FOR SWEET CORN 71 (Table 16). This tendency, however, was relatively slight as compared with the great reduction which occurred as the number of plants per hill was increased. In drilled-row plantings the relationship was quite similar. DC- TABLE 15. AVERAGE HEIGHT" OF PLANTS: WHEN GROWN IN CHECKED Rows AND IN DRILLED Rows AT VARIOUS PLANTING RATES AND DISTANCES Height when number of plants Height when distance between Distance between rows P" hm was ~ plants in row was ~ (inches) 2 3 4 5 20 inches 14 inches 8 inches Country Gentleman, 1933 42... in. 77.9 in. 79.1 in. 81.3 in. in. 79.2 in. in. 40 79 6 80 2 82.1 814 38 73.9 75.2 72.1 75.4 36 72.3 72.6 73.7 73.4 .... Narrow Grain Evergreen, 1933 42... 83.1 85.5 86.0 87.7 40 85 2 87.1 89.9 89 4 . ... .... 38 80 6 83.0 82.0 85.0 .... 36 79.7 82.0 79.2 79 . 7 Country Gentleman, 1935 42... 89 . 8 93.4 94.9 92.8 87.3 90.8 93.0 40 90 . 3 94.1 96.7 98.7 92.0 94.7 96.7 38 88 6 94 93 6 92 5 86 9 91.6 92.4 36 91.2 94.7 97.6 96.8 89.5 92.7 95.9 Narrow Grain Evergreen, 1935 42... 98 6 103 9 106.4 107 6 96.4 100 , 101.4 40 101 4 106 7 108 8 110 104 106 109.2 38 98 101 8 102.2 105 100.9 103 7 99.3 36 102 S 105 S 106.8 108 9 101.5 104 7 107.3 Country Gentleman, 1936 42 75 6 74 8 76 5 75 72 S 72 6 70.8 40 72 8 76.0 75.5 75 2 70 S 73 7 71 .0 38... 69 6 71.6 71.4 74 ? 68 68 8 66.0 36 72 } 73 1 70 8 69 ^ 68 4 67 67.6 Narrow Grain Evergreen, 1936 42... 80 6 81. 1 80 7 80.2 79.6 78 ? 75.4 40... 77 9 83, 4 81 ? 80.0 78.6 81 77.3 38 ... 74 9 78 78 9 78 4 74 2 74 ,9 74.0 36 79 4 76, \ 76, 7 75.8 76.2 72, 8 72.7 In the checked-row plantings, 10 hills in the center of each plot were measured just before harvest from the ground to the tip of the tallest tassel. Each of the 4 replications was measured sep- arately and the average heights are therefore the means of 40 hills. In the drilled-row plantings, 10 plants instead of hills were measured as described above, the average heights therefore being means of 40 plants. 72 BULLETIN No. 487 TABLE 16. AVERAGE NUMBER OF SUCKERS PRODUCED" GROWN IN CHECKED Rows AND IN DRILLED Rows AT VARIOUS PLANTING RATES AND DISTANCES [May, : PLANTS Distance between rows Suckers when number of plants Suckers when distance between per hill was plants in row was (inche; 3) 2 345 20 inches 14 inches 8 inches Country Gentleman, 1931 42 2 .10 .30 .31 .61 1.17 .76 .78 .40 .75 .45 .96 .61 42 16 07 32 1 1, 1 1 36 75 58 58 .79 .37 .41 .83 40 1 38 1 36 ... 1 Narrow Grain Evergreen, 1931 42 1 .62 .54 .46 .52 .68 .47 .92 .41 .82 .46 .79 .50 06 25 18 14 1 1 1 ,72 ,35 .83 68 1.03 .88 1.15 1.31 40 1 38 . 1 36 1 Country Gentleman, 1932 42. .. 2 .04 .97 .34 .62 1.13 .57 1 . 29 .86 1.52 1.07 .87 .27 39 34 67 18 3 3 3 2 .09 .44 .38 ,92 2.24 2.52 2.73 2.05 1.14 1.44 1.58 1.07 40 1 38 . 2 36 ... 1 Narrow Grain Evergreen, 1932 42 . 2 .11 .95 .19 .75 1.26 .60 1.23 .85 1.44 .97 1.40 .58 44 38 69 28 2 2 3 2 .89 .89 .14 30 2 2 2 1 .12 .18 .46 56 .98 1.35 1.39 .94 40 1 38 2 36 1 Country Gentleman, 1935 42 3 .28 .28 .20 .48 2.42 .98 2 . 20 1 . 46 .96 .40 .88 .28 34 92 16 04 1 2 2 1 .90 .46 .04 ,73 1 1 1 1 .48 ,87 ,55 ,23 .74 .75 .61 .40 40 3 38 2 36 2 Narrow Grain Evergreen, 1935 42 4 .00 .12 .88 .14 2.06 1.18 1.84 1.18 1.22 .46 1.32 .80 56 60 18 20 1 2 2 1 .91 .33 .44 97 1 2 1 1 .42 .20 .57 .37 .57 .39 .46 .41 40 4 38 2 36 3 Country Gentleman, 1936 42... . 3 .29 .45 .12 .26 2.29 1.90 2.96 2.00 1. 2.54 1.58 1.29 .28 99 20 81 10 1 1 1 j .86 .91 .98 90 1 1 1 1 .12 .40 32 25 .40 .24 .45 .23 40 3 38 3 36 2 Narrow Grain Evergreen, 1936 42... 2 .95 .59 .39 .64 2.15 1.26 1.84 .99 1.26 .65 .86 .49 45 36 41 22 1 1 1 1 .52 .68 72 .72 ,70 98 15 ,82 .14 .17 .78 .15 40 2 38 ... 2 36 1 The average number of suckers per plant was obtained by counting and averaging the suckers on the two center rows of each plot. Only suckers more than 12 inches long just before harvest were counted. The means in the table are averages of 4 replications. 1942\ PLANTING RATES AND DISTANCES FOR SWEET CORN 73 creasing the distance between rows had relatively little effect on num- ber of suckers, but reducing the distance between plants in the row reduced the number of suckers very markedly. Time of Reaching Maturity Reducing the distance between hills in the checked-row plantings tended to delay maturity slightly (Table 17), altho in some years, 1935 for instance, there was scarcely any delay. On the other hand, increas- ing the number of plants in the hill delayed maturity very appreciably. The tendencies were similar in the drilled-row plantings. Reduc- ing the distances between rows had no consistent effect on time of maturity, but reducing the spacing in the row tended to delay maturity. GENERAL DISCUSSION OF RESULTS None of the experimental work on spacing of sweet corn pre- viously reported was sufficiently extensive to determine the effect of varying both number of plants in the hill and distance between hills on the several yield components in sweet corn. With few exceptions, drill plantings were almost entirely ignored. In the subsequent discus- sion the complex relationships which exist will be explained so far as the data permit. The most recent work reported was that by Watson 10 * and Watson and Davis, 11 * in Puerto Rico, wherein it was shown that close spacing increased the yields of both ears and forage in what would be con- sidered drilled-row planting, as the plants were thinned to one per place. But tho close spacing increased the number of ears, it reduced the weight per ear, and it also reduced the stalk diameter. The authors concluded that the optimum area per plant is 3 square feet. Haber, 4 * from an extensive experiment at the Iowa Station with Country Gentleman and Stowell's Evergreen sweet corn, where the number of stalks per hill varied from 2 to 7, all planted 42"x 42", made the following observations on the effect of increasing the number of stalks per hill: (1) weight per ear declines; (2) number of ears per stalk declines; (3) yields increase up to the rate of 4 stalks per hill ; and (4) weight of fodder increases. Haber also ran a single experiment using Stowell's Evergreen planted in drilled rows 42 inches apart with single plants 12 inches apart in the row. He concluded that the checked-row method was far superior to the drilled row. Eisele, 2 * working with field corn at the same station, found that higher rates per hill increased the total number of ears produced per unit of area, but that the ratio of nubbins also increased markedly. Magruder, 7 * in experiments at Wooster and Marietta, Ohio, with Early Adams, a small variety of an early flint type sold as sweet corn, 74 BULLETIN No. 487 [May, TABLE 17. DAYS REQUIRED FOR MATURITY: PLANTS GROWN IN CHECKED Rows AND IN DRILLED Rows AT VARIOUS PLANTING RATES AND DISTANCES (Figures indicate number of days between planting and date when 75 percent of the total silks had appeared 8 ) When number of plants When distance between Distance between rows *** hil1 was ~ P lants in row was ~ < inches > 2 4 , 20 14 8 inches inches inches Country Gentleman, 1932 42... . 62 63 64 66 64 64 67 40 62 63 64 66 63 63 65 38 63 64 65 66 63 63 66 36 63 64 66 68 63 64 67 Narrow Grain Evergreen, 1932 42... .62 63 64 65 63 64 67 40 63 64 64 66 64 65 67 38 63 63 65 64 63 64 66 36 64 64 66 68 64 64 67 Country Gentleman, 1933 42... . 61 63 64 66 40 62 64 65 68 38 63 63 66 67 36 64 65 66 67 Narrow Grain Evergreen, 1933 42... .63 64 65 66 40 .' 64 66 66 68 38 64 63 65 67 36 64 65 66 68 Country Gentleman, 1935 42... .61 62 63 64 62 63 65 40 61 62 62 64 63 61 60 38 61 62 64 65 61 62 65 36 60 61 63 67 63 60 59 Narrow Grain Evergreen, 1935 42 .60 61 63 63 64 62 61 40 61 62 63 63 62 61 61 38 60 62 64 67 64 61 61 6 60 61 63 66 62 60 60 Country Gentleman, 1936 42... 71 71 72 73 72 72 74 40 71 71 72 72 72 72 73 38 72 72 74 74 72 72 74 36 72 73 74 75 72 72 74 Narrow Grain Evergreen, 1936 42... 71 72 73 74 71 72 73 40 71 72 72 74 71 71 73 38 72 72 74 74 72 72 74 36 72 73 74 76 72 73 75 The number of days given in each case is the average of 4 replications. The two center rows of each plot were counted. This is equivalent to half the total plot. 194Z} PLANTING RATES AND DISTANCES FOR SWEET CORN 75 and with Stowell's Evergreen, was unable to reach any definite con- clusions. He stated that proper distance of planting depends upon such factors as size of plant, soil fertility, supply of moisture, and purpose 'for which the crop is grown. No experimental evidence was presented to show the relationship between these factors. The author in 1930 and 1931 carried on a series of preliminary tests at Urbana (page 37) which formed the basis from which to estimate the probable optima in rates and distances, and the layout for the main test during the following five years. For Country Gentle- man the highest yields of unhusked ears in 1930 were obtained, with only one exception, from plantings at the rate of 2 kernels per hill at each distance of planting. The most favorable distance seemed to be 42"x 38". Yields from most of the drilled-row plantings were ex- tremely low, indicating that drilled rows may not be so well adapted to dry seasons as checked rows. In 1931 the optimum rate of planting Country Gentleman was 3 kernels per hill at all distances except one ; and the yields from the drilled plantings were again much below those of the more productive checked plots. Differences in moisture dur- ing the two seasons probably accounted for the fact that 2 kernels per hill gave best yields in 1930 but 3 per hill gave best results in 1931. The behavior of Narrow Grain Evergreen, included in 1931, was considerably different from that of Country Gentleman, for Narrow Grain Evergreen did not seem to be very selective, the optimum rates at each distance being 3, 4, or 5 plants per hill but never 1 or 2. In general, the highest yields of Narrow Grain Evergreen were obtained from the 42-inch spacings and 3, 4, or 5 plants per hill. In drilled rows Narrow Grain Evergreen did better than Country Gentleman. The optimum drilled plantings were nearly all confined to the rows 42 inches apart, 42"x 8" giving the best yield of husked ears. Space Occupied by Each Plant as a Criterion The trends shown in the analysis of experimental results in the foregoing sections are rather diverse and sometimes contradictory. It is this apparent confusion, however, which indicates that the rela- tionships existing in these experiments are quite complex and further- more that the yield of one component may not be used as an index to the yield of another component under the same conditions. Before proceeding to discuss this matter further, the data need to be examined on the basis of differences due to a single factor, space occupied per plant. Where corn plants stand alone, as in drilled rows, there is no question concerning the actual area occupied by each, but in hill plant- ings the actual area for each must be assumed. For instance, the area occupied by one hill 42"x 42" is 1,764 square inches. In a 1-per-hill 76 CHECKED J 'S '?S 500 600 SQUARE INCHES PER PLANT FIG. 10. POUNDS OF SORTED UNHUSKED AND PRIME HUSKED EARS AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932-1936 AVERAGES) planting this would also be the area occupied by the plant. But the question is whether in the plots having 2, 3, 4, and 5 plants per hill the area occupied may be assumed to be respectively 1764 1764 1764 . 1764 - ' and - square inches. There is a question also whether checked-row plantings, in which the plants are grouped in hills, may not give better mutual protection than drilled plantings, where the plants stand singly. The frequency distributions and the freehand curves which have been plotted indicate that the assumption as to space occupied per plant in checked plantings is justified, as the curves for total weights of ears (Figs. 10, 21, 22, and 23) tended to follow a normal distribu- tion. Moreover since the yields of the drilled plantings did not differ consistently from the yields of the checked plantings, it is clear that there was no better mutual protection in one type of planting than in the other. PLANTING RATES AND DISTANCES FOR SWEET CORN ACTUAL PLANTING RATE 77 CHECKED 8 000 IT 4OO 500 600 700 SQUARE INCHES PER PLANT FIG. 11. NUMBER OF SORTED UNHUSKED EARS AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932-1936 AVERAGES) ACTUAL PLANTING RATE j j ; V 'o '4 500 COO SQUARE INCHES PER PLANT FIG. 12. NUMBER OF PRIME HUSKED EARS AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932-1936 AVERAGES) 78 V BULLETIN No. 487 ACTUAL PLANTING RATE j j ; ; s s i ; [May, 500 600 SQUARE INCHES PER PLANT FIG. 13. WEIGHT PER PRIME HUSKED EAR AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932-1936 AVERAGES) The data from the preliminary experiments of 1930 and 1931 lend themselves particularly well to an analysis based on space occupied per plant because there were 10 different checked-row spacings with rates varying from 1 to 5 plants per hill, a total of 50 variations. In the drilled-row plantings there were 4 different widths between rows and 10 spacings in the row, a total of 40 variations. The data from the preliminary experiments are plotted in Figs. 21 to 32 and those from the 1932-1936 experiments in Figs. 10 to 20. The yields have not been corrected in any way, and freehand curves are interpolated in order to indicate the trends more clearly. In some instances where the trends are sufficiently clear or where no trends exist, the freehand curves have been omitted. The unhusked and husked weights (Figs. 10 and 21 to 26) tend to follow a normal or a skewed frequency distribution. The principal differences are with respect to the varietal tolerances. The modes of the freehand curves show that Country Gentleman required more space per plant than Narrow Grain Evergreen. Unhusked and husked weights within each variety do not necessarily follow the same trends. In the experiments of Watson 10 * and Haber 4 * there was a close relationship between space occupied per plant and number of unhusked ears. In the present experiments also the number of sorted unhusked ears declined as the space per plant was increased, both in the checked and in the drilled plots (Fig. 11). The respective freehand curves are 7942] PLANTING RATES AND DISTANCES FOR SWEET CORN 79 almost parallel, as are also the plotted curves, where the irregularities are practically the same. The fact that these irregularities are virtu- ally parallel suggests that while space per plant exerted a general effect on number of unhusked ears, some other factor had a partially inde- pendent effect. In the checked-row plantings this factor seems to have been number of plants per hill and in the drilled-row plantings, distance between rows. The number of prime husked ears (Fig. 12) also declined as space per plant was increased, Narrow Grain Evergreen being affected much more strongly in this respect than Country Gentleman. The plotted curves, however, do not show the parallelism which occurred with respect to number of unhusked ears. The marked differences between the curves for weights and for numbers of prime husked ears (Figs. 10 and 12) indicate that weight per ear increased as space per plant increased (Fig. 13). In the experiments of Watson 10 * and Haber 4 * the weights of green ACTUAL PLANTING RATE "17000 500 600 SQUARE INCHES PER PLANT FIG. 14. YIELD OF GREEN FODDER AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932-1936 AVERAGES) 80 BULLETIN No. 487 [May, fodder produced, which is a direct measure of plant growth, increased as the spacings of the plants became narrower. According to the freehand curves in Figs. 14, 29, and 30, this would seem to have been true in these experiments also, but at the same time the extra- ordinarily wide fluctuations in the plotted curves indicate that some other factor, which could hardly have been soil variation alone, was exerting a strong influence. In the checked- row plantings, (Fig. 14), this factor was the 40-inch distance between the rows, a distance which seems to be especially favorable to high yields of green fodder. The curve for Narrow Grain Evergreen has three distinct modes, each of which coincides with a 40"x 40" planting. Similarly, that for Country Gentleman has four modes, each of which also coincides with the 40"x 40" planting. The curves for the drilled-row plantings also are trimodal, the modes coinciding with the 38-inch rows except in the case of the 40"x 20" planting of Country Gentleman, which was more favorable than the 38"x 20" planting. The wide fluctuations in the fodder yields of the preliminary experiments (Figs. 29 and 30) can probably be explained on somewhat the same basis, altho the data are insufficient for many conclusions to be drawn, being the results of a single year (1931) without replica- tions. However, there is evidence that altho space occupied per plant '. b V, ACTUAL PLANTING RATE ; *; ; V ' ' 'o ' 500 600 SQUARE INCHES PER PLANT FIG. 15. AVERAGE PLANT HEIGHT AS AFFECTED BY SPACE OCCUPIED PER PLANT (AVERAGES OF 1933, 1935, AND 1936 FOR CHECKED ROWS AND OF 1935 AND 1936 FOR DRILLED ROWS) 1942~\ PLANTING RATES AND DISTANCES FOR SWEET CORN ACTUAL PLANTING RATE c u LJ tr * u 5OO 000 SQUARE INCHES PER PLANT FIG. 16. POUNDS OF UNHUSKED CULLS AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932-1936 AVERAGES) 81 is the primary factor determining total fodder yields, other factors may in individual instances greatly modify the general trend. Another measure of plant growth besides yield of fodder is the average height per plant, plotted in Fig. 15. When the points showing the actual results are connected, the resulting curves also tend to be multi-modal, and the modes are associated with the 40-inch planting distance. ACTUAL PLANTING RATE 500 600 SQUARE INCHES PER PLANT FIG. 17. POUNDS OF HUSKED CULLS AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932-1936 AVERAGES) 82 V, 'a b IM BULLETIN No. 487 ACTUAL PLANTING RATE j V ; 3 ' % 'H [May, PERCENT RECOVERY (SORTED UNHUSKED EARS\- 100 500 600 SQUARE INCHES PER PLANT FIG. 18. PERCENT RECOVERY OF PRIME HUSKED EARS AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932-1936 AVERAGES) According to these data on green- fodder weights and average height per plant, plant growth is partly dissociated from space occupied per plant. Space occupied per plant, in other words, is not the only factor which determines growth. A comparison of Figs. 10, 14, 22, and 23 with 29 and Figs. 25 and 26 with 30 shows that the relation between fodder weights and weights of unhusked and husked ears is not particularly close. However, it is also evident that while the freehand curves in Figs. 10, 22, 23, 25, and 26 suggest a relationship between space per plant and yield of un- husked and of husked ears, nevertheless the irregularities of the plotted curves, which are quite similar for the corresponding weights and treatments of the respective varieties, indicate the existence of optimum distances and rates, as did also the data on green fodder. The percentages of prime husked ears calculated from the formula total weight prime husked ears total weight sorted unhusked ears X 100 are plotted in Figs. 18, 31, and 32. These percentages are important as a measure of waste in the form of husks. The curves are exceed- ingly irregular, but there seems to have been a slight tendency for recovery to decrease when the plantings were either extremely close or far apart, with the exception of the drilled plantings of 1931 (Fig. 32). Mean weight per prime husked ear does not seem to have been closely associated with percentage of recovery (Figs. 18, 27, and 28). Mean number of suckers per plant was associated closely with 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 83 ACTUAL PLANTING RATE 400 500 600 700 SQUARE INCHES PER PLANT FIG. 19. NUMBER OF SUCKERS PER PLANT AS AFFECTED BY SPACE OCCUPIED PER PLANT (1932, 1935, AND 1936 AVERAGES) space occupied per plant (Fig. 19). Number of suckers per plant bore no close relation to total weight of green fodder, according to Fig. 14. Relations between space occupied per plant and number of days to the midsilking period, a measure of maturity discussed by Huelsen and Michaels, 5 * are shown in Fig. 20. There is a very noticeable tendency for later maturity to be associated with the closer plantings. The responses of the various yield components to the amount of space occupied by the sweet-corn plants are thus seen to have been exceedingly variable. Increasing or decreasing the area per plant may cause corresponding increases or reductions in certain yield com- ponents, but the effect on other yield components may be quite differ- ent. There is also evidence that certain yield components are asso- ciated with certain optimum distances between rows, number of plants per hill, or spacing in the row in drilled plantings, irrespective, within limits, of the area occupied by the plant. Furthermore the two varieties used in these experiments sometimes responded similarly and sometimes differently, leading to the conclusion that reaction to spacing is a matter of varietal character and that generalization is not permissible. Optimum Planting Rates and Distances The discussion based on Tables 3 to 8 and the curves in Figs. 4 to 9 has brought out the fact that the conditions which lead to the optimum production of one yield component are not necessarily the same as those which lead to optimum production of another yield component. This was especially noticeable with respect to number and weight of unhusked and of husked ears. 84 BULLETIN No. 487 [May, ACTUAL PLANTING RATE DRILLED > lo ^t Xiio o en ; ; ; g o o * o 'N ' o Vi '? 5f S f 9 o A bo ru o Xi NUMBER OF DAYS FROM PLANTING TO MIDSILK Ol Ol Ol Ol Ol Ol -A u- 01 -J oo ID < \ NCE CHECKED CC CHECKED NGE DRILLED CC DRILLED \ iS J 1 AYS INC FROM TO M ) 1 il 1 u p \ PLANT DSILf \ \ \ V 1 $v ^ \ \ /; V )/ \ \ / X \ 200 300 4OO 6(50 600 700 800 900 SQUARE INCHES PER PLANT FIG. 20. NUMBER OF DAYS FROM PLANTING TO MIDSILK AS AFFECTED BY SPACE OCCUPIED PER PLANT (AVERAGES OF 1932, 1933, 1935, AND 1936 FOR CHECKED Rows AND OF 1932, 1935, AND 1936 FOR DRILLED Rows) Checked-Row Plantings. The conclusions based upon the checked- row plots are summarized in Table 18. The consistent performance of Country Gentleman at the 40"x 40" spacing is very striking, this spacing unquestionably being the optimum planting distance no matter what yield component is considered the most important. The optimum rate of plants per hill, however, varies between 3 and 4. From the standpoint of weights of unhusked and of husked ears the 3-per-hill rate is superior to the 4, but if number of ears is the important factor, the 4-per-hill rate is preferable. These observations are confirmed by the conclusions regarding weight per prime husked ear and percentage of recovery of prime husked ears. The performance of the Narrow Grain Evergreen variety was not nearly so consistent as that of Country Gentleman, indicating that Narrow Grain Evergreen is not so selective as Country Gentleman in its requirements, and that it may be planted closer than Country Gentleman without adversely affecting yields. So far as weights both of unhusked ears and of husked ears are concerned, plantings of Narrow Grain Evergreen at distances of 40"x40" and 42"x42" give about equal results, and the rate may be as heavy as 4 plants per hill. A 38"x 38"x 2 planting also would be 1942} PLANTING RATES AND DISTANCES FOR SWEET CORN 85 TABLE 18. CHECKED-ROW PLANTINGS: OPTIMUM RATES AND DISTANCES FOR COUNTRY GENTLEMAN AND NARROW GRAIN EVERGREEN SWEET CORN Yield component On basis of increasing rate per hill On basis of decreasing distance between rows Country Gentleman Weight of unhusked ears 40" x 40" x 3 (42" x 42" x 4) 40" x 40* x 3 Weight of prime husked ears 40" x 40" x 3 40" x 40" x 3 Number of sorted unhusked ears 40" x 40" x 4 40" x 40" x 4 Weight per prime husked ear 40" x 40" x 3 40" x 40* x 4 b Percent recovery of prime husked ears . . 40" x 40" x 4 C Weight of green fodder 40* x 40" x 4 40" x 40" x 3 40" x 40" x 4>> 40* x 40" x 4 C 40" x 40" x 4 Narrow Grain Evergreen Weight of unhusked ears 40" x 40" x 4, 42" x 42" x 4 Weight of prime husked ears 40" x 40" x 4, 42" x 42" x 4 (38" x 38" x 2) 40" x 40" or 42" x 42" at 3 or 4 rate 40" x 40" x 4, 42" x 42" x 4 (38* x 38" x 2) Number of sorted unhusked ears. . 38" x 38" x 4, 40" x 40" x 4 38" x 38" x Weight per prime husked ear Not more than 3 per hill Effect slight except when rate is over 4 per hill 40" x 40" x 4 b Percent recovery of prime husked ears. . No appreciable effect Weight of green fodder 40" x 40" x 4 40" x 40" x 4 b Any distance except 36" x 36" 40" x 40" x 4 Note. Rates shown in parentheses indicate second choices. Heaviest planting advisable if total weight per acre is the important factor. ''Heaviest planting advisable if number of ears per acre is the important factor. ^Heavier planting gives somewhat higher yields, but this is the heaviest advisable. satisfactory as regards weights of prime husked ears, but because decreasing the distances between rows adds to the cost of cultivation, while increasing the number of plants per hill adds no such costs, the 38"x 38" spacing would not be so practical as the others. On the basis of number of ears per acre the situation with regard to Narrow Grain Evergreen is somewhat confusing, owing to incon- sistent performance. The 38"x 38"x 4 planting seems to be the optimum for number of sorted unhusked ears. Neither the 40"x 40"x 4 nor the 42"x42"x4 planting proved optimum for weight per prime husked ear in the case of Narrow Grain Evergreen. From the standpoint of maximum weight per prime husked ear, where sweet corn is sold on the basis of tonnage per acre, the rate should not be more than 3 plants per hill. On the basis of count, that is, where sales are based on number of ears per acre, 4 plants per hill is indicated, and the closest planting advisable is 40"x40". Considering both total weights and weight per ear, 42"x 42"x 4 and 40"x 40"x 4 are probably the best plantings, but involve some sacrifice in weight per ear. From the standpoint of number of ears, a planting 86 BULLETIN No. 487 [May, TABLE 19. DRILLED-ROW PLANTINGS: OPTIMUM DISTANCES BETWEEN Rows AND BETWEEN PLANTS IN THE Row FOR COUNTRY GENTLEMAN AND NARROW GRAIN EVERGREEN SWEET CORN Yield On basis of distance On basis of distance component between plants between rows Country Gentleman Weight of unhusked ears 40* x 14" 40* x 14* Weight of prime husked ears 40" x 14* 40* x 14* Number of sorted unhusked ears 40" x 8" 40* x 8* Weight per prime husked ear 14* minimum Very slight effect Percent recovery of prime husked ears No particular effect No particular effect Weight of green fodder 38" x 8* highest 38* rows closest* Narrow Grain Evergreen Weight of unhusked ears 40* x 14* 40" x 14* Weight of prime husked ears 40" x 14" 40* x 14" Number of sorted unhusked ears 40* x 8" 38* x 8* Weight per prime husked ear 14* minimum Very slight effect Percent recovery of prime husked ears No particular effect No significant difference Weight of green fodder 38* x 8* highest 38" rows closest" Note. In comparing distances between plants in the row the 2-per-hill checked-row planting for the corresponding distance between rows was used as the base. In comparing distances between rows, the comparison was entirely within the drilled series, the widest rows, 42 inches, being used as the base. Heavier planting gives somewhat higher yields, but this is the heaviest advisable. of 38"x 38"x 4 would be justified, but would also involve some sacri- fice in weight per prime husked ear. The percentage of recovery of prime husked ears did not differ appreciably for any of the foregoing plantings. A 40"x 40"x 4 planting is very favorable also for the production of fodder, a component that needs to be very carefully considered because under the usual low prices for cannery sweet corn there is no profit for the grower unless a high production of fodder is obtained and fed to livestock. Drilled-Row Plantings. There is no evidence from the 1932-1936 experiments that drilled-row plantings are in any way inferior to checked-row plantings so far as yields of ears are concerned, altho in the preliminary tests of 1930 and 1931 the checked-row plantings seemed to be superior. On the other hand there seems to be no basis for the belief that more fodder is produced per acre when sweet corn is planted in drilled rows. The data for the drilled plantings are summarized in Table 19. Yields of Country Gentleman were very consistent, the 40"x 14" planting proving to be optimum on the basis of weights of unhusked 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 87 K H M K H K K oo so oc oo o o CM X X X X X X X 00 CM O CM O CM CM mini v ta

O f5 CM CM CM CM CM CM X X X X X X X * i S S 4 * i CM so \O so 00 vO 00 X X X X X X X * S * i * S * CM SO OC O 00 CM O Tf ro <" Tf <5 ^ Tf I I M Q r* fi m f "> & n .III 00 O> O ** CM nil X X -X X X X X SO O so CM SO 00 so m f m t n 1*5 r<> X X X X X X X SO CM 00 CM O 00 CM ro * ro * t m q- i i i T 1 i i O> O -< CM ^- >O \r> in u-. XXX _ so oo _ n fO ro fO fO X X X X X O 00 CM O CM 1 W Q X 3DV b3d SONOOd 88 BULLETIN No. 487 \_May, 3d SdNCIOd 1942} PLANTING RATES AND DISTANCES FOR SWEET CORN 89 90 BULLETIN No. 487 [May, a 2000 CC UNHUSKED 1930 100 136" X 4" 238" x 4" 3 40" x 4" 4 42" x 4" 5 36" x 5" 6 38" x5" 7 40" x 5" 8 42" x 5" 300 936" x 6" 10 38" x 6" 11 40" x 6" 1242" x 6" 13 36" x 7" 14_38" x 7" 15 40" x 7" 1636" x 8" 4.00 500 600 SQUARE INCHES PER PLANT 17 42" x 7" 18 38" x 8" 19 40" x 8" 20 42" x 8" 2136" x 10" 22 38" x 10" 23 40" x 10" 24 42" x 10" 25 36" x 12" 26 38" x 12" 27 40" x 12" 2842" x 12" 2936" x 14" 30 38" x 14" 31 40" x 14" 3236" x 16" 800 33 42" x 14" 34 38" x 16" 35 40" x 16* 3636" x 18" 37 42" x 16" 38_38" x 18" 39 40" x 18" 40 42* x 18" FIG. 24. POUNDS OF SORTED UNHUSKED EARS AS AFFECTED BY SPACE OCCUPIED PER PLANT IN DRILLED Rows: COUNTRY GENTLEMAN 1930 and of husked ears, and 40"x 8" on the basis of number of unhusked ears. Weight per prime husked ear was lower from the 40"x 8" plant- ing, and there were more culls. However the percentage of recovery was not reduced when plantings closer than 40"x 14" were made. From the standpoint of green fodder, 38"x 8" gave the maximum yields, but ear yields in this planting were seriously reduced. For Narrow Grain Evergreen a 40"x 14" planting was also the optimum for maximum weights of unhusked and of husked ears. For number of ears, 38"x 8" or 40"x 8" was best, tho the weight per ear was somewhat lower in these plantings and weight of culls higher. The percentage of recovery of prime husked ears was not notice- ably affected by any of these plantings. The maximum yield of green fodder was obtained from the 38"x 8" planting. Comparative Effects of Increasing Rates and Decreasing Distances of Planting At several points in the previous discussion mention was made of the fact that increasing the number of plants in the hill had a some- what different effect on certain of the yield components than planting the rows closer together. Owing to the diversity of the data, differ- ential effects are difficult to determine, and therefore in order to 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 91 evaluate them the total yields of the 1931-1936 experiments have been averaged. Thus in order to determine the effect of rate per hill, all the mean yields of each rate were averaged irrespective of the distance between the hills and rows. This means that for each rate the 42"x 42", 40"x 40", 38"x 38", and 36"x 36" plantings were averaged, making a total of 84 replications. Similarly, in order to determine the means for each distance between rows and hills, all the plantings irrespective of rate were averaged, again giving 84 replications. The same general procedure was followed in averaging the results for the drilled-row plantings. Of course the same means were used for averaging rates and distances, the differences being only in the dis- tribution. Thus the increases listed within each of the two tables, Nos. 20 and 21, are strictly comparable. 30O 400 500 600 SQUARE INCHES PER PLANT 1 36" x 4" 238" x 4" 3 40" x 4" 4 42" x 4" 536" x 5" 6 38" x 5" 7 40" x 5" 8 42" x 5" FlG. 9 36" x 6" 1038" x 6" 1 1 40" x 6" 12 42" x 6" 13 36" x 7" I A 38" x 7" 1540" x 7" 1636" x 8" 17_42" x 7" 18 38" x 8" 19 40" x 8" 20 42" x 8" 2136" x 10" 2238" x 10" 23 40" x 10" 24 42" x 10" 2536" x 12" 2638" x 12" 27 40" x 12" 2842" x 12" 29 36" x 14" 3038" x 14" 31 40" x 14" 3236" x 16" 3342" x 14" 34 38" x 16" 3S_40" x 16" 36 36" x 18" 3742" x 16" 3838" x 18" 3940" x 18" 4042" x 18" 25. POUNDS OF SORTED UNHUSKED AND PRIME HUSKED EARS AS AFFECTED BY SPACE OCCUPIED PER PLANT IN DRILLED Rows: NARROW GRAIN EVERGREEN 1931 92 BULLETIN No. 487 {.May, 0^2000 300 400 500 600 SQUARE INCHES PER PLANT 1 36" x 4" 2 38" x 4" 3 40" x 4" 4 42" x 4" 5_36" x 5" 6 38" x 5" 7 40" x 5" 8 42" x 5" 936" x 6" 10 38" x 6" 1 1 40" x 6" 12 42" x 6" 13_36" x 7" 14 38" x 7" 15 40" x 7" 1636" x 8" 17 42" x 7" 1838" x 8" 19 40" x 8" 20 42" x 8" 2136" x 10" 2238" x 10" 23 40" x 10" 24 42" x 10" 25 36" x 12" 2638" x 12" 27 40" x 12" 28 42" x 12" 2936" x 14" 3038" x 14" 31 40" x 14" 32 36" x 16" 33 42" x 14" 34 38" x 16" 35 40" x 16" 3636" x 18" 37 42" x 16" 3838" x 18" 39 40" x 18" 4042" x 18" FIG. 26. POUNDS OF SORTED UNHUSKED AND PRIME HUSKED EARS AS AFFECTED BY SPACE OCCUPIED PER PLANT IN DRILLED Rows: COUNTRY GENTLEMAN 1931 Checked-Row Plantings. So far as weights of unhusked and of husked ears of Narrow Grain Evergreen are concerned, decreasing the distance between rows had a relatively slight effect in increasing yields as compared with increasing the rate per hill (Table 20). The same relationship occurred with reference to number of sorted unhusked ears and number of prime husked ears. Weight per prime husked ear was reduced more rapidly by increasing the planting rate than by reducing the distance between rows. The percentage of recovery of prime husked ears was not affected either by number of plants per hill or by distance between rows. The weights of both unhusked culls and husked culls increased in the heavier plantings. Green fodder, however, responded a little more quickly to reduced distances between hills than to an increased rate of planting. As to Country Gentleman, increasing the rate per hill had virtu- ally the same effect on weights of unhusked and of husked ears as decreasing the distance between hills, a tendency in contrast to that of Narrow Grain Evergreen. The number of sorted unhusked ears in- creased for Country Gentleman as the rate per hill increased and as 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 43 3. Yields from the 42"x42" checked-row planting were paired with the yields from each of the three others (40"x 40", 38"x 38", and 36"x 36") at the same rate per hill, thus giving four groups of pairs, one for each of the rates 2, 3, 4, and 5 plants per hill. 4. Yields from the plantings in drilled rows 42 inches apart were paired with yields from the drilled rows 40, 38, and 36 inches apart in three groups, according to the distances of the plants apart in the rows 20, 14, and 8 inches. Other pairings could be made, of course, but it is believed that the four kinds just described are sufficient. The significance of the mean difference between the replications of each pair was determined according to the method described on page 114 of Fisher. 3 * The values of t were determined from Fisher's Table IV. Where the value of P is 5 percent, the difference is sig- nificant. Below the 5-percent point the difference is considered highly significant. TABLE 2. MONTHLY RAINFALL AND MEAN MONTHLY TEMPERATURES AT URBANA, ILLINOIS, 1929-1936 Month 1929 1930 1931 1932 1933 1934 1935 1936 Average 1888- 1938 Rainfall January t . . . 3 n. S6 in. 4.81 in. .47 in. 2.60 in. 1.96 i 1 n. .42 in. 2.17 in. 1.28 in. 2.16 February 53 1 77 1 26 1 69 1 40 76 1 27 2.81 1.83 March . . . 2 92 1.87 2 62 1 83 5 38 1 60 2 69 1.55 3.09 April . . . 6 ,40 4.07 4.43 1 .31 3 35 1 .03 2.87 3.00 3.42 7 80 1 53 3 97 1 28 5 84 53 6 93 3 94 3 91 June . . . 2 .71 2 23 4 33 3 57 1 19 S 33 3 64 .47 3.68 July . . . 6 46 .47 4.26 2.41 .61 7 .09 4.12 1.35 3.14 August 4 77 2 02 2 90 2 63 4 40 4 87 2 36 3 54 3 29 September .94 2 98 5 41 3 63 5 14 6 19 3 94 5.83 3.32 October . . . 3 .72 1.62 2 27 3 84 3 41 .87 1.65 3.49 2.44 1 36 1 49 2 54 2 37 67 s 44 4 25 4 16 2 62 December. . . 2 96 .22 2.00 3.33 1.12 ? ?? 1.32 3.67 2.10 Mean 44.13 25.08 36.46 30.49 34.47 35.15 37.21 35.09 35.06 Mean temperature January . . 21 f_ 4 20 8 32 4 F. 35 8 37 7 32 8 29 r 19 9 26.7 February ... 23 4 39 3 37 2 37 7 28 8 24 6 33 19.0 28.3 March 46 4 38 6 35 8 33 39 9 35 2 46 ft 43 39 2 April .... . . 54 1 54 6 52 5 52 5 51 6 51 9 48 8 47 6 50.7 May. . ... 58 6 63 4 58 9 63 2 63 4 67 4 56 1 65.4 61.3 June . . 68 6 70 7 73 9 72 9 77 8 78 5 67 7 71 9 70 8 July . . 75 78 2 78 2 76 7 78 2 80 7 77 7 83 75.3 August ... 70 6 76 74 7 74 2 73 73 9 74 s 79.0 73.1 September . 64 q 68 9 72 65 6 72 2 64 5 66 7 70 66 1 October ... 53 ll 52 8 59 54 2 53 2 57 9 55 7 54.7 53.7 November 36 ft 42 2 50 2 35 6 40 4 45 9 40 1 38 5 40 6 December . . 28 7 31 39 2 29 4 34 2 27 7 24 34 30 2 Mean. .. . 50 1 53.0 55.3 52.6 54.2 53.4 SI 7 52.2 51.3 44 BULLETIN No. 487 [May, CLIMATOLOGICAL DATA Some of the most severe drouths and highest temperatures ever recorded in the Middle West occurred during the period covered by these experiments in 1933, 1934, and 1936. The rainfall and tempera- ture means listed in Table 2 do not fully indicate the severity of the conditions, tho the mean temperatures were above normal, especially during June, July, and August, in all years of the tests except 1935. The experiments, including the preliminary tests, covered the entire drouth cycle of 1930-1936. The experimental results were therefore probably modified by the facts that moisture was definitely a limiting factor in 1930, 1933, 1934, and 1936 and that high tempera- tures were common every year except 1935. However, conditions such as these may be expected at any time in the Middle West ; and if the results were modified by the weather, the modifications were in the right direction. That is to say, planting distances and rates for sweet corn in Illinois should be determined by the expectation of heat and drouth rather than of ample rainfall and moderate weather, for there are but few seasons during which there are no dry periods. If such dry periods coincide with a critical period in the development of sweet corn (at time of tasseling and silking, for instance), yields may be greatly reduced. EXPERIMENTAL RESULTS, CHECKED PLANTINGS Weights of Sorted Unhusked Ears Number of Plants per Hill. Increasing the rate of planting above 2 plants per hill gave significant increases in weights of sorted un- husked ears of Narrow Grain Evergreen at all planting distances except the 38"x 38" (Table 3 1 and Fig. 4). These increases were con- fined to the 3- and 4-per-hill rates of planting except in the 42"x42" series, where there was a slight increase for the 5-per-hill rate over the 4-per-hill rate. Four plants per hill is therefore definitely the heaviest rate advisable for planting Narrow Grain Evergreen. In the plantings of Country Gentleman, on the other hand, in- creasing the rate above 2 plants per hill led to only one significant increase over the 2-per-hill rate (Table 3 and Fig. 4). The one signifi- cant increase was obtained at the 42"x42" distance at 4 plants per hill, but because this increase is inconsistent with the remainder of the plantings it is probable that 3 plants per hill is the maximum rate for Country Gentleman. Distance Between Rows. The effect of distance of planting upon yields of Narrow Grain Evergreen is influenced by the rate per hill (Table 4 and Fig. 5). Since 4 plants per hill is the maximum rate 'Tables 3 thru 14 will be found on pages 55 to 66. 1942} PLANTING RATES AND DISTANCES FOR SWEET CORN 93 av3 a 3d 9QNnod 94 BULLETIN No. 487 [May, <.35 A CG NGE *JI^~ * i--r ;I k * 100 1 36" x 4" 238" x 4" 3 40" x 4" 4 42" x 4" 5 36" x 5" 6 38" x 5" 7 40" x 5" 8 42" x 5" 300 400 500 SQUARE INCHES PER PLANT 600 9 36" x 6" 10 38" x 6" 1 1_40" x 6" 12 42" x 6" 13 36" x 7" 14 38" x 7" 15 40" x 7" 1636" x 8" 17 42" x 7" 18 38" x 8" 19 40" x 8" 20 42" x 8" 21 36" x 10" 2238" x 10" 23 40" x 10" 2442" x 10" 2536" x 12" 2638" x 12" 27 40" x 12" 28 42" x 12" 2936" x 14* 3038" x 14" 31 40" x 14* 3236" x 16" 800 33 42" x 14" 34 38" x 16" 35 40" x 16" 36 36" x 18* 37 42" x 16* 38 38" x 18" 39 40" x 18" 40 2" x 18* FIG. 28. WEIGHT PER PRIME HUSKED EAR AS AFFECTED BY SPACE OCCUPIED PER PLANT IN DRILLED Rows: 1931 the distances between rows decreased. The number of prime husked ears, however, failed to increase when there were more than 3 plants per hill, and there was an actual decrease in number for distances of less than 40"x40". Weight per prime husked ear in Country Gentle- man declined more rapidly when rate per hill was increased than when the hills were planted closer together. In this respect the reactions of Country Gentleman and Narrow Grain Evergreen were the same. Weights of unhusked culls in the case of Country Gentleman were affected more by increased rate per hill than by reduced distances between rows. Weights of husked culls, on the other hand, were affected more by reduced distances than by increased rates. The percentage of recovery of prime husked ears in the Country PLANTING RATES AND DISTANCES FOR SWEET CORN 95 COO o5? oo * o 3 ^ ^ *O " O* 3 S o oo -2 IO i/> f^ O 00 IO - So f*5 1/5 Tf 0* $ ^ S2 SSS oo * ^ CMIO 1 * CMC IO IO 2 oo 00 CN CM 00 oooo ?Tf Ot^ TfCM IO CM IO o O IO - - 00 o 10 IO 33 oc **! S S "* IOCS ^ s 1/5 - 10 Ov IT: CM OOCN c oe O X vO0 CC 00 * <* a O't CO -co ** oi e 1 5 " i, W500 10 fO ro ^^ IO cc IO IO IO IO c 22 So - OC j : X s | OOO 10 * 9 ~* e "^ OOtM f~co ~ vr-, bl c * X O 41 IM >, 41 O ^* *^ 0000 O 00 r*. CO CO CM O O* CM <* CO ^ ^ ^ K 0000 -I 1 "5 <* IO o e OO> CM-* OCM *". s 41 U E 0) t.^. 2 - IO t U oco oa -" 10 2 JX, U ^: 00 5S? S3 i s SK 8 1O IO o o r*. Tf COO ^ Tf \f) r*} ^\ 00 P* CM c - e | | C S. o ' T3 3 r/ c 41 C V a I ; 1 1 1 Sorted unhusked ears, pounds Prime husked ears, pounds. . Sorted unhusked ears, numbe Prime husked ears, number. . Weight per prime husked ear. Unhusked culls, pounds Husked culls, pounds Percent recovery of prime hus Green fodder, pounds Sorted unhusked ears, pounds Prime husked ears, pounds. . Sorted unhusked ears, numbel Prime husked ears, number. . Weight per prime husked ear. Unhusked culls, pounds Husked culls, pounds Percent recovery of prime hus Green fodder, pounds Means of 80 to 84 repli 96 BULLETIN No. 487 [May, 1942] PLANTING RATES AND DISTANCES FOR SWEET CORN 97 Gentleman plots was reduced by closer planting; whereas with Nar- row Grain Evergreen recovery was not affected by closer planting. In production of green fodder both Country Gentleman and Nar- row Grain Evergreen responded slightly more to closer planting of rows than to increasing the number of plants in the hill. 0000 1 36" x 4" 238" x 4" 3 40" x 4" A 42" x 4" S 36" x 5" 6 38" x 5" 7_40" x 5" 8 42" x 5" 400 500 SQUARE INCHES PER PLANT 600 700 800 9 36" x 6" 10 38" x 6" 11 40" x 6" 12 42" x 6" 1336" x 7" 14_38" x 7" 15_40" x 7" 1636" x 8" 17 42" x 7" 1838" x 8" 19 40" x 8" 20 42" x 8" 21 36" x 10" 2238" x 10" 23 40" x 10" 24 42" x 10" 2536" x 12" 2638" x 12" 27 40" x 12" 2842" x 12" 2936" x 14" 3038" x 14" 31 40" x 14" 3236" x 16" 33 42" x 14" 34 38" x 16" 35 40" x 16" 36 36" x 18" 37 42" x 16" 3838" x 18" 39 40" x 18" 40 42" x 18" FIG. 30. POUNDS OF GREEN FODDER AS AFFECTED BY SPACE OCCUPIED PER PLANT IN DRILLED Rows: 1931 98 BULLETIN No. 487 [May, C 1HOI3M A9 5 lN3D3d 194Z] PLANTING RATES AND DISTANCES FOR SWEET CORN 99 Drilled-Row Plantings. In the drilled rows the weights of both unhusked and husked ears responded more quickly and more favor- ably to closer distances between the rows than to closer spacing in the row, the two varieties reacting the same in this respect (Table 21). On the other hand the number of unhusked ears and of prime husked ears of both varieties responded very rapidly to closer spacing in the row but more slowly to closer distances between rows. Likewise, as might be expected from the response of number of ears to spacing in the row and distances between rows, the weight per prime husked ear of both varieties decreased very rapidly with closer spacing of plants in the row but was not affected by closer rows. The recovery of prime husked ears was adversely affected by heavier plantings, the closer distances between rows seeming to have no more adverse effect than closer spacing in the row. The weights of unhusked culls of both varieties increased much more rapidly with closer spacing in the row than with reduced dis- tances between rows. On the other hand, the weights of husked culls increased more rapidly as distances between rows were reduced than as the spacing in the row was reduced. PERCENT RECOVERY 1931 DRILLED CSORTED UNHUSKED EARS = 100 30 100 1 36" x 4 238" x 4 3 40" x 4 4 \2" x 4 536" x 5 6 38" x 5 7 40" x 5 842" x 5 300 400 500 600 SQUARE INCHES PER PLANT 9 36" x 6" 1038" x 6" 11 40" x 6" 1242" x 6" 13 36" x 7" 14 38" x 7" 15 40" x 7" 16 36" x 8" 17 42" x 7" 18 38" x 8" 19 40" x 8" 20 42" x 8" 21 36" x 10" 2238" x 10" 23 40" x 10" 2442" x 10" 2536" x 12" 2638" x 12" 27 40" x 12" 28 42" x 12" 29 36" x 14" 30 38" x 14" 31 40" x 14" 32 36" x 16" 800 33 42" x 14" 3438" x 16" 3540" x 16" 3636" x 18" 37 42" x 16" 3838" x 18" 39_40" x 18" 4042" x 18" FIG. 32. PERCENT RECOVERY OF PRIME HUSKED EARS AS AFFECTED BY SPACE OCCUPIED PER PLANT IN DRILLED Rows: 1931 100 BULLETIN No. 487 [May, 8 g OClO OOO 1 ^ 1 CS^ O^ IO O OO GO ^* ^0 9 ** i s -0. ^^ vO-j OW 2| z $ M g to H E E d o e t* ^ t^ir^^ fj f^ C 00 M IO5 *~ ~ O O ^f r- 10 10 fs H ^ 00 t ^ ^* O ^ 1C t^- C~.CC- - ir. u-. M M i WJ efl ^ W O 1 1 22 |5 SS 3 | s 1st is s s a o. >C **5 O O* * 1O IO - u c B 9 ^ *i ^-i " ~* o 5 T3 HH *^ V f*SOO l/)TfOO ^*CJ IO O j* *C(N OOO- O<*> " S o 5 fS *O^t COO *N S tf ^ aoo - S ^ w 2 Q S 5 faQ 1 o OOiO lOO^^* OO^O t^ *f) X i " lO*-** P^*O f} fNO .00 OOlO >O IO Cl- t^OO 3 f. r > ^ c 1"* ^ fj ^ \T} t*+ O f*5 * O* *t IO IO a 55 D I 00 * "" fa b] ], & ^ > a O M ch'Q rt w 1 Ef O^OO PSO\O O M O ^ oooo *oco o^ 10 d **3 O W 00 IO ^> ^ M Q^ zl li S5 : : 2 ^ *" : 2 : 2 j d compone : - 1 1 i. it i i| 31-fl 1 D. r CCU n o 5 .; a Jrf sis If l{i . 1 s V > Q 3 "^ '^" -0 -3-2 "0 'C 2& 2cS S.3 ^ B S E" 11 * 1 ^ "S2 "ggg m - _ jj ^ "Ort *Ocdfi .0 ^> 2 |1 llu 1| I I S-o IS^'o, -* > 3 -S ^-^w JT5 * TS 4, -O t,J3 4) g B = 5 '^J 1 j<-o ^ >? "8 | "2 |"M J.* g O'C O'C*' C3 flj JM n'C n'C^ C3 S b. /. - /.^ __ cu O /. /^ _ cu O PLANTING RATES AND DISTANCES FOR SWEET CORN 101 Yields of green fodder showed a greater increase as a result of closer spacing of rows than of closer spacing of plants in the row, the two varieties responding similarly. Summary of Varietal Responses. The data in Tables 20 and 21 bring out definitely that changes in distances between rows or between plants or hills in the row have a differential effect upon the several yield components and, furthermore, that varietal response may be quite different. In order to show these different responses, the data are sum- marized below by the type of response given. Checked-Row Plantings Components affected Dominant factor Increasing rate per hill. Narrow Grain Evergreen .Weight unhusked ears Weight husked ears Number unhusked ears Number prime husked ears Weight per husked ear Decreasing distance between hills Weight green fodder No dominant factor. Recovery prime husked ears Weight unhusked culls Weight husked culls Country Gentleman Number prime husked ears Weight per husked ear Weight unhusked culls Weight green fodder Weight husked culls Weight unhusked ears Weight husked ears Number unhusked ears Recovery prime husked ears Drilled-Row Plantings Components affected Dominant factor Closer spacing in the row Narrow Grain Evergreen . Number unhusked ears Number prime husked ears Weight per husked ear Recovery prime husked ears Weight unhusked culls Decreasing distance between rows Weight unhusked ears Weight husked ears Weight green fodder Weight husked culls Country Gentleman Number unhusked ears Number prime husked ears Weight per husked ear Recovery prime husked ears Weight unhusked culls Weight unhusked ears Weight husked ears Weight green fodder Weight husked culls The two varieties reacted practically the same in drilled-row plantings, but quite differently in checked-row plantings. It is obvious that in checked plantings, increasing the rate per hill had a stronger influence on Narrow Grain Evergreen than planting the rows closer together. Country Gentleman, on the other hand, tended to be affected more indiscriminately and was much more sensitive to extremes than was Narrow Grain Evergreen. 102 BULLETIN No. 487 {.May, SUMMARY AND CONCLUSIONS Preliminary experiments in 1930 and 1931 with fifty different checked- row and forty different drilled-row plantings of Country Gentleman and Narrow Grain Evergreen sweet corn indicated that changing the distance between rows, the number of plants to the hill, and the spacing between plants in the rows had a highly complex and varying effect on yields. Further experiments with sixteen different checked-row and twelve different drilled-row plantings replicated four times and extending over the five years 1932-1936 made it possible to analyze the differential effects of changing rates and distances of planting on several of the yield components of the same two varieties. The data were analyzed both in detail and on the basis of differences due to a single factor, namely, space occupied per plant. Effect of Space per Plant. Analysis on the basis of space occupied per plant showed that in general the yields were reduced as plantings became unusually heavy or unusually light, but that responses were not the same among the several yield components nor for the two varieties. In addition the responses to amount of space per plant in the drilled rows differed from those in the checked rows. The nature of the yield variations were such as to suggest that while space occupied per plant may have strongly influenced yields, other factors exercised a partially independent effect. These factors consisted of unusually favorable distances between rows, favorable number of plants per hill, favorable spacing in the row, or favorable combinations of distance and rate in the checked-row plantings or distance and spacing in the row in the drilled-row plantings. The dominant effect of unusually favorable combinations of plant- ing was especially noticeable in weights of green fodder and heights of plants, showing that plant growth is partly dissociated from space occupied per plant. The weights of usable unhusked and prime husked ears tended to respond in the same manner as the two growth factors, but the relationship was not very close. Some of the other yield components, especially number of unhusked ears, weight per prime husked ear, number of suckers per plant, and maturity as determined by silk counts, seemed to be more dependent on space occupied per plant. Comparative Effect of Increasing Rate in the Row or Distance Between Rorvs. In general, planting distances and rates which are favorable for the maximum production of one yield component are not necessarily favorable for the maximum production of any of the others ; therefore the yield of one component under a certain set of conditions cannot be used as the basis for determining the yield of another. Furthermore since varieties have an individual response to changing distances and rates of planting, the behavior of one variety PLANTING RATES AND DISTANCES FOR SWEET CORN 103 cannot be used to predict the behavior of another even under the same set of conditions. Increasing the rate per hill in checked rows or the distance between plants in drilled rows may have a quite different effect from that of planting the rows closer together. With Narrow Grain Evergreen, increasing the rate per hill in checked rows had a far more marked effect on yields than reducing the distances between hills. Country Gentleman, on the other hand, was affected to as great an extent by rate per hill as by distance between rows. From the practical stand- point, changing the distance between rows in a Narrow Grain Ever- green planting in an effort to influence the yield was relatively in- effective compared with changing the rate per hill. But Country Gentleman was much more sensitive to changes in either rate or dis- tance, and it will therefore pay the grower of Country Gentleman to set his planter for the optimum distance between rows and to obtain plates giving the proper drop. In drilled-row plantings Narrow Grain Evergreen and Country Gentleman reacted practically the same, the correct distance between rows being a more important factor than the correct distance between plants in the row. This means that within reasonable limits there can be a considerable variation in the drop by the planter without yields being appreciably affected, but that care should be taken to set the planter so that the rows will be the optimum distance apart. In dry seasons, when soil moisture is a limiting factor, decreasing the distances between hills reduced the heights of the plants, but in- creasing the number of plants in the hill had only a slight effect on plant height. In drilled-row plantings closer distances between rows and closer spacing in the row reduced the plant heights during dry seasons but led to greater heights in normal seasons. Changing the distance between rows had a relatively slight effect on number of suckers compared with the great reduction when the rate per hill was increased. In drilled-row plantings the effects were similar ; reducing spacing in the row had a much more marked effect on number of suckers than reducing the distance between the rows. Maturity was delayed much more markedly by increasing the rate per hill or by closer spacing in the row than it was by reducing the distance between rows. RECOMMENDATIONS From the results of the present study certain plantings can be recommended for regions whose soils and climate are in general comparable to those at Urbana, Illinois, where these studies were made. In the checked-row plantings Narrow Grain Evergreen can be planted more heavily than the smaller Country Gentleman variety, 104 BULLETIN No. 487 but in drilled rows the requirements of the two varieties are the same. There is no evidence that plantings in drilled rows produce yields consistently different from those in checked rows. Truck growers who wish to produce the largest number of fair- sized ears per acre should plant at the following rates and distances: Country Gentleman: in checked rows, 40"x40" with 4 plants per hill ; or in drilled rows 40 inches apart with plants 8 inches apart in the row. Narrow Grain Evergreen: in checked rows, 38"x 38" with 4 plants per hill ; or in drilled rows 40 inches apart with plants 8 inches apart in the row. Cannery growers who are interested in producing the maximum weights of heaviest ears should plant at the following rates and distances: Country Gentleman: in checked rows, 40"x40" with 3 plants per hill; or in drilled rows 40 inches apart with plants 14 inches apart in the row. Narrow Grain Evergreen: in checked rows, 40"x40" with 4 plants per hill ; or in drilled rows 40 inches apart with plants 14 inches apart in the row. LITERATURE CITED 1. DAVENPORT, E., and FRASER, W. J. Corn experiments, 1895. 111. Agr. Exp.. Sta. Bui. 42. 1896. 2. EISELE, H. F. Influence of environmental factors on the growth of the corn plants under field conditions. Iowa Agr. Exp. Sta. Res. Bui. 229. 1938. 3. FISHER, R. A. Statistical methods for research workers. 4th ed. Oliver and Boyd, London. 1932. 4. HABER, E. S. Check rowed or drilled corn? Effect of number of plants per hill on yields of sweet corn. Canner 71, No. 3, pp. 13, 14, and 16. 1930. 5. HUELSEN, W. A., and MICHAELS, W. H. The yield complex of sweet corn. 111. Agr. Exp. Sta. Bui. 432. 1937. 6. HUME, A. N., CENTER, O. D., and HEGNAUER, L. Distance between hills for corn in the Illinois corn belt. 111. Agr. Exp. Sta. Bui. 126. 1908. 7. MAGRUDER, ROY. Distance of planting sweet corn to increase yields. Ohio Agr. Exp. Sta. Bimo. Bui. 13, 68-72. 1928. 8. McCLUER, G. W. Sweet corn, thickness of planting, 1891. In 111. Agr. Exp. Sta. Bui. 21, pp. 101-102. 1892. 9. MORROW, G. E., and GARDNER, F. D. Experiments with corn. In 111. Agr. Exp. Sta. Bui. 31, pp. 333-360. 1894. 10. WATSON, A. N. Report of activities of the Puerto Rico Experiment Station of the Office of Experiment Stations, U. S. Department of Agriculture, for the month of August, 1936. Mimeo rpt. Mayaguez, P. R. Jan. 15, 1937. 11. - and DAVIS, R. L. Statistical analysis of a spacing experiment with sweet corn. Amer. Soc. Agron. Jour. 30, 10-17. 1938. 27505-4222187