N.QN CIRCULATING CHECK FOR UNBOUND CIRCULATING COPY UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN No. 271 AN EXPERIMENT IN SELECTING CORN FOR YIELD BY THE METHOD OF THE EAR-ROW BREEDING PLOT BY LOUIE H. SMITH AND ARTHUR M. BRUNSON URBANA, ILLINOIS, NOVEMBER, 1925 SUMMARY The possibility of improving the yield of corn by continuous ear- row selection has been rather generally assumed, and no little effort has been expended in attempting to produce higher yielding strains thru one or another of the various possible modifications of this method of breeding. The remarkable results in altering, thru ear-row breeding, certain special characters such as protein and oil content of the grain and height of ear on the stalk, led to the assumption that yield might be in- fluenced by a similar process of selection. In view of a doubt as to whether breeding for these special characters and breeding for yield represent truly analagous cases, it seemed desirable to secure some actual experimental evidence. To this end a test was made covering ten years of selection for yield by the method of the ear-row breed- ing plot. The results of this investigation led to the conclusion that the simpler method of mass selection, that is, picking seed ears from stand- ing stalks in the field, ordinarily will be just as effective in improving the yield as the more complicated method of continuous ear-row breeding. The experiment involved the use of an unnamed variety of no par- ticular breeding but adapted to the region. A high-yield and a low-yield breeding plot were founded upon the basis of the relative productive- ness of the seed ears as determined by a preliminary ear-row test. Continued selection in these two opposite directions resulted in a marked separation of the two strains with respect to yield. The High Yield strain, however, did not significantly surpass in yield a control strain propagated from the original stock by careful field selection without pedigree breeding. It appears, therefore, that the difference in productiveness between the High. Yield and Low Yield strains was brought about mainly thru a decrease in the Low Yield strain. AN EXPERIMENT IN SELECTING CORN FOR YIELD BY THE METHOD OF - THE EAR-ROW BREEDING PLOT .;_ By LOUIE H. SMITH AND ARTHUR M. BRUNSON* THE PROBLEM Many years ago this Experiment Station demonstrated in a strik- ing way the effect, on various special characters in corn, of ear-to-row, or "ear-row," selection. By this method the chemical composition of the grain has been so modified that strains of high and of low protein content, as well as of high and of low oil content, have been produced from a single original variety. 8 Likewise, habits of growth have been influenced to produce strains bearing ears high on the stalk and low on the stalk, according to the direction of the selection, and in similar manner a strain bearing erect ears and another bearing declining ears have been produced by selection in opposite directions. 9 Following these demonstrations the question arose whether the productive capacity of the corn plant might not likewise be modified by a similar process of continuous selection. A number of seed corn growers, assuming that this would be the case, undertook to improve their varieties by systematic ear-row selection. After working along this line for a few years, some of these breeders became doubtful whether they were making any progress. Unfortunately, they had failed for the most part to plan a check by which a comparison of the selected strains could be made with the original unselected stock. In view of the dearth of experimental evidence at the time the present investigation was undertaken, as to the efficiency of the ear-row system as a means of improving the yield of corn, it seemed desirable to test the matter by a carefully checked experiment. This bulletin presents the data obtained in an experiment at this Station extending over a period of ten years and includes a brief review of work done at other stations. INVESTIGATIONS AT OTHER EXPERIMENT STATIONS Published results of investigations dealing with this particular phase of corn breeding are rather meager, but a summary of the experience of different investigators would seem to show that the ear-row system of selection which has been so effective in influencing special characters in LouiE H. SMITH, Chief in charge of Publications of the Soil Survey, (formerly Chief in Plant Breeding); ARTHUR M. BRUNSON, formerly Associate in Plant Breeding. 567 I 568 BULLETIN No. 271 [November, corn does not apply with the same success to that exceedingly intricate complex of characters that determines yielding capacity. Montgomery, 5 working at the Nebraska Experiment Station, re- ported after the first few years of an ear-row breeding-plot experiment an apparent gain by the use of seed selected in this way over seed rep- resenting the original stock. According to a later account of this same experiment by Kiesselbach, 3 however, it appears that the gain thus ob- tained in the earlier years of the work was subsequently lost. Noll 6 described some experiments at the Pennsylvania Station in which he compared yields of seed produced by ear-row breeding with ordinary field-grown seed of the same variety. The results on the whole indicated no consistent gains by the use of breeding-plot methods. Hume, 2 of the South Dakota Station, presented data based upon relative yields of rows within the breeding plot, which apparently indi- cated to him that some improvement attributable to the ear-row selec- tion had been effected; but when seed from these same breeding plots was brought into a variety test series, the comparisons failed to show any convincing evidence of such improvement. More favorable results from a somewhat similar method of breed- ing are shown by Williams and Welton, 12 of the Ohio Station. Of twenty strains produced under a breeding-plot system, eighteen yielded more than, the parent stock, the increases ranging from about 1% bushels to 11 bushels an acre. Hayes and Alexander, 1 of the Minnesota Station, have recently published an account of some experiments on the relative efficiency of different methods of seed-corn selection. In these experiments Mont- gomery's method of preliminary ear-row testing and Williams' method are compared with simple mass selection from the field. The authors express the following conclusion: "There seems to be little or no value, from the farmer's standpoint, of using the ear-to-row plan. Under any circumstances its continued use appears undesirable." After a careful summary of the various published investigations, Richey, 7 of the U. S. Department of Agriculture, came to the following conclusion: "It seems probable that the yield of an entirely unselected or unadapted variety could be improved by a few years of intelligent ear-to-row selection. However, in view of the expense, the uncertainty with which larger yields have been obtained, and the small increases secured during a series of years in the most favorable cases, so far there appears to be little to recommend ear-to-row breeding as a practical method of corn improvement." PLAN OF THE PRESENT INVESTIGATION In brief, the plan adopted in the present investigation included the following points: (1) the use of a well-adapted local strain which, in its immediate history at least, had not been subjected to systematic X 1925~\ SELECTING CORN FOR YIELD 569 selection; (2) the use of a foundation stock extensive enough to insure a reasonably adequate sample of the various types represented in that strain; (3) provision for the continuation of a composite sample of all foundation ears by mass selection in an isolated field, in order to have a basis for comparison; (4) the determination of the relative potential productive capacity by means of a preliminary ear-row test of all foundation ears; (5) the employment of an isolated "High Yield" ear- row breeding plot originated from the remnant seed of the forty rows showing highest production in the preliminary ear-row test; (6) the employment of a corresponding "Low Yield" ear-row breeding plot started from the remnant seed of the forty rows showing lowest produc- tion in the preliminary ear-row test; (7) a comparison of annual yields of replicated plots planted from seed composites taken from their re- spective breeding plots, in this way measuring the effectiveness of the selection. THE FOUNDATION STOCK For the purpose of this experiment several bushels of ear corn of an unnamed yellow variety were obtained from a near-by farm. During the known history of the corn it had had no particular breeding other than crib selection of viable seed ears, and had been subjected to no close selection for type. Nine hundred ninety ears were finally taken from the lot to represent the original stock. THE NON-PEDIGREE STRAIN In order to measure progress in improving corn it is necessary that the selected strain be compared from year to year with the original stock. For the purpose of perpetuating the foundation strain, a com- posite lot of seed representing all the original 990 ears was taken. This strain was grown each year in an isolated field of several acres and propagated by simple mass selection. Each fall enough good seed ears were selected from the standing corn to plant the field the following year. This strain was designated as the Non-pedigree strain, as dis- tinguished from the High Yield and Low Yield strains to be produced under pedigree* selection. THE HIGH YIELD AND Low YIELD STRAINS The Preliminary Ear-row Test Seed from each of the original 990 ears was planted in an individual ear-row in 1911 to determine its relative yielding capacity as a basis for the selection of remnant seed with which to start the High Yield and the Low Yield breeding plots. These rows were 33 hills long and were 'Strictly speaking, the High Yield and Low Yield strains should perhaps be re- ferred to as representing partial pedigree selection, since the individual pollen parentage was not controlled. 570 BULLETIN No. 271 [November, planted two stalks to a hill. Every tenth row was planted from a com- posite lot of seed to serve as a check row. The field in which this test was planted proved to be lacking in uniformity of productiveness, as evidenced by the extremely wide fluctuations in yield. The range in the yield of the check rows was from 6.5 to 29.2 pounds a row. However, TABLE 1. YIELDS OF SELECTED Rows IN THE PRELIMINARY EAR-ROW TEST OF 990 EARS OF FOUNDATION STOCK, AND THE YIELDSJSF THEIR CORRESPONDING CHECK Rows Parent ears selected for high yield Average of two nearest check rows Parent ears selected for low yield Average of two nearest check rows Ear row No. Weight of ear corn Weight of ear corn Ear row No. Weight of ear corn Weight of ear corn 36 Ibs. 18.6 20.0 23.7 21.0 20.3 22.7 30.8 26.5 29.5 22.1 27.5 20.3 23.5 20.5 19.6 20.2 16.1 18.4 16.1 24.4 24.3 23.3 27.1 31.0 21.5 14.3 16.5 20.3 25.4 35.6 29.6 26.6 33.0 18.5 30.4 32.6 34.7 26.3 30.8 29.6 Ibs. 17.1 12.1 13.3 15.9 13.1 16.8 16.8 16.8 19.2 20.5 18.4 14.2 15.0 11.8 15.9 12.6 11.1 13.3 9.0 11.4 18.7 13.0 19.2 21.7 14.5 8.6 10.1 11.6 18.5 19.8 12.2 15.6 25.9 11.9 22.1 24.1 27.5 18.1 20.3 21.3 19 Ibs. 7.5 5.1 10.4 11.6 7.6 10.4 9.5 10.8 11.5 14.4 16.6 9.7 7.3 9.7 9.1 5.2 7.7 5.4 9.2 13.5 10.8 7.4 7.5 12.4 12.4 4.3 4.7 7.7 7.8 9.4 16.6 8.6 15.2 19.7 10.3 10.7 18.5 10.7 14.5 17.9 Ibs. 13.1 17.1 13.7 13.3 14.8 11.9 14.0 16.8 16.5 20.5 18.4 14.2 15.0 11.8 15.9 11.1 13.3 8.7 17.1 19.6 16.8 13.0 13.6 17.2 19.2 12.9 8.6 12.9 14.0 18.5 18.0 15.6 21.0 15.8 11.9 18.6 24.1 16.3 18.1 21.3 51 34 68 46 88 67 115 97 128 108 159 141 179 154 183 166 194 195 203 202 223 222 256 255 272 271 299 294 306 338 337 367 363 383 399 453 408 471 523 534 543 549 616 576 649 604.. 705 651 751 717 .... 774 752 807 816 854 825 876 858 899 861 908 904 931 921 974 955 993 975 1006 984 1027 1007 1058 1047 1065 1059 1087 1088 Average 24.3 16.2 ! Average 10.5 15.6 1925] SELECTING CORN FOR YIELD 571 forty rows were selected that were most productive as judged by the nearest check rows, and in similar manner 40 rows that proved to be low yielding were selected. The remnant seed from the ears used in planting these rows was taken as the foundation stock for the High Yield and Low Yield strains respectively. The yields of these 80 selected rows in 1911, together with the averages of the corresponding check rows, are shown in Table 1. Altho the average of the check rows was almost the same for the two selections about 16 pounds the averages of the ear-rows selected for High Yield and for Low Yield differed widely, being 24.3 and 10.5 pounds respectively. The Breeding Plots The High Yield and Low Yield breeding plots consisted of 40 indi- vidual ear-rows each. The rows were at least 80 hills long, the hills being 39.6 inches apart. The seed was planted three grains in a hill and the stand thinned to two stalks a hill at about the time of the first culti- vation. Every fifth row was planted from a composite lot of seed to serve as a check, and in order to prevent contamination in the breed- ing all plants in these check rows were emasculated by detasseling. In the breeding rows, all the plants in alternate halves of alternate rows were also detasseled, thereby excluding all self-fertilization and prac- tically all sister-brother combinations between plants in the same row. Shortly before harvest time each year, a search was made in the breeding plots for the most desirable plants from which to obtain seed for the following year. The most vigorous plants, with erect, sturdy stalks and well-developed ears and as free as possible from disease, were tagged in the detasseled portion of every breeding row. At harvest, the crop from each row was weighed separately. In the High Yield plot the tagged ears from the ten highest-producing rows were saved and from the Low Yield plot those from the ten lowest-yielding rows were retained. A germination test and subsequent inspection finally deter- mined the four best ears from each of the ten selected rows in each plot, which constituted the forty ears with which to carry on the plot the fol- lowing year. An attempt was made to tag only the best plants impar- tially in both the High Yield and the Low Yield breeding plots, in order that selection would be based entirely upon the yielding capacity of the row, the two plots having equal opportunity from the standpoint of the vigor of the parent plants. Pedigree records were kept in such manner as to permit tracing the maternal ancestry of every seed ear planted thruout the ten genera- tions of the experiment. SPECIAL HIGH YIELD STRAIN This strain originated from the High Yield plot described above, after the work had been under way for five years. It represents an 572 BULLETIN No. 271 [November, attempt to overcome in some degree the obstacle to controlled breeding presented by the open-pollinating habit of the corn plant. Altho seed selected each year for high yield is confined to the highest-yielding rows, this seed may receive the inheritance of very inferior stock thru fertiliza- tion by pollen from lower-yielding, unselected rows. With the Special High Yield strain, greater control was exercised over the pollen parent. The plan is based on the use of remnants of tested seed ears and follows essentially the system devised by Williams 11 of the Ohio Experiment Station. An ear-row test plot and a mating plot were planted each year. The ear-row test plot contained 80 rows planted from 80 individual ears produced in the mating plot of the preceding year and contained also 20 check rows interspersed at five-row inter- vals. Remnants of the nine most productive seed ears as determined by this test were carried into the mating plot the year following. This mating plot was made up of 12 rows, 8 of which were planted from individual seed ears and were detasseled. The other 4 rows were planted from a single ear and were allowed to produce pollen for the entire plot. In harvesting the mating plot, 80 ears were chosen from the detasseled rows to be tested in the ear-row plot of the following year. In order to prevent the alternation of two separate strains in this system, the ear from which the four pollen-producing rows were to be planted was reserved for use in the mating plot the second year after its selection. In getting the system started it was necessary to modify it slightly by planting the pollen-producing rows with seed from the same ear two years in succession. RESULTS: YIELDS OF THE VARIOUS STRAINS Since the breeding plots for the High Yield and Low Yield strains, as well as for the Non-pedigree strain, were isolated in order to prevent contamination from other pollen, it was impossible to make any accurate TABLE 2. AVERAGE ANNUAL YIELDS OF THE VARIOUS STRAINS IN THE YIELD TEST PLOT Bushels per acre Year High Yield strain Low Yield strain Non- pedigree strain Special High Yield strain Reid Yellow Dent 1913... 41 3 38 36 7 37 5 1914 58 9 55 1 60 3 54 3 1915 58 3 52 7 ^6 54 6 1916 29 9 20 3 28 6 27 5 1917 70 9 64 3 71 5 61 3 1918 69 8 58 3 73 3 72 5 65 9 1919 77 9 70 73 2 75 2 61 7 1920 76.9 60 9 74 9 79 1 78 2 1921 68 8 45 7 61 2 63 4 61 1 1922 70.1 52.6 73.6 72.7 68.4 1925~\ SELECTING CORN FOR YIELD 573 comparison of the relative productiveness of the strains from the yields obtained in those plots. Composite lots of seed from each strain were therefore planted each year in a yield test plot, where their productive- ness could be compared under as similar conditions as possible. In the earlier years of the work these plots were duplicated, and in later years the replications were increased to four. In addition to the High Yield, Low Yield, Non-pedigree, and Special High Yield strains, the Station Strain of Reid Yellow Dent, as representative of a standard, high- yielding variety, was also included for the sake of comparison. A sum- mary of the yields of these various strains is given in Table 2. In attempting to measure the progress that may have resulted from these lines of selection, two methods of analysis are employed: (1) the annual yields of the various strains are divided into two five- year periods for comparison; and (2) a graphic and algebraic repre- sentation is made by means of fitted straight lines. ANALYSIS BY FIVE-YEAR PERIODS Dividing the ten years thru which the test continued into two periods of five years each, a measure of any progressive change in yield is obtained in which the annual fluctuations are largely ironed out. A summary of these comparisons is presented in Table 3. TABLE 3. COMPARISONS OF YIELDS OF DIFFERENT STRAINS, BY FIVE-YEAR PERIODS Strains compared Period Difference in bushels per acre Odds that difference is significant High Yield over Low Yield First 5 years. . 5.80 > 9999:1 High Yield over Non-pedigree Second 5 years First 5 years . . 15.17 1.27 > 9999:1 3.1:1 Non-pedigree over Low Yield Second 5 years First 5 years . . 1.42 4.53 3.4:1 34.6:1 Second 5 years 13.75 > 9999:1 High Yield over Special High Yield 1918-1922 .09 1.1:1 High Yield over Reid Yellow Dent First 5 years. . Second 5 years 4.58 6.85 216:1 37:1 Non-pedigree over Reid Yellow Dent . . . First 5 years. . Second 5 years 3.31 5.43 18:1 18:1 NOTE The statistical measure used in the above table is that proposed by "Student" and further explained as to its adaptation to agronomic work by Love and Brunson. 4 The detailed data upon which this table is based are given in Tables A to F of the Appendix. Comparing the High Yield with the Low Yield strain, it will be observed that the average annual difference increases from 5.80 bushels an acre in the first five-year period to 15.17 bushels in the second five- year period. Both these differences are highly significant. The increas- 574 BULLETIN No. 271 [November, ing divergence of nearly 10 bushels an acre between the means of these two periods shows the possibility of effectively separating superior and inferior strains of corn from an ordinary variety by this means of selection. In each of the same two periods the Non-pedigree strain produced almost as much as the High Yield. Indeed the small differences cannot be considered statistically significant in either of the five-year periods, as shown by the very small odds. The gain of the High Yield over the Non-pedigree strain is negligible; in other words, there was practically no change in the relative.' productiveness of the strains. Under the con- ditions of this experiment at least, the simpler method of mass selection carefully carried out would appear to be as effective in maintaining an ordinary variety of corn at a high level of production as is the more complicated and more expensive method of the pedigree ear-row plot. The increases of the Non-pedigree over the Low Yield strain for the two periods are very similar to the corresponding differences of the High Yield over the Low Yield strain noted above. The close corre- spondence of the Non-pedigree strain to the High Yield strain would inevitably lead to this result. Since the Special High Yield strain was not started until the fifth year of the experiment, we can compare it only during the last period. During that time the average yields of the High Yield strain and the Special High Yield strain were practically identical. Thus even the more complicated system of the Special High Yield plot resulted in no advantage. Both the High Yield and Non-pedigree strains rather consistently outyielded the Experiment Station's strain of Reid Yellow Dent, and with both strains the increase was greater during the second period than during the first five years. The increase in the yield of the High Yield strain over Reid Yellow Dent is statistically significant, as signifi- cance is ordinarily measured, and that of the Non-pedigree strain over Reid Yellow Dent is possibly significant. If we may consider the pro- ductiveness of the Reid Yellow Dent to have remained constant thruout the experiment, the slight gains of the High Yield and Non-pedigree strains on this basis are of considerable interest. ANALYSIS BY FITTED STRAIGHT LINES The second method of studying the results of the experiment in- volves the fitting of straight lines to the annual yields by the method of least squares, a device frequently employed in statistical analyses where it is desired to show trends. The equations representing the lines are calculated in the form y = mx -f- n, where y equals the value of any ordinate (yield); x equals the value of any abscissa (crop year); n, the y-intercept; and m, the slope of the line. By using the annual yields displayed in Table 2, the following equations were calculated. 1925~\ SELECTING CORN FOR YIELD 575 EQUATIONS FOR STRAIGHT LINES Tenr-Year Results High Yield y = 46.8873 + 3.4206 x Low Yield y = 44.9800 + 1.5133 x Non-pedigree y = 45.4254 + 3.4455 x Reid Yellow Dent y = 42.0254 + 3.3388 x Five-Year Results High Yield y = 74.4000 0.8500 x Special High Yield y = 74.8600 1.1400 x The annual yields, together with their fitted straight lines, are shown graphically in Figs. 1 and 2. It may be observed that the straight lines representing the High Yield and the Low Yield strains show a pro- nounced divergence. On the other hand, the lines for the High Yield so 60 SO 10 High Lot* l/ield Non-pedigree Q 1913 191-4 1915 1916 1917 1913 1919 I9SO /92I 1922 FIG. 1. FITTED STRAIGHT LINES FOR HIGH YIELD, Low YIELD, AND NON-PEDIGREE CORN SELECTIONS strain and the Non-pedigree strain are practically parallel, with the former showing the higher yields thruout. The lack of divergence be- tween these lines suggests that perhaps the High Yield strain gained a slight superiority as a result of the first selection by the preliminary ear-row test, and maintained this advantage thereafter. In Fig. 2 the straight lines representing the High Yield strain and the Special High 576 BULLETIN No. 271 [November, Yield strain are nearly identical, indicating little difference in their relative performance. DIRECTION OF STRAIGHT LINES Mean annual divergence, Relative slope bushels per acre 3.4206 1.9073 1.5133 3.4206 0.0249 3.4455 3.4206 0.0818 3.3388 3.4455 0.1067 3.3388 0.2900 Strain High Yield Low Yield High Yield Non-pedigree High Yield Reid Yellow Dent. Non-pedigree Reid Yellow Dent High Yield (5 years only) 0.8500 Special High Yield (5 years only) 1.1400 eo 70< 60 $ High yield Spec/a Expressing these results numerically rather than graphically, and comparing the relative slopes in terms of mean annual divergence, we find a divergence between the High and Low Yield strains which re- duced to the average annual basis amounts to 1.91 bushels an acre. In contrast to this, with the slopes of the High Yield and the Non- pedigree lines almost identical, the mean annual divergence is only .02 bushels an acre. Comparing the High Yield with Reid Yellow Dent, an average yearly gain of .08 bushels an acre is observed. A mean annual divergence of nearly .11 bushels an acre is noted in a comparison of the slopes of the Non-pedigree and Reid Yellow Dent strains. The relative slopes of the High Yield and the Special High Yield strains indicate that the Special strain, in comparison with the High Yield strain, was losing ground at the rate of .29 bushels an acre yearly. In general, the method of study- ing the data by fitted straight lines bears out in a striking way the conclusions reached in the preceding method of analysis, where the re- sults of first and second five-year periods are compared. eo 10 I9t8 /9I9 1920 I92/ J928 FIG. 2. ANNUAL YIELDS AND FITTED STRAIGHT LINES FOR HIGH YIELD, Low YIELD, AND NON-PEDIGREE CORN SELECTIONS 1925~\ SELECTING CORN FOR YIELD 577 DISCUSSION The Non-pedigree strain was planned originally to represent the productiveness of the foundation stock and so furnish a basis for judg- ing the performance of the pedigreed strains. For this purpose, the yielding capacity of the Non-pedigree strain should have remained con- stant for the duration of the experiment. It is observed, however, that there is a slight upward trend of the Non-pedigree strain when com- pared with Reid Yellow Dent. The superiority of the Non-pedigree strain over Reid Yellow Dent increased from. 3.31 bushels an acre dur- ing the first five-year period to 5.43 bushels during the second five-year period. Similarly, the comparative slopes of the fitted straight lines show an increasing divergence of the Non-pedigree strain and Reid Yellow Dent amounting to an average annual increase of about .11 bushel an acre. Altho the number of comparisons is too small to make this slight improvement very significant, it would seem that the pro- ductive capacity of the Non-pedigree strain probably was slightly raised by good practices of mass selection. In the ear-row selections a very pronounced divergence between the High Yield and the Low Yield strains occurred. Altho the High Yield strain thruout the experiment yielded slightly more than the Non- pedigree strain, the performances of the two strains were remarkably parallel. This forces the conclusion that the divergence between the High Yield and the Low Yield strains was due mainly to a decrease in the yielding capacity of the latter. Apparently ear-row breeding pro- duced in the Low Yield strain an effect comparable to the changes produced in the physical and chemical properties of the corn plant by this method of breeding, but in the High Yield selection it failed to cause any significant change. The modified method of the Special High Yield plot was equally ineffective in the five years of its trial. The reason for this failure to increase productiveness is not alto- gether clear. In part, it may be related to soil variability and the con- sequent difficulty of accurately determining the rows of highest yielding capacity, but this difficulty should apply equally in the Low Yield selec- tion, where distinct progress was made in decreasing the yield. Again, the fact that a given factorial complex that makes for a high yield one season may not fit the conditions of the following season should also apply to the Low Yield selection, altho perhaps in a less degree. Prob- ably one of the serious limitations in breeding for high production by ear-to-row selection lies in the effects of the unavoidable close breeding in a small plot. The great mass of available evidence concerning in- breeding in corn points consistently toward lowered yields whenever corn undergoes inbreeding. Altho precautions against inbreeding were taken, such as systematically distributing over the plot seed ears from a parent row, and detasseling all plants from which the seed ears were to be selected, it was inevitable that much close breeding should have 578 BULLETIN No. 271 [November, taken place where four rows in any year traced back to a single row of the previous year. The slight superiority of the High Yield strain over the Non-ped- igree strain appears to have been present from the first and in all proba- bility was the result of the initial selection of the forty remnant ears from the foundation stock based on their performance in the preliminary ear-row test. No further increase in productiveness over that of careful mass selection was obtained during ten years of ear-to-row breeding. CONCLUSIONS The outcome of this investigation leads to two conclusions con- cerning practical methods of corn breeding: 1. Continuous selection by means of the ear-row breeding plot cannot be recommended as a means of increasing the yield of a well- adapted variety of corn. 2. By continuous mass selection the yield of a well-adapted variety of corn can be maintained and perhaps somewhat increased. The practical recommendation to the corn grower who desires to maintain the productiveness of his crop on a high plane, or possibly to increase his yields, is to use mass selection as the most effective simple method of selecting corn for yield. For a more complete dis- cussion of such method the reader is referred to Circular 284 13 of this Station, in which the details of the method are described. .7925] SELECTING CORN FOR YIELD 579 LITERATURE CITED 1. HAYES, H. K., AND ALEXANDER, LEE 1924. Methods of corn breeding. Minn. Agr. Exp. Sta. Bui. 210. 2. HUME, A. N. 1919. Corn families of South Dakota. S. Dak. Agr. Exp. Sta. Bui. 186. 3. KlESSELBACH, T. A. 1916. Recent developments in our knowledge concerning corn. Neb. Corn. Imp. Assoc. Ann. Rpt. 1916, 1542. 4. LOVE, H. H., and BRUNSON, A. M. 1924. Student's method for interpreting paired experiments. Jour. Amer. Soc. Agron., 16, 60-68. 5. MONTGOMERY, E. G. 1909. Experiments with corn. Neb. Agr. Exp. Sta. Bui. 112. 6. NOLL, CHARLES F. 1916. Experiments with corn. Pa. Agr. Exp. Sta. Bui. 139. 7. RICKEY, FREDERICK D. 1922. The experimental basis for the present status of corn breeding. Jour. Amer. Soc. Agron., 14, 1-17. 8. SMITH, LOUIE H. 1908. Ten generations of corn breeding. 111. Agr. Exp. Sta. Bui. 128. 9. SMITH, LOUIE H. 1909. The effect of selection upon certain physical characters in the corn plant. 111. Agr. Exp. Sta. Bui. 132. 10. STUDENT 1908. The probable error of a mean. Biometrica 6, 1-25. 11. WILLIAMS, C. G. 1907. Corn breeding and registration. Ohio Agr. Exp. Sta. Cir. 66. 12. WILLIAMS, C. G., AND WELTON, F. A. 1915. Corn experiments. Ohio Agr. Exp. Sta. Bui. 282. 13. WOOD WORTH, C. M. 1924. A program of corn improvement. 111. Agr. Exp. Sta. Cir. 284. APPENDIX The tables in this Appendix show the annual yields of the plots in the variety tests, which were planted with a composite of seed produced in the breeding plots the previous year. For the earlier years of the work (1913-16), when the plots were only duplicated, each yield shown in these tables represents one plot. In the later years (1917-21) each strain was represented by four plots and each yield is the average of two plots from two different series. For 1922 each yield represents but a single plot. TABLE A. First five years Second five years Year High Yield Low Yield Gain H.Y. over L.Y. Year High Yield Low Yield Gain H.Y. over L.Y. 1913 43.7 39.0 69.1 48.8 61.5 55.1 25.6 34.1 72.5 69.3 42.7 33.3 65.6 44.6 56.0 49.4 17.0 23.5 67.9 60.7 1.0 5.7 3.5 4.2 5.5 5.7 8.6 10.6 4.6 8.6 1918 72.2 67.3 80.8 75.1 78.9 74.8 73.7 63.8 69.6 70.7 59.2 57.5 72.0 68.1 62.1 59.7 50.6 40.8 55.2 50.0 13.0 9.8 8.8 7.0 16.8 15.1 23.1 23.0 14.4 20.7 1914 1919 1915 1920 ' 1916 1921 1917 1922 Mean 51.87 46.07 5.80 2.67 2.17 > 9999:1 Mean 72.69 57.52 15.17 5.47 2.77 >9999:1 r Z Odds Odds TABLE B. HIGH YIELD VERSUS NON-PEDIGREE (Bushels per acre) First five years Second five years Year High Yield Non- pedigree Gain H.Y. over N.P. Year High Yield Non- pedigree Gain H.Y. over N.P. 1913 43.7 39.0 69.1 48.8 61.5 55.1 25.6 34.1 72.5 69.3 36.3 37.1 61.2 59.3 55.9 56.0 27.3 29.9 75.1 67.9 7.4 1.9 7.9 -10.5 5.6 -.9 -1.7 4.2 -2.6 1.4 1918 72.2 67.3 80.8 75.1 78.9 74.8 73.7 63.8 69.6 70.7 69.6 77.0 77.4 69.1 78.2 71.7 67.0 55.5 75.4 71.8 2.6 -9.7 3.4 6.0 .7 3.1 6.7 8.3 -5.8 -1.1 1914 1919 1915 1920 1916 1921....... 1917 1922 51.87 50.60 1.27 5.26 .24 3.1 : 1 Mean 72.69 71.27 1.42 5.36 .27 3.4:1 z Odds Odds 582 BULLETIN No. 271 [November, TABLE C. NON-PEDIGREE VERSUS Low YIELD (Bushels per acre) First five years Second five years Year Non- pedigree Low yield Gain N.P. over L.Y. Year Non- pedigree Low yield Gain N.P. over L.Y. 1913 36.3 37.1 61.2 59.3 55.9 56.0 27.3 29.9 75.1 67.9 42.7 33.3 65.6 44.6 56.0 49.4 17.0 23.5 67.9 60.7 -6.4 3.8 -4.4 14.7 -.1 6.6 10.3 6.4 7.2 . 7.2 1918 69.6 77.0 77.4 69.1 78.2 71.7 67.0 55.5 75.4 71.8 59.2 57.5 72.0 68.1 62.1 59.7 50.6 40.8 55.2 50.0 10.4 19.5 5.4 1.0 16.1 12.0 16.4 14.7 20.2 21.8 1914 1919 1915 1920 ... 1916 1921 1917 1922 . . . 50.60 46.07 4.53 6.16 .73 34.6:1 71.27 57.52 13.75 6.32 2.18 >999:1 z Odds Odds TABLE D. HIGH YIELD VERSUS SPECIAL HIGH YIELD (Bushels per acre) Second five years Year High Yield Special High Yield Gain H.Y. overS.H.Y. 1918 72.2 68.9 3.3 1919 67.3 80.8 76.2 76.8 -8.9 4 1920 75.1 78.9 73.6 82.2 1.5 -3.3 1921 74.8 73.7 76.0 66.9 -1.2 6.8 1922 63.8 69.6 59.9 74.2 3.9 -4.6 70.7 71.3 -.6 Mean 72.69 72.60 .09 a 4.51 z .02 Odds. . . 1.1 : 1 7925] SELECTING CORN FOR YIELD 583 TABLE E. HIGH YIELD VERSUS REID YELLOW DENT (Bushels per acre) First five years Second five years Year High Yield Reid Yellow Dent Gain H.Y. over R.Y.D. Year High Yield Reid Yellow Dent Gain H.Y. over R.Y.D. 1913 43.7 39.0 69.1 48.8 61.5 55. 1 25.6 34.1 72.5 69.3 42.7 32.3 58.7 49.9 53.2 56.0 23.4 31.5 65.7 59.5 1.0 6.7 10.4 -1.1 8.3 -0.9 2.2 2.6 6.8 9.8 1918 72.2 67.3 80.8 75.1 78.9 74.8 73.7 63.8 69.6 70.7 64.5 67.3 61.7 57.3 81.3 78.8 52.7 62.3 67.9 64.6 7.7 0.0 19.1 17.8 -2.4 -4.0 21.0 1.5 1.7 6.1 1914 . ... 1919 1915 1920 1916 1921 1917 1922 51.87 47.29 4.58 4.11 1.11 216 : 1 Mean 72.69 65.84 6.85 8.81 .78 37:1 z Odds Odds TABLE F. NON-PEDIGREE VERSUS REID YELLOW DENT (Bushels per acre) First five years Year Non- pedigree Reid Yellow Dent Gain N.P. over R.Y.D. Year Non- pedigree Reid Yellow Dent Gain N.P. over R.Y.D. 1913 36.3 42.7 -6.4 1918 69.6 64.5 5 1 1914 37.1 61.2 32.3 58.7 4.8 2.5 1919 77.0 77.4 67.3 61.7 9.7 15 7 1915 59.3 55.9 49.9 53.2 9.4 2.7 1920 69.1 78.2 57.3 81.3 11.8 -3 1 1916 . .. 56.0 27 3 56.0 23 4 0.0 3 9 1921 71.7 67 78.8 52 7 -7.1 14 3 1917 29.9 75.1 31.5 65.7 -1.6 9 4 1922 55.5 75 4 62.3 67 9 -6.8 7 5 67.9 59.5 8.4 71.8 64.6 7.2 Mean 50 60 47.29 3.31 71 27 65 84 5 43 a 4.83 7.94 70 68 Odds 29: 1 Odds 29:1 Second five years AUTHOR INDEX 585 AUTHOR INDEX PAGE Bonnen, C. A., and Eauchenstein, Emil. Successful Threshing Ring Management 373-404 Brunson, Arthur M., and Smith, Louie H. An Experiment in Selecting Corn for Yield by the Method of the Ear-Row Breeding Plot 567-84 Case, H. C. M., and Myers, K. H. Cattle Feeding in Relation to Farm Management 213-44 Crawford, C. W., and Edmonds, J. L. Feeding Purebred Draft Fillies 245-60 Davidson, F. A. Measuring the Breeding Value of Dairy Sires by the Records of Their First Few Advanced Registry Daughters 543-66 Davidson, F. A., Overman, O. R., and Sanmann, F. P. Relation of Solids in Milk to Fat and Specific Gravity in the Milk 261-72 Dungan, G. H., Koehler, Benja- min, and Holbert, J. R. Fac- tors Influencing Lodging in Corn 309-72 Dungan, G. H., McKinney, H. H., and .Webb, R. W. Wheat Rosette and Its Control. . .273-96 Edmonds, J. L., and Crawford, C. W. Feeding Purebred Draft Fillies 245-60 Gaines, W. L., and Nevens, W. B. The Sunflower as a Silage Crop : Composition and Yield at Different Stages of Ma- turity 405-56 Harland, M. B., and Wimer, D. C. The Cultivation of Corn: Weed Control vs. Moisture Conservation 173-96 Holbert, J. R., Koehler, Benja- min, and Dungan, G. H. Fac- tors Influencing Lodging in Corn 309-72 Kammlade, W. G., and Mackey, A. K. The Soybean Crop for Fattening Western Lambs ..197-212 PAGE Keith, M. Helen. Bibliography of Researches Bearing on the Composition and Nutritive Value of Corn and Corn Products 1-152 Koehler, Benjamin, Dungan, G. H., and Holbert, J. R. Fac- * tors Influencing Lodging in Corn 309-72 Mackey, A. K., and Kammlade, W. G. The Soybean Crop for Fattening Western Lambs 197-212 McKinney, H. H., Webb, R. W., and Dungan, G. H. Wheat Rosette and Its Control. . .273-96 Myers, K. H., and Case, H. C. M. Cattle Feeding in Relation- ship to Farm Management. 2 13-44 Nevens, W. B., and Gaines, W. L. The Sunflower as- a Silage Crop: Composition and Yield at Different Stages of Ma- turity 405-56 Overman, O. R., Davidson, F. A., and Sanmann, F. P. Relation of Solids in Milk to Fat and Specific Gravity of the Milk 261-72 Plunkett, O. A., and Stevens, Frank Lincoln. Tulip Blos- som Blight 297-308 Rauchenstein, Emil, and Bonnen, C. A. Successful Threshing Ring Management 373-404 Ross, H. A. The Marketing of Milk in the Chicago Dairy District 457-540 Sanmann, F. P., Overman, O. R., and Davidson, F. A. Rela- tion of Solids in Milk to Fat and Specific Gravity in the Milk 261-72 Smith, Louie H., and Brunson, Arthur M. An Experiment in Selecting Corn for Yield by the Method of the Ear- Row Breeding Plot 567-84 583 AUTHOR INDEX PAGE PAGE Smith, Raymond S. Experiments Webb, R. W., McKinney, H. H., with Subsoiling, Deep Till- and Dungan, G. H. Wheat ing, and Subsoil Dynamit- Rosette and Its Control. . .273-96 ing 153-72 Wimer, D. C., and Harland, M. B., Stevens, Frank Lincoln, and The Cultivation of Corn : Plunkett, O. A. Tulip Bios- Weed Control vs. Moisture som Blight ,297-308 Conservation 173-96 INDEX 587 INDEX (The headings in capitals are subjects of entire bulletins) PAGE Alfalfa hay vs. soybean hay in feeding lambs . : 201, 205 Aplanobacter stewarti 366 Barley, Literature on studies of at different stages 452 Black-bundle disease, cause of broken stalks in corn 333 Blight, see Tulip blossom blight Bulls, see Dairy sires Butterfat market in Chicago dis- trict 531-32, 540 Buttermilk, Consumption in Chi- cago 491-97 Use of surplus milk for 521, 522 Cane, sugar, Disease of similar to wheat rosette 283 Cannery refuse, Bibliography on feeding 132 CATTLE FEEDING IN EELA- " TION TO FARM MAN- AGEMENT 213-43 Cost of producing beef 219-33 how determined 220-21 reduction thru use of rough- age 231-32 relation to other farm costs 232-33 relative importance of items of expense ; 221-24 variation on different farms 228-30 variation with size of cattle 225-28 Necessary margin in 230-31 Place of feeding on corn-belt farms 234-42 effect on farm as a whole. 241-42 maintains fertility 240-41 reduces cost of other enter- prises 240 utilizes farm-raised crops. 235-37 utilizes labor often wasted 237-39 Summary of study 215 Cephalosporium acrcmonium Corda 322-23, 333, 366, 369 Cerealine feed, Bibliography on feeding 132 Cheese, Price of milk for. 528-30, 539 Utilization of surplus milk as ... ..521-22 PAGE Chicago dairy district, Expansion of 469 Factors retarding extension of 473-78 increased use of trucks. . .476-78 large investments in coun- try 473-75 limitation of direct ship- ment 475-76 Intensity of dairying in inner and outer 478-79 Milk production in 479-89 seasonal production and price 487-89 seasonal variation 483-87 variation from year to year 480-83 Regional production in 469-71 Transportation costs in 471-73 Chicago cream, Consumption of 489-500 Chicago maize feed, Bibliography on feeding 132 Chicago milk consumption, As affected by price.... 503-10 As affected by temperature . 500-503 In different sections of city. 490-93 Long-time trend of 494-95 Per capita 489-90 Ratio of pints to quarts. 490-92, 538 Relation of to consumption of cream 492-93 Seasonal variation in 495-98 Variation by days of week. 498-500 Chicago milk distribution, Cost of 512-13 Chicago milk distributors 463-69 Bottle exchange of 467-69, 537 Decrease in number of 464 Types of 465-67 Variation in size of companies 465 Chicago milk prices, Effect of alternative markets on... 527-32 Effect of on consumption. . .503-10 Factors determining 532-33 Relation of to prices for cream 523-25 Tables showing 536-40 Trend of in Chicago 526-33 Chicago surplus milk 510-35 Amount necessary to carry. . . . 519 588 INDEX PAGE Daily variation in amount of 516-19 Relation between prices of sweet cream and whole milk 523-25 Relation between size of busi- ness and amount of 513-15 Seasonal variation in amount of 515-16 Utilization of 519-25 Variation in from year to year 511-13 Waste of surplus skim milk . . 522-23 Clover, Literature on studies of at different stages 452 Condensed milk, Utilization of surplus milk as 521-22 Condensery prices for milk in Chicago 527, 538 CORN, AN EXPERIMENT IN SELECTING FOR YIELD BY THE METHOD OF THE EAR-ROW BREEDING PLOT 565-83 Bibliography 579 Conclusions 578 Discussion of 577-78 Investigations at other Sta- tions 567-68 Plan of investigations 568-72 Results 572-76 Summary 566 Corn, Breeding of, see Corn, An experiment in selecting Comparison of nutritive yields of sunflowers and 434-35 Cultivation of 173-96 Literature on studies of at different stages 449-52 Lodging of, see Lodging Root systems of, Relation to leaning and pulling resist- ance 357-64 CORN AND CORN PRODUCTS, BIBLIOGRAPHY ON RE- SEARCHES BEARING ON THE COMPOSITION AND NUTRITIVE VALUE OF... 1-151 Analytical determinations. . .94-100 Balance experiments 138-39 Books, pamphlets, and articles on 150 Chemical composition of, Spe- cific effects of 142^44 Comparisons of white and yel- low corn 108 Composition of, Conditions affecting 100-104 Corn breakfast foods, Studies of . . 106 PAGE Corn cobs, Studies of 107 Corn oil, Studies of 104 Corn pollen, Studies of 107 Corn proteins, Studies of 105 Corn starch, Studies of 106 Corn sugar, Studies of 106 Digestion experiments with. 132-37 Energy metabolism of animals fed on 139 Energy values of 104 Enzymic digestion of 104 Feeding tests with 109-32 Nutritive value of, Studies of conditions affecting 13942 Other studies with animals .... 149 Physiological and anatomical effects of 145-48 Pop corn, Studies of 106 Silo, Studies of processes and agents working in 107 Spoilage of, Studies of 108 Cost accounting, Plan of studies in Hancock county 218 Study of in beef production219-43 Value of in analyzing busi- ness 242-43 Cream, Butterfat market for.. 531-32 Consumption in Chicago. . .489-500 Relation between prices of whole milk and 523-25 Utilization of surplus milk as 519 CULTIVATION OF CORN. . .173-96 Early experiments on depth, frequency, and root prun- ing ..177-78 Experiments on free growth of weeds, surface scraping, and shallow cultivation 191-96 Experiments on value of seed- bed preparation, irrigation, and fertilizing 179-89, 191 Need no greater in dry years!83-84 Purpose of 175 Shallow, Advantages of 175-77 Summary of experiments 174 DAIRY SIRES, MEASURING THE BREEDING VALUE OF BY THE RECORDS OF THEIR FIRST FEW ADVANCED REGISTRY DAUGHTERS 543-66 Bibliography 565 Conclusions 56465 Discussion of results 556-60 Method, Application of 564 Derivation of 560-61 Number of daughters necessary to measure value of sire. . . . 548 Outline of investigation 546-55 INDEX 589 PAGE Smallest number of daughters whose production will ap- proximate that of large num- ber 548-51 Source of data 546 Diplodia zeae 3 ! 14 7 21 > 333 > 369 Distillers ' grains, Bibliography on feeding 136 Distillery refuse, Bibliography on feeding 136 Slop, Bibliography on feeding 136 Dynamite for subsoiling, Cost of 170 Effect on subsoils 157 Experiments in Kansas 157 Experiments on Toledo field. 161-67 For fruit trees 158 Practical for true hardpan 165 Ear-row method of breeding, see Corn, An experiment in select- ing ECONOMIC FACTORS IN CAT- TLE FEEDING: FEEDING IN RELATION TO FARM MANAGEMENT 213-43 Evaporated milk, Utilization of surplus milk as 521-22 EXPERIMENT IN SELECT- ING CORN FOR YIELD BY THE METHOD OF THE EAR-ROW BREEDING PLOT 565-83 FACTORS INFLUENCING LODGING IN CORN 309-71 Fairfield experiment field, Culti- vation experiments on 191 Farm management, Cattle feeding in relation to . . 218-i3 Feed costs, Method of calculat- ing 208-11, 258-59 Feeding, Advantages in cattle . . . 243 FEEDING PUREBRED DRAFT FILLIES 245-60 Feeding sovbeans to lambs . . . 197-211 FILLIES," FEEDING PURE- BRED DRAFT 245-60 Development of fillies 255-56 Feeds, amounts used 249-54 cost of 257-59 kinds of 248 method of calculating cost of per head 258-59 Plan of experiment 247 Shelter and care : 249 Summary of experiment ... 246, 260 Summary of previous experi- ments 259-60 Value of pasture 25455 Foot rot of wheat 290 See Wheat rosette Fruit trees, Effect of dynamiting subsoil for . . . 158 PAGE Fusarium moniliforme 314-15, 333, 369 Germ oil meal, Bibliography on feeding 136 Gibberella saubinetii 328-32, 333, 337, 344, 369 Gluten feed, Bibliography on feeding 136 Meal, Bibliography on feeding 137 Guernsey milk yields, Age correc- tion for 562 Hancock county, Types of farm- ing in 217 Cost accounting studies in.... 218 Cattle-feeding cost studies in 219-43 "Hardpan," So-called in Illinois not true 165 Hclminthosporium sativum, Ex- periments in relationship with wheat rosette. . .282, 283-92, 278-79 Hessian fly injury, Resemblance to wheat rosette 282 Not cause of rosette 283 Hominy chop, feed, and meal, Bibliography on feeding 137 Horses, see Fillies Irrigation, Effect of on weeds and corn 187 Jersey milk vields, Age correction for 563 Kaffir corn, Literature on studies of at different stages 452 Kans. Exp. Sta., Experiments with dynamiting . ; 157 Lambs, Fattening with soy- beans 197-211 Limestone, Effect of on lodging in corn 344-51 Linseed oil meal vs. soybean oil meal 203, 205-06 LODGING IN CORN, FACTORS INFLUENCING ....309-71 Bibliography 371 Comparisons of leaning in self- fertilized strains 354-64 Comparison of stalk breaking in self -fertilized strains 364-69 Methods of experiments. .. .311-14 Nonparasitic factors affecting differences in strains 334-35 previous cropping 33944 rate of planting 338-39 soil treatments 34451 time of planting 335-38 yield 351-54 Parasitic factors, Effect of on broken stalks infected seed 332-33 starchy scutellum-infected seed . 334 590 INDEX PAGE Effect of on leaning Cephalosporium 322-23 Diplodium 314-21 Fusarium 31415 Gibberella 328-32 scutellum 323-28 Summary 369-70 Lucern, Literature on studies of at different stages 452 Macon county experiment on in- fluence of limestone on lodg- ing of corn 345 ' ' Maize-cake, ' ' Bibliography on feeding 137 Maizena, Bibliography on feeding 137 MARKETING OF MILK IN THE CHICAGO DAIRY DIS- TRICT 457-540 Conclusions 533-34 MEASURING THE BREEDING VALUE OF DAIRY SIRES BY THE RECORDS OF THEIR FIRST FEW ADVANCED REGISTRY DAUGHTERS. 543-66 Milk dealers' bottle exchange 467-69, 537 Can exchange 469 Milk distribution, Cost of 512-13 Milk drivers' wage in Chicago. 512-13 Milk powder, Utilization of sur- plus milk as 521-22 Milk production, marketing, and consumption in Chicago dairy district, see Chicago MILK, RELATION OF SOLIDS IN TO FAT AND SPECIFIC GRAVITY OF THE MILK. 261-71 Bibliography 271 Conclusions 270 Plan of investigation 264-65 Results 265-69 Summary 269-70 Milk tank car, Use of in Chi- cago district . . . .471-73, 476, 478 Milk yields, Age correction fac- tors for 562-63 Mosaic disease, Resemblance of to wheat rosette 282-83, 291 Nematode disease of wheat, Re- semblance of to wheat rosette 282 "New corn product," Bibliogra- phy on feeding 137 Nutrition experiments with corn and corn products, Bibliogra- phy on 109-49 Oat straw vs. soybean straw in feeding lambs 206 Oats, Literature on studies of at different stages 452 PAGE Odin experiment field, Plowing and dynamiting experiments at 158-61 Ohio Exp. Sta., Plowing experi- ments at 156 Ophiobolus graminis 275, 278 Pa. Exp. Sta., Plowing experi- ments at 156-57 Pasteurizing plants in Chicago . . 464 Pasture, Value for fillies 254-55 Phytophthora cactorum 306, 307 Plowing, Cost of deep 155, 170 Effect of deep on drainage 154, 166-67 Experiments in Illinois 158-69 summary of 154 Experiments in other states. 156-57 Purpose of 155 Pop Corn, Bibliography on stud- ies of 106 RELATION OF SOLIDS IN MILK TO FAT AND SPE- CIFIC GRAVITY OF THE MILK 261-71 Ehisopus spp 323 Rock phosphate, Effect of on lodging in corn 345 Rosette disease, see Wheat rosette Rye, Literature on studies of at different stages 452 Scutellum rot, Influence of on breaking in corn stalks. 333, 337 Influence of on leaning in corn 323-28 Silage, Sunflower 405-55 Silo, Bibliography on processes and agents working in 107 Skim milk, Waste of surplus in Chicago 522-23 Sorghum, Literature on studies of at different stages 452 SOYBEAN CROP FOR FAT- TENING WESTERN LAMBS 197-211 Calculating cost of gains. . .208 11 Ground beans vs. whole 201 Hay vs. alfalfa hay 201, 205 Hay vs. straw 203 Meal vs. whole or ground beans 201-03, 205 Oil meal vs. linseed oil meal 203, 205-06 Plan of experiments 199-200, 203-05 Straw vs. oat straw 206 Summary and conclusions.... 199, 206-08 Subsoil, Effect of tight clay on plants' sensitiveness to drouth 160, 163 INDEX 591 Subsoiling, see Plowing SUBSOILING, DEEP TILLING, AND SUBSOIL DYNAMIT- ING, EXPERIMENTS WITH 153-70 SUCCESSFUL THRESHING RING MANAGEMENT... 373-403 SUNFLOWER AS A SILAGE CROP: Composition and Yield at Different Stages of Ma- turity 405-55 Bibliography 45455 Comparative yields and compo- sition of sunflowers and corn ' 434-35 Composition of crop 429-34 Fertility removed by 436-42 Growth, Mathematical expres- sion of 415-29 Objects and plan of investiga- tion . . . 408-11 Review of previous literature on 447-53 Summary and conclusions. . .445-47 Thickness of planting, Effect of 442-43 Time of planting, Effect of. .443-45 Yield of crop 411-15 as ensiled 429-34 indigestible nutrients . . .435-36 Surplus milk, Problem of in Chicago 510-35 Sweet clover pasture for fillies. 252-56 Take-all disease, distinct from rosette of wheat 275, 278, 282 Temperature, Effect of on milk consumption iu Chicago. . . .500-503 Threshing, Survey of Acreages threshed by machines of various sizes 377-78 Organization of labor 385-88 Proportionate cost of to pro- duction 375 Summary of time requirements 389 Variation in labor require- ments 379-84 Threshing machines, Acreages threshed by various sized. 377-78 Advantages of large and small 389-91 Ownership of by threshing rings 397-403 Size of tractors needed for vari- ous sized 378-79 PAGE Threshing ring management, La- bor settlements in 391-97 Methods of securing data on . . 376 Ownership of machines. .. .397-403 written agreements for.. 401-403 Summary of study of 374 Tilling, deep, Use of machine for 162-63 See also Plowing Toledo experiment field, Plowing and dynamiting experiments at 161-67 Tractors, Number of in Illinois. . 375 Ownership of in threshing rings 397 Sizes used with various sized threshing machines .' . . . .378-79 Trucks, Use of in hauling milk to Chicago 476-78 TULIP BLOSSOM BLIGHT. 297-307 Causal organism 301 cultural characters of .... 305-306 description of 303-305 taxonomic position of 306 Influence of environment on ... 301 Inoculation studies of 301-03 Recommendations for 307 Summary of study 307 Symptoms of 301 Urbana experiment field, Experi- ments on Cultivation 177-90, 191-96 Lodging of corn 339-44, 345 Plowing 167-70 Weeds, Effect of on corn yields 176-77 Experiments in, see Cultiva- tion of corn Wheat, Literature on studies of at different stages 452 WHEAT ROSETTE AND ITS CONTROL .273-96 Bibliography 296 Cause of 283-92 Cell inclusions 292 Conclusions 295 Control by resistant varie- ties 292-95 Crops affected by 277 Distribution of 275-76 Losses caused by 276-77 Resistant varieties of wheat . . . 294 Spread of disease 292 Summary 274 Symptoms 277-83 I Hi 1927 ? ? Ml UNIVERSITY OF ILLINOIS-URBANA