UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN ACES 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 The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Thett, mutilation, and underlining of books ^.f nary action and may result in dismissal from the Un To renew call Telephone Center, 333-8400 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN L161O1096 ACES SI JUN 1 6 2005 UNIVERSITY OF ILLINOIS Agricultural Experiment Station. BULLETIN NO. TOO. DIRECTIONS FOR THE BREEDING OF CORN, INCLUDING METHODS FOR THE PRE- VENTION OF IN-BREEDING BY CYRIL G. HOPKINS, LOUIE H. SMITH, AND EDWARD M. EAST. URBANA, ILLINOIS, MARCH, 1905. SUMMARY OF BULUETIN No. 100. 1. Nine years of corn breeding at the Illinois Experiment Station have proven the possibilities of corn improvement in both yield and quality. Page 601. 2. The investigations have shown that continued cross-breeding by detasseling alternate rows in the breeding plot increases the yield of corn more than 10 bushels after the first year. Page 610. 3. A method has been worked out and adopted which gives a perpetual system of planting designed to avoid in-breeding. Page 617. 4. All seed corn selected is produced by cross-breeding. Page 616. 5. Breeding plots should be started with the best obtainable seed corn. It is recommended that ninety-six ears be planted in the breeding plot. Plant by the row system, that is, corn from a single ear in each row. Page 614. 6. Examination of seed corn for improvement in composition may be made by mechanical methods described. Page 611. 7. The Experiment Station offers to analyze composite samples of the seed and crop from breeding plots for systematic corn breeders of Illinois. Page 614. 8. Plant corn from detasseled rows, according to a guide system for both "sire" and "dam" seed. Detassel all even-numbered rows. Select seed only from the best-yielding detasseled rows. Page 619. 9. Mix all good selected seed not required for the breeding plot, and plant in a multiplying plot. Page 621 . 10. Plant commercial fields, from which to sell pedigreed seed corn, from the best seed obtained from the multiplying plot. Page 621. 11. Keep a pedigree register of all seed ears planted and of all rows harvested in the breeding plot. The Experiment Station will furnish blank forms to any Illinois farmer who wishes to become a seed corn breeder. Page 620. 12. The Illinois Agricultural Experiment Station has no seed corn for sale. Page 623. 13. This bulletin will be sent free of charge to any one interested in Illinois agriculture upon request to E. Davenport, Director, Agricultural Experiment Station, Urbana, Illinois; and, if so requested, the name of the applicant will be placed upon the permanent mailing list of the Experiment Station, so that all bulletins will be sent to him as they are issued. DIRECTIONS FOR THE BREEDING OF CORN, INCLUDING METHODS FOR THE PRE- VENTION OF IN-BREEDING BY CYRIL G. HOPKINS, CHIEF IN AGRONOMY, LOUIE H. SMITH, CHIEF ASSISTANT IN PLANT BREEDING, AND EDWARD M. EAST, FIRST ASSISTANT IN PLANT BREEDING. It is now nine yea/s since one of the writers began investigations with a view to the improvement of corn by breeding. Credit belongs to Dr. T. J. Burrill and to Director Eugene Davenport for the original suggestions as to the possibilities of such improvement and its impor- tance to the industries related to corn. The investigations have included the breeding of corn for increased yield and for improved quality; and the results which have been achieved have far surpassed our original expectations; for not only was it discovered and clearly established that corn could be bred for increased power to yield and for higher protein con- tent or higher oil content, as may be desired, but, as soon as these practical scientific facts were fully ascertained and the methods of corn breeding worked out, progressive seed corn growers of Illinois united themselves into the world's first seed corn breeders association, and at once began the business of corn breeding on a commercial scale. Subsequently seed corn breeders associations have been organized in nearly every important corn-growing state. The Illinois Seed Corn Breeders Association was organized in 1900 and began breeding corn in 1901. At the same time the Illinois Experi- ment Station began searching for possible obstacles, or improvements, in the methods of corn breeding which we had employed, and which had been adopted by the commercial corn breeders. The most important improvement which we have thus far made in the system of corn breeding is that which relates to the prevention of in-breeding. In the row system of corn breeding, in which each field row is planted with seed from a separate ear, the performance record of the plants from each individual seed ear can be observed and accurately measured; and it thus becomes possible to base our subsequent seed selected upon the performance records of the progeny from individual mother ears. In this system of planting we not only have the usual possibility of corn being self-pollinated, but we have an unusual possibility of consid- erable corn being close-pollinated. (In self-pollination the pollen from 601 602 BULLETIN No. 100. [March, a given tassel falls upon the silk of the same plant. In close-pollination the pollen from a given plant falls upon the silk of another plant in the same row, both of which grew from seed from the same mother ear. In cross-pollination the pollen from the tassel of one plant falls upon the silk of another plant in a different field row, which grew from seed from a different mother ear.) Because of the well-known principle, established by the investiga- tions of Darwin and others, that injurious effects are produced from the self-pollination of plants which are naturally cross-pollinated, many investigators have conducted miscellaneous detasseling experiments in corn growing, during the past twenty years or more. The plan com- monly followed has been to detassel alternate rows in an ordinary corn field and to compare the yields of the tasseled and detasseled rows. The combined data from all such experiments point tq no marked effect pro- duced by detasseling. In the investigations which we have carried on at the Illinois Station during the past four years, including one year's work on a small scale, we have systematically detasseled the even-numbered rows in breeding plots and have then successively planted the even-numbered rows with seed selected from the best detasseled rows and have planted the odd- numbered rows with seed selected from the highest yielding tasseled rows. For three years this system has been practised on two large breeding plots, containing 44 field rows in each plot,* the two plots being conducted entirely independent of each other. The system in each of these plots is really a double system, one set of 22 rows being conducted without detasseling, in all respects like an independent breeding plot of 22 rows, the seed being saved each year from the 10 highest yielding rows. But alternating with these tasseled rows were detasseled rows of corn, which however could scarcely exert any influence upon the breeding of the tasseled rows. On the other hand, the 22 detasseled rows are necessarily cross-bred each year, although it should be borne in mind that the pollen for these detasseled rows was always furnished by the 22 tasseled rows, which are themselves becoming more or less in-bred. If benefits are produced from this imperfect system of cross-breeding, which we were compelled to adopt in order to obtain comparative data from alternating rows in the same field, it seems probable that even greater benefit will result from a practical commercial system which we have now adopted in which the seed for both sire and dam is cross-bred. The results obtained from three years' work with these two large breeding plots are given in detail in Tables 1 to 6. For detailed comparison there are given from every individual row in each plot in each year the actual yield, the actual increase in yield, *Only 40 rows the first year. 1905] DIRECTIONS FOR BREEDING OF CORN. 603 the percent of stand, and the yield and increase in yield calculated to 100 percent stand. Where there was a lower yield from the detasseled row it is indicated by the minus ( ) sign. There is also given the average of the tasseled rows and of the detasseled rows, for each plot and for each of the three years, 1902, 1903, and 1904. The register number and the dam number of each seed ear are given. These numbers also show the field row in which each ear grew, the row in which each seed ear is planted, and the number of years it has been bred, as fully explained in the following pages. For example the last row in the high-protein plot in 1904 (see Table 3) produced 100.8 bushels of corn, actual yield per acre, with 96.4 percent stand, which would make 104.6 bushels if calculated to 100 percent stand. The register number of the seed ear which was planted in this row is 344, which means year 3 in the history of its breeding and row 44 in which it was planted. This seed ear was produced the previous year (year 2 of its breeding) in row 34 of the breeding plot as shown by the dam number 234. Referring to Table 2 we find that row 34 produced 80.8 bushels of corn per acre in 1903, and that ear 234 grew in row 12 the previous year, as shown by the dam number 112. In Table 1 we see that row 12 produced 88.5 bushels of corn per acre in 1902. Thus we have the complete pedigree: Ear No. 344 (in year 3, row 44) produced 100.8 bushels. The dam, Ear No. 234 (in year 2, row 34) produced 80.8 bushels. The grand dam, Ear No. 112 (in year 1, row 12) produced 88.5 bushels. The results reported in columns 3 and 6 in the tables, under the heading "Bushels increase by detasseling" are obtained by comparing the weight of each row with the average of the two adjoining rows, ex- cept with the first and last rows, which are compared with the one adjoin- ing row. 604 BULLETIN No. 100. [March, TABLE 1. EFFECT OF DETASSELING; FIRST YEAR'S BREEDING. High-Protein Learning; Mechanical Selection; Grown in 1902. Dam No. Register No. Calculated to actual stand. Percent of stand. Calculated to 100 percent stand. Corn, bushels per acre. Bushels increase by detas- seling. Corn, bushels per acre. Bushels increase by detas- seling. 101 102 103 104 81.8 74.3 82.5 83.5 ' -7.5 -7.9 -3.6 49 97.5 94.5 97.0 99.6 83.9 78.6 85.1 83.8 -5.3 -5.9 -3.9 3.4 105 106 107 108 74.6 82.6 86.4 86.0 85 2.1 -2.1 32 98.7 96.2 97.5 96.2 75.6 85.9 88.6 89.4 14.3 38 -0.9 1.3 109 110 111 112 79.1 85.6 81.3 88.5 6.7 5.4 58 5.3 90.3 99.1 97.0 98.3 87.6 86.4 83.8 90.0 0.3 0.7 4.4 5.5 113 114 115 116 85.1 88.0 78.4 85.0 3.2 6.2 8.1 3.5 100.0 99.1 99.6 98.7 85.1 88.8 78.7 86.1 4.3 6.9 8.8 41 117 118 119 120 84.5 87.1 81.1 89.2 -1.4 -1.7 4.1 56 99.1 96.2 89.8 99.1 85.3 84.3 90.3 90.0 O.I -3.5 -3.1 1.7 121 122 123 124 86.0 89.4 88.0 84.1 3.3 2.4 -1.2 -3.6 99.6 100.0 100.0 98.3 86.3 89.4 88.0 85.6 3.4 22 -0.5 -7.5 125 126 127 128 87.3 85.6 80.4 86.9 -2.4 1.7 5.9 6.5 89.0 99.6 98.7 96.2 98.1 85.9 81.5 90.3 -12.3 -3.9 6.7 7.0 129 130 131 132 80.4 84.2 78.3 76.3 5.2 48 20 -1.8 94.5 98.7 94.5 100.0 55.1 85.3 82.9 ?6.3 2.7 13 -2.1 -5.5 133 134 135 136 77.9 85.1 86.9 80.8 28 2.7 -3.9 -4.6 96.6 98.7 99.1 98.3 80.6 86.2 87.7 82.2 07 20 -3.5 -3.8 137 138 139 140 83.9 78.3 86.1 81.9 -4.3 -6.7 -6.0 -4.2 99.6 95.3 97.5 100.0 84.2 82.2 88.3 81.9 -2.0 -4.1 -6.2 -6.4 Average of detasseled, 84.1 Average of tasseled, 82.5 85.4 85.3 Average increase, 1 . 6 0.1 1905] DIRECTIONS FOR BREEDING OF CORN. 605 TABLE 2. EFFECT OF DETASSELING; SECOND YEAR'S BREEDING. High-Protein Learning; Mechanical Selection; Grown in 1903. Dam No. Register No. Calculated to actual ctand. Percent of stand. Calculated to 100 percent stand. Corn, bushels per acre. Bushels increase by detas- seling. Corn, bushels per acre. Bushels increase by detas- seling. 103 122 117 108 201 202 203 204 63.3 60.4 51.0 70.5 -2.9 3.2 14.5 17.9 98.6 96.8 90.9 97.3 64.2 62.4 56.1 72.5 -1.8 22 II. 4 16 1 135 114 103 126 205 206 207 208 54.1 70.0 60.6 75.7 16.2 12.6 12.3 15.9 95.5 98.2 97.3 99.1 56.7 71.3 62.3 76.4 15.2 11.8 11.6 14.7 117 108 135 114 209 210 211 212 58.9 70.0 55.2 68.1 14.0 12.9 13.9 6.0 96.4 98.6 94.1 96.4 61.1 71.0 58.7 70.6 12.6 III 12.1 6.0 107 126 121 108 213 214 215 216 68.9 76.8 37.4 77.7 3.6 23.6 39.9 26.1 97.7 95.0 50.9* 95.9 70.5 80.8 73.5 81.0 5.2 88 7.4 9.9 137 116 107 128 217 218 219 220 65.8 73.6 63.9 67.4 99 87 66 -1.9 95.9 98.6 96.4 95.9 68.6 74.6 66.3 70.3 92 7.1 62 -0.6 121 110 137 116 221 222 223 224 74.7 74.0 56.8 71.5 -4.0 82 16 2.2 99.1 98.6 96.8 95.9 75.4 75.0 58.7 74.6 -2.7 7.9 16.1 2.6 107 128 123 110 225 226 227 228 81.8 81.3 56.3 70.3 -5.4 12 2 19 5 10 4 95.9 98.2 93.2 96.4 85.3 82.8 60.4 72.9 -6.6 9.9 17.5 9.3 139 120 113 134 229 230 231 232 63.4 77.7 54.8 64.9 10.6 18 6 16.5 4.7 95.0 97.3 94.5 95.0 66.7 79.9 58.0 68.3 9.7 17.5 16.1 4.6 125 112 123 120 233 234 235 236 65.6 80.8 51.5 64.9 7.3 22.2 21.4 3.2 94.5 99.5 93.2 97.3 69.4 81.2 55.3 66.7 5 4 18.8 18.7 28 139 112 125 120 237 238 239 240 71.8 69.4 53.9 65.0 -4.1 6.5 13.3 4.5 99.1 97.3 96.4 97.3 72.5 71.3 55.9 66.8 -3.5 7.1 13.2 4.5 113 134 139 122 241 242 243 244 67.1 73.8 61.4 81.2 2.3 9.5 16.1 19.8 97.7 95.5 98.6 98.2 68.7 77.3 69.3 82.7 3.4 8.3 10.7 13.4 Average of detasseled, 72.0 Average of tasseled, 61 . 9 74.1 64.8 Average increase, 10.1 9.3 * Yields discarded from average (one row). 606 BULLETIN No. 100. [March, TABLE 3. EFFECT OF DETASSELING; THIRD YEAR'S BREEDING. High-Protein Learning; Mechanical Selection; Grown in 1904. Dam No. Register No. Calculated to actual stand. Percent of stand. Calculated to 100 percent stand. Corn, bushels per acre. Bushels increase by detas- seling. Corn, bushels per acre. Bushels increase by detas- seling. 219 214 213 244 301 302 303 304 81.5 90.9 75.7 86.9 94 12.3 13 2 10.6 97.7 98.6 98.2 95.0 83.4 92.2 77.1 91.5 88 II. 1 14 8 10.9 201 208 241 234 305 306 307 308 76.8 100.0 82.8 90.1 16.7 20 2 12.3 10 5 91.4 98.6 95.9 98.2 84.0 101.4 86.3 91.8 12.5 16.2 10.3 9.2 217 242 233 208 309 310 311 312 76.3 88.5 56.8 91.5 13.0 21 9 33.2 22 2 96.8 98.6 64.1* 98.6 78.8 89.8 88.6 92.8 12.0 6.1 2.7 4.4 213 244 237 222 313 314 315 316 81.8 96.5 76.7 88.9 12 2 17 2 16 4.3 92.7 94.1 95.9 98.6 88.2 102.6 80.0 90.2 9.5 18 5 16 4 3.5 225 214 229 242 317 318 319 320 92.5 95.6 83.0 89.2 -0.2 78 9.4 84 99.1 97.7 97.7 98.2 93.3 97.8 85.0 90.8 0.7 86 93 79 221 216 225 222 321 322 323 324 78.6 79.2 80.1 96.4 5.6 -0.2 7.7 12 6 97.3 94.1 95.0 97.3 80.8 84.2 84.3 99.1 6.7 1.6 7.4 11.3 219 230 229 218 325 326 327 328 87.5 91.6 78.7 94.0 65 85 14 1 II. 95.9 98.2 94.1 98.2 91.2 93.3 83.6 95.7 50 59 10.9 92 237 226 221 218 329 330 331 332 87.2 94.0 90.7 89.0 6.8 5.0 08 46 97.7 97.7 98.6 97.3 89.3 96.2 92.0 91.5 6.7 55 19 56 213 234 217 214 333 334 335 336 78.0 100.8 82.2 97.0 16 9 20.7 16 7 116 97.7 98.2 96.4 97.7 79.8 102.7 85.3 99.3 17 3 20 1 15 7 10 5 241 230 201 226 337 338 339 340 88.5 79.8 95.2 93.7 -0.1 -12.1 -8.4 50 95.9 87.7 97.3 97.3 92.3 91.0 97.8 96.3 29 -4.1 -4.1 50 233 216 219 234 341 342 343 344 82.1 83.5 74.7 100.8 65 5.1 17 5 26 1 96.8 90.9 96.4 96.4 84.8 91.9 77.5 104.6 93 10 7 20 8 27.1 Average of detasseled, 91 . 7 Average of tasseled, 82 . 4 94.9 85.4 Average increase, 9.3 9.5 * Yields discarded from average (one row). 1905] DIRECTIONS FOR BREEDING OP CORN. 607 TABLE 4. EFFECT OF DETASSELING; FIRST YEAR'S BREEDING. Low-Protein Learning; Mechanical Selection; Grown in 1902. Dam No. Register No. Calculated to actual stand. Percent of stand. Calculated to 100 percent stand. Corn, bushels per acre. Bushels increase by detas- seling. Corn, bushels per acre. Bushels increase by detas- seling. 101 102 103 104 45.6 41.6 64.1 52.3 -4.0 -13.3 -17.1 .-12.2 80.5 67.3* 88.1 84.7 56.6 61.8 72.8 61.8 5.2 -2.9 -11.0 -11.1 105 106 107 108 64.8 63.7 66.4 62.0 -6.8 -1.9 -3.5 -1.4 88.9 92.3 90.0 85.2 72.9 69.0 73.8 72.8 -7.5 -4.4 -2.9 1.4 109 110 111 112 60.4 53.4 58.5 54.5 -2.7 -6.1 -4.5 -2.6 87.7 77.9* 48.7* 83.5 69.8 68.5 120.1 65.3 1.8 -26.0 -53.2 -30.5 113 114 115 116 55.7 61.8 56.1 61.4 2.5 5.9 5.5 -1.7 77.9* 88.6 83.5 90.7 71.5 69.8 67.2 67.7 -3.9 0.4 1.6 -3.3 117 118 119 120 70.0 57.2 71.0 60.6 -10.7 -12.3 -12.1 2.9 93.6 85.2 86.0 86.0 74.8 67.1 82.6 70.5 -7.4 -11.6 -13.8 -9.6 121 122 123 124 44.3 50.1 45.2 61.2 II. 1 5.3 10.5 16.1 57.2* 87.7 60.2* 86.9 77.5 57.1 75.1 70.4 -13.7 -19.2 -11.3 1.6 125 126 127 128 45.0 50.0 45.8 47.2 10.6 4.6 2.8 2.8 72.0* 77.5* 80.5 73.7* 62.5 64.5 56.9 64.0 5.0 48 7.4 -0.6 129 130 131 132 42.9 48.4 53.8 41.5 4.9 0.0 -8.8 -17.4 59.3* 83.9 75.8* 69.5* 72.3 57.7 71.0 59.7 -11.4 -14.0 -12.3 -11.9 133 134 135 136 64.0 50.4 57.7 53.6 -18.0 -10.5 -5.7 -4.9 88.6 84.7 84.7 83.1 72.2 59.5 68.1 64.5 -17.6 -0.7 -6.1 -5.2 137 138 139 140 59.2 56.1 64.4 56.8 -4.3 -5.7 -7.9 -7.6 83.1 83.1 84.3 74.1* 71.2 67.5 76.4 76.7 -5.2 -6.3 -4.3 0.3 Average of detasseled, 56.6 Average of tassel ed, 60.7 65.8 70.4 Average increase, -5.9 -5.4 * Yields discarded from average (thirteen rows). BULLETIN No. 100. [March, TABLE 5. EFFECT OF DETASSELING; SECOND YEAR'S BREEDING. Low-Protein Learning; Mechanical Selection; Grown in 1903. Dam No. Register No. Calculated to actual stand. Percent of stand. Calculated to 100 percent stand. Corn, bushels per acre. Bushels increase by detas- seling. Corn, bushels per acre. Bushels increase by detas- seling. 103 114 109 124 201 202 203 204 59.4 83.7 58.2 82.5 24.3 24.9 24.9 11.9 72.7* 94.1 91.4 87.7 81.7 . 88.9 63.7 94.1 7.2 16.2 27.8 15.0 119 106 103 116 205 206 207 208 85.0 100.4 69.6 69.9 6.5 23.1 15.6 -2.6 90.0 98.2 72.3* 75.5* 94.4 102.2 96.3 92.6 3.8 6.8 |!a 109 124 133 106 209 210 211 212 75.4 100.7 93.6 74.6 9.9 16.2 -5.9 -7.9 96.4 . 100.0 90.9 87.7 78.2 100.7 103.0 85.1 18.1 10. 1 -10.1 -7.1 111 138 105 108 213 214 215 216 71.3 92.7 43.4 112.6 12.4 35.3 59.3 52.9 87.7 96.8 85.5 98.6 81.3 95.8 50.8 114.2 8.2 29.7 54.2 48.0 111 116 133 108 217 218 219 220 76.0 93.8 87.2 83.3 27.2 12.2 1.4 24.9 93.2 96.4 90.0 72.3* 81.5 97.3 96.9 115.2 24.3 8.1 9.4 18 4 137 118 105 138 221 222 223 224 29.5 104.5 87.8 94.4 64.4 45.8 11.7 19.3 30.5* 94.1 92.7 94.5 96.7 111.1 94.7 99.9 16.6 15.4 10.8 1.7 107 116 137 114 225 226 227 228 62.4 96.9 85.5 82.6 33.3 22.9 4.3 0.2 61.4* 94.1 94.5 93.6 101.6 103.0 90.5 88.3 -0.1 -6.9 5.2 3.0 117 120 109 106 229 230 231 232 . 79.3 81.9 79.0 81.3 3.0 2.7 2.6 3.7 99.1 93.2 89.5 88.2 80.0 87.9 88.3 92.2 8.1 3.7 1.8 -6.9 139 120 139 112 233 234 235 236 76.2 100.2 59.4 73.9 14.6 32.4 27.7 -0.5 92.7 95.9 65.5* 77.3* 82.2 104.5 90.7 95.6 16.2 18.0 9.4 4.0 117 140 107 118 237 238 239 240 89.4 92.9 82.3 97.8 -6.0 7.0 13.1 32.4 96.8 96.4 87.3 93.2 92.4 96.4 94.3 104.9 3.6 3.0 6.4 13.6 139 112 119 140 241 242 243 244 48.5 30.0 32.2 95.5 15.4 -10.4 30.6 63.3 55.0* 24.1* 29.5* 98.6 88.2 124.5 109.2 96.9 26.5 25.8 1.5 -12.3 Average of fletasseled, 92 . 7 Average of tasseled, 78.0 98.0 84.8 Average increase, 14.7 14.2 * Yields discarded from average (eleven rows). 1905] DIRECTIONS FOR BREEDING OF CORN. 609 TABLE 6. EFFECT OF DETASSELING; THIRD YEAR'S BREEDING. Low-Protein Learning; Mechanical Selection; Grown in 1904. Dam No. Register . No. Calculated to actual stand Percent of stand. Calculated to 100 percent stand. Corn, bushels per acre. Bushels increase by detas- seling. Corn, bushels per acre. Bushels increase by detas- seling. 219 210 231 226 301 302 303 304 56.3 73.2 61.7 84.7 16.9 14 2 17.3 25.4 90.0 97.7 94.1 96.8 62.6 74.9 65.6 87.5 12.3 10 8 15.6 23.6 205 244 219 234 305 306 307 308 56.8 73.1 69.6 68.2 22.1 9.9 II -0.4 91.4 95.5 93.6 93.2 62.1 76.5 74.4 73.2 19.9 82 05 -1.0. 227 224 231 218 309 310 311 312 67.5 80.2 64.3 77.3 6.7 14.3 14.5 4.3 91.4 97.3 93.2 96.4 73.9 82.4 68.8 80.2 3.9 II. 12.5 3.0 237 244 211 234 313 314 315 316 81.7 63.0 68.3 81.3 -11.5 -15.0 3.9 16.6 95.5 78.6* 93.2 94.6 85.5 80.2 73.3 85.9 -5.3 0.8 9.9 15.3 223 218 229 224 317 318 319 320 61.1 88.8 79.5 72.8 24.0 18.5 1.3 -0.6 90.0 96.8 93.6 96.4 67.9 91.7 84.9 75.5 20.9 15.3 -1.3 -2.4 233 210 239 226 321 322 323 324 67.3 91.2 68.3 85.7 14.7 23.4 20.2 29 7 95.0 100.0 93.2 95.9 70.8 91.2 73.3 89.4 12.6 19.1 17.0 11.7 205 240 219 222 325 326 327 328 43.7 86.4 71.4 74.8 42.4 28.8 9.2 5.9 53.2* 94.1 95.0 97.7 82.1 91.8 75.2 76.6 8.5 13 1 90 47 227 206 231 226 329 330 331 332 66.4 89.0 59.3 67.4 15.5 26 1 18 9 -0.6 96.8 98.6 93.6 81.8 68.6 90.3 63.4 82.4 14.9 24.3 23.0 II. 1 237 240 211 216 333 334 335 336 76.7 82.4 69.7 87.8 -1.8 9.2 15.4 20.3 96.8 96.4 93.6 98.6 79.2 87.1 74.5 89.0 56 10.2 13.6 17.3 223 210 229 222 337 338 339 340 65.2 78.4 77.8 85.9 17.9 69 4.4 9.3 94.6 95.9 96.4 96.4 68.9 81.8 80.7 89.1 16.5 7.0 4.8 7.7 233 206 239 216 341 342 343 344 77.3 80.2 78.5 83.9 5.8 2.3 3.6 5.4 94.1 92.7 96.4 95.0 82.1 86.5 81.4 88.3 5.7 4.7 60 6.9 Average of detasseled, 80.6 Average of tasseled, 68 . 8 84.3 73.2 Average increase, 11.8 11.1 * Yields discarded from average (two rows). 610 BULLETIN No. 100. [March, A study of the yields of individual rows shows results similar to those commonly obtained in corn breeding; namely, that each separate mother ear possesses a distinct individuality which is stamped upon the offspring, as shown by the performance record when the yield is measured. Thus, in the high-protein plot in 1902 row 5 produced 74.6 bushels and row 7 produced 86.4 bushels per acre; and in 1904 row 22 produced 79.2 bushels and row 24 produced 96.4 bushels per acre. In the high-protein plot in 1902 the average of all tasseled rows is .82.5 bushels, and the average of all detasseled rows is 84.1 bushels, showing an average increase of 1 . 6 bushels in favor of detasseling. On the low-protein plot the average increase was minus 5.9 bushels. Thus, the first year's results are similar to those commonly reported from a single year's experiment in detasseling corn, no uniform effect being produced. On the contrary, we have obtained some very striking results in 1903 and 1904, when we have the effects due to breeding for one year and two years, respectively. In 1903 the average yield of 44 tasseled rows (including both plots) was 70 . bushels, while 82 . 4 bushels was the average yield from the 44 detassel^d rows, an average increase of 12.4 bushels in favor of detasseling. In 1904 the corresponding yields were 75.6 bushels and 86.2 bushels of corn per acre, making an average increase of 10.6 bushels in favor of detasseling. This evidence in favor of detasseling the rows which are to furnish future seed seems so conclusive that we are now detasseling alternate rows in our corn breeding plots, and selecting all seed ears from detasseled rows only; and, in order to obtain the greatest possible benefit from cross-breeding of plants of no relation or of the most distant relation, we have worked out and adopted a mathematical arrangement of seed ears for planting which is designed continuously to maintain these desirable conditions. "Corn improvement should embrace both quantity and quality. But, because of the great importance of increased yield per acre, all selection looking toward improvement should be first based upon yield, this to be followed, so far as practicable, with efforts which aim toward higher standards of quality. It is with these ideas that the following methods for corn breeding are arranged. PHYSICAL SELECTION OF SEED CORN. The most perfect ears obtainable of the variety of corn which it is desired to breed should be selected. As a rule, these seed ears should be obtained from some reliable seed corn breeder in preference to starting with unknown and unimproved corn. In making the selection for desirable ears, as judged from the physical characteristics, the larger the number of ears examined the better can be the selection. If the breeder wishes to improve the quality (chemical 1905] DIRECTIONS FOR BREEDING OF CORN. 611 composition) of the grain, as well as the yield and type of his corn, it is recommended that he choose at least 200 ears of the desired physical type to be further examined as to quality. CHEMICAL SELECTION BY MECHANICAL EXAMINATION. The following table fairly illustrates the results obtained by the use of the method of mechanical examination in the selection of high-protein seed ears. TABLE 7. RESULTS OF SELECTION FOR PROTEIN IN CORN BY METHOD OF MECHANICAL EXAMINATION. ; Selected by Total number ears examined. Ears selected as high in protein. Ears Rejected as not high in protein. Number of ears. Ave. % protein. Number of ears. Ave. % protein.- 111. Exp. Station (1902) Ralph Allen (1902) .... Ralph Allen (1903) .... A. L. Woodhams . . 200 165 225 187 200 200 134 (?) 4 bushels 42 15 1-5 36 40 25 26 24 14 12 14 13.56 13.15 11.59 10.94 11.59 11.37 10.64 11.71 : 42* 150 210 151 160 175 108 (?) (?) 10.67 12.10 11.51 10 29 10.88 II 29 10.78 9.94 9.70 Hunt Bros William Berg H. A. Winter W. G. Griffith Ohio Exp. Station * Selected for low protein from same lot of 200 ears. The success of this method in the hands of several practical farmers is demonstrated. We notice that m every case there was a gain made in average protein content of the selected ears, and in some of these cases the gains were very decided. METHOD OF MECHANICAL EXAMINATION. The method of making a chemical selection of ears of seed corn by a simple mechanical examination of the kernels is based upon the fact that the kernel of corn is not homogeneous in structure, but consists of several distinct and readily observable parts of markedly different chemi- cal composition. (See Plates 1 and 2.) For a complete detailed study of " The structure of the corn kernel and the composition of its different parts," see Bulletin No. 87. For our particular purpose of judging from the structure qf the kernel as to its composition, we need consider but three principal parts, namely: 612 BULLETIN No. 100. [March, HIGH-PROTEIN KERNELS (Much horny part; little white starch). LOW-PROTEIN KERNELS (Little horny part; mugh white starch). PLATE 1. 1. The darker colored and rather horny layer lying next to the hull, principally in the edges and toward the tip end of the kernel. This part is fairly rich in protein and contains from one-half to two-thirds of all the protein of the kernel. (See Plate 1.) 1905] DIRECTIONS FOR BREEDING OF CORN. 613 HIGH-OIL KERNELS (Large germs). Low-OiL KERNELS (Small germs). PLATE 2. 2. The white, starchy-appearing part occupying the crown end of the kernel and usually also immediately surrounding, or partially 614 BULLETIN No. 100. [March, surrounding, the germ. This part is poor in both protein and oil, con- sisting mainly of starch. (See Plate 1.) 3. The germ itself, which occupies the central part of the kernel toward the tip end. This is very rich in oil.. More than four-fifths of the entire oil of the kernel resides in the germ. It is also rich in protein, containing nearly one-fifth of all the protein in the kernel, although the germ itself constitutes only about one- tenth of the weight of the kernel. (See Plate 2.) In selecting seed corn by mechanical examination for improvement in composition, we remove from the ear a few average kernels, cut these kernels into cross sections, preferably near the tip end of the kernel (see longitudinal sections), and examine these sections as they are cut, usually simply with the naked eye, selecting for seed those ears whose kernels show the qualities desired. SAMPLES FOR ANALYSIS. In order that the breeder may know what he has accomplished in his work of mechanical selection, the Experiment Station offers to analyze for any Illinois farmer who wishes to improve the quality of his corn by breeding according to these directions and who agrees to make the best selection of seed possible, two composite samples representing each of the two lots of ears; that is, the selected lot and the rejected lot. One composite sample should be made by taking 10 average kernels from each of the selected ears (96 ears preferred), and another sample should be made by taking 10 average kernels form each of the rejected ears (100 ears or more). Each of these two samples should be put in a separate sack, properly labeled, and sent to the Plant Breeding Labora- tory, Agricultural Experiment Station, Urbana, 111. Of course, if the breeder desires to breed for physical type and increased yield only, then no chemical analysis is needed, and all that is necessary to begin work is to select the 96 most nearly perfect ears obtainable for the breeding plot. SIZE OF BREEDING PLOT. The best number of ears to use in a breeding plot is as yet an unsettled question. There are several conflicting factors entering into the con- sideration. On the one hand, the smaller the number of ears taken, the choicer can be the selection of the seed planted ; while on the other hand the larger the number of breeding rows to choose from, the better can be the selection of seed for the next crop. Then again, there is undoubtedly some danger of evil effects from too close in-breeding, by the use of too small a number of ears. From our present knowledge we believe, however, that 96 ears is a safe number to use, so far as in-breeding is concerned, and this is the 1905] DIRECTIONS FOR BREEDING OF CORN. 615 number that we suggest in these directions, it being understood that alternate rows are to be detasseled and all seed corn selected from de- tasseled rows. PLANT BY THE Row SYSTEM. The 96 selected seed ears are planted in 96 separate rows. These rows should be at least 100 hills Ibng, but they may well be 40 rods long, as the amount of seed will usually permit this. It is recommended that these 96 seed ears be numbered* from 1 to 48 and from 51 to 98, the numbers 49 and 50 being omitted; also that ears 1 to 48 be planted in one half of the plot and ears 51 to 98 be planted in the other half, preferably end-to-end with the first half, leaving one hill unplanted to mark the line between the two halves, also leaving one row unplanted to mark the line between rows 24 and 25 and between rows 74 and 75; that is, between quarters. In this way row 51 (planted with seed from ear 51) is a continuation of row 1 (planted with seed from ear 1) and the two rows may well extend 80 rods, across a 40-acre field. The breeding plot can be planted with a corn planter, although it will require some time and patience, and if the planter is an edgedrop it will be necessary to put a suitable cone or inverted funnel in each seed box so as to keep the small amount of corn to the outside. Place the shelled corn from ear No. 1 in one box and from ear No. 2 in the other; drive to the middle line of the plot, thus planting rows 1 and 2; clean out the boxes; move forward one hill; put in the corn from ears 51 and 52; use the foot- trip till the corn begins to drop; then drive on and plant rows 51 and 52. Turn at the end; clean out the seed boxes ; put in ears 53 and 54; plant back to the middle ; clean out, put in ears 3 and 4, and then plant on back to the beginning line, thus continuing until the breeding plot is all planted. The planting may then be continued for the commercial field, using the same variety of corn, which should be of similar breeding, finishing, perhaps, with the multiplying plot on the opposite side of the field from the breeding plot. Each one of the breeding plot rows should be numbered to correspond with the "register number" of the ear from which it is planted, as will be explained under the heading of "Pedigree Register." The breeding plot should be well protected from foreign pollen, by being planted as far away as possible from other varieties of corn. DETASSELING. From the data which we have secured and are securing upon the subject, we now strongly recommend that every alternate row of corn in the breeding plot be completely detasseled before the pollen matures * These numbers would be 101 to 148 and 151 to 198 the first year, 201 to 248 and 251 to 298 the second year, etc., etc. (See under Register Number, page 621.) 616 BULLETIN No. 100. [March, and that all of the seed corn to be taken from the plot be selected from these 48 detasseled rows. This method absolutely prohibits self-polli- nation or close-pollination of the future seed. By self-pollination is meant the transfer of pollen from the male flower (tassel) of a given plant to the female flower (silk) of the same plant; and by close-pollination is meant the transfer of pollen from the male flower of one plant to the female flower of another plant in the same row, both of which grew from kernels from the same seed ear. It is recommended that no plants in any of the rows which appear imperfect, dwarfed, immature, barren, or otherwise undesirable, should be allowed to mature pollen. Occasionally an entire row should be detasseled because of the general inferiority of the row as a whole. Detasseling is accomplished by going over the rows as many times as may be necessary and carefully pulling out the tassels as they appear. Indeed, great care should be exercised in this part of the work in order not to injure the plants and thereby lower the yields. The tassels should not be cut off, as this produces an external injury and at the same time the stalk is often deprived of several undeveloped leaves. But the tassel should be allowed to develop far enough so that it can be separated alone at the top joint by a careful pull. It is now fully deter- mined that the detasseling of the breeding rows is necessary. This insures cross-pollination and markedly increases the yield of succeeding crops. SELECTION OF FIELD Rows AND SEED EARS. As the crop matures, the corn from each of the detasseled breeding rows is now harvested. First, all of the ears on the row which appear to be good ears and which are borne on good plants, in a good position, and with good ear shanks and husks, are harvested, placed in a bag, with the number of the row, and finally weighed, together with the remainder of the crop from the same row. No seed ears should be taken within two or three rods of the inside ends of the rows. The total weight of ear corn which every detasseled row yields should be determined and recorded, for the yield is the primary factor in determining the rows from which all of the ears for the next year's seed selection must be taken. Each lot of ears from each of the detasseled rows, and finally each single ear of the 96 seed ears ultimately selected is kept labeled with the number of the row in which it grew and finally with its own ear number also, and permanent records are made of the number and the description of the ear, the performance record of the row, etc., so that as the breeding is continued an absolute pedigree is established, on the female side, for every ear of corn which may be produced from this seed so long as the records are made and preserved. We also know absolutely that we have good breeding on the male side, although the exact individual pedigree of the males cannot be known and recorded. 19051 DIRECTIONS FOE BREEDING OF CORN. 617 PLANTING FOR CROSS-POLLINATION. In order to insure cross-breeding to the greatest possible extent the plan given in Table 8 should be adopted. TABLE 8. PLAN FOR PLANTING THE BREEDING PLOT TO AVOID IN-BREEDING. The numbers given in the "Guides" designate the field rows from which the seed ears are taken. (All even-numbered rows are detasseled.) Field row No. Guide system for even years. Guide system for odd years. Model example for an even year. Field row No. Guide system for even years. Guide system for odd years. Model example for an even year. . 1. . .76.. 78... 76 51 . ... 2 4 4 2. .... 3. 4. .... 5. .... 6. .... 7. 8. 2.. 80.. 6.. 84.. 10.. 78.. 4.. 2... 82... .... 6... ....86... ....10... ....76... 4.. . 4... ....84... ....10... ....90... ....16... ....80... 8 ....52. ....53. ....54. 55. ....56. ....57. 58 52.. 6.. 56.. 10.. 60.. 4.. 54 ....52... .... 8... 56... 12... 60... 2... . . 54 ....52... ....10... ....58... 16... ....66... .... 8... 56 .... 9. 10. 11. 12. 82.. 8.. 86.. ..'...12.. ....80... .... 8... ....84... 12... ....86... 14... ....92... 20... ....59. ....60. ....61. 62. 8.. 58.. 12.. 62 .. 6... ....58... 10... 62 . . . 14... ....60... 20... 68 . . 13. 78.. 76.. . 80.. . 63. 4 . . . . . 2 . . . 8 14. 2 . 2.. . 4 64. 52 . . . . .52 52 . 15. 16. 17. 82.. 6.. 86.. ....80... .... 6... 84... ....86... ....10:.. 92... ....65. ....66. 67. 8.. 56.. 12.. 6... 56... 10... 14... ....58... 20.. . 18. 10.. 10.. . 16. . . 68. 60. . 60. . . 66.. . 19. 76.. 78... 76 . 69. 2.. 4 . . 4. . . ....20. ....21. ....22. 23. 4.. 80.. 8.. 84.. 4... ....82... .... 8... 86.. . .... 8... ....84... ....14... 90. . . ....70. ....71. ....72. 73. 54.. 6.. 58.. 10.. 54... 8... 58... 12... ....56... ....10... ....60... 16... 24. 12. . 12... 20. .. 74. 62.. 62.. . 68.. . 25. 52.. ..54.. . .52.. . .75. . .26.. . .28.. ..30.. 26. 26.. 26.. . 30... 76. 76.. 76... 76... 27. 56. . 58... 58.. . 77. 30. . 32.. . 36... 28. 30.. 30. . . 36... 78. 80.. 80... 84... 29. 60. . 62 66.. . 79. 34. . 36... 42.. . ....30. 31. 34.. 54.. ....34... 52... 42... 56... ....80. 81. 84.. 28.. 84... 26.. . ....90... 34... 32. 28.. 28.. . 34.. . 82. 78.. 78... 80... 33. 58. . 56.. . 60.. . 83. 32.. 30... 38.. . 34. 32.. 32.. . 38.. . 84. 82 . 82.. . 86.. . 35. 62.. 60 . . 68.. . 85. 36. . 34... 46.. . 36. 36. . 36 . . 46. . . 86. 86 . 86. . . 92... . . .37. 54 52 56 . . 87. . ... 28 26 . . 34 . , . 38. 26.. 26.. . 30.. . 88. 76.. 76.. . 76... 39. 58.. 56.. . 60. . . 89. 32.. 30.. . 38... 40. 30.. 30.. . 36. . . 90. 80.. 80. . . 84... 41. 62.. 60. .. 68... 91. 36.. 34... 46.. . 42. 34.. 34. . . 42.. . 92. 84. . 84... 90. . . 43. 52.. 54. . . 52... 93. 26. . 28.. . 30.. . 44. 28.. 28 . 34 94. 78 . 78.. . 80... ....45. ....46. 47. 56.. 32.. 60.. 58... 32... 62.. . ....58... ....38... 66... ....95. ....96. 97. 30.. 82.. 34.. 32... 82... 36.. . ....36... ....86... 42.. . 48. 36.. 36.. . 46... 98. 86.. 86.. . 92... 618 BULLETIN No. 100. [March, In this plan the breeding plot is considered by quarters. Each quarter contains 24 rows and each row is planted with corn from a separate seed ear. All even-numbered rows are detasseled and seed for the next year's breeding plot is taken from the six best-yielding detasseled rows in each quarter, four ears being taken from each selected row, making 96 ears in all. For convenience we use the term "sire seed/' or "sire ears," to designate the ears which are to be planted in odd-numbered rows to produce tassels (the male flowers) and to furnish pollen; and we use the term "dam seed" or "dam ears" to designate the ears to be planted in the even-numbered rows to produce future seed ears. Of the four seed ears taken from each selected field row, two are used for sire seed and two for dam seed. In the column headed "Guide system for even years" is given a key or guide, by which to work out the actual plan for planting in all even-numbered years, and under the heading "Model example for an even year" is given an actual plan which has been worked out, using four seed ears from six selected rows from each quarter of the breeding plot. In the guide system, for the sake of simplicity, we use four seed ears from each of the first six even-numbered rows in each quarter, a selection which would probably never occur in actual practice. It will be observed that the dam seed ears for each quarter are ears which grew in the same quarter, while the sire seed is always brought from another quarter. For the first quarter (rows 1 to 24) , sire ears are brought from the fourth quarter. For the second quarter, sire seed is brought from the third. In each of these cases sire seed is carried dia- gonally across the breeding plot. For the third quarter sire seed is brought from the first quarter, and for the fourth, from the second, the sire seed being carried lengthwise of the breeding plot in these cases. It will also be observed that there is a definite order of planting for "even years" and another definite order for "odd years." Thus, in the first quarter, the even-numbered rows are planted in ascending order with dam seed selected from rows numbered: 2, 6, 10, 4, 8, 12, 2, 6, 10, 4, S, 12. The alternating even numbers are repeated in sets of three and six. The odd-numbered rows are planted with sire seed selected from rows numbered: 76, 80, 84, 78, 82, 86, 78, 82, 86, 76, 80, 84. This is the same order as for the dams except that the two sets of three are reversed in the second set of six. The only change required for odd- numbered years is to transpose the two sets of six in planting the sire seed. Exactly the same system is used in each quarter of the breeding plot, 19051 DlKECTlONS FOR BREEDING OF CORN. 619 ARRANGING SEED EARS FOR PLANTING. By referring to the "Model example for an even year" it will be seen that it becomes an easy matter to follow the "Guide system" in arranging seed ears for planting. Suppose, for example, that in 1905 the best six rows in the first quarter of the breeding plot are 4, 8, 10, 14, 16, 20. Then for the dam seed for planting the first quarter in 1906 these numbers, in ascending order, are to be substituted for the numbers 2, 4, 6, 8, 10, 12, which are given in the "Guide system." Thus: For 2, substitute 4; for 4, substitute 8; for 6, substitute 10; for 8, substitute 14; for 10, substitute 16; for 12, substitute 20. Arranging these for planting the field rows, we have: ROW GUIDE ACTUAL No. SYSTEM. PLAN. 2 2 4 4 6 8 6 10 10 8 4 14 10 8 16 12 12 20 14 2 4 16 6 8 18 10 10 20 4 14 22 8 16 24 12 20 If the best six rows in the fourth quarter of the 1905 breeding plot are 76, 80, 84, 86, 90, 92, then for the sire seed for planting the first quarter in 1906 these numbers are to be substituted in regular order for the numbers 76, 78, 80, 82, 84, 86, which are given in the "Guide system." Arranging these by threes as indicated in the "Guide system" we have the order for planting the odd-numbered rows in the first quarter: 76, 84, 90, 80, 86, 92, 80, 86, 92, 76, 84, 90. Thus we have both the dam and sire seed ears for the first quarter, arranged exactly as shown under the heading "Model example" in Table 8. The seed ears are arranged for each quarter of the breeding plot in a similar manner by following the "Guide system" and substitut- ing in regular ascending order the actual numbers of the best-yielding rows for the numbers given in the "Guide system" in Table 8. It will be seen that with this selection of best rows, as given in. this "Model example," we would take the four best seed ears from row No. 4 (1905) and plant two as dam ears in rows 2 and 14 and the other two as sire ears in rows 51 and 69 (1906) ; we would take the four best seed ears from row No. 84 (1905) and plant two as dam ears in rows 78 and 90 and the other two as sire ears in rows 3 and 21 (1906). In arranging seed ears selected from the 1906 breeding plot for planting the 1907 breeding plot, we are to follow the "Guide system" for odd- numbered years, again returning to the system for even-numbered years for 1908. 620 BULLETIN No. 100. 8 tw o I GO Q < W W EH CO Jgr ^J M 1C p O tf t.^ O O CO h* oo oco Oi o GS c; cs 5 'UI13J3 UI 'l<0 (juaoiaj bb bbb o a i arej8 ui ajajoad' JU30J8J 3 1 a ^ 8 AVOJ ui SJB8 JO j8((iun\ ! 1 "a. a o 2 4 s tj,iB J3d spqsnq ujoo ! 1 aS ERFOR] AVOJ J3d spunod uaoo w 'S 'S i i fU ON MOJ ppg Ul pS^UBIJ -5 ^ aiBj3 ui 'IP JU90J9J UIB02 UI uiajojri ^uaojtaj a qoo jo 30UOJ9JIIH1.) -jp ;;ng w a qoo jo aauajajuina -JW d!X 8 co 9 qoo jo q3!M IVIDUj JB8 JO ?q8iaAV z h Aioa ni pOHli aaquinjij K o H sjauja^ JO SMOJ ja()nin\ = X u JB3 JO youajajuino -Jio ^;ng JBO jo a.majajiuiio -- 1 ! 3 d ?X JB3 JO q^3ua r j oj>i ja IBnuuy ON UIBQ 1 ON jajsiaajj