. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. .'^ELECTIONS 329 The futility of attempting to generalize regarding (he effects of selec- tions in plants must be obvious from what we now know ai)Out the com- position of plant populatipns. With the application of Johannsen's genotype conception in analyzing the composition of a field of maize the problem of explaining the role of selection in the Illinois corn breeding experiments was immediately simplified. This was perceived by Shull who pointed out that the results of these experiments might b
. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. .'^ELECTIONS 329 The futility of attempting to generalize regarding (he effects of selec- tions in plants must be obvious from what we now know ai)Out the com- position of plant populatipns. With the application of Johannsen's genotype conception in analyzing the composition of a field of maize the problem of explaining the role of selection in the Illinois corn breeding experiments was immediately simplified. This was perceived by Shull who pointed out that the results of these experiments might be readily explained on the ground that some hybrid combinations of genotypes have greater capacity for the production of the desired qualities than other combinations, and that the selection has gradually brought about. Fig. 135.—Result of selecting corn for high and low ears during .5 generations. The white tape marks the position of the ears on the front row of plants in both plots. the segregation of those genotype combinations which had the highest capacity for the production of the desired quality. Meanwhile Surface had made an illuminating analysis of the data from the first f 0 years of selection as reported by Smith. This treatment is so valuable as to warrant its examination in some detail. At the time the selections were made a careful record of the pedigree of each ear was kept. These pedigrees are of course for the maternal side only since self-pollination was not practised. From these data Siu'face prepared a pedigree chart for each of the four strains. The chart for the high- protein strain is reproduced in Tables XLVIII and XLIX. As stated above 24 ears containing the highest per cent, of protein were selected for the 163 ears analyzed in 1896. These were given registry numbers from 101 to 124 inclusive as shown in column one of the two tables. For convenience we may refer to these ears as the first generation of liigh- Digitized by Microsoft®. Please note tha
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