. Breeding crop plants. Plant breeding. MODE OF REPRODUCTION IN RELATION TO BREEDING 49 cross between different varieties a large percentage of the plants are homozygous and will breed true for their characters if self- fertilization is continued. The number of different biotypes which can be isolated from a cross depends upon the number of allelomorphic pairs of factors involved and their linkage relations. Formerly the heterozygous condition was believed to carry with it an increased developmental stimulus. It was also believed that this stimulus was greater when the mate to an allelomorphic
. Breeding crop plants. Plant breeding. MODE OF REPRODUCTION IN RELATION TO BREEDING 49 cross between different varieties a large percentage of the plants are homozygous and will breed true for their characters if self- fertilization is continued. The number of different biotypes which can be isolated from a cross depends upon the number of allelomorphic pairs of factors involved and their linkage relations. Formerly the heterozygous condition was believed to carry with it an increased developmental stimulus. It was also believed that this stimulus was greater when the mate to an allelomorphic Percentage of Heterozygous Individuals in each Selfed Generation when the Number of Allelomorphs Concerned Are: 1,5,10, 123456 789 10 Segregating GenerationE Fig. 12.—The percentage of heterozygous individuals and the percentage of heterozygous allelomorphic pairs in the whole population in each generation of self-fertilization. (After Jones.) pair was lacking than when both were present. The physioloo;- ical cause of this growth stimulus was not known although it was recognized that ''the greater the degree of heterozygosis the greater is the vigor of the resulting plant" (East and Hayes, 1912). A considerable number of studies showed that the rapidity and amount of cell division was increased. A Mendelian explanation of this growth stimulus which is so frequently found in crosses, has been advanced. Jones (1918) has explained the vigor of Fi which has been called heterosis on the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hayes, Herbert Kendall, b. 1884; Garber, Ralph John, b. 1890. New York [etc. ] : McGraw-Hill book company, inc.
Size: 1569px × 1592px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectplantbr, bookyear1921
