Maize Plant Type Trait Loci Effect Study

The selection of plant-type traits is an important component of maize breeding target, and the research of their genetic expression can provide theoretical basis for their selection. The inheritances of 14 plant type traits were studied by means of a series of mixed inheritance models of quantitative traits of major genes plus polygenes based on parents, F1, F2, backcross from two different combinations of maize. The results were as follows: 0 Four kinds of genetic models such as 2 major genes inheretance,polygenes inheretance,and 2 major genes plus polygenes mixed inheretance were identified in maize plant-type traits. The optimum genetic models of the traits such as plant height, tassel length, the first leaf length below ear ,the first leaf orientation value above ear in combination A, and ear leaf length , the first leaf length below ear, the first leaf orientation value above ear in combination B were C-O their inheritances were controlled by additive- dominance-epistasis polygenes .As for ear height, tassel branch number, tassel branch length, ear leaf angle ,the first leaf angle below ear, the first leaf orientation value below ear in combination A; And plant height, ear height, the first leaf length above ear, ear leaf orientation value in combination B, their inheritance models were E-O, namely, these traits were dominated by 2 additive-dominance-epistasis major genes plus additive- dominance-epistasis polygenes.Not only the first leaf angle above ear, the first leaf length above ear, ear leaf length , and ear leaf orientation value in combination A, but also tassel length , tassel branch number, 47 tassel branch length , ear leaf angle , and the first leaf orientation value below ear in combination B ,their inheritance models were E- 1 ,that is, their inheritances were controlled by 2 additive-dominance-epistasis major genes plus additive-dominance-epistasis polygenes. The most suitable inheritance models of the first leaf angle above and below ear position in combination B were both B-i, namely, the inheritance of the two traits were dominated by 2 additive- dominance-epistasis major genes. So the genetic models of most of plant-type traits differed in two combinations, and the inheretances of majority of plant-type traits were dominated by 2 major genes plus polygenes. ㏕he additive , dominant, and epistatic effects of major genes affect the genetic variation of most plant-type traits , and major genes showed partial dominance or over-dominance . The additive and dominant effects of polygenes were tested nearly in all traits, however, the epistatic ones were found in part of traits. ()The heritabilities of plant height, tassel branch number, ear leaf angle ,the first leaf angle below ear, and ear leaf orientation value were high , but the heritabilities of tassel length and tassel branch length were low. At last, the importance of compact inbred-line in maize ideotype breeding and the questions of its breeding and combining were discussed.