三重测交法在玉米群体改良中的应用研究

据前人所介绍的三重测交法(TTC)的基理与方法,以综合种群体代替原设计中的F_2代,以此检测一玉米优良综合种的21个数量性状的遗传分量,结果表明,在14个性状中,有非等位基因互作存在。其中穗粗行粒数同时存在着只三类互作分量:另外9个性状的上位性分量为i+1类;剩下3个性状则主要为i类上位性分量。在除粒深外的20个性状中,都发现了加性遗传分量(D);而显性分量(H)仅在15个性状中存在;在绝大多数性状的遗传变异中,D的作用较大,H次之、通过对显性基因中的增、减效基因的分布和相对频率的探测,发现多数性状的有利基因呈双方向分布、

STUDY ON THE APPLICATION OF TTC TO POPULATION IMPROVEMENT

The triple test cross (TTC)design proposed by M.J. Kearsey and J.L. Jinks(1968)was conducted to detect addive, dominant and epistatic components of variation for 21 traits with slight modification that a syntretic variety Was used to repla ce the F_2 generaton of, normal TTC in maize. Two inbred lines(testers L1 and L2) and their F1(L3)were crossed to 32 So plants of the synthetic variety to produce 32 sets, each consisting of Lli, L 2 i, and L 3 i progeny families. Epistasis was found in 14 traits. Evidence of additive gene action was obtained in all traits except biological accumulated emperature and grain depth. However, dominance gene action was observed tto play an important role in their genetic system in 15 traits. The dominance is ambidirectional. The application of estimated genetic parameters to breeding programmes has been discussed in detail with some examples.