红花烟草数量性状的遗传研究 Ⅱ.部分性状的世代间遗传变异

Genetic analysis of quantitative traits in Nicotiana tobaccum Ⅱ. Genetic variation between generations

分别以红花烟草（Ｎｉｃｏｔｉａｎａｔｏｂａｃｕｍ）杂种（亲本为Ｋ３２６×Ｇ１４０）后代Ｆ５和Ｆ６系谱为材料，进行了田间试验。对三个不同时期的株高、叶宽、开花时间及总叶数等４个性状在Ｆ５世代１２８个家系和Ｆ６世代６４个家系中的表现进行两个世代间的协方差分析，迭代估计各性状的主要遗传参数并计算狭义遗传力。株高等４个性状基本符合加性显性模型。除移栽大田后的第５周株高性状的加性和显性效应同时存在外，其它性状的遗传方差中均以加性方差为主，而其值较小，狭义遗传力较低。Ｆ６世代环境方差普遍低于Ｆ５世代。

Sixty four families in F 5 generation and 128 in F 6 were studied from progenies of hybrids with two pure breeding varieties of Nicotiana tobaccum , K 326 and G 140. The experimental design to estimate genetic variances via the natural selfing was extended to advanced generations so that enough equations were available for analysis of covariances between the 2 generations. The genetic variances were estimated and tested by iteration. The results showed that the heritabilities of the 4 traits were basically low and the additive effect was the main genetic component for all the traits except for PH 5 (the plant height at the 5th week after transplanting). It was also revealed that the environmental variances in F 6 were less than those in F 5.