小麦抗赤霉病基因库群体后代的抗赤性选择响应分析

ANALYSIS OF SELECTION RESPONSE FOR RESISTANCE TO SCAB(Gibberlla zeae)IN A GENE POOL OF WHEAT

应用表型混合选择和后代测定选择相结合的轮回选择方案对小麦抗赤基因库中不育株和可育株分别进行了四轮抗赤轮选,结果表明,通过选择显著降低了轮回群体的平均病小穗数,群体中抗赤性强的中矮杆植株的频率逐轮增加。而株高、每穗粒数、千粒重等性状产生正向间接选择效应。抗赤性状和农艺性状的遗传方差逐轮下降,但相对变异度仍基本保持稳定。多元分析表明,改良群体与基础群体间的抗赤性农艺性状的平均数向量的差异显著。连续抗赤轮回选择导致多元方差下降,但仍维持群体的相对综合变异度。

Four cycles of recurrent selection with intergration of phenotypic mass selection for male-sterile plants and progeny testing selection for fertile plants in each of four successive cycles were practiced in a scab-resistant gene pool in wheat to evaluate the responses of mean and variance-covariance of traits to selection for scab-resistance. The results of this study showed that spikelets infected with scab were reduced signifi- cantly over four cycles of selection.Spikelets infected with scab were decreased by 0.32 per cycle from C_0 to C_4 as measured by the bulk populations of selection for sterile plants,and 0.94 per cycle from Co to C_3S as measured by lines of selection for fertile plants.The largest gain from selection was realized in the first cycle of phenotypic mass selection for male-sterile plants and progeny selection for fertile plants,respectively. Frequencies of scab-resistant plants(MR～R)with medium-tall or semidwarfstalks were increased over four cycles of selection.Positive indirect effects of progeny selection for scab resistance were observed in agronomic traits.Gradual decreases of genetic vari- ances for scab resistance and agronomic traits occurred through continuous selection for fertile plants of each of four successive cycles.Relative variability of scab resistance was not decreased over four cycles of progeny selection.Analysis of multivariate showed that there were significant differences between improved population and the basic population in scab resistance and agronomic traits vectors.The variance-covariance matrix of C_0S was significantly different from that of the selected sub-populations of the following cy- cles,the gradual decreases were observed in muhivariability and multigenetic variance over four cycles of progeny selection for fertile plants.