What the genetic variation was declined slowly is possible due to the continuous artificially selection for the early silking and the genetic drift induced by selection intensity or smaller effective population size.

• 所有结果均表明选择群体的遗传变异逐渐减小,这可能是由于连续对开花期性状定向选择的结果,也可能还与群体的有效含量较小和选择强度大所引起的遗传漂变有关。