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利用28个玉米杂交组合F_1的10个性状两年的资料,进行了方差和协方差分析。同时计算了表现型相关,基因型相关,并构成了对于籽粒产量的选择指数。在籽粒产量与单株穗数和穗上叶数之间发现高度显著的正向表现型相关和基因型相关。单株穗数与单株幼穗数,单株抽丝幼穗数和穗上叶数之间表现高度的关联。开花前日数与株高和穗位高之间,株高和穗位高之间表现有强的正向关系。更为重要的是,穗上叶数表现与籽粒产量,单穗株数和单株幼穗数之间有高度正相关。因此,穗上叶数是与改良产量或多穗性有关的重要性状之一。由于表现型变异中的一大部分是由基因型效应所引起的,所以对于籽粒产量的选择指数相对效率不高。但在单独选择产量以图取得进一步收益的前景不佳时,利用由单株穗数、穗上叶数和籽粒产量所构成的选择指数,可能会取得更大的选择进度。
Variance and covariance analysis were performed using data from two traits of 10 traits of 28 maize hybrids F_1. Simultaneous phenotypic correlations, genotype correlations were calculated and constitute a selection index for grain yield. Significant positive phenotypic and genotypic correlations were found between grain yield and panicles per panicle and panicles on panicle. The number of panicle per plant was highly correlated with the number of panicles per plant, the number of panicles per plant and the number of panicle leaves. There was a strong positive correlation between days before flowering and plant height and ear height, plant height and ear height. More importantly, there is a highly positive correlation between the number of upper leaves and the grain yield, the number of single spikes and the number of spikes per plant. Therefore, the number of upper leaves is one of the important traits associated with improved yield or panicle. Since a large proportion of phenotypic variation is caused by genotypic effects, the selection index for grain yield is relatively inefficient. However, in the case of a poor prospect of selecting yields separately for further gains, a greater selection schedule may be achieved using selection indices consisting of the number of ears per panicle, the number of upper leaves and the grain yield.