Correlations between agronomic traits and path analysis for silage production in maize hybrids

ABSTRACT The aim of the current study is to estimate the correlation coefficients and the consequence of genotypic correlations on direct and indirect effects through path analysis between agronomic traits of maize hybrids used for silage production. Eight (8) topcross hybrids and seven (7) checks were analyzed in completely randomized blocks, with six replications, in two environments: Campos do Goytacazes and Itaocara counties – Rio de Janeiro State, in the crop year 2015/2016. The following agronomic traits were assessed: plant height, first ear height, culm diameter, number of ears, ear yield with straw at silage maturity, ear yield without straw at silage maturity, grain yield at silage maturity, grains ratio in the fresh matter and fresh matter yield. The highest correlation estimates were found between the variables ear yield without straw and grain yield, and between ear yield with straw and ear yield without straw, with magnitudes 0.95 and 0.92, respectively. The coefficient of determination was high, which indicates that the assessed components explain most of the existing variation in fresh matter yield. According to the path analysis, the trait showing the strongest direct effect on fresh matter yield was the ear yield with straw at silage maturity, in association with the high correlation (r = 0.91), which showed the possibility of achieving significant gains through indirect selection.

摘要
本研究旨在通过通径分析（path analysis），估算用于青贮生产的玉米杂交种农艺性状间的相关系数，以及基因型相关对性状直接与间接效应的影响。本试验于2015/2016生长季在巴西里约热内卢州的Campos do Goytacazes与Itaocara县两个试验点开展，采用完全随机区组设计（completely randomized blocks），设置6次重复，共分析8个顶交杂交种（topcross hybrids）与7个对照品种（checks）。本试验测定的农艺性状包括：株高、穗位高、茎粗、穗数、青贮成熟期带秆穗产量、青贮成熟期去秆穗产量、青贮成熟期籽粒产量、鲜物质中籽粒占比以及鲜物质总产量。相关性分析结果显示，去秆穗产量与籽粒产量间、带秆穗产量与去秆穗产量间的相关系数最高，分别为0.95和0.92。本试验的决定系数（coefficient of determination）较高，表明所测定的性状组分可解释鲜物质总产量绝大多数的表型变异。通径分析结果表明，对鲜物质总产量直接效应最强的性状为青贮成熟期带秆穗产量，该性状与鲜物质总产量的相关系数达0.91，说明可通过间接选择实现鲜物质总产量的显著遗传增益。