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，估算用于青贮生产的玉米杂交种农艺性状间的相关系数，以及基因型相关对直接效应与间接效应的影响。试验于2015/2016作物季，在巴西里约热内卢州坎波斯杜戈伊塔卡泽斯（Campos do Goytacazes）与伊塔奥卡拉（Itaocara）两个试验环境中，采用完全随机区组设计，设置6次重复，共分析8个顶交杂交种与7个对照品种。本次评估的农艺性状包括：株高、第一果穗位高、茎秆直径、果穗数、青贮成熟期带秸秆果穗产量、青贮成熟期不带秸秆果穗产量、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。相关性最高的两组变量分别为不带秸秆果穗产量与籽粒产量，以及带秸秆果穗产量与不带秸秆果穗产量，相关系数分别为0.95与0.92。测定系数较高，表明所评估的性状组分可解释鲜物质总产量中绝大多数的现存变异。经通径分析可知，对鲜物质总产量直接效应最强的性状为青贮成熟期带秸秆果穗产量，其与鲜物质总产量的相关系数达0.91，这表明可通过间接选择实现显著的遗传增益。