Development and selection of super-sweet corn genotypes (sh2) through multivariate approaches

ABSTRACT The aim of the present study was to investigate relations among ten traits in super-sweet corn genotypes assessed by means of simple correlation, path and canonical variable analyses, as well as to investigate the relative importance of such traits to the super-sweet corn breeding program developed at Darcy Ribeiro Northern Fluminense State University in order to develop strategies able to improve the efficiency in the selection of superior genotypes. Thus, trials comprising 3 × 6 partial diallel of super-sweet (sh2) corn were carried out, according to a short_textrandomized block design (RBD)short_text with four repetitions, in two different environments located in Northern Rio de Janeiro State, Brazil (Itaocara and Campos dos Goytacazes counties). The correlation study showed that traits such as ear diameter and useful short_textearshort_text length contributed the most to increase short_textearshort_text yield (without husk); the variable ear diameter stood out for having stronger direct effect on ear yield, as well as for presenting high heritability (0.95). The trait number of grains per ear row contributed the most to the variation between hybrids, whereas the trait useful ear length contributed the least. The canonical variables showed that the genetic backgrounds of sh2-gene donor populations had effect on recurrent populations, even after five backcrossing cycles, thus resulting in the formation of two divergent groups.摘要 本研究旨在通过简单相关分析、通径分析及典型变量分析，探究超甜玉米基因型的10个性状间的关联，并明确这些性状对巴西达西·里贝罗北弗鲁米嫩塞州立大学开展的超甜玉米育种项目的相对重要性，以期制定可提升优良基因型选择效率的育种策略。本研究在巴西里约热内卢州北部的两个试验点（伊塔奥卡拉市与坎普斯多斯戈伊塔卡泽斯市）开展超甜（sh2）玉米的3×6部分双列杂交试验，采用随机区组设计（RBD），设置4次重复。相关分析结果显示，果穗直径与有效穗长对裸果穗产量的提升贡献最为突出；果穗直径不仅对果穗产量的直接效应最强，还具有较高的遗传力（0.95）。每穗行粒数对杂交种间的遗传变异贡献最大，而有效穗长的贡献最小。典型变量分析结果表明，即便经过5次回交循环，携带sh2基因的供体种群的遗传背景仍会对轮回种群产生影响，最终形成两个分化类群。