Combining ability and genetic divergence in the selection of testers regarding grain yield and forage potencial in maize topcrosses

ABSTRACT Genetic divergence analysis among testers and progenies and the correlation of genetic distance with combining ability can be an important alternative to select maize progenies regarding grain yield and forage potential since testers suitable to both purposes are rare.The objective of this work was to select testers suitable for the evaluation of grain yield and forage traits is topcrosses with S3 progenies of maize based on the association between genetic divergence, general combining ability and genetic parameters. The experiments were carried out in the 2015/16 and 2016/17crop seasons in Guarapuava-PR. We evaluated 150 topcrosses among 30 S3 progenies and testers five testers (single hybrids AG8025 and P30B39, the elite inbred lines 60.H23.1 and 70.H26.1, and a mixture of inbred lines MLP102), The evaluated traits were plant height, ear height, grain yield, dry mass yield, neutral detergent fiber and acid detergent fiber andforage in situ digestibility. There was not a single suitable tester regarding grain yield and forage traitssimultaneously. The 70.H26.1 tester is the most recommended for grain yield. The 60.H23.1 tester is the most recommended for forage traits. There was not linear correlation between genetic divergence, general combining ability and genetic parameters.

摘要：对测验种与玉米后代开展遗传分化分析，并探究遗传距离与配合力的相关性，可作为筛选兼具籽粒产量与饲草潜力的玉米后代的重要备选方案，因同时适配这两类育种目标的测验种较为稀缺。本研究旨在基于遗传分化、一般配合力与遗传参数间的关联，筛选可用于评价玉米S3代自交后代顶交组合的籽粒产量与饲草性状的测验种。本试验于2015/2016及2016/2017作物季在巴西巴拉那州瓜拉普阿瓦（Guarapuava-PR）开展。本试验共评价了30个玉米S3代自交后代与5个测验种组配得到的150个顶交组合，供试测验种包括单交种AG8025、P30B39，优良自交系60.H23.1、70.H26.1，以及自交系混合群体MLP102。供试性状包括株高、穗位高、籽粒产量、干物质产量、中性洗涤纤维（neutral detergent fiber）、酸性洗涤纤维（acid detergent fiber）以及原位饲草消化率。研究结果显示，未筛选到可同时适配籽粒产量与饲草性状评价的测验种。其中，测验种70.H26.1是籽粒产量评价的最优备选测验种，测验种60.H23.1则为饲草性状评价的最优备选测验种。遗传分化、一般配合力与遗传参数间未检测到线性相关关系。