Combining ability and genetic divergence in the selection of testers regarding grain yield and forage potencial in maize topcrosses¹

Capacidade combinatória e divergencia genética na seleção de testadores para produtividade de grãos e potencial forrageiro em topcrosses de milho

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.

Key words:
Zea mays L; Topcross; Maize forage