DESEMPENHO DE PROGÊNIES S3 DE MILHO EM CRUZAMENTOS TOPCROSSES PARA PRODUTIVIDADEDE GRÃOS E POTENCIAL FORRAGEIRO

Abstract

Grain yield is a polygenic characteristic and it is directly related to environmental conditions. In the breeding for this purpose it is necessary to combine high yield with appropriate agronomic characteristics such as short stature for plant height and ear and cycle precocity. To forage breeding, the maize crop is considered one of the best forage plants due to the high productive potential, wide cultivation region, high nutritional value, good fermentation capacity, and high dry mass yield. The objective was to evaluate S3 maize progenies in topcross with different testers, for agronomic characteristics and grain yield, as well as characters related to forage production and forage bromatological quality. The experiment was conducted in the 2015/16 and 2016/17 harvests at the CEDETEG campus of the Universidade Estadual do Centro-Oeste, in Guarapuava-PR, in a randomized block design with three replications. 30 S3 maize progenies were evaluated in topcross with the AG8025, P30B39, MLP102, 60.H23.1 and 70.H26.1 testers forming 150 topcross hybrids. There were evaluated the characteristics plant height (PH) and ear height (EH), male flowering (MF), grain yield (GY), cycle of forage maturity (CFM), dry mass (DM), dry mass yield of forrage (DMY), neutral detergent fiber (NDF) and acid detergent fiber (ADF) and in situ dry matter digestibility of forrage (DIG). The P30B39 and 70.H26.1 testers were better to dicrimining the variability to the characteristics PH and EH, whereas for MF and GY, the 60.H23.1 and 70.H26.1 testers showed higher efficiency. Progenies 96.3, 218.3 and 16.5 were, in this order, the ones that presented the best performance considering the GY characteristic. The topcross hybrid 96.3 x 70.H26.1 was outstanding in relation to the others by the favorable specific combining ability (SCA) and by the good performance for the GY, PH and MF characteristics. The 60.H23.1 and 70.H26.1 testers best dicrimineted the existing variability for DMY, NDF, and ADF characteristics. The hybrid 59.6 x 60.H23.1 stood out with low estimates for NDF and ADF and high estimates for DMY and DIG. Progenies 59.6, 205.2, 159.6 and 199.2 presented in this order the best performance for DMY, NDF, ADF and DIG. There was a predominance of the action of non-additive effects genes for all the forage characteristics in both environments.