Parâmetros genéticos e fenotípicos em híbridos intervarietais em VPAs de milho no RS

Abstract

Maize (Zea mays L.) is among the cultivated species of greatest socioeconomic importance, considered a staple food, especially in underdeveloped or developing countries. In scientific terms, the species is widely studied due to its genetic variability, which can be explored for the identification of favorable genes and / or alleles or for the selection of superior plants for the formation of hybrids. Thus, determining the population to be used is crucial to obtain selection gains. Studies concerning the combinatorial capacity of these open pollination varieties and the heterosis existing in intervarietal hybrids originating from such varieties are important tools for breeding programs. Given the above, the present study aimed to estimate the genetic parameters in half-sib families of open pollinated varieties of corn via mixed models (REML / BLUP), as well as to evaluate the combinatory capacity and its reciprocal effect on such varieties, and still, through heterosis studies, to identify promising intervarietal hybrids formed from these VPA's. For the estimates of genetic parameters, combinatorial capacities and effects of heterosis, fifteen open pollination varieties were used: AL 25, AL 30, Argentino Amarelo, Argentino Branco, Bico de Ouro, BR 5202, BR 473, BRS Missões, BRS Planalto, Cateto Amarelo, Dente de Ouro, Pampeano, Sangria Branca, Sete Sanga e Taquarão, grown in a randomized block design with three replications. For the studies of combinatorial capacity and heterosis, crossings between eight VPA’s were performed, in a complete diallel scheme. The intervarietal hybrids were conducted in a randomized block design with three replications. Both experiments were carried out in the experimental area of the Genomics and Phyto-improvement of the Federal University of Pelotas, in the municipality of Capão do Leão / RS, in the 2017/2018 and 2018/2019 seasons. According to the estimates of the genetic parameters, it was possible to observe the existence of genetic variability between and within the IMF of the populations under study. Such parameters also showed that the varieties Sete Sanga and Taquarão have the highest values of average heritability for most of the evaluated characters. Regarding the combinatorial capacity of the varieties, the genetic action that prevailed was that of non-additive effects, that is, the specific combination capacity showed greater prominence among the populations. As for heterosis, hybrids superior to the parents were identified, being the populations Argentino Amarelo and BRS Missões, the most promising in hybrid combinations for traits related to grain yield.