SELEÇÃO DE ACESSOS DE UROCHLOA HUMIDICOLA PARA PRODUTIVIDADE DE SEMENTES

Abstract

Urochloa humidicola is an important forage species due to its adaptation to acidic and poorly drained soils, but it has limitations that can be selected and genetically improved, especially for seed productivity. Due to its low productivity, high prices and little access to producers, the amount of U. humidicola seeds is insufficient to supply the market. Therefore, the development and introduction of new cultivars of this species with, seeds that have good productivity, become a necessity for livestock. In this context, objecting to select Urochloa humidicola genotypes with good capacity for seed production. A total of, 54 accessions and, having as controls the cultivars Llanero, Humidicola and BRS Tupi were evaluated during five years in two experiments. The first experiment was carried out in the years 2018 and 2019, consisted of implantation in randomized blocks, in plots with two clonal plants, with four replications. Estimates of genetic parameters and selection gains were obtained and genotypic values predicted through the mixed models methodology, by the SELEGEN-REML/BLUP software. Of the 54 genotypes evaluated, ten superior genotypes then commercial cultivars of U. humidicola were pre-selected. In the second experiment, the ten pre-selected genotypes of U. humidicola in the first experiment were evaluated during two consecutive years (2020/2021 and 2021/2022), regarding the productivity of pure seeds. The experiment was implanted by seedlings in

randomized blocks, with four replications and plots of 10 x 15 meters. Estimates of genetic parameters and selection gains were obtained and genotypic values predicted by the mixed-model methodology, by the SELEGEN-REML/BLUP software. Fron the ten genotypes of U. humidicola tested, four were selected based on pure seed productivity: 2, 3, 1 and 8, these genotypes will be evaluated in the next steps of the Embrapa Beef Cattle U. humidicola breending program, and can be used as candidates for new cultivars and as parents for the program development continuation.