Desempenho de progênies parcialmente endogâmicas de milho em cruzamento top-cross

Abstract

The objective of this work was to select partially self-fertilized progenies of maize, through the evaluation of their performance in top-crosses hybrids, identifying those that showed best combining ability for the traits of commercial interest. The experiment was carried out at the Center for Scientific and Technological Development of the Federal University of Lavras (UFLA), located in Lavras, Minas Gerais, during the 2020/2021 crop year. 220 top-crosses hybrids, obtained from crosses between 110 partially inbred progenies with two testers A and B, were evaluated. Five commercial maize hybrids (SHS 5560 PRO2, SHS 7939 PRO2, NS 45 VIP3, HL 1767 PRO2 e BM 790 PRO2), as well as the two testers (A and B), were used as checks. A randomized complete block design with two replicates was used. Data of maize diseases incidence (DI), maize white spot severity (MWS), plant height (PH), ear insertion height (EH), 100-kernel weight (KW), number of kernels per ear (NKE), and grain yield (GY), were collected. The statistical analyses were performed using the mixed model REML/BLUP approach through R software. The combining abilities of each hybrid were estimated, and progenies selection was performed based on Mulamba & Mock index. The top-crosses hybrids outperformed the commercial hybrids. The combining abilities with tester A were not significant for GY, NKE, PH, and EH traits. None of the top-crosses presented greater combining abilities for all traits jointly. However, the top-cross 292, in crossing with tester B, presented great and relevant combining abilities for GY and MWS traits. In conclusion, the evaluated progenies presented great potential for use in the maize breeding program, outperforming the commercial hybrids. 38 progenies were selected based on Mulamba & Mock index. The expected genetic gains for tester A were 0.88, -3.06, -3.74, -7.14, -28.54% for KW, PH, EH, DI, and SMB, respectively. And for B, they were 2.44, 1.96, 2.02, -1.42, -1.57, -7.24, -23.39%, for GY, KW, NKE, PH, EH, DI and MWS, respectively.