Precisão experimental, relações lineares e progresso genético em caracteres de trigo de ciclo precoce, médio e tardio na região sul do Brasil

Abstract

The objectives of this work were to evaluate the experimental precision of grain productivity, verify whether there are linear relationships between productive traits and grain protein and evaluate the genetic progress of grain productivity, in competition trials of wheat genotypes from early, medium and late cycles, conducted in the states of Rio Grande do Sul and Paraná. Data on the following productive traits were used: grain productivity (PROD, in kg ha-1 ), weight of a thousand grains (TGW, in g) and hectoliter weight (HW, in kg hL-1 ) and grain protein (PROT, in %). These data were obtained in 106 trials with early-cycle, 36 medium-cycle and 124 late-cycle genotypes, conducted over five years (2015, 2016, 2017, 2018 and 2019), in the states of Rio Grande do Sul and Paraná, by company Biotrigo Genética. The 266 trials were conducted in a randomized block design, with four replications. Experimental precision statistics and partial correlation coefficients between these four traits were calculated and the methodology of Vencovsky et al. (1988) for the study of genetic progress. The experimental precision in competition trials of wheat genotypes from early, medium and late cycles is similar. According to heritability, F test value for genotype, selective accuracy and repeatability coefficient, 95.86% of wheat genotype competition trials present high or very high precision. However, 1.13% of the trials could be discarded, due to insufficient experimental precision. There are linear relationships between productive traits and protein in wheat grains from early, medium and late cycles. Wheat genotypes from early and late cycles show a negative correlation between grain productivity and grain protein. Mediumcycle wheat genotypes show no correlation between grain productivity and grain protein. The selection of genotypes with higher grain productivity and hectoliter weight can be carried out indirectly through the weight of a thousand grains. The genetic progress of early cycle wheat was 2.52% year-1 for PROD, -0.13% year-1 for TGW, 0.68% year-1 for HW and 0.48% year-1 for PROT. The genetic progress of late cycle wheat was 4.24% year-1 for PROD, -0.10% year-1 for TGW, -0.65% year-1 for HW and 0.44% year -1 for PROT. There was genetic gain for PROD and PROT and genetic loss for TGWin early and late cycle genotypes. There was a genetic gain for the HW of the early cycle genotypes and genetic loss for the late cycle genotypes.