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Dynamism of the breeding program for irrigated rice in Southeast Brazil

Author(s): A.C. Silva Júnior, V.Q. Carneiro, I.G. Santos, W.G Costa, R.D.S. Rosado, C.D. Cruz and P.C. Soares

The estimation of the genotypic replacement rate is aimed at evaluating the performance of breeding programs. Thus, the objective of this study was to evaluate the dynamics of the genetic improvement program of flooded rice, developed in Minas Gerais, during the period from 1993 to 2016. We evaluated 210 lines in three environments between 1993 and 2016, in blocks, ranging from three to four replicates. The mean genotype replacement rate and the mean of genotypes included, maintained and excluded in each year were estimated. The average genotypic replacement rate was 44% for Lambari and Janaúba, and 43% for Leopoldina. The average maintenance in Lambari was 39%, and in Janaúba and Leopoldina this consisted of 40%. The average number of the genotypes excluded from the evaluation in the following year and the average number of the evaluated genotypes in the year that allows concluding on the dynamics of the rice improvement program, in terms of replacement of improved varieties over the years. In all locations, the mean inclusion was higher than the mean exclusion, indicating the good efficiency of the irrigated rice breeding program. These results were satisfactory for the dynamics of the genetic improvement program of irrigated rice in Minas Gerais.