Emprego dos índices de seleção no melhoramento de arroz

Abstract

The objective of this study was to verify the efficiency of selection indexes in upland rice lines in order to identify genotypes that gather desirable characteristics for recommendation and consumption. Thirty-six lines of the preliminary trials from Federal University of Lavras upland rice breeding program were evaluated. The experiments were carried out in Lavras city, at Federal University of Lavras and in Lambari city at the EPAMIG experimental farm, during the 2015/2016 harvest. The experimental design was a randomized complete block design with three replications. To compose the indices, the following characteristics were evaluated: grain yield, height, number of days to flowering, thousand grain weight, total milling yield, milling yield, leaf blast incidence and grain length/width ratio. The selection indexes compared were: Classic index of Smith and Hazel, base index of Willians, sum of ranks index Ranks of Mulamba e Mock, index of standardized variables (Z Index) and direct selection through grain yield. It was found that the Classical and Base Index obtained good gains in relation to the grain yield character, but they were not efficient in selecting superior lines for all the desirable characteristics. Z Index and Ranks index allowed higher and more balanced gains among the characters, being more efficient in the selection of upland rice lines.