Ganho genético em caracteres agronômicos de soja em 46 anos de melhoramento no Brasil

Abstract

Soybean (Glycine max (L) Merrill) is currently one of the world's most important crops because it contains high levels of oil (20%) and protein (45%). In addition, it is a source of raw material for the manufacture of various products such as feed, oils, PTS, biodiesel, among others. The productivity of the crop has been showing significant increases over the years due to improvements in management practices and improved cultivars introduced with greater genetic potential. Genetic gain estimates are a measure used by breeding programs to measure gains over the years, to pinpoint the most efficient selection strategy, and to predict the success of breeding programs. The objective of the present work was to evaluate the genetic progress for the agronomic traits of soybean cultivars developed in the last decades. Twenty-nine cultivars from 1965 to 2011 were evaluated for their main agronomic characteristics: lodging index, plant height, first pod insertion height, number of nodes, branches and pods per plant, number of seeds per pod, weight of one thousand seeds, total biomass, harvest index, grain yield, total cycle, vegetative and reproductive period, and total chlorophyll index, a and b. Genetic gain was observed for the grain yield character in the order of 17.54 kg ha-1 year-1. The number of grains per pod and harvest index were the ones that contributed the most to the increment of grain yield of the soybean crop, from 1965 to 2011, tending to be prioritized in breeding programs for selection of strains with higher yields .