Chemical composition of grains and environmental efficiency in soybeans grown under low latitude conditions
Soybeans are one of the main commodities in Brazil, with soybean oil and meal used as raw material for food and animal feed production. However, information on the chemical characteristics of soybeans produced at different times of the year and on the efficiency of genotypes under low latitude conditions is scarce. This study evaluates the environmental efficiency of soybean genotypes based on oil and protein contents during in-season and off-season periods, in Tocantins State. The experimental design was a randomized block with seventeen treatments (genotypes) and three replicates. The treatments were composed by cultivars TMG 1288 RR; AS 3810 IPRO; CD 2792 RR; CD 251RR; CD 2737RR; SHS 820 IPRO; TMG 1180 RR; M 8766 RR; P 98Y70RR; M 9144 RR and strains 5X6-1; 5X6-2; 5X6-3; 4X6-12; 4X6-17; 4X6-19 and 4X5-2. There was effect of sowing times on the oil and protein contents of the grains. Genotype TMG 1288 RR presented the highest levels of oil and protein. The best sowing time for protein content was the first of the in-season (12/01). For oil content, in turn, the off-season stood out (06/01), evidencing that early sowing resulted in better results. Since the contents of these two elements are inversely proportional, one must verify the desired purpose to choose the material to be used. The identification of superior genotypes by the proposed index was effective only for unfavorable environments.