Studies about the combining ability and genetic diversity can provide information on the genetic resources contained in the working collection of germplasm. The objective of this study was to estimate the combining ability of ten soybean parents and their hybrids in the F 1 generation using diallel analysis and genetic diversity analysis to evaluate the dissimilarity between parents and crosses. The experiment was carried out in a greenhouse, in a completely randomized design with five replications, during the 2019/2020 crop season, in the municipality of Rio Verde, State of Goiás, Brazil.Agronomic and physiological variables were evaluated. Data were subjected to analysis of variance. Diallel analysis was performed using the Griffing method 2. Analysis of genetic diversity was performed with the Mahalanobis generalized distance and the hierarchical average linkage clustering. Additive gene effects were predominant in the control of all variables analyzed in the F 1 generation. The parents SYN 1163 RR and CG 7370 RR showed good complementarity for the variable grain yield. The thirty-five genotypes were separated into six groups, and the variable weight of one hundred seeds had the greatest contribution to genetic diversity.

Soybean crop yield is affected in the absence of favorable conditions for its complete development, and one of the most limiting factors is the water availability throughout the crop cycle. Therefore, the objective of this study was to evaluate the behavior of three soybean genotypes, in two sowing dates, during two harvests, in the city of Rio Verde, Stat of Goiás. Four experiments were carried out in a randomized block design, with four replicates in the 2018/2019 and 2019/2020 harvests. The variables analyzed in the experiment were plant height at maturity, days to maturity, and grain yield. The water balance in the soil considered the water storage of 46.8 mm. It was observed periods with greater water deficiency (53.5 mm) in the 2018/2019 harvest for all genotypes. In short, for genotypes with 100 to 110 days of the cycle, the sowing time that showed to be the most promising to obtain higher yields, was between October 20 and November 20, for genotypes with a cycle of 120 days. This range of adaptation becomes broader, mainly because these genotypes have a longer vegetative period, being, therefore, the period of least water requirement for the crop.