Selection of soybean genotypes resistant to insects adapted to the cerrados
Mara Fernandes Moura and José Baldin Pinheiro
This study aimed to select productive soybean genotypes, adapted to the conditions of the “Cerrado” and with insect resistance. The experimental material involved 170 soybeans lines F7:2 obtained from partial diallel crosses (4 x 4), that is, four parents with insect resistance and four other parents with high agronomic performance and the other three lines obtained from the plant breeding program of the ESALQ/USP. The F7, F8 and F9 generations were evaluated in Goiânia-GO, being the last one evaluated during three different sowing periods (October/21/98, November/09/98 and December/11/98). The following characters were evaluated: days to flowering; plant height at flowering; days to maturity; plant height at maturity; period of grain growth; spotted seeds; 100 seeds weight; foliar area sectioned; lodging; agronomic value; and grain yield. The augmented design was used for the F7 generation while the complete randomized block design for the F8 and F9 generations. An analysis of variance was carried out for each generation and one joint analysis of variance was made for the three sowing periods with F9 generation. Based on grain yield, through the different experiments, they were identified as to which were the most promising lines for the area, having the best combination of characteristics including insect resistance. The following results were obtained from the analysis: a) ten lines from the early cycle, with high yield, were considered favorable for the cultivation in the “cerrado”, showing high resistance to sucker and defoliator insect, and they involve the genitor IAC-100; b) the line 81-9-13 (OCEPAR-04 x IAC-100) had the best agronomic performance, because it was classified above the mean of the check for all characters evaluated in the F9 generation; c) the second sowing period (11/09/98) was considered the most favorable for the cultivation of soybean in the region; d) the parental IAC-100 (used as the check) showed good characteristics for grain yield and insect resistance. So, evaluation of this parental should occur in the region, in order to recommend it for cultivation.