A total of 188 soybean [Glycine max (L.) Merrill] lines developed by the Department of Genetics, Faculty of Agriculture "Luiz de Queiroz" (ESALQ) University of São Paulo (USP), classified in four maturity cycles, were studied with the objective of estimating the effect of genotype x location (G x L) interaction on seed yield. The lines were evaluated in twelve experiments in three localities (Anhembi, Areão and ESALQ) of Piracicaba, State of São Paulo, Brazil, at 540 m of altitude, 22o45' South latitude, and 47o38' West longitude, during the summer season of 1996/97. For each locality and maturity cycle, a randomized complete block experiment was designed, with two replications stratified in experimental sets and four common checks. The experimental plot corresponded to four rows 5.0 m x 0.5 m, where the four central meters of the two intermediate rows were evaluated. Effects of lines (G), localities (L), and G x L interaction were detected in the four maturity cycles. Anhembi was the most favourable locality for the expression of the seed yield potential in the semi-early, intermediate, and semi-late maturity lines; ESALQ offered the best environmental conditions for selecting among early maturity lines; the locality Areão was unfavourable for all maturity cycles. The seed yield of the lines varied according to the maturity cycle, and was ranked in decreasing order: intermediate, semi-early, early, and semi-late maturity. In average, for the three localities, the highest yielding seed line of each maturity cycle, was: USP 94-1086 (early), USP 93-2316 (semi-early), USP 93-5243 (intermediate), and USP 93-5513 (semi-late).
soybean; Glycine max; seed yield; genotype-location interaction; maturity cycle
