Genotype by environment interaction of advanced generation soybean lines for grain yield in Uganda.

Grain soybean (Glycine max L.) is the primary source of vegetable protein for food and feed supplements, and accounts for much of the world’s oil supply. In most parts of Africa, soybean production potential is yet to be realised largely due to lack of improved varieties. Uganda’s soybean breeding programme has been actively involved in developing varieties to meet the needs of farmers in different parts of the country. This study was, conducted to determine the adaptation of new advanced generation soybean lines to identify high yielding stable lines, the most ideal testing environment and to determine the presence of soybean production mega environments in the country. Twenty one advanced generation soybean lines and three standard check varieties were evaluated in five sites and three consecutive rainy seasons. Results of AMMI analysis indicated the presence of a scale genotype-by-environment interaction for soybean grain yield. Through AMMI estimates and GGE visual assessment, BSPS48A was the highest yielding genotype in the most discriminating and stable environment, Nakabango. BSPS48A was, therefore, recommended for release subject to evaluation for commercial value. From the environmental focusing plot, the five multi-locations tested were grouped into two putative mega environments for soybean production.