Cultivar variability and stability of vegetable-type soybean for seed yield and pod shattering

Abstract

Vegetable-type soybean, also known as “edamame”, was introduced to South Africa in 2009 to serve as an alternative high-protein cash crop for production by small-scale growers. Since their introduction, cultivars have been evaluated and morphologically characterised to identify suitable cultivars for production in specific environments and also to gather data for future breeding programmes. The objective of this study was to investigate genotype by environment interaction and cultivar stability through additive main effects and multiplicative interaction (AMMI) as well as genotype plus genotype by environment biplot analysis across seven environments and two growing seasons in 15 vegetable-type soybean cultivars for seed yield and pod shattering. Based on AMMI stability values and genotype stability index scores, cultivars AGS418, AGS457 and AGS458 were the most desirable in terms of stability and performance for both seed yield and pod shattering resistance and could be considered for commercial release. Of all vegetable-type soybean cultivars studied, cultivar AGS354 had the best pod shattering resistance and it showed specific adaptation to the Winterton, and Mariannhill October and Mariannhill November planting dates mega-environment in terms of seed yield. This cultivar should be considered for production in these environments. Ladysmith was identified as the most suitable environment for selecting and breeding cultivars with wider adaptability.