Biplot yield analysis of heat-tolerant spring wheat genotypes (Triticum aestivum L.) in multiple growing environments

It is important to identify and develop stable wheat varieties that can grow under heat stress. This important issue was addressed in Bangladesh using six wheat genotypes, including three existing elite cultivars ('BARI Gom 26', 'BARI Gom 27', 'BARI Gom 28') and three advanced lines ('BAW 1130', 'BAW 1138', 'BAW 1140'). Six sowing dates, namely early sowing (ES) (10 November), optimum sowing (OS) (20 November), slightly late sowing (SLS) (30 November), late sowing (LS) (10 December), very late sowing (VLS) (20 December) and extremely late sowing (ELS) (30 December) were assessed over two years in four locations, representative of the diversity in Bangladesh's agro-ecological zones. In a split plot design, sowing dates were allocated as main plots and genotypes as subplots. A GGE biplot analysis was applied to identify heat tolerance and to select and recommend genotypes for cultivation in heat-prone zones. All tested genotypes gave greatest grain yield (GY) after OS, followed by SLS, ES and LS, while VLS and ELS gave smallest GY. When GY and the correlations between GY and stress tolerance indices were considered, 'BAW 1140', 'BARI Gom 28' and 'BARI Gom26' performed best under heat stress, regardless of location or sowing date. In contrast, 'BARI Gom 27' and 'BAW 1130' were susceptible to heat stress in all locations in both years. Ranking of genotypes and environments using GGE biplot analysis for yield stability showed 'BAW1140' to be most stable, followed by 'BARI Gom 28' and 'BARI Gom 26'. Wheat sown on November 20 resulted in highest GY but that sown on December 30 resulted in lowest GY in both years. In conclusion, 'BAW 1140', 'BARI Gom 28' and 'BARI Gom 26' are the recommended wheat genotypes for use under prevailing conditions in Bangladesh.