Breeding climate-resilient wheat for Nepalese agricultural system under diverse abiotic stresses using an integrated AMMI, GGE and stress tolerance indices

Climate change has been a significant concern for the production and productivity of wheat throughout the world, including Nepal due to an increasing frequency of heat, drought, and erratic rainfall. The study evaluated the stability and adaptability of twenty elite wheat genotypes across irrigated, heat stress, rainfed, and drought environments across two growing season (2022–2024). In addition, the study evaluated the suitability of 11 stress tolerance indices (STIs) across varying stress levels. The additive main effect and multiplicative interaction (AMMI) model revealed that environment was the primary source of yield variation, while which-won-where (WWW) model identified, G6 (NL 1402) as the most stable genotype across all eight test environments, with the lowest AMMI stability value (ASV) of 0.34. Similarly, G18 (NL 1512), G16 (NL 1501), G9 (NL 1492), and G6 (NL 1402) showed high adaptability under combined irrigated, heat stress, rainfed, and drought environments, respectively. Genotypes G17 (RR21) and G18 (NL 1512) had the least G × E interaction across combined environments (df = 7), where G10 (NL 1488), G13 (NL 1506), G14 (NL 1504), and G8 (BL 5116) under combined irrigated, heat stress, rainfed, and drought (df = 1), respectively. Stress tolerance indices dynamics revealed the predictive power of many indices declined with increasing stress severity, with mean stable yield (MSY), modified stress tolerance index 2 (MSTI2), and harmonic mean productivity (HMP) emerging as the most reliable indicators under rainfed and drought environments. Under severe drought, MSY consistently explained the highest proportion of the yield variation, with the coefficient of determination (R2) reaching 1.000. These findings provides both promising genotypes and validated tolerance indices that suggest valuable tool for breeding climate-resilient wheat for Nepal and similar South Asian agro-ecologies.