Environmental variables contributing to differential performance of tropical maize hybrids across heat stress environments in South Asia

Heat stress resilience in maize hybrids is emerging as an important trait in germplasm targeted for cultivation in the post-rainy season spring in South Asia. One of the major challenges in targeted breeding for these agro-ecologies is the differential response of maize genotypes to heat stress across locations during the spring season. This study is targeted at identifying the major environmental variables that contributed to the genotype x environmental (GEI) yield variations observed among genotypes grown in response to heat stress. The trial dataset used for this study constitutes 46 trials x location combinations spread over a period of three years (2013-2015). Partial least square (PLS) regression analysis was implemented to decipher the important environmental variables contributing to the observed yield variation among maize trials planted during spring across locations of South Asia. The first two factors from the PLS study explained the 30 per cent yield variation across trials. The largest contributor of this variation was relative humidity (RH) and vapor pressure deficit (VPD) during flowering stage of the crop across the years.