2025/09/08 by da Conceição dos Santos, Luis Filipe, Cano González, Alejandro, Garruña Hernández, René +1
paper · doi:10.5073/jabfq.2025.098.012
Drought and heat stress are major constraints for crop productivity worldwide. Maize is the most important crop in Mexico contributing to food security. Maize landraces in Mexico exhibit remarkable diversity and most farmers continue to cultivate them. The present study investigated the effects of combined drought and heat stress on the physiological and yield responses of maize landraces in Mexico. Six maize landraces and two improved varieties were evaluated. Two treatments were used: a well-watered control and drought stress, applied at the reproductive stage for 20 days. Maize physiological and yield responses were analyzed by one-way ANOVA. Five drought tolerance indices were calculated and multivariate analyses were used to classify drought-tolerant from sensitive maize genotypes. Drought and heat stress reduced the photosynthetic rate (Pn), stomatal conductance (gs), transpiration (Tr), and increased water use efficiency (WUE) compared to well-watered plants. Yield under drought conditions was 46% lower than under irrigation conditions and yield losses were caused mainly by a significant reduction in ear and kernel weights. Multivariate analyses identified the maize genotypes XNM, SB, and CHTZ as drought-tolerant. Tolerant varieties help farmers mitigate climate challenges and sustain food supply. Moreover, local maize landraces offer the potential for discovering valuable tolerance traits.