High temperature-induced male fertility impairment in maize pollen development stages

Knowledge of the maize pollen development stages at which high temperature (HT) stress leads to male sterility and yield loss would support targeted breeding strategies. In a cross between Zhengdan 958 (HT-tolerant) and Xianyu 335 (HT-sensitive) the contributions of maize traits to effective grain number (EGN) loss under HT stress were measured during pollen development stages, with loss increasing with the approach of flowering. Traits including pollen number per anther, total tassel spikelets, and pollen germination and shedding were the strongest contributors at various stages. The stage-specific vulnerabilities of maize tassels to HT stress suggest increasing pollen production before the tetrad stage and increasing pollen fertility and shedding during the microspore development stage. In the short term, increasing pollen developmental quality offers the greatest potential for reducing HT-caused EGN loss.