Effects of high temperature on pollen development and rice yield

Abstract

This study was conducted to evaluate the impact of high temperature on pollen viability, early anthesis, amylose content and yield components of two promising rice lines, TNN162 and TNN156. The results indicated that high temperature negatively impacted all growth and yield parameters. Specifically, the pollination rate, yield per hill, and amylose content of both lines decreased under high-temperature conditions. However, TNN162 and TNN156 demonstrated superior heat tolerance compared to the sensitive check variety IR64, exhibiting substantially lower yield reductions. Under high-temperature stress, the peak anthesis of TNN162 and TNN156 shifted one hour earlier (9-10 h) compared to normal conditions. This heat escape mechanism allowed the pollen to avoid the most extreme temperatures of the day, thereby maintaining higher pollen germination rates and spikelet fertility. Pearson correlation analysis further confirmed a strong positive relationship between pollen germination rate and pollination rate (r²=0.92***). These findings identify TNN162 and TNN156 as valuable genetic resources for developing climate-resilient rice varieties in the Mekong Delta.