Shading stress has become a worldwide phenomenon and can lead to rice (Oryza sativa L.) yield loss by decreasing the seed setting percentage (the percentage of filled spikelets to total spikelets per panicle), which depends primarily on spikelet fertility. However, the effect of shading stress on rice spikelet pollination and fertilization processes is not fully understood. Here, a field experiment, spanning two years (2019 and 2020), was conducted using two rice varieties (Huanghuazhan and Fyou 498) grown under full sunlight and 53 % shade. No significant difference in pollen I₂-KI staining rate was observed between the full sunlight control and the shading treatment in 2019 and 2020. However, shading stress significantly decreased the in vitro pollen germination rate of spikelets that opened 5 d and 8 d after shading in 2020. Shading stress also significantly reduced the anther dehiscence rate of both varieties in both years (except for Huanghuazhan at 2 d after shading in 2019), and a mass of pollen grains remained in the anthers. Together with a reduction in the stigma exsertion rate, shading stress reduced the number of pollen grains per stigma by 29.4–71.2 % and the number of germinated pollen grains per stigma by 9.8–63.2 %. Consequently, shading stress significantly decreased the fertilization rate in these varieties, which contributed to a marked yield loss. We assert that shading stress decreased the fertilization rate by inhibiting key pollination and fertilization processes, particularly anther dehiscence and pollen grain release.

遮荫胁迫已成为一种世界性现象，可通过降低结实率（饱满小穗占每穗总小穗的百分比）而导致水稻（Oryza sativa L.）产量损失，这主要取决于小穗肥力。然而，遮荫胁迫对水稻小穗授粉和受精过程的影响尚不完全清楚。在这里，一项为期两年（2019 年和 2020 年）的田间试验使用在充足阳光和 53% 遮荫下生长的两个水稻品种（黄花展和 Fyou 498）进行。花粉 I ₂无显着差异-KI 染色率在 2019 和 2020 年完全日照控制和遮荫处理之间观察到。但遮荫胁迫显着降低了 2020 年遮荫后第 5 天和第 8 天开放的小穗的离体花粉萌发率。遮荫胁迫也显着降低两个年份的花药开裂率均降低（2019年遮荫后2 d的黄花盏除外），花药中残留大量花粉粒。随着柱头外露率的降低，遮荫胁迫使每个柱头的花粉粒数量减少了 29.4-71.2%，每个柱头的发芽花粉粒数量减少了 9.8-63.2%。因此，遮荫胁迫显着降低了这些品种的受精率，导致显着的产量损失。