Effect of sowing date on radiation and temperature use efficiencies of rice in the low-light region of China

Abstract

Sowing date optimization is an effective measure for adapting to climatic change and has been widely used to optimize the use of solar radiation and temperature resources in rice production. To evaluate the influences of sowing date on radiation and temperature use efficiencies (RUE and TUE, respectively) and grain yield of rice in low-light regions, field experiments with three rice varieties and four sowing dates (S-0, S-10, S-30, and S-40) were conducted at Dayi, Anzhou, Nanbu, and Shehong, in Sichuan, China, in 2018 and 2019. The results showed that the yield, RUE, and TUE of rice were significantly and negatively correlated with delayed sowing dates across the study sites. Generally, delayed sowing dates increased the daily total solar radiation, daily mean temperature, and effective cumulative temperature before heading, but decreased the growth duration and cumulative total solar radiation before heading, which resulted in a reduction in the effective panicle number per unit area. Meanwhile, delayed sowing dates increased the growth duration after heading, but reduced the daily total solar radiation, daily mean temperature, cumulative total solar radiation, and effective cumulative temperature after heading, contributing to a decrease in both the seed setting rate and 1000-grain weight across study sites. Therefore, S-30 and S-40 markedly decreased the rice yield, RUE, and TUE at Anzhou, Nanbu, and Shehong in both years and at Dayi in 2019, compared to S-0 and S-10. Moreover, growth duration, solar radiation, and temperature parameters before and after heading could explain the 73.7 % variation in the relative grain yield, relative RUE, and relative RTUE across the study sites. Ensuring that the daily mean temperature after heading and growth duration before heading are greater than 25.8°C and 113 d, respectively, and the daily total solar radiation and mean temperature before heading and growth duration after heading are lower than 14.7 MJ m–2 d–1, 23.1°C, and 42 d, respectively, by earlier sowing, is required to improve the RGY, RRUE, and RTUE in the low-light regions of China.