ABSTRACT

Few studies have tested the influence of climatic factors on yields by adjusting sowing dates at both low and high altitudes. We investigated the influence of the synergistic effects of temperature and solar radiation by conducting field experiments using different rice varieties and sowing dates in the low-altitude plains of Chongzhou and the high-altitude mountainous region of Hanyuan, Sichuan Province, China, in 2017 and 2018. The results showed that from transplanting to maturity, biomass yield and grain yield were significantly (p < 0.01) correlated with the average daily temperature and solar radiation. The Hanyuan site experienced higher solar radiation and lower temperature than those of Chongzhou, which contributed to higher dry matter accumulation (DMA) and crop growth rate values pre- and post-anthesis and more panicles per m², leading to higher biomass yields and grain yields at Hanyuan. The rice sowed earlier was subjected to higher solar radiation and lower temperature at Chongzhou and Hanyuan, resulting in increased DMA post-anthesis, panicles per m², and spikelet filling, improving biomass yield and grain yield. These results indicate that the high potential yield from the early sowing date in the high-altitude region was primarily due to increased solar radiation and decreased temperatures.