Effects of 1.5℃ Field Warming on Rice Yield and Quality in High Latitude Planting Area

Rice (Oryza sativa L.) is the most important cereal crop in China. An importance rice cultivation location in high latitude in China is Northeast region due to its superior production area. This region accounts for over 50% high quality japonica rice production in China. However, for nearly half a century, the annual average temperature of this region has increased by 1.1℃, making it the most obvious region of climate warming in China.

To ensure the continuous production of high-yielding and good quality japonica rice, it is of great significance to assess the impact of climate warming on rice yield and grain quality in the Northeast region of China.

A 2-year field warming experiment (1.5℃) with two japonica rice cultivars (Longdao 5 and Longdao 18) employed under a free air temperature increase (FATI) facility was conducted in Harbin city, Heilongjiang province. The aim of this study was to evaluate the effects of elevated temperature (ET) on rice growth period, grain yield, milled quality, appearance quality, nutrient and cooking quality.

The results of the study showed that the growth duration of rice under ET was reduced by 6-7 days and 4-5 days when compared with CK in 2017 and 2018, respectively. This was as a result of the shortened duration from the transplanting stage to heading stage. The average yield of Longdao 5 and Longdao 18 for the two-year increased by 5.8% and 14.4%, respectively, mainly due to the increase in effective panicle number per unit area. The ET significantly decreased amylose content in the rice grain, but varied slightly in-terms of brown rice rate, milled rice rate, head rice rate and protein content. The peak viscosity, hot paste viscosity and cool paste viscosity increased under ET, while consistence viscosity decreased. There was no significant influence of elevated temperature on setback viscosity in both Longdao 5 and Longdao 18.

Based on the lower background air temperature, increasing temperature by 1.5℃ in the high latitude region of Northeast promoted japonica rice yield and cooking quality, however, the continued warming would increase the uncertainties of rice quality variation in the future.