Abstract:

As the main rice−producing areas in China, the low temperature is the main meteorological limiting factor for rice production in northeast China. So it’s important to study the impact of extreme low temperatures on rice yield in the three provinces of northeast China for local high and stable rice production and national food security. Taking rice of northeast China as the research object, this paper analyzed the influence of cool days on rice yield in the three provinces of northeastern China from 1980 to 2021, in order to solve the problem of unclear impact of extreme low−temperature events on rice yield, and to provide a reference for the impact assessment of such events on rice yield. The results showed that from 1980 to 2021, the cool days in the four growth stages of rice as transplanting−regreening, regreening−booting, booting−heading and heading−ripening in the three provinces of northeast China all showed a decreasing trend. The abrupt changed of cool days occurred in 2009, and the downward trend became statistically significant since 2016. The cool days during the rice field growing season exhibited an extremely significant negative effect on the relative meteorological yield of rice. Among all growth phases, the transplant−regeneration phase showed a positive effect, whereas the others demonstrated negative effects. The cool days during the booting−heading stage had the greatest contribution rate to the relative meteorological yield, reaching 43%, indicating that the cool days in this period had the greatest impact on the rice yield in the three provinces of northeast China. Among the three provinces of northeastern China, Liaoning exhibited the highest contribution rate of cool days to the relative meteorological yield of rice, at 55%, demonstrating that the cool days in Liaoning had the greatest impact on rice yield. The cool days at different growth stages exhibited a certain interactive effects on the relative meteorological yield of rice, and these interactive effects may amplify the positive contribution of cool days during the transplanting−regreening stage. In future rice production management across the three northeastern provinces, particular attention should be paid to the occurrence of cool days during the booting−heading stage, and corresponding measures should be taken in a timely manner to reduce their effects to ensure high and stable rice production.

Key words: Three provinces of northeast China, Extreme low temperature event, Rice, Meteorological yield, Contribution rate