Abstract:

In order to clarify the evolutionary rules of climate conditions for double-cropping rice cultivation in Yichun under the background of climate change, this study used meteorological data of 10 national meteorological stations in Yichun during 1961-2020, and selected 7 key climatic indicators closely related to the growth of double-cropping rice (including ≥10℃ accumulated temperature and number of days during the period from the first day when the daily average temperature stably reached 10℃ to the last day when the daily average temperature stably reached 20℃, first day and last day of the period, precipitation in the main flood season, number of days with daily maximum temperature ≥35℃ in summer, and precipitation in autumn). The variation characteristics of these indicators were analyzed by dividing the study period into two 30-year periods (1961-1990 and 1991-2020). The results showed that: the caloric conditions in Yichun were significantly optimized. From 1961 to 2020, both the ≥10℃ accumulated temperature and the number of days in the suitable growth period showed an increasing trend, and spatially, both presented a pattern of “high (abundant) in the southeast and low (scarce) in the northwest”. From 1961 to 2020, the scope of high-value areas expanded while the scope of low-value areas narrowed. The first day when the daily average temperature stably reached 10℃ advanced by 5-10 days, and the last day when the daily average temperature stably reached 20℃ was delayed, which extended the time for heat utilization. The regional differentiation of precipitation conditions was obvious, in the main flood season, precipitation decreased in 50% of the areas and increased in the other 50%, and the scope of high-value areas expanded in 1991-2020; in autumn, precipitation increased in 70% of the areas and decreased in 30%, and in 1991-2020, the scopes of both high-value and low-value areas narrowed while the scopes of sub-high-value and sub-low-value areas expanded, indicating that the precipitation distribution tended to be more uniform. The high-temperature risk in summer increased, the number of days with daily maximum temperature ≥35℃ increased in 90% of the areas, and in 1991-2020, the high-value areas extended to the north and their scope expanded. These changes pose differentiated challenges and adaptive opportunities for the adjustment of double-cropping rice planting structure, breeding of stress-resistant varieties and disaster risk management.

Key words: double-cropping rice, climate condition, adaptability zoning