[Dynamic identification of double-early rice heat and its spatiotemporal characteristics in Jiangxi Province, China]. / 江西早稻高温热害等级动态判识及时空变化特征.

Constructing evaluation indicator for rice heat damage based on hot weather process (occurring time of hot weather and its duration) can realize the dynamic identification of rice high-temperature heat damage level, which is of great importance to the precisely monitoring, warning and assessment of rice heat. Meteorological, historical disaster and phenological data on double-early rice in Jiangxi Province were integrated to retrieve the historical heat of double-early rice. The dynamic index of high temperature heat injury on early rice based on high temperature weather process was constructed based on K-S distribution fitting test and confidence interval method. The results were verified with reserved independent samples. A rice heat index (M) was calculated, with which rice heat risk was analyzed. The results showed that the starting time and duration of hot weather were key factors affecting the occurrence of rice heat damage, with the effect of starting time greater than the duration. Light, moderate, and severe rice heat for 3-5 d was identified at 10-12, 5-9 and 2-4 d after heading respectively. Similarly, light, moderate and severe rice heat lasting for 6-8 d and >8 d started at 11-18, 8-10, 1-7 d after heading and 12-18, 8-11, 0-7 d after heading respectively. The coincident rate of rice heat damage indicator was 73.7%, and that verified to be identical or one grade different was 89.5%. The linear tendency rate of M from 1981 to 2015 was 0.04·a-1, with abrupt change from low to high around 1999. A high M (>0.18) was mainly found in the middle and the northeast part of the study area. Increasing trends of a high M occurred in the middle, northeast and south of Jiangxi, with tendency rates > 0.04·a-1. In general, the indicators constructed in this study realized the dynamic identification of process-based rice heat. The middle and northeast parts of Jiangxi Province were identified as high risk areas for double-early rice heat.

[Climatic potential productivity of winter wheat and summer maize in Huanghuaihai Plain in 2011-2050].

Based on the daily data under B2 climate scenario (2011-2050) and baseline climate condition (1961-1990) extracted from the regional climate model PRECIS, and by using the Agro-Ecological Zone (AEZ) model, a prediction was conducted on the possible spatiotemporal changes of the climatic potential productivity of the two crops in the Huanghuaihai Plain in 2011-2050. Under baseline climate condition, the climatic potential productivities of winter wheat and summer maize presented a regional differentiation, i.e., higher in southeast and lower in northwest regions, and higher along coast and lower in inland at the same latitudes, and fluctuated within the ranges of 3893-11000 kg x hm(-2) and 5908-12000 kg x hm(-2), respectively. Under B2 climate scenario, the climatic potential productivity of winter wheat and summer maize would have a greater inter-annual change, due to the different matching degrees of light, temperature and water during the growth periods of the crops. The climatic potential productivity of winter wheat in 2011-2030 and summer maize in 2021-2040 would have an obvious increase, with great potential for development. Under the conditions of maintaining the present production, the climatic potential productivity of winter wheat in 2011-2050 would present an overall regional differentiation of reverse change in southeast and northwest regions and the same change in coastal and inland areas, whereas the climatic potential productivity of summer maize in 2011-2050 would have little regional differentiation.

[Change trends of China agricultural thermal resources under climate change and related adaptation countermeasures].

Based on the 2011-2050 A2 climate scenario derived from the regional climate model PRECIS and the daily data of 1961-1990 baseline climate condition, this paper analyzed the possible changes of the agricultural thermal resources in China from 2011 to 2050. Comparing with the baseline climate condition in 1961-1990, the average frost-free periods in most parts of China in 2011-2050 under A2 climate scenario would have an obvious extension, mainly manifested in the advance of last frost date and the postpone of first frost date. The days with the daily average temperature stably passing 0 degrees C would also prolong significantly, and extend from 1 day to 14 days in most parts of the country. Especially from 2041 to 2050, the days with the daily average temperature stably passing 0 degrees C in most regions of Qinghai-Tibet Plateau, middle and lower reaches of Yangtze River, and western and southwestern regions of Gansu and Xinjiang could be extended by 49 days. The > or = 0 degrees C accumulated temperatures in most parts of the country would have increasing trends. In order to meet the future change trend of our agricultural thermal resources and to realize the sustainable development of agriculture in China, some countermeasures should be formulated, e.g., further adjusting agricultural cropping system, optimizing agricultural production distribution, developing biotechnology, and so on.