[Predicting the impact of climate change in the next 40 years on the yield of maize in China].

Climate change will significantly affect agricultural production in China. The combination of the integral regression model and the latest climate projection may well assess the impact of future climate change on crop yield. In this paper, the correlation model of maize yield and meteorological factors was firstly established for different provinces in China by using the integral regression method, then the impact of climate change in the next 40 years on China's maize production was evaluated combined the latest climate prediction with the reason be ing analyzed. The results showed that if the current speeds of maize variety improvement and science and technology development were constant, maize yield in China would be mainly in an increasing trend of reduction with time in the next 40 years in a range generally within 5%. Under A2 climate change scenario, the region with the most reduction of maize yield would be the Northeast except during 2021-2030, and the reduction would be generally in the range of 2.3%-4.2%. Maize yield reduction would be also high in the Northwest, Southwest and middle and lower reaches of Yangtze River after 2031. Under B2 scenario, the reduction of 5.3% in the Northeast in 2031-2040 would be the greatest across all regions. Other regions with considerable maize yield reduction would be mainly in the Northwest and the Southwest. Reduction in maize yield in North China would be small, generally within 2%, under any scenarios, and that in South China would be almost unchanged. The reduction of maize yield in most regions would be greater under A2 scenario than under B2 scenario except for the period of 2021-2030. The effect of the ten day precipitation on maize yield in northern China would be almost positive. However, the effect of ten day average temperature on yield of maize in all regions would be generally negative. The main reason of maize yield reduction was temperature increase in most provinces but precipitation decrease in a few provinces. Assessments of the future change of maize yield in China based on the different methods were not consistent. Further evaluation needs to consider the change of maize variety and scientific and technological progress, and to enhance the reliability of evaluation models.

[Effects of climate change on flax development and yield in Guyuan of Ningxia, Northwest China].

Based on variations of the annual mean temperature and precipitation analyzed using ob- servation data in Guyuan of Ningxia, the effects of climate change on the local flax developmental process and yield were investigated. The results showed that the annual mean temperature had an increasing trend (0.3 °C · (10 a)-1) and the annual precipitation had a decreasing trend (-20 mm · (10 a) -1) from 1957 to 2012. While the increasing trend of mean temperature during growing season of flax was more obviously than that of the annual temperature, the decreasing trend of precipitation during growing season was similar to that of annual precipitation. With temperature increasing and precipitation decreasing, the flax development rate was accelerated, resulting in the reduced growing period. Seedling stage was advanced 0.7 d with 1 °C increase in temperature during the period from sowing to seedling emergence. The duration from seedling emergence to two pairs of needles was shortened by 0.8 d with 1 °C increase in temperature and 0.1 d with 1 mm decrease in precipitation. Maturity stage was advanced 1.8 d with 1 °C increase in temperature and 0.1 d with 1 mm decrease in precipitation during the period from technical maturity to maturity. The flax development was accelerated because of temperature increasing and precipitation decreasing in the vegetative growth phase, which was one of the main causes of flax yield reduction year by year. Meanwhile, flower bud differentiation and pollination of flax were influenced by temperature increasing in the reproductive growth phase, which would affect the number of capsules and the seed setting rate per plant and lead to the decrease of flax yield. Therefore, adjusting plant structure and enlarging the planting area of late or middle-late variety were the important measures to reduce the effects of climate change on local flax production.

[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.