Systematic Synthesis of Impacts of Climate Change on China's Crop Production System

Global climate change is real and already taking place. The most recent Fifth Assessment Report of the Intergov- ernmental Panel on Climate Change （IPCC AR5） stated that global land and ocean surface temperature increased by 0.85℃ over the period of 1880 to 2012 （IPCC Climate Change 2013）. China is among the most affected countries by global climate change.

Study on Rice Water Requirement of Liangping County under Climate Change Background

Under global climate change background,using daily meteorological data at Liangping ground meteorological station during 1961- 2012,we calculated crop water requirement and net irrigation water requirement during rice growth period in Liangping County,and analyzed its climate tendency rate. Results showed that climate tendency rate of crop water requirement during growth period of rice was only- 0. 007 mm /10 a; climate tendency rate of rainfall was- 0. 06 mm /10 a,but interannual change was relatively larger; climate tendency rate of net irrigation water requirement was 0. 011 mm /10 a. In the years when drought occurred,such as 2006 and 2011,both rice water requirement and net irrigation water requirement in Liangping were greatly higher than means over the years. Therefore,we should focus on drought pre-warning and risk management improving drought disaster prevention in Liangping in the future.

CHANGE OF CLIMATE AND ITS INFLUENCE ON THE CROPPING SYSTEM IN CHINA

Tne global change of climate and its influence on the cropping system in China have been investigated in this paper.It is found that the temperature was increased during the last decade and the precipitation decreased in northern China and increased in southern China during the last 30 years.The sea level has been rising by about 21—26 cm in the coastal areas south of 30°N in China during the last 100 years. The most of results as simulated by the general circulation models(GCMs)show that the temperature increase would amount to about 2°—4°C in the most parts of China and precipitation and soil moisture might be decreased in northern China and increased in sourthern China due to doubling of carbon dioxide(CO_2). The effects of doubled CO_2 on growth period and climatic yield capability in China have been estimated roughly.It is shown that the regions of the growth period in China would be moved northward about five degrees latitude and the climatic yield capability might be increased by about 10％ in the most parts of China.

Impact of Climate Change on Maize Potential Productivity and the Potential Productivity Gap in Southwest China

The impact of climate change on maize potential productivity and the potential productivity gap in Southwest China（SWC） are investigated in this paper.We analyze the impact of climate change on the photosynthetic,light-temperature,and climatic potential productivity of maize and their gaps in SWC,by using a crop growth dynamics statistical method.During the maize growing season from 1961 to 2010,minimum temperature increased by 0.20℃ per decade（p 〈 0.01） across SWC.The largest increases in average and minimum temperatures were observed mostly in areas of Yunnan Province.Growing season average sunshine hours decreased by 0.2 h day^（-1） per decade（p 〈 0.01） and total precipitation showed an insignificant decreasing trend across SWC.Photosynthetic potential productivity decreased by 298 kg ha^（-1）per decade（p 〈 0.05）.Both light-temperature and climatic potential productivity decreased（p 〈 0.05） in the northeast of SWC,whereas they increased（p 〈 0.05） in the southwest of SWC.The gap between lighttemperature and climatic potential productivity varied from 12 to 2729 kg ha^（-1）,with the high value areas centered in northern and southwestern SWC.Climatic productivity of these areas reached only 10%-24%of the light-temperature potential productivity,suggesting that there is great potential to increase the maize potential yield by improving water management in these areas.In particular,the gap has become larger in the most recent 10 years.Sensitivity analysis shows that the climatic potential productivity of maize is most sensitive to changes in temperature in SWC.The findings of this study are helpful for quantification of irrigation water requirements so as to achieve maximum yield potentials in SWC.