The vast area and marked variation of China make it difficult to predict the impact of climate changes on rice productivity in different regions.Therefore,analyzing the spatial and temporal characteristics of rice pot...The vast area and marked variation of China make it difficult to predict the impact of climate changes on rice productivity in different regions.Therefore,analyzing the spatial and temporal characteristics of rice potential productivity and predicting the possible yield increment in main rice production regions of China is important for guiding rice production and ensuring food security.Using meteorological data of main rice production regions from 1961 to 1970（the 1960s） and from 1996 to 2005（the 2000s） provided by 333 stations,the potential photosynthetic,photo-thermal and climatic productivities in rice crop of the 1960s and 2000s in main rice production regions of China were predicted,and differences in the spatial and temporal distribution characteristics between two decades were analyzed.Additionally,the potential yield increment based on the high yield target and actual yield of rice in the 2000s were predicted.Compared with the 1960s,the potential photosynthetic productivity of the 2000s was seen to have decreased by 5.40%,with rates in northeastern and southwestern China found to be lower than those in central and southern China.The potential photo-thermal productivity was generally seen to decrease（2.56%） throughout main rice production regions,decreasing most in central and southern China.However,an increase was seen in northeastern and southwestern China.The potential climatic productivity was observed to be lower（7.44%） in the 2000s compared to the 1960s,but increased in parts of central and southern China.The potential yield increment from the actual yield to high yield target in the 2000s were no more than 6×103 kg ha-1 and ranged from 6×103 to 12×103 kg ha-1 in most of the single-and double-cropping rice growing regions,respectively.The yield increasing potential from the high yield target to the potential photo-thermal productivity in 2000s were less than 10×103 kg ha-1 and ranged from 10×103 to 30×103 kg ha-1 in most of the single-and double-cropping rice growing regions,re展开更多
The spatial pattern of paulownia witches＇ broom was investigated using an Iwao＇s （m^＊-m） model in Shaanxi Province, China. Iwao＇s （m^＊-m） model revealed that spatial pattern of paulownia witches＇ broom exhib...The spatial pattern of paulownia witches＇ broom was investigated using an Iwao＇s （m^＊-m） model in Shaanxi Province, China. Iwao＇s （m^＊-m） model revealed that spatial pattern of paulownia witches＇ broom exhibited a uniform distribution in sample plots. In this model, characteristics of contagiousness coefficient （a） justified the probability of infection by virus-transmission vectors. For tree age less than six, susceptible individuals were aggregated as clusters in the plots and then mutually repelled over age. A preliminary survey of stand volume show that from age five to six, stand volumes of disease grade II showed excessive vegetative growth and returned to normal level between ages ten and 11. Loss rate of volume increment with disease grade II decreased, and then returned to raising trend both at grades III and IV. This phenomenon is possibly caused by an over-compensation effect and by environmental factors. The redundancy of growth hormones in branches, shoots, leaves, buds and roots increased the stem volume of entire trees.展开更多
基金supported by the Key Technologies R&D Program of China during the 12th Five-Year Plan period (2011BAD21B03)the National Basic Research Program of China (2009CB118608)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (PAPD)
文摘The vast area and marked variation of China make it difficult to predict the impact of climate changes on rice productivity in different regions.Therefore,analyzing the spatial and temporal characteristics of rice potential productivity and predicting the possible yield increment in main rice production regions of China is important for guiding rice production and ensuring food security.Using meteorological data of main rice production regions from 1961 to 1970（the 1960s） and from 1996 to 2005（the 2000s） provided by 333 stations,the potential photosynthetic,photo-thermal and climatic productivities in rice crop of the 1960s and 2000s in main rice production regions of China were predicted,and differences in the spatial and temporal distribution characteristics between two decades were analyzed.Additionally,the potential yield increment based on the high yield target and actual yield of rice in the 2000s were predicted.Compared with the 1960s,the potential photosynthetic productivity of the 2000s was seen to have decreased by 5.40%,with rates in northeastern and southwestern China found to be lower than those in central and southern China.The potential photo-thermal productivity was generally seen to decrease（2.56%） throughout main rice production regions,decreasing most in central and southern China.However,an increase was seen in northeastern and southwestern China.The potential climatic productivity was observed to be lower（7.44%） in the 2000s compared to the 1960s,but increased in parts of central and southern China.The potential yield increment from the actual yield to high yield target in the 2000s were no more than 6×103 kg ha-1 and ranged from 6×103 to 12×103 kg ha-1 in most of the single-and double-cropping rice growing regions,respectively.The yield increasing potential from the high yield target to the potential photo-thermal productivity in 2000s were less than 10×103 kg ha-1 and ranged from 10×103 to 30×103 kg ha-1 in most of the single-and double-cropping rice growing regions,re
文摘The spatial pattern of paulownia witches＇ broom was investigated using an Iwao＇s （m^＊-m） model in Shaanxi Province, China. Iwao＇s （m^＊-m） model revealed that spatial pattern of paulownia witches＇ broom exhibited a uniform distribution in sample plots. In this model, characteristics of contagiousness coefficient （a） justified the probability of infection by virus-transmission vectors. For tree age less than six, susceptible individuals were aggregated as clusters in the plots and then mutually repelled over age. A preliminary survey of stand volume show that from age five to six, stand volumes of disease grade II showed excessive vegetative growth and returned to normal level between ages ten and 11. Loss rate of volume increment with disease grade II decreased, and then returned to raising trend both at grades III and IV. This phenomenon is possibly caused by an over-compensation effect and by environmental factors. The redundancy of growth hormones in branches, shoots, leaves, buds and roots increased the stem volume of entire trees.
