Water Potential Productivity And Benefit Assessment Of Dryland Farming In District Of High Temperature And Summer Drought

Conception and developmental history of crop potential productivity was recommended in this paper. The recent situation of research on corp.potential productivity was summarized and some research methodologies in common use were introduced.Firstly, according to the frequency of summer drought, we can distinguish all counties in Chongqing into four types as Center, High Frequency, Common Area, Low frequency, assigning them 0,1,2 and 3.Water potential productivities of every district were calculated respectively based on the Miami Model and Thortwaite Memorial Model.Furthermore, the agricultural photosynthesis potential productivities, photo-temperature potential productivities and water potential productivities of six main crops(Including wheat, maize, sweet potato, potato, rape, bean in monoculture) and five multi-cropping planting patterns(Including potato-maize-sweet potato, rape-maize-sweet potato, wheat-maize-sweet potato, wheat-maize-bean, rape-maize) for seven districts (Including Fengjie, Pengshui, Youyang, Shapingba, Wanxian, Fuling, Liangpin) selected for representatives were calculated based on mechanism method and analyzed.At last, take the district of Shapingba as a sample,research on the possible impact of High Temperature and Summer Drought on the water potential productivities. The crops and planting patterns as same sa above.The construction of evaluation index system was based on the study results and sown areas and output of major farm crops in Chongqing.The result shows that:(1)In monoculture, maize is the best in the photosynthesis potential productivities, photo-temperature potential productivities and water potential productivities, and sweet potato and potato are better, bean, rape and wheat are poor. The districts of Shapingba and Wanxian are better than the others due to the good condition of illumination, temperature and water. Altough the districts of Youyang and Pengshui have fair Water use efficiency, the whole potential is poor due to low illumination.(2)In multi-cropping, potato-maize-sweet potato and rape-maize-sweet potato are better among the five planting patterns, and the following pattern are wheat-maize-sweet potato, wheat-maize-bean and rape-maize. The districts of Fengjie, Liangpin and Wanxian are best by region. (3)The high temperature and summer drought could affect water potential productivities more than the photosynthesis potential productivities and photo-temperature potential productivities. From this perspective we conclude that water is the most important impact factor in the districts of high temperature and summer drought.(4)In multi-cropping, all of the five planting patterns can get a good harvest in the years of Low frequency of high temperature and summer drought or sufficient rainfall.This shows that all of planting patterns can suit the districts of high temperature and summer drought.(5)In this paper three models were used to calculate and analyze the water potential productivities of the districts of high temperature and summer drought. This result shows that Mechanism Method and Thortwaite Memorial Model can be used in the study area but Miami Model.(6)Evaluation of production potential was constructed and development of the productive potential of the corresponding measures was proposed based on the above research.