Effect of Long-Term Continuous Cropping System on Leaf Photosynthetic Characteristics and Yield of Processing Tomato

To illustrate the effect of continuous cropping on photosynthetic characteristics and yield of processing tomatoes,we performed a position-plot experiment to investigate the growth characteristics,photosynthetic characteristics and yield under continuous cropping.The results showed that compared with 1 year cropping,intercellular CO2 concentration from seedling stage to mature period were significantly increased under 3-7 years continuous cropping,while with the time of continuous cropping increasing,the leaf photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs),water use efficiency(WUE),chlorophyll content and biomass were more remarkably decreased than that of 1 year continuous cropping(P0.01).Meanwhile,the yield were also decreased by 9.46%,15.61 % and 33.94%,respectively,under 3-7 years continuous cropping.The obstacles of continuous cropping existed in processing tomato during the whole growth period,the leaf photosynthetic performances and yield were significantly decreased under long-term continuous cropping.