[Effects of potato/soybean intercropping on photosynthetic characteristics and yield of three soybean varieties].

The potato/soybean intercropping trials using three soybean varieties including Zhonghuang 30 (early-maturing variety) , Jidou 17 (mid maturing variety) and Qihuang 34 (late maturing variety) with the sole cropping potato as control were carried out to determine the dynamic changes of leaf area index (LAI) of soybean, accumulation of dry matter, photosynthetic characteristics, yield and yield components. The results showed that the LAI, dry matter accumulation, net photosynthesis (Pn), transpiration rate (Tr) and stomatal conduction (g(s)) of soybean in all intercropping systems were lower than in monoculture because of the influence of intensified lower light during earlier growing stage, and the duration from planting to flowering was extended. When the potato was harvested, the LAI, dry matter accumulation, Pn, Tr and g(s) of soybean in all intercropping systems increased, especially for mid-maturing and late-maturing varieties, which became much closer to those in the monoculture. Compared with sole cropping, the pods per plant, seeds per plant and seeds per pod in intercropping system significantly decreased by 22.0%, 36.0% and 17.6% for early-maturing soybean, 5.1%, 13.1% and 8.9% for mid-maturing soybean, 5.7%, 7.6% and 2.1% for late-maturing soybean, respectively. The yields of mid-maturing and late-maturing varieties in intercropping systems were higher than that of the early-maturing, which increased by 92.4% and 163.4%, with the land equivalent ratio (LER) of 1.81 and 1.84, respectively. This suggested that mid-maturing and late-maturing soybean varieties were suitable for intercropping with the potato to improve photosynthetic efficiency, dry matter accumulation and yield of intercropping soybean.