[Effects of different tillage methods on photosynthetic characteristics, dry matter production and economic benefit of double cropping soybean].

: In order to explore suitable mode of high yield cultivation of double cropping soybean after wheat under drip irrigation in northern Xinjiang, field trials were set in 2013-2014 to investigate physiological indices and agronomic traits of double cropping soybean under different tillage methods under drip irrigation. The results showed that leaf area index (LAI), chlorophyll content (SPAD), leaf net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (g(s)) during the determination period under different tillage methods were in the order of tillage plus film covering (TP)> tillage (T)> rotary tillage (RT) > no-tillage (NT) , and the concentration of intercellular CO₂(Ci) was the opposite. LAI, SPAD, Pn, Tr, and g(s) of TP were higher than that with NT by 55.0%, 9.1%, 41.8%, 37.5% and 56.4%, respectively, and Ci was decreased by 22.1%. TP enhanced the photosynthetic efficiency of soybean and improved the ability of CO₂assimilation, consequently leading to the increase of soybean yield under TP compared to NT. The plant dry matter accumulation of TP treatment was improved greatly, with the pod number and seeds number per plant, 100-seed mass and yield of quadric sowing soybean being increased by 50.3%, 48.1%, 11.8% and 20.8% compared with that under NT, and the differences were significant. Therefore, the plastic film mulching combined with tillage under drip irrigation technology was suitable for double cropping soybean after wheat in northern Xinjiang under this experimental condition.