Effects Of Different Tillage Methods On Grain Yield And Physiological Charactoristic In Summer Soybean

In this experiment, took the yellow13as materials to study the effects of conventional tillage(CT), conventional tillage＆mulch(CTS), rotary(RT), rotary＆mulch(RTS), no tillage＆mulch(NTS), subsoiling tillage/no tillage＆mulch(STS+NTS), subsoiling tillage＆mulch(STS) on the growth and development, photosynthetic characteristics,dry matter accumulation, senescence characteristics, nitrogen metabolism indicators and yield of summer soybean, the results were as follows:1. The effects of different tillage system on dry matter accumulation and yield of summer soybean.(1) height: With the advance of growth process, the height of summer soybean increased, and the increasing rate was fast in early stage, then the increasing rate started to decline, until the soybeans mature. CT and RT could promote the soybean height growth in early stage, and plant height was relatively lower under NTS, the performance of the plant height in seedling and branching stage was as follow: CT＞RT＞RTS＞CTS＞STS＞STS+NTS＞NTS, the late period rank of plant height were STS＞STS+NTS＞RTS＞CTS＞NTS＞RT＞CT.(2) stem diameter: the growth trend of stem diameter was consistent with the height in the whole growth process of soybean. Compare between different tillage, CT and RT had the highest stem diameter in seedling and branching stage, then the growth of stem diameter was being accelerated. At maturity, the effect of different tillage on stem diameter showed: STS＞STS+NTS＞NTS＞RTS＞CTS＞RT＞CT.(3) Leaf area index: Soybean leaf area index under different tillage measures showed“first increased and then decreased”, leaf area index had been increased in blossom period, then decreased and trended to stable at last. Compare between different tillage, the rank of leaf area index were: STS＞STS+NTS＞RTS＞CTS＞NTS＞RT＞CT.(4) The content of chlorophyll: The content of chlorophyll a, chlorophyll b and chlorophyll (a+b) showed “first increased and then decreased trend” after flowering, and come to the highest in21days after anthesis, the performance of chlorophyll content was as follow: STS＞STS+NTS＞NTS＞RTS＞CTS＞RT＞CT.(5) Dry matter accumulation and distribution: Soybean dry matter accumulation showed an upward trend before filling period, then started to decline, the differences of dry matter accumulation were not significant under different tillage measures in blossom period, in other stages, STS was highest, followed by STS+NTS, NTS, RTS, CTS, RT and CT. The change tendency of stems, leaves, petioles dry matter accumulation were almost the same as total dry matter accumulation trends, in early growth period the amount of dry matter accumulation was mainly in the leaf, then transferred to the petiole and stem, last transferred to the grain. Effects of different tillage measures on dry matter accumulation in different organs of soybean were different, on average, the dry matter accumulation showed: STS＞STS+NTS＞NTS＞RTS＞CTS＞RT＞CT.(6) The formation characteristics of grain: The grain filling rate of soybean was consistent with Logistic growth curve. At late grain filling stage, dry matter accumulation showed: STS＞STS+NTS＞RTS＞CTS＞NTS＞RT＞CT.(7) yield: Conservation tillage produced a significant effect on grain weight and yield of soybean, the final rank of yield were: STS+NTS＞STS＞NTS＞RTS＞CTS＞RT＞CT.2. Effects of different tillage measures on summer soybean senescence. Conservation tillage could increase SOD and POD activity, decrease the content of MDA in soybean leaves at late growth stage, enhance stress resistance of seedling, delay plant senescence. Leaf SOD activity had been "down" trend, POD presented "first increased and then decreased trend" after flowering. Effects of different tillage measures on SOD and POD activity were: STS＞STS+NTS＞NTS＞RTS＞CTS＞RT＞CT. MDA content had been showing a rising trend, MDA content was the lowest under STS treatment, followed by STS+NTS, NTS, RTS, CTS, RT, lower than that of CT38.87%,30.18%,26.77%,21.06%,13.95%,7.26%. The effects of different tillage measures on the content of soluble sugar showed “first increased and then decreased” trend, and came to the highest in14days after anthesis. At peak, STS was highest, followed by STS+NTS, RTS, NTS, CTS, RT, CT, STS and STS+NTS, in the late stage had been maintained at a high level, and laid the material foundation for the grain filling of soybean.3. Effects of different tillage measures on nitrogen metabolism of summer soybean. The straw mulching and subsoiling tillage could increase the content of soluble protein, free amino acid and nitrate nitrogen, the final effect of tillage methods on metabolism characteristics of soybean leaves after flowering were manifested as: STS is the highest, followed by STS+NTS, RTS, CTS, NTS, RT, CT. Conservation tillage could reduce the content of free proline in leaves, reduce stress on soybean leaves, from the average value during the whole growing period after anthesis, CT was the highest, followed by RT, CTS, RTS, NTS, STS+NTS, STS. Different tillage measures on nitrate reductase activity in soybean leaves showed "first increased and then decreased" trend, nitrate reductase activity in each treatment was higher than that of CT, and the differences were significant.