Effects Of Tillage Practices On Wheat Yield Formation And Carbon Metabolism In Rainfed Areas Of Longzhong

Central Gansu dryland region in the western part of the Loess Plateau is a typical semi-arid,rain-fed agricultural area.The scarcity of water supplies has become the most important factor restricting agricultural production,and conservation tillage practices primarily with straw cover are conducive to the efficient use of limited precipitation and crop yield increase.In order to explore the mechanisms of conservation tillage practices affecting spring wheat yield from the carbon metabolism perspective,this study is focused on the positioning test of long-term different tillage practices developed in the Loess Plateau dry farming area in 2001,which has a total of 4 treatments,respectively conventional tillage with no straw(T),no tillage without straw(T)cover(NT),conventional tillage with straw incorporated(TS),no-till with straw cover(NTS).The effects of various tillage practices on yield formation were studied in 2019,and the main mechanism of spring wheat yield carbon metabolism influenced by tillage measures from the photosynthesis and sucrose metabolism aspects were addressed.The principal findings of the analysis are as follows:1.No-till with straw cover(NTS)increased the amount of water in 0-30 cm soil during the wheat growth era,especially in 0-5 cm soil during the sowing era,which was 26.6% higher than traditional non-straw(T)tillage.The Tillage method had a major impact on 0-200 cm wheat water storage,and no-till treatments(NT,NTS)increased by 6.7% ~12.3% compared with tillage treatments(T,TS).2.Tillage conservation practices delayed the senescence of the wheat leaf after flowering,and improved photosynthetic efficiency.The NTS treatment chlorophyll content and leaf area index was significantly higher than that of other milky-stage treatments.In the filling point,no-tilting and straw mulching increased the activity of RuBP carboxylase and the activity of RuBP carboxylase in NTS treatments was 1.95 times that of T.Wheat flag leaf photosynthetic rate,transpiration rate,stomatal conductance in the flowering stage is higher than the filling stage,NTS effectively increases the spring wheat flowering cycle and photosynthetic output filling stage,compared to T an average increase in photosynthetic rate is 17.4 per cent.3.NTS increased the metabolism of wheat sugar.During the grouting stage,NTS treatment increased the soluble sugar and saccharose content of flag leaves in wheat,and the average concentration of sucrose was 14.9 percent higher than T.Tillage steps had no impact on the activity of the flag leaves in the flowering cycle of Sucrose phosphate synthase(SPS)and Sucrose synthase(SS).During the grouting phase,the no-tillage treatment(NT,NTS)increased the SPS activity while the straw mulching treatments(TS,NTS)reduced the activity.The NTS treatment increased the SPS activity by 92.0% and the SS activity by 53.7% compared with T.4.Conservation tillage methods have increased the efficiency of transporting photosynthetic materials.Post-flowering dry matter accumulation contribution rate under no-tillage treatment(NT and NTS)was 41.7 per cent higher than in tillage treatments(T and TS).Post-flowering accumulation of dry matter under straw mulching treatments(TS and NTS)was 71.2 per cent higher than in non-mulching treatments.NTS raised the number of spikes and the weight of 1000 grains of wheat substantially,and the yield was 18.7 per cent higher than that of T.During the growth period,straw mulching treatments(NTS,TS)improved production and water use,and NTS' water-use efficiency was 12.7 per cent higher than T significantly.5.The comprehensive factors of wheat's photosynthetic physiological characteristics were positively associated with spikes,weight and yield of 1000 grains,the comprehensive factors of the sucrose metabolism.The detailed metabolism factor for sucrose has been positively associated with spikes and wheat yield.Yield was positively correlated with comprehensive factor photosynthetic and physiological characteristics,comprehensive factor for sucrose metabolism,number of panicles and WUE,while WUE was only positively correlated with yield of wheat.The spikes were positively associated with the weight of 1000 grains but no meaningful association occurred between grains and other indexes.To sum up,the application of no-till with straw cover can improve wheat flag leaf area index,chlorophyll content,and increase RuBP carboxylase activity and photosynthetic efficiency,improve the filling stage flag leaf SPS activity,increase the concentration of sucrose,improve the performance of photosynthetic and sucrose metabolism,improve the efficiency of photosynthetic product transport,encourage accumulation of dry matter after flowering and transshipment,thereby enhancing efficiency in yield and water usage.