Effects Of Tillage And Seeding Method,Planting Density,and Fertilizer Application On Population Composition And Grain Yield Of Wheat Following Rice

There is a tendency of "emphasizing rice production and weakening wheat production" in the areas using the rice-wheat rotation ststem.In order to improve the rice yield,the harvest time has be delayed,which leads to the lack of enough time for soil drying and soil preparation for wheat sowing.Moreover,in these areas,there are more rainfalls during the wheat planting season,and the soil moisture and texture are high in the field,which seriously affect the operation quality of mechanized tillage and sowing,negatively influencing on the growth and development of wheat and the final grain yield.Therefore,the choice of mechanical tillage and sowing methods and how to adopt appropriate cultivation measures have become be urgent problems to be solved.In this experiment,Yangmai 25 was used as the test material,and the field test was carried out at Jiangyan during 2018-2019 and 2019-2020 seasons.Under the condition of the rice straw returned into the field with a full amount,different tillage planting way[TS1(rotary tillage sowing machine+small pendulum twice),TS2(rotary tillage twice+medium rotary drill),TS3 stubble(plate+medium no-till drill)]were used to study the differences in soil physical and chemical properties,wheat sowing quality,seedling quality,population quality,photosynthetic physiological,nitrogen accumulation and utilization,and grain yield and its components,grain quality,and nitrogen efficiency.Besides,the effects of different densities(225×104 plant·hm-2 and 300×104 plant·hm-2)and nitrogen fertilizer application ratios(basal fertilizer:tillering fertilizer:jointing fertilizer:(5:1:2:2,6:0:4:0,7:0:3:0 and 7:0:0:3)were investigated.We also analyzed the effects of soil physical and chemical properties on the growth of wheat seedlings and the relationships between seedling growth and population quality and grain yield.The results were expected to provide theoretical and technical references for large-scale mechanized production of rice stubble wheat,and put forward the tillage and sowing methods and the corresponding agronomic measures that are conducive to the robust wheat growth and the high yield,high quality,and high efficiency production.The main results are as follows:1.In the two years,the emergence rate and evenness of wheat seedlings sown under TS1 and TS2 after rotation tillage were higher than those under TS3,but the population dry matter weight per plant,dry matter accumulation,and nitrogen accumulation,plant nitrogen content,soluble sugar content,and Rubisco enzyme activity in the fourth leaf were higher under TS3 at the beginning of overwintering stahe under the same basic seedling.The results indicated that TS1 and TS2 tillage and sowing methods were helpful to ensure the number of seedlings,but the seedling quality under the same basic seedling was poor,while seedling quality was better under TS3.Although the soil bulk density under TS3 method was higher than those under TS1 and TSe with ranging 1.6 g.cm-3 at seedling stage,the surface soil was enriched with more available nitrogen,phosphorus,and potassium nutrients.Therefore,the root system coordinated the nutrient absorption.In addition,the water content in 0-20 cm soil layer under TS3 method was higher than that under TS 1 and TS2 when the soil was dry at seedling stage.There was no obvious difference in soil moisture between tillage and sowing methods under the wet soil condition.Compared with TS1 and TS2,the soil temperature under TS3 decreased more gently with the deepening of soil layer,and the daily variation was also relatively gentle.The results showed that TS3 soil conditions were favorable for moisture preservation under dry conditions and heat preservation under low temperature conditions,which promoted seedling growth.Increasing seedling number from 225×104 plant·hm-2 to 300×104 plant·hm-2 had no significant effects on individual growth and physiology,but significantly increased dry matter accumulation,leaf area index(LAI),and nitrogen accumulation.Increasing basal N application rate could significantly improve seedling quality,but excessive N application did not promote tiller number and soluble sugar content.135 kg·hm-2 N application rate was the best.There were significant interaction effects of tillage and sowing method,density and basal fertilizer on the growth of wheat seedlings.In conclusion,under different mechanical tillage and seeding methods,sowing amount can be controlled precisely and sufficient basic fertilizer can be applied at the same time to ensure the number of seedlings,which is the key achieving engough and strong seedlings.2.In the two years,single plant dry weight,population dry matter accumulation,and leaf area index at the beginning of over-wintering stage were significantly positively correlated with leaf area index at flowering stage,leaf area index at milking stage,and dry matter accumulation at maturity stage.The dry weight per plant,leaf area per plant,number of secondary rooting per plant,plant soluble sugar content and Rubisco activity in the fourth leaf at the beginning of overwintering stage were significantly positively correlated with SPAD value,Rubisco activity,and SOD activity at flowering and milk maturity stage.In addition,dry weight per plant,number of secondary roots per plant,population leaf area index,population dry matter accumulation,plant soluble sugar content,and Rubisco enzyme activity in the fourth leaf at the beginning of over-wintering stage were significantly positively correlated with grain yield.These results indicate that cultivating strong seedlings before winter is beneficial to the subsequent population development,improving population quality,delaying senescence of flag leaves,and promoting photosynthetic production capacity,thus contributing to the increase of grain yield.3.The effects of tillage and sowing methods on wheat growth and grain yield varied with annual conditions.The number of tillers in the field was lower in 2019 than that in 2020 due to more rainfall and lower winter temperature in 2019.Under the same basic seedling,the grain yield under TS1 and TS3 was significantly higher than that under TS2 in 2019.The sowing method of TS1 was broad-seeding,acheving sufficient growth space,more tillers,significantly higher tiller number and tiller heading rate in the field compred with other treatments,resulting to higher leaf area index and dry matter accumulation during the medium and late growth period,and higher photosynthetic production capacity,and antioxidant capacity after anthesis.These caused a higher final yield under TS1.Although the number of tillers in the field and the tiller feritity were not high under TS3 compared with other methods,the leaf area index and dry matter accumulation in the middle and late growth period of TS3 were higher.Besides,the leaf senescence after anthesis was slower under TS3,and the photosynthetic production capacity was stronger.Finally,TS3 achieved a higher yield due to significantly higher grain number per panicle and 1000-grain weight.In 2020,TS3 seedlings were robust with a better population quality,slow senescence of flag leaves after flowering,and strong photosynthetic productivity.Finally,TS3 achieved the highest yield due to the combined effect of significantly higher panicle number and grain number per panicle.In the two years,the seedling number increased from 225 ×104 plant·hm-2 to 300×104 plant·hm-2,tiller number,leaf area index(LAI),and dry matter weight accumulation in the field were increased during the medium and late growth period,the photosynthetic production capacity of flag leaf was stronger,the senescence was slow,panicle number,1000-grain weight,and grain yield were increased.In the two years,compared with other nitrogen application ratios,leaf area index and dry matter accumulation of 7:0:3:0 treatment were higher during the medium and late growth period,photo synthetic production capacity was improved,and final yield increased.The differences in grain yiled was not significant between 5:1:2:2 and 6:0:4:0 In conclusion,under different tillage and sowing methods,the supporting regulation of basic seedling and nitrogen fertilizer management is more conducive to the construction of strong seedling and high yield population.4.In the two years,TS3 was conducive to the absorption of nitrogen under the same basic seedling,achieving higher agronomic efficiency and apparent use efficiency of nitrogen fertilizer compared with TS1 and TS2.The seedling number increased from 225×104 plant·hm-2 to 300×104 plant·hm-2 and the application of nitrogen fertilizer 7:0:3:0 improved the nitrogen accumulation and grain nitrogen accumulation at maturity stage,increasing the agronomic efficiency and apparent utilization rate of nitrogen fertilizer.In general,a combination of 300×104 plant·hm-2 and nitrogen fertilizer application ratio of 7:0:3:0 could achieve higher nitrogen efficiency under different tillage and sowing methods.5.In the two years,the ghrain protein content and wet gluten content under TS2 and TS3 after rotary tillage and no-tillage TS3 under the same basic seedling were higher than TS1.There was no significant difference in grain protein content between the two different basic seedlings.The grain protein content and wet gluten content under nitrogen application ratio of 5:1:2:2 and 7:0:0:3 treatments were higher than those under 6:0:4:0 and 7:0:3:0 treatments.In general,the effect of basic seedling on grain quality was limiting.Under the condition of a certain amount of total nitrogen application,the delay application of nitrogen fertilizer was helpful to improve the grain quality of middle-gluten wheat.The results also showed that tillage and sowing methods,basic seedlings,and nitrogen fertilizer management had significant interaction effects on the measured grain quality indexes.6.There were differences in the basic seedling and nitrogen fertilizer management achieving high yield,high quality,and high efficiency of wheat fllowing rcie under different tillage and sowing methods with depending on years.The grain yield and nitrogen agronomic efficiency of TS3 combined with 225×104 plant·hm-2 and N management strategy 7:0:3:0 or 300×104 plant·hm-2 and N management strategy 7:0:3:0 were higher than those under other combinations in the two years.Therefore,TS3 could be recommended as a high-yield and high-efficiency cultivati-on mode for wheat planting after rice.In addition,the combination of TS3,basic seedling 225 ×104 plant·hm-2 and N operation strategy 6:0:4:0 in 2020 also had higher grain yield and N agronomic efficiency.Under the conditions of TS1 and TS2,300×104 plant·hm-2 and nitrogen fertilizer management 7:0:3:0 could be recommended to carry out the matching cultivation,which was conducive to the high-yield and efficient production of wheat.Although the above combinations are helpful to achieve high yield and high efficiency of rice stubble wheat,the grain quality is not the best compared with other combinations,which needs further study to improve grain quality.