Effects Of Nitrogen Fertilizer Management On Yield Physiology And Nitrogen Use Efficiency Of Spring Wheat Under Drip Irrigation In Southern Xinjiang

In order to explore the suitable nitrogen application rate,nitrogen application period and proportion of spring wheat in southern Xinjiang,this paper uses Xinchun 6?large spike type?and Ning 2038?multi-spike type?as test materials,through soil column cultivation test,mainly The differences in growth,root characteristics,yield,dry matter and nitrogen accumulation,distribution and operation of spring wheat under different nitrogen application rates and different nitrogen application periods were studied.In this study,three nitrogen application levels were set:N₁?103.5kg/hm²?,N₂?207kg/hm²?,and N₃?310.5kg/hm²?.Four nitrogen application periods were set for each nitrogen application level:R₁ 100%base fertilizer;R₂ 60%base fertilizer+40%jointing fertilizer;R₃ 40%base fertilizer+40%jointing fertilizer+20%booting fertilizer;R₄ 20%base fertilizer+40%jointing fertilizer+20%booting fertilizer+20%filling fertilizer;One N₀?0kg/hm²?was not fertilized and a total of 13 treatments were performed.The test results are as follows:?1?The plant height of Xinchun 6 and Ning 2038 increased with the increase of nitrogen application rate and times.The maximum of Xinchun 6 and Ning 2038 was 79.27 cm under N₃R₄treatment,74.71 cm under N₃R₃ treatment,and the maximum of Xinchun 6 and Ning 2038 was 3times and 2 times respectively.At booting stage,leaf area per plant reached the maximum under N₃R₄ treatment,108.72 cm² and 112.88 cm²,respectively.Leaf area per plant of Ning 2038 was more sensitive to nitrogen.Spring wheat leaf senescence could be delayed by applying nitrogen fertilizer at booting and filling stages.The SPAD value of leaves decreased first and then increased with the development of growth.The SPAD value of nitrogen fertilizer treatment was the smallest at booting stage,and that of non-nitrogen fertilizer treatment was the smallest at heading stage.At filling stage,the SPAD value of each treatment reached the maximum under N₃R₄ treatment,62.10 and 67.54,respectively.Leaf SPAD value was the largest under N₃ and R₄treatments,and the decline and deceleration rate of SPAD could be delayed by postponing the nitrogen application period.The change trend of net photosynthetic rate of spring wheat was basically consistent with SPAD value.Topdressing nitrogen fertilizer at booting stage can increase net photosynthetic rate and prolong the functional period of leaves.The transpiration rate of wheat at the later growth stage can be increased by the postponement of nitrogen application period.The higher the amount of nitrogen applied,the higher the transpiration rate of wheat.?2?At the same nitrogen application rate,the fractional application of nitrogen fertilizer could increase the dry matter distribution and proportion in grains,and the accumulation of assimilates after anthesis could be increased by topdressing nitrogen fertilizer at booting stage.The accumulation of dry matter in vegetative organs at jointing stage,flowering stage and milk ripening stage increased with the increase of nitrogen application rate under the same nitrogen application period and proportion.N₃R₃ treatment had the largest amount of dry matter transported in pre-anthesis vegetative organs of Xinchun 6,N₃R₄ treatment had the largest amount of dry matter transported in pre-anthesis vegetative organs of Ning 2038,N₁R₁ treatment had the largest rate of dry matter transported in pre-anthesis vegetative organs of two varieties of wheat,N₃R₃ treatment had the largest amount of dry matter accumulated after anthesis,and Xinchun 6 had the largest amount of dry matter accumulated after anthesis to seeds.The contribution rate of grain was the highest under N₃R₄ treatment,and that of Ning 2038 was the highest under N₃R₃ treatment.?3?Nitrogen accumulation in organs of Xinchun 6 and Ning 2038 was highest in jointing stage,in flowering stage,in N₃R₃ and in wax ripening stage.Under the same nitrogen application period and proportion,the accumulation of nitrogen in jointing stage,flowering stage and wax ripening stage of spring wheat increased with the increase of nitrogen application,but there was no significant difference between middle and high nitrogen treatments.With the same amount of nitrogen application,the nitrogen accumulation of wheat could be increased by applying nitrogen fertilizer in different stages,which had the most significant effect on the wax ripening stage.?4?Under the same nitrogen application rate,R₃ treatment had the largest number of grains per panicle,1000-grain quality and yield,while N₃ treatment had the highest yield components and yield under the same nitrogen application period and proportion,but there was no significant difference with N₂ treatment.When the amount of N application was 310.5kg/hm²,the period and proportion of N application were base fertilizer:jointing fertilizer:booting fertilizer was 4:4:2and base fertilizer:jointing fertilizer:booting fertilizer:filling fertilizer was 2:4:2:2,both varieties of wheat could obtain higher yield,Xinchun 6 reached 1.21¹.26 g/plant?converted into yield 8511.78⁸930.72 kg/hm²?,Ning 2038 reached 1.09¹.12 g/plant converted into yield8190.62⁸362.59 kg/hm²).The accumulation of dry matter is the basis of yield formation.The relationship between dry matter accumulation and yield at wax ripening stage of spring wheat was fitted by one-dimensional quadratic curve.The fitted relationship of Xinchun 6 was y=-0.00002x²+0.9883x-3254.947,where R²=0.9922,Ning 2038 is y=-0.000024x²+1.1338x-4702.601,where R²=0.9943.?5?The average root diameter,root surface area and root dry mass density of Xinchun 6and Ning 2038 increased with the increase of nitrogen application,while the root length density increased first and then decreased with the increase of nitrogen application.When the amount of nitrogen applied was the same,delaying the period of nitrogen application was beneficial to increase the average root diameter and root surface area of wheat,so as to promote the absorption of nutrients by roots.The root diameter,root surface area,root dry mass density and root length density of 20⁶0 cm soil layers reached the maximum when the basal fertilizer,jointing fertilizer and booting fertilizer were applied at 4:4:2.The root dry mass density and root length density of 0²0 cm soil layers reached the maximum under N₃R₁ treatment.?6?Among the combinations of nitrogen application treatments,Xinchun 6 had the lowest nitrogen use efficiency,nitrogen absorption efficiency,Nitrogen Agronomic utilization efficiency and partial productivity under N₃R₁ treatment,the highest under N₁R₂ treatment,and the lowest grain production efficiency under N₂R₃ treatment was 22.11 kg/kg,and the highest under N₁R₁treatment was 30.64 kg/kg;Ning 2038 had the lowest nitrogen utilization efficiency,nitrogen absorption efficiency and partial productivity under N₃R₁ treatment.The nitrogen use efficiency and nitrogen absorption efficiency were the highest under N₁R₃ treatment,the partial productivity of nitrogen fertilizer reached 52.84 kg/kg under N₁R₁ treatment,the agronomic utilization efficiency of nitrogen reached 3.64 kg/kg under N₁R₄ treatment,12.75 kg/kg under N₃R₃ treatment,and the grain production efficiency reached 19.01 kg/kg under N₂R₃ treatment and 29.46 kg/kg under N₁R₁ treatment.