Physiological And Ecological Mechanism Of High Water And Nitrogen Use Efficiency In Integrated Management Of Supplemental Irrigation And Fertilization With Micro-sprinkling Hose Of Winter Wheat

In order to solve the problem of low water and nitrogen use efficiency caused by the traditional irrigation and fertilization methods,the research team innovated the integrated management technology of supplemental irrigation and fertilization with micro-sprinkling hose for winter wheat,and intensively studied its regulation mechanism to achieve high and stable yield,efficient utilization of water and nitrogen,and ecological environment protection in winter wheat,so as to deepen the research on irrigation and fertilization technology for high-efficiency utilization of water and nitrogen,and improve water-saving,fertilizer saving,high-yield and high-efficiency cultivation of winter wheat,and in order to provide a theoretical basis for water-saving,high-yield and high-efficiency cultivation of winter wheat.This experiment was conducted in the 2017-2019 winter wheat growing season,with Shannong 29 as the test material.In this experiment,the experiment adopted split plot design of three factor,the irrigation mode was the main-plot,and two irrigation modes were set up:micro-sprinkling supplemental irrigation?W1?and traditional border irrigation?W2?,the total nitrogen application rate in the wheat growing season was the sub-plot,with three levels of 96 kg ha-1?N1?,192 kg ha-1?N2?and 288 kg ha-1?N3?;nitrogen topdressing method at the jointing stage was deputy-plot,uniform nitrogen application?T1?and concentrated nitrogen application?furrow application,T2?were set up.In the micro-sprinkling supplemental irrigation mode,the uniform nitrogen application?W1T1?adopted the method of fertilization with irrigation water,that is,the integrated operation of water and fertilizer.In the traditional border irrigation mode,the uniform nitrogen application?W2T1?spread the nitrogen fertilizer evenly before irrigation,and then irrigated in time.Explore the effects of different water and nitrogen supply methods on root morphology,leaf photosynthesis,yield formation,and water and nitrogen use efficiency winter wheat.The main results were as follows:1 Changes of water consumption characteristic under different water and nitrogen application regimes in winter wheatUnder the W1N2 and W1N3 conditions,compared with the T2 treatment,the T1 treatment had no significant difference in the soil water content of the 0²00 cm soil layer from sowing to the flowering stage,but significantly reduced the relative soil water content of the 20⁶0 cm soil layer in the maturity stage,and significantly increased soil water consumption during flowering to maturity stage,thereby increasing total water consumption and water use efficiency.Under the conditions of the same nitrogen application rate in the W2 model,there were no significant differences in soil water content,soil water consumption,total water consumption and water use efficiency in the 0²00 cm soil layer during each growth stage between T1 and T2 treatment.Under the same nitrogen application rate,compared with W2T1treatment,W1T1 treatment reduced irrigation amount and total water consumption,but can maintain high surface soil relative water content during flowering and maturity,reduce soil relative water content in deep soil layer,and increase soil water consumption in deep soil layer,and significantly improve water use efficiency.2 Temporal and spatial changes of soil nitrate content under different irrigation and nitrogen application regimesUnder W1N2 condition,compared with T2 treatment,T1 treatment significantly increased the fertilizer application uniformity after topdressing at the jointing stage,increased the soil nitrate content in the 0⁴0 cm soil layer,and increased the nitrogen supply in the root zone.Under W2N2 condition,there was no significant difference in the fertilizer application uniformity and the average soil nitrate nitrogen content of each soil layer in T1 and T2treatments.Compared with the W2N2T1 treatment,the W1N2T1 treatment significantly improved the fertilizer application uniformity at the jointing stage and the distribution ratio of nitrate nitrogen in the 0⁴0 cm soil layer after topdressing.Under the W1N2 and W1N3 conditions,compared with T2 treatment,T1 treatment significantly reduced the nitrate nitrogen content in the 0¹60 cm soil layer at the fertilization line in the maturity stage,and reduced the risk of nitrate nitrogen leaching into the deep soil.Under the same nitrogen application rate in the W2 model,there was no significant difference in the nitrate nitrogen content of the 20²00 cm soil layer at the maturity stage between the T1and T2 treatments.Under the same nitrogen application rate,compared with the W2T1treatment,the W1T1 treatment can increase the soil nitrate nitrogen content in the 0⁸0 cm soil layer,reduce the soil nitrate nitrogen content in the 120²00 cm soil layer,and reduce the risk of groundwater pollution.3 Effect of irrigation and nitrogen application regimes on root morphology in winter wheatUnder W1N2 conditions,compared with T2 treatment,the root length density,root surface area density and root weight density of 0⁶0 cm soil layer increased by 21.7³0.2%in T1treatment of non-fertilization stage at flowering and maturity stage,and the root length density of 0⁶0 cm fertilized row,root surface area density and root weight density decreased by7.1⁹.2%,thereby significantly increasing the average root length density,root surface area density and root weight density of 0⁶0 cm during flowering and maturity.Under W1N3conditions,T1 treatment increased the root length density,root surface area density and root weight density of 0⁶0 cm soil layer in fertilizing and non-fertilizing rows at anthesis and maturity stage.Under the same nitrogen application rate in the W2 mode,there was no significant difference in the average root length density of the 0¹00 cm soil layer between the T1 and T2 treatment during flowering and maturity stages.Compared with W2T1 treatment,W1T1 treatment significantly increased root length density,root surface area density and root weight density of 40¹00 cm soil layer under the same nitrogen application rate,and promoted the absorption of deep soil moisture and nitrogen.4 Effect of irrigation and nitrogen application regimes on nitrogen absorption and utilization in winter wheatUnder W1N2 and W1N3 conditions,T1 treatment significantly increased nitrogen assimilation enzyme activity before and after flowering,increased nitrogen accumulation of plants from jointing to maturity stage,and increased grain nitrogen accumulation and nitrogen absorption efficiency compared to T2 treatment.Under the W2 mode,,there was no significant difference in nitrogen assimilation enzyme activity and nitrogen accumulation in mature plants between T1 and T2 treatment under the same nitrogen application rate.Under the same nitrogen application rate,compared with W2T1 treatment,W1T1 treatment significantly increased the flag leaf nitrogen assimilation enzyme activity,increased post-flowering nitrogen assimilation amount,increased nitrogen harvest index and nitrogen utilization efficiency,and maintained a higher nitrogen accumulation in grain.Under W1N2 and W1N3 conditions,T1 treatment significantly reduced flag leaf proteolytic enzyme activity during the early and middle filling stages,and increased proteolytic enzyme activity during the late filling stage,which was beneficial to delay protein decomposition and transport in leaves.Under the same nitrogen application rate in W2 mode,there was no significant difference in flag leaf proteolytic enzyme activity between T1 and T2treatment.Compared with W2T1 treatment,W1T1 treatment significantly increased flag leaf proteolytic enzyme activity during the middle and late filling stages and promoted the transportation of flag leaf nitrogen to grains under the same nitrogen application rate.5 Effect of irrigation and nitrogen application regimes on photosynthetic characteristics and day matter accumulation and distribution in winter wheatUnder the conditions of W1N2 and W1N3,T1 treatment significantly increased the nitrogen distribution of flag leaf photosynthetic components?carboxylation system,bioenergetic components and light-harvesting system?after flowering,and increased the relative content of flag leaf chlorophyll and actual photochemical efficiency during the filling period,thereby increasing the net photosynthetic rate of flag leaves and increasing the amount of dry matter assimilation after anthesis.Under the same nitrogen application rate in W2 mode,there was no significant difference in the photosynthetic characteristics of flag leaves between T1 and T2 treatment.Under the same nitrogen application conditions,compared with W2T1treatment,the nitrogen content per unit area of flag leaves decreased in W1T1 treatment,but the distribution ratio of nitrogen in flag leaves after flowering in photosynthetic apparatus was significantly increased.There is no significant difference in the relative content of chlorophyll,actual photochemical efficiency and net photosynthetic rate of flag leaves,which significantly increases the utilization efficiency of photosynthetic nitrogen,maintains a high amount of post-anthesis dry matter assimilation,and at the same time increases the dry matter transfer rate of temporary storage before flowering,and significantly improves the harvest index.6 Effects of irrigation and nitrogen application regimes on grain yield in winter wheatIn the W1 and W2 modes,with the increase of nitrogen application,the grain yield increased,but excessive nitrogen application(>192 kg ha^-1)will not increase the grain yield of winter wheat.Under W1N2 and W1N3 conditions,compared with T2 treatment,T1 treatment significantly increased 1000-grain weight and grain yield.Under the same nitrogen application rate in W2 mode,there was no significant difference in grain yield between T1 and T2treatment.Under the same nitrogen application rate,compared with W2T1 treatment,there was no significant difference in grain yield in W1T1 treatment.7 Effects of irrigation and nitrogen application regimes on ecological and socioeconomic benefitIn the W1 and W2 modes,with the increase of nitrogen application,the total output value and net income increase.Excessive nitrogen application(>192 kg ha^-1)will not increase the total output value and net income of winter wheat.Under W1N2 and W1N3 conditions,T1treatment significantly increased total output value and net income compared to T2 treatment,under the same nitrogen application rate in W2 mode,there was no significant difference in total output value and net income between T1 and T2 treatment.Compared with W2T1treatment under the same nitrogen application rate,W1T1 treatment can significantly increase the total output value and net income by increasing the effective planting area,while reducing irrigation water input and labor costs,saving electricity,and achieving significant ecological benefit.In summary,under the middle and high nitrogen application rate condition in micro-sprinkling supplemental irrigation mode,compared with the fertilizer concentrated application treatment at the jointing stage,the integrated of irrigation and fertilization treatment significantly improved the fertilizer application uniformity,and increased the root length density,root surface area density and root weight density of 0⁶0 cm soil layer,and increased the plant nitrogen accumulation amount from jointing to maturity stage,and nitrogen absorption efficiency;increased the nitrogen distribution amount of the photosynthetic components in the flag leaf after anthesis,and improved the photosynthetic performance and dry matter assimilation after anthesis,and increased the water consumption from anthesis to maturity stage,which satisfied with the water demand at the critical stage of yield formation,significantly increased grain yield and water use efficiency.Compared with fertilizer broadcast application in border irrigation treatment,integrated management of supplemental irrigation and fertilization with micro-sprinkling hose significantly increased root length density,root surface area density and root weight density in the 40¹00 cm soil layer during anthesis and maturity stage,while significantly improving the fertilizer application uniformity,increasing nitrate nitrogen content in the root layer,post-anthesis plant nitrogen assimilation,nitrogen harvest index and nitrogen use efficiency,and reduced risk of soil nitrate leaching into deep layers;increased the nitrogen distribution proportion in photosynthetic components,and maintained the nitrogen distribution amount in the photosynthetic components and photosynthetic performance of flag leaf after anthesis,maintained high post-anthesis dry matter assimilation,promoted pre-anthesis reserved dry matter translocate to the grain,maintained high yield with improving the harvest index;significantly reduced irrigation and total water consumption amount,and increased soil water consumption,then improved water use efficiency.Under the conditions of integrated management of supplemental irrigation and fertilization with micro-sprinkling hose,with the increase of nitrogen application,the grain yield increased,but excessive nitrogen application(>192 kg ha^-1)will not increase the grain yield,but significantly reduced the water and nitrogen use efficiency.Therefore,the combination of nitrogen application rate of 192 kg ha^-1 and integrated management of supplemental irrigation and fertilization with micro-sprinkling hose was the water and nitrogen saving,stable production and high efficiency cultivation measure for winter wheat in this study area.