Physiological Basis Of Integral Regulation And Control Of Micro-spray Supplemental Irrigation And Fertilizer On Wheat Yield,Water And Nitrogen Use Efficiency

This experiment was carried out in the winter wheat growing season of 2015-2016 and2016-2017 at Xuan Village?36°12?N,116°54?E?in Daolong Town,Tai'an City.The tested variety was high-yielding winter wheat Shannong 29.Three-factor cracking zone design was used in the experiment.The irrigation mode was the main-region,included no irrigation?W0?,traditional irrigation?W1?and micro-spray irrigation?W2?;the nitrogen fertilizer level was the sub-region included the traditional nitrogen application at 240 kg·hm^-2?N1?,nitrogen reduction 20%nitrogen application at 192 kg·hm^-2?N2?;the top dressing method is the deputy-region,included the deep strip application?T1?,uniform application?T2?,and water and fertilizer integration with water spray application?T3?.The effect of irrigation mode and nitrogen fertilizer management on the yield,water and nitrogen use efficiency of winter wheat were discussed and the ¹⁵N isotope tracer technique was used to study the characteristics of nitrogen uptake and utilization of winter wheat under different fertilizer dressing methods in jointing.The main results are as follows:1 Effects of different treatments on water consumption characteristics and water use efficiency of wheatThe single irrigation volume and the total irrigation volume of the growing season in the W2 irrigation mode were lower than the W1 irrigation mode.Under the two irrigation modes,the soil water consumption and total water consumption in the N1 treatment were significantly higher than that in N2 treatment,the 30-100 cm soil soil water consumption in W2 irrigation treatment was significantly lower than the W1 irrigation treatment,the soil water consumption of the 120-200 cm soil layer is relatively high.The irrigation water use efficiency and water use efficiency of W2N2 treatment were significantly higher than those of W1 irrigation treatment.It shows that appropriate reduction of nitrogen application can reduce water consumption in wheat fields and increase water use efficiency.Compared with traditional irrigation,micro-spray irrigation can reduce irrigation volume,promote the use of soil water storage below 120 cm,and increase irrigation water use efficiency and water use efficiency.2 Effects of different treatments on the distribution of nitrate nitrogen in wheat fieldAfter supplemental irrigation at jointing stage,The distribution uniformity of nitrate nitrogen in the direction along the long axis of W2N1T3 treatment is significantly higher than that of W1N1T2 treatment.Under W1 irrigation mode,the soil nitrate nitrogen content in0-40 cm soil layer of T2 was significantly lower than that in the trench treatment?T1-Y?at the same nitrogen application level,but was significantly higher than that in the non-fertilizer treatment?T1-N?,Soil nitrate content in 100-200 cm soil layer was significantly lower than that in T1-Y,but there was no significant difference with T1-N.Under the same conditions of top-dressing atjointing stage,the nitrate content in the 20-100 cm soil layer treated with N1 was significantly higher than that in the N2 treatment.Under W2 irrigation mode,the soil nitrate content in 0-40 cm soil layer treated with T3 was significantly lower than that of T1-Y,but significantly higher than T1-N,and there was no significant difference below 40 cm soil layer.It shows that nitrogen fertilization at jointing stage,the distribution of soil nitrate in fertilized and non-fertilized wheat fields was not uniform,which is not conducive to the uptake of nitrogen by wheat.Compared with nitrogen fertilization treatment under traditional irrigation mode,the integration of water and fertilizer with nitrogen topdressing under the micro-spray irrigation mode can increase the uniformity of fertilizer distribution and reduce soil nitrate leakage to soil layers below 100 cm,which is beneficial to the uptake and utilization of topdressing nitrogen by wheat.3 Effect of different treatments on the growth of wheat populationThe highest population of W1 irrigation treatment was significantly higher than W2irrigation treatment.Under the various irrigation modes,The number of populations in the wintering,returning and jointing stages of N1 treatment was significantly higher than that of N2 treatment.Under the W1 irrigation mode,the number of spikes and the percentage of spikes at the mature stage of T2 treatment intwo nitrogen levels were higher than those of T1 and T3 treatments.Under the W2 irrigation mode,the number of spikes and the percentage of spike at the mature stage of T1 treatment were lower than those of T2 and T3 treatments.It shows that under the traditional irrigation mode,the application of topdressing fertilizer at jointing stage can promote the formation of spikes from the stems and the higher number of spikes and the rate of success.However,reducing the amount of nitrogen applied reduces the number of the highest population and the number of ineffective tillers,which can increase the percentage of spikes.Under the micro-spraying irrigation mode,the application of the topdressing gutter was not conducive to the formation of spikes in the stems,and the number of mature spikes and the rate of succession of spike were reduced.Compared with the traditional irrigation mode,the number of the highest population in the micro-spray irrigation mode decreased,the number of invalid tillers decreased,the spike success rate increased,and there was no significant difference in the final spike number.4 Effects of different treatments on photosynthetic characteristics and senescence of flag leaves after wheat anthesisUnder the W1 irrigation mode,the net photosynthetic rate of flag leaves,photochemical system II photochemical efficiency and senescence enzyme activity of N2T2 treated at 20 and30 days after anthesis were significantly lower than that of N1T2 treatment.Under the W2irrigation mode,the net photosynthetic rate,photosynthetic efficiency of photosystem II and senescence enzyme activity of N2T3 at the 20th and 30th days after flowering were significantly lower than those of N1T3 treatment,and there was no significant difference with W2N2T3 treatment.The results showed that under the traditional irrigation mode,reducing the amount of nitrogen applied and applying fertilizer,the ability of photosynthesis of single flag stems in the middle and late stages of grain filling was reduced,and aging accelerated.This was not conducive to the accumulation of dry matter in the assimilate after anthesis.Under the micro-spray irrigation mode,the amount of nitrogen applied was reduced and the top-dressing water-fertilizer integrated with water was applied.The activity of the senescence enzyme and the ability of photo-convergence of the flag leaf were high after anthesis,which was favorable for delaying the aging of wheat flag leaves and improving the dry matter accumulation after anthesis.5 Effects of different treatments on nitrogen accumulation,translocation and utilization in wheatUnder W1 irrigation mode,nitrogen accumulation and nitrogen accumulation in vegetative organs during mature period in N1 treatment were higher than those in N2treatment,but nitrogen transfer efficiency and nitrogen harvest index in vegetative organs were lower than those in N2 treatment.Under the same nitrogen application level,the nitrogen accumulation in anthesis stage of T2 treatment was significantly higher than that of T1 and T3 treatment,but the nitrogen transfer efficiency and nitrogen harvest index of vegetative organs were significantly lower than those of T1 treatment.Under W2 irrigation mode,nitrogen accumulation at maturity stage of T3 treatment was significantly higher than that of T1 and T2 treatment at the same nitrogen application level;nitrogen utilization rate of each treatment at N1 level was significantly lower than that of N2 treatment.The results showed that under the traditional irrigation mode,nitrogen accumulation decreased,nitrogen transfer efficiency and nitrogen harvest index of vegetative organs increased with the decrease of nitrogen application rate.Nitrogen fertilization under the same nitrogen application level increased nitrogen transfer efficiency and nitrogen harvest index of vegetative organs.Under the micro-spray irrigation mode,the water-fertilizer integration of topdressing fertilizer during jointing stage was beneficial to the absorption of nitrogen by plants after flowering,and increased the nitrogen accumulation in mature stage.6 The difference of nitrogen uptake and utilization after topdressing with ¹⁵N-labeled Urea at the jointing stageUnder the W1 irrigation mode,The ¹⁵N abundance of plant organs,N accumulation from topdressing nitrogen fertilizer and ¹⁵N accumulation of N2 treatment at the anthesis stage and mature stage were significantly higher than that of N1 treatment under the same topdressing mode.The ¹⁵N accumulation in all organs of T2 treatment at anthesis stage was significantly higher than that of T1 treatment,but T1 treatment in mature stage was significantly higher than T2 treatment under the same level of nitrogen application.Under the W2 irrigation mode,The ¹⁵N abundance and ¹⁵N accumulation of N2T3 in all organs were significantly higher than those in other treatments at flowering and maturing stages.It shows that under the traditional irrigation mode,the appropriate reduction of nitrogen application rate is beneficial to the uptake of topdressing nitrogen by wheat after anthesis and fertilizer nutrients from nitrogen fertilization have a rapid effect,but the amount of nitrogen accumulation in the plants decreased from anthesis to maturity and the utilization of topdressing reduces.Under the micro-spray supplement irrigation mode,appropriately reduce the amount of nitrogen application,water and fertilizer integration with the top dressing fertilizer to promote the uptake and utilization of nitrogen in wheat.7 Effects of different treatments on wheat production and yield componentsUnder the W1 irrigation mode,there was no significant difference in grain yield of N2T2treatment with N1 treatment during 2015-2016.In 2016-2017,the grain yield of N2T1treatment was no significant difference with N1 treatment.Under the W2 irrigation mode,the grain yield of N2T1 treatment was significantly lower than that of N2T2 and N2T3 treatment,the number of spikes was significantly lower than that of the N2T2 treatment,and the number of grains per spike was significantly lower than that of the N2T3 treatment.There was no significant difference in grain yield of N2 treatments,but they were all significantly lower than N1 treatments of T2 and T3.It shows that under the traditional irrigation mode,the appropriate reduction of nitrogen application will not negatively impact the yield.Compared with the treatment of the highest yield of traditional irrigation,the amount of nitrogen applied by the micro-spray irrigation was reduced,and high yield could be obtained with fertilizer application or water and fertilizer integration,nitrogen fertilization was not conducive to the increase of grain yield.but not conducive to the increase of grain yield when nitrogen fertilization.In summary,under the two irrigation modes,reducing 20%of nitrogen application can maintain high grain yield and water and nitrogen use efficiency.Micro-spraying irrigation and fertilizer integration with water-spraying nitrogen fertilizer can significantly increase water use efficiency while maintaining high yield.