Effect Of Water And Nitrogen Interaction On Population Quality And Yield Formation Of Dripping Spring Wheat

There had high yield field occurred sometimes on the production of drip spring wheat in Xinjiang,however,the reproducibility of high yield was poor and large-scale continuous and stable high yield oftheoretical guidance was so lacking that it couldn’t achieve large area high yield. The paper researchedpopulation structure and production formation rule of drip spring wheat under different water and nitrogentreatment from the perspective of crop community development, plot experiment and field survey werecarried out synchronously. By controlling the root zone irrigation and nitrogen fertilizer and optimizing thedrip spring wheat population structure, clarified key regulatory process of drip spring wheat high yieldpopulation structure characteristics and function characteristics and revealed the high yield mechanism ofdrip spring wheat photosynthetic material production, storage and transportation, drip spring wheat yieldand super high yield population index was put forward.The main experimental conclusions weresummarized as follows:Under the condition of drip irrigation, the moderate amount of nitrogen and water (300kg/hm2,6000m3/hm2) could increase the height of wheat plants and the total number of spikelets, decline sterile spikeletnumber; If water and nitrogen were too much or too little, the spring wheat plant height would decreaseand sterile spikelet would increase. Stem tillers earing rate, grain leaf ratio and the material productivityafter anthesis were very significant positive correlation with yield, there was a quadratic function relationbetween LAI and yield (r=0.964**), the yield reached the maximum value about8422.5kg/hm2when LAIwas7.6on booting stage; Under different water and nitrogen treatment, W3N2(6000m3/hm2,300kg/hm2)population quality indicators was optimal, groups the tillers number and stem tillers earing rate reached520.6×104/hm2and71.4%, LAI in booting stage was6.22, grain number leaf ratio and grain weight ratioreached3602.1/m2and120.1g/m2, the productivity of dry matter after flowering was85.9g/m2.Drip spring wheat flag leaf Pn, Tr and Gs firstly increased and then decreased with the increase ofwater and nitrogen fertilizer, Ci showed the opposite trend; there were very significant positive correlationbetween flag leaf photosynthetic rate and yield after anthesis, it showed that different water and nitrogentreatment could regulate photosynthetic characteristics of wheat leaf to improve wheat yield. Fluorescenceparameters of PSⅡ photochemical maximum efficiency (Fv/Fm) decreased gradually with the advanceme-nt of reproductive period, too much or too little water and nitrogen would cause of the Fv/Fm changedsignificantly so that the energy conversion reduce and the degree of photoinhibition improve; Thelight-intercepting capability of wheat was closely related to yield, but the light interception rate did notmean the higher the better, it would decrease light conversion efficiency to affect photosynthetic rate whenThe light-interception rate reached a certain level then continuing to increase, so as to affect yield.Thisexperiment results showed that photosynthesis characteristic of optimum nitrogen and water combinationwas optimal flag leaf photosynthetic rate was26.75μ mol·m-2·s-1, Fv/Fm was0.89and population lightinterception rate was93%,after anthesis.With the increase of the contents of nitrogen grain yield and yield components increased under thesame water treatment, the tendency slowed down gradually even declined slightly when nitrogen was over300kg/hm2(N2). With the increase of the amount of irrigation grain yield and yield components firstlyincreased and then decreased under the same contents of nitrogen; the yield of W4N2(8250m3/hm2,300kg/ hm2)、W2N2(3750m3/hm2,300kg/hm2)、W1N2(1500m3/hm2,300kg/hm2) decreased by9.1%、18.1%、40.2%compared with W3N2. The effect of nitrogen fertilizer was greater than water on grain yield under waterand nitrogen two factors interaction. The two factors of water and nitrogen had a significant effect onWUE, WUE of W3N2was the highest, WUE of W1N2、W2N2、W4N2respectively decreased by26.8%、11.1%and13.1%compared with W3N2,and W1treatment increased by3.4%compared with W3N2.Thegrain yield of drip irrigation spring wheat could be up to7811.89kg/hm2when nitrogen fertilizer was300kg/hm2and irrigation amount was6000m3/hm2in the local environmental conditions. Therefore, N3W2treatment was the best combination of two factors, the optimum combination of water and nitrogen couldplay the best interaction and get the highest yield, so as to achieve efficient use of water and fertilizerresources.The field investigation results showed that spring wheat earbearing tiller rate, gain-leaf ratio, dry mattercontribution proportion after anthesis were very significant positive correlation with yield under thecondition of drip irrigation. The LAI had a quadratic parabola relationship with the yield. The populationculm number were775.2×104/hm2at jointing stage.Earbearing tiller rate was88.7%; The leaf area index atthe booting stage and grain filling period was7.83and6.22respectively. Grain no.-leaf area ratio and Grainweight-leaf area ratio was4314.4grain/m2and224.3g/m2respectively, dry matter accumulation and drymatter contribution proportion after anthesis were7001.95kg/hm2and79.14%respectively, the yield couldbe as high as10967.4kg/hm2.Consequently,the high yield could be gained by improving the earbearingtiller rate,controlling the population LAI in booting stage, promoting the material production and storageoperation after anthesis, coordinating the relationship between source and sink.