Studied On Coupling Effect Of Water And Nitrogen Of Maize In The Middle Reaches Of Heihe River

The oasis of middle reach of Heihe river basin is an important majorgrain-producing area, also it is a famous efficient irrigation farming region in Gansuprovince. The shortage of water resource is the key factor that restrains the sustainabledevelopment of the agriculture and village in the drought-hit area. Using water andnitrogen coupling, balance of nitrogen and water use efficiency, is the importantmeans to realize the high-efficient and high-yield crops. The experiment wasconducted at Linze station in2012, using corn hybrid No.1256(Origin AgritechLimited) as materials. in seedling stage, jointing stage booting, maturation, Accordingto soil water suction, three moisture gradients were set in stage of seedling, jointing,booting and maturation(200KPa,400kPa,800kPa), and three nitrogen gradients (180kg/hm2,360kg/hm2,540kg/hm2). Researched the influence of on plant growth,photosynthetic characteristics, yield and water use efficiency in different growthstages of corn hybrid. Aimed to determine which is the suitable water and nitrogencoupling style in the oasis of middle reach of Heihe river basin. The main results areas follows:(1) The maize plant height, stem diameter and leaf area were significant effectedunder different water and nitrogen coupling treatments in jointing stage. At the samenitrogen level, there were not significant difference between high nitrogen and middlenitrogen. And it had small difference with low nitrogen; Under the same watertreatments, with the increase of nitrogen fertilizer showed good effect of waternitrogen interactions. Compared with middle water level, it had no significant of plantheight, stem diameter and leaf area. But the plant height, stem diameter and leaf areaunder high water treatment were higher than lower water level24%,23%,36%.Different middle and high water and nitrogen coupling treatments showed significantdifference with other treatments of. High water condition with high nitrogen haslargest dry matter accumulation.(2) The high water and nitrogen （22.98μmol.m-2.s-1） showed biggest photosynthetic rate, which was higher than high nitrogen with middle water, highnitrogen with lower water, middle nitrogen and lower nitrogen14.4%,27.2%,15.2%and26.0%. The change of transpiration rate and stomatal conductance were the sameas photosynthetic rate. The transpiration rate of middle water and nitrogen treatmentwas significant lower than any other treatments, but had batter instantaneous waterefficiency, which showed batter water saving effect. The decline of stomatalconductance is markedly lower than the photosynthetic rate and transpiration ratefrom jointing stage to booting stage. The photosynthetic rate and transpiration ratewas significant positive correlation with stomatal conductance.(3) The influence of middle water with high nitrogen and middle water withmiddle nitrogen on yield of corn hybrid had no significant difference with high waterwith high nitrogen. The high water with high nitrogen treatment had the largest yield(12500kg/hm2).(4) The leaf instantaneous water use efficiency under middle water and nitrogentreatment increased significantly than other treatments; Middle water with mediumamount of nitrogen (22.66kg.hm-2.mm-1) appeared largest water use efficiency.Compared to high water with high nitrogen increased29.72%in water saveefficiency.(5) The experiment showed that mild water deficit with medium amount ofnitrogen is the appropriate treatment, which can have high yield and high water effectin the oasis of middle reaches of Heihe river.