Study On Water And Nitrogen Coupling On Winter Wheat In Photosynthetic Traits And Nitrogen Metabolization And Yield

The experiment was conducted on field conditions during 2006-2007.The Water and Nitrogen Coupling on winter wheat in photosynthetic traits and nitrogen metabolization and yield were studied.The exprimental varieties,were Shixin 733(SX 733)and Shimail 5 (SM15).1 The result showed that suitable Nitrogen(N)could evidently increase the chlorophyll content and photosynthetic rate.The water and nitrogen coupling had similiar effect.The chlorophyll content and photosynthetic rate of winter wheat leaves increased with the amount of nitrogen when irrigated one time during jointing stage.The demand of nitrogen that composing chlorophyll in flag leaves tend to decrease remarkably under the conditions of watered two times at jointing and anthesis stages.The excessive nitrogen had a negative effect on chlorophyll and photosynthetic rate.Anthesis water could delay the decomposition of chlorophyll after 20 Days After Anthesis(DAA).Shixin 733(SX 733)had the highest chlorophyll content and photosynthesis rate under 240 kilograms pure nitrogen per hectare at irrigation two times treatment;While for SM15 was 120 kilograms pure nitrogen per hectare at the same condition.2 The result showed that the Nitrate Reductase(NR)activity of ShiXin733 increased with the nitrogen amount,but the NR activity of ShiMai15 had the highest point among 180-240 kilogram nitrogen amount per hectare,decreased when too much or too less nitrogen.The nitrate reductase activity decreased When the nitrogen was too much or too less on the high soil water content,increased with the increasing nitrogen on the low soil water content.Proper nitrogenous fertilizer could promote nitrogen absorption of the plant,but the anthesis irrigation improved the nitrate reductase activity of the flag leaves and grain yield,but remarkably reduced the whole nitrogen content of the grain and had less effection on the whole nitrogen absortption of the plant.On the experimental conditions,Shixin 733 had the highest yield when it was irrigated two times and feilizered 180 kilograms per hectare,Shimai 15 had the highest yield when it was irrigated two times and feilizered 60 kilograms per hectare.3 The anthesis irrigation could accelerate the transpriation rate of leaves,there was not remarkble difference among the nitrogen treatments,but the whole trend was that the transpriation rate of leaves was decreased with the increasing nitrogen amount.4 The soluble sugar and sucrose in stems and photosynthetic rate of leaves were remarkbly higher on the irrigation two times condition than that of irrigation one time.On the condition of orrigation one time,the photosynthetic rate of NO of both varieties was lower and yield was decreased,there was no significant difference among more than N8 nitrogen fertilizer treatments which had the slowly incresing trend.The soluble sugar content in stems and leaves had the opposite trend,which was remarkbly dcreased with the incresing nitrogen amount.The sucrose had the similar trend.On the irrigation two times condition,the photosynthetic rate of leaves in Shixin733 was low on NO treatment,but the soluble sugar content in stems and leaves were higer,so did the yield.The photosynthetic rate of higer nitrogen amount treatment was low,so did soluble sugar content and the nitrate reductase activity,thus the yield was low too.The machanism of Shimai15 was different,on the irrigation two times condition,the photosynthetic rate was not decreased, the yield was higer,althouth the soluble sugar content in stems and leaves were low.5 The average grain filling days of winter wheat was relatively shortened on irrigation one time,the grain filling rate was increased revantly,the time of the biggest grain filling rate was brought forward.Good water condition on grain filling phase on irrigation two times could postphone grain filling course and the sustaining time of the biggest grain filling rate was prolonged,meanwhile,the duration of rapid increasing stage and slowly increasing stage was longger than that of one time irrigation,but the grain filling rate two phases was slower instead.The time reached the biggest grain filling tide and the biggest grain filling rate and the duration of rapid inreasing stage were all increasing firstly and decreasing secondly with incrasing nitrogen amount.The active growth stage was also ahead of schedule with incrasing nitrogen amount.The decline of grain filling rate at the back of grain filling phase was relatively slow.Too much or less nitrogen were not benefit for potential of yields.These showed the anthesis irrigation could promote the grain filling rate and yield of wheat and yield.On irrigation one time condition,N4 treatment of both wheat varieties had the highest yield.On irrigation jointing and anthesis irrigation condition,non-fertilizer treatment and N4 had the highest yield.The result showed that few nitrogen fertilizer should be used on good irrigation condition,too much nitrogen might decreased yield instead.