Effects Of Water Deficit And Nitrogen Application On Spring Wheat Growth And Water And Nitrogen Use In Hexi Region

In order to explore suitable regulation model for high-yield and high-efficiency water and fertilizer use of spring wheat that promotes the absorption and utilization of nitrogen in spring wheat,reduces the leaching of nitrogen in the soil.Field plot experiments were carried out with the spring wheat species of yongliang4,There are four irrigation treatments were set up during three growing stages,including seeding to the jointing;booting to the flowering and filling to the maturity,which namely W1(the lower limit for soil moisture content was 55%of field water holding capacity),W2(the lower limit for soil moisture content was 60%of field water holding capacity),W3(the lower limit for soil moisture content was 55%of field water holding capacity)and W4(full irrigation at full growth stage,the lower limit for soil moisture content were70%;75%and 65%of field water holding capacity);and three nitrogen rate levels(kg/hm~2):N1(120),N2(180),N3(240),Growth indexes and soil water were measured during the growing season and yield was measured after the final harvest.The effects of water deficit and nitrogen application on the growth,yield and water and nitrogen utilization of drip irrigation spring wheat in Hexi region were studied.The main research results of the test are as follows:(1)The effects of water deficit and nitrogen application on the growth of spring wheat in Hexi region showed that the nitrogen application rate of 120 kg/hm~2~180 kg/hm~2 could promote the growth of crops.The nitrogen application rate higher than 240 kg/hm~2 will restrain the growth of spring wheat.Under the condition of consistent fertilization level,the deficit treatment at seedling stage to jointing stage and booting stage to flowering stage significantly inhibited the growth of plant height and leaf area index of spring wheat,and the deficit treatment of grain filling to maturity would aggravate leaf aging.The maximum value of the leaf area index appears at the booting stage.The overall trend of dry matter accumulation under different water and nitrogen treatment conditions is N2>N3>N1,W2>W4>W3>W1.(2)The effects of water deficit and nitrogen application on spring wheat yield in Hexi region showed that the yield of spring wheat was W2>W4>W3>W1,and W2 increased yield by 2.3%,8.7%and 11.6%respectively compared with W4,W3 and W1;With the increase of fertilization amount,the yield of spring wheat increased first and then decreased,and N2 increased by 11.3%and 24.0%respectively compared with N3 and N1.The NFP of spring wheat decreased with the increase of nitrogen application rate,N1 treatment NFP was the largest,and N3 treatment NFP was the smallest.When the amount of fertilizer applied was the same,there was no significant difference between W2 treated NFP and W4treatment,which was 9.9%and 8.7%higher than W1 and W3 treatment,respectively.(3)The effects of water deficit and nitrogen application on physiological characteristics of spring wheat showed that the change trend of net photosynthetic rate of spring wheat in different growth stages was the“double peak”curve,The overall trend of water deficit at different growth stages on photosynthesis of spring wheat was W3>W4>W2>W1.The change trend of transpiration rate shows a"parabolic"type change.The higher the irrigation amount,the higher the transpiration rate,and the timely and appropriate water deficit during the crop growth period can inhibit the increase of crop transpiration rate significantly.The diurnal variation characteristics of crop stomatal conductance under different experimental treatment conditions also showed a“double peak”curve,which showed a trend of rising first and then decreasing,which is similar to the daily variation of net photosynthetic rate.Under different experimental conditions,the trend of Gs is N2>N1>N3;W4>W3>W2>W1 The leaf water use efficiency is N1>N2>N3,and the water use efficiency at different growth stages is the heading stage>filling stage.(4)The effect of water deficit and nitrogen application on the water consumption characteristics of spring wheat showed that the water consumption of wheat in the whole growth period increased with the increase of the lower irrigation limit and the increase of fertilizer application.The water consumption of farmland under different experimental conditions the overall trend is N3>N2>N1,W4>W3>W2>W1.The daily water consumption intensity of high nitrogen condition crops is larger,the maximum value can reach 6.25mm/d;the water consumption intensity of crops under low nitrogen condition is drop;The water consumption intensity under the water deficit condition reached the maximum at the booting stage-flowering stage;Under different nitrogen application levels,the water consumption modulus with high nitrogen treatment was the largest,and the water consumption modulus of all trial treatments was the maximum during the booting-flowering period,Water deficit during the growth period can effectively reduce the water consumption modulus of the crop.(5)Water deficit and nitrogen application on nitrogen uptake assimilation in spring wheat showed that under the same nitrogen application level,water deficit at heading stage-flowering stage had significant compensatory effect on plant nitrogen uptake.The water deficit at seedling stage to jointing stage and filling stage to mature stage significantly reduced the nitrogen uptake of spring wheat plants.Compared with W4,the nitrogen uptake of W2 treatment increased by an average increase of 5.1%,The nitrogen uptake by W1 and W3 treatments decreased by 25.2%and 9.4%,respectively.Under the same water condition,the nitrogen uptake of N1,N2 and N3 is 163.5 kg/hm~2,244.7 kg/hm~2and 184.8 kg/hm~2 on average.(6)The effects of water deficit and nitrogen application on nitrogen allocation of spring wheat plants showed that the nitrogen distribution of various organs of the plant showed grain>stalk+leaf sheath>cob+glume>leaves,The nitrogen allocation of stalk+leaf sheath,leaf and cob+glume of each treated wheat satisfies the trend of CK>W2>W3>W1;However,under W2 treatment condition,the nitrogen distribution in the grain is the largest,which is 217kg/hm~2.Nitrogen uptake of W4 treatment was the highest at the maturity stage,which increased by 18.7%,22.1%,16.8%and 8.9%,6.9%,and 10.6%,respectively,compared with W1 and W3 treatments.The difference between W4 and W2treatment was not significant.However,the amount of nitrogen absorbed in the grain was8.6%lower than that of the W2 treatment.(7)The effects of water deficit and nitrogen application on nitrate accumulation in0-100 cm soil layer of spring wheat and nitrate nitrogen residue in soil showed that With the increase of nitrogen application rate,the accumulation of nitrate nitrogen in the 0-100cm soil layer increased gradually.When the nitrogen application rate is the same,the soil nitrate nitrogen accumulation is generally W3>W1>W4>W2.Among them,W2 treatment is the smallest,which is 6.5%,19.5%and 8.3%lower than W1,W3 and W4 respectively.The nitrate content of W1 and W3 treatment in 0-40cm soil layer increased by 7.7%?24.5%and 17.0%?28.2%compared with W4 treatment.At 60-100 cm,the nitrate content of W4treated soil increased by 8.8%?25.7%and 7.3%?19.5%on average.