Effect Of Water And Nitrogen Supply To Water Consumption And Growth Characteristics Of Potted Young Jujube Trees

Jujube industry is the main pillar industry of Aksu,southern Xinjiang and located in the arid area.The area is located in arid area.Due to the backward irrigation methods,unreasonable fertilization,that resulted in low use efficiency of irrigation water and fertilizer.4 years old potted jujube trees were chosen as the research object in this paper,irrigation and fertilization as two factors that were considered.There were 3levels of irrigation amount:200m~3/hm~2(W1),300m~3/hm~2(W2)and 400m~3/hm~2(W3),4 levels of nitrogen:1199kg/hm~2(N1),1598kg/hm~2(N2),1998kg/hm~2(N3),2398kg/hm~2(N4),come up to 6 treatments.Effects of different water and nitrogen supplied to soil moisture,nutrients,crop physiological indexes,yield,water use efficiency(WUE)and fertilizer productivity(FP)were studied to explore the optimal water and nitrogen combination,and provide a reference for the local water and fertilizer coupling system.The main conclusions of this paper as follows:(1)Same dynamic change of soil water under different irrigation amount can be seen,minimal soil water content appeared before irrigation and maximum appeared after irrigation.Though water consumption increased with the increasing irrigation water supply,growth of water consumption decreased.The characteristics of water consumption in year 2015 and 2016 showed that same irrigation amount led to similar water consumption in the whole growth period,the maximum modulus of water consumption appeared in flowering phase,which were 36.20%,46.03%respectively.Crop coefficient was different in two years,may be related to meteorological factors and different phenological phase.(2)Under different nitrogen supply levels and fix irrigation amount,during flowering and fruit period of nitrate nitrogen in soil with the depth of soil layer downward migration.nitrate nitrogen content in underlying soil increased with the increasing nitrogen supply amount,maximum nitrate nitrogen content of each layer appeared during stage of fruit enlargement.Under different irrigation amount and same nitrogen supply,amount of soil nitrate nitrogen migrating to deep layer increased with the increasing irrigation amount,and change trend of soil nitrate nitrogen in every layer was similar.except the fruit enlargement period,during other growth period soil nitrate nitrogen content increased with increase of soil depth.Significant differences in nitrate accumulation under different water and nitrogen treatments could be seen.greater amount of nitrogen application led to greater the accumulation of nitrate nitrogen in the late stage.(3)With the advance of the growth period,change of leaf area index and canopy interception of radiation were similar:They all increased first and then decreased,maximum value appeared during fruit development,change of transparency.direct site factor and indirect site factor was opposite.correlation between the canopy parameters was good.(4)During fruit growing period,under different water and nitrogen supply,the growth rate of chlorophyll and fruit volume reached the maximum and there was significant difference between all the treatments.Branch length increased rapidly during early growth stages and growth rate decreased during late growth stage.there was significant differences between each treatment and average fruit weight reached the maximum under W2N3 treatment.too much irrigation and fertilization went against to increasing of single fruit weight.(5)There was significant effect of different water and nitrogen supply on jujube yield,WUE and FP.suitable irrigation and fertilizer was benefit to increase the yield,deficiency or excess of fertilizer led to obvious negative effect on WUE.regression analysis showed that the leaf area index,irrigation and fertilization were key affecting factors to the yield.W2N3 treatment was the best irrigation and fertilizer combination.