| Scientific water and nitrogen management of maize is an important means to achieve high yield and save water and fertilizer resources.The corn planting area in Hexi Corridor is vast,and sufficient water and fertilizer supply is the key to give full play to the high-yield potential of corn.In view of the situation of drought and water shortage and low utilization efficiency of water and nitrogen in Hexi Corridor Area,this study adopts the way of water stress in three main growth stages of maize:jointing stage,tasseling and silking stage and grain filling stage,and applies different gradients of nitrogen application rate to maize.This experiment adopts the two factor interaction experiment of water stress and nitrogen application level,and designs pure nitrogen 0(N0),150(N1),225(N2)300(N3)kg/hm~2four nitrogen application levels,normal irrigation treatment(T0),water stress at jointing stage(T1),water stress at heading stage(T2)and water stress at filling stage(T3).The responses of physiological traits,yield,nitrogen accumulation,nitrogen accumulation after anthesis and soil inorganic nitrogen content of Maize to water stress were studied.In order to provide a theoretical basis for the selection of reasonable nitrogen application level and irrigation time for maize water-saving and yield increase,fertilizer saving and efficiency increase in Hexi corridor.The main conclusions of this study are as follows:(1)The effects of water stress at different growth stages on plant height,leaf area index and ear traits of Maize under different nitrogen application levels were analyzed.It was found that under the same nitrogen application conditions,water stress at jointing stage had the greatest impact on plant height,leaf area index and other vegetative organs of maize.Water stress at this growth stage hindered the development of vegetative organs of maize,Affect the transport of nutrients from vegetative organs to reproductive organs such as grains in the later stage,and finally reduce the yield of maize.Although water stress at heading stage had little effect on plant height and leaf area index of maize,it seriously affected the development of ear traits of maize,significantly reduced ear length,ear diameter and grain number per ear,and increased bald tip length,which directly affected the economic yield of maize.(2)The effects of water stress at different growth stages on biomass yield,economic yield,constituent elements and dry matter mass distribution of Maize under different nitrogen application levels were revealed.It was found that under the same nitrogen application level,water stress in heading stage increased the interval between heading and silking,hindered maize pollination,increased the risk of maize grain abortion,seriously affected maize grain yield and reduced the distribution of dry matter in grains.In addition,the dry matter yield and grain yield of maize without nitrogen application treatment were significantly lower than that of nitrogen application treatment,and when the amount of nitrogen application gradually increased,the biomass yield and grain yield of maize increased first and then decreased.(3)The accumulation and distribution of nitrogen in maize plants under different nitrogen application and water stress treatments were studied,such as nitrogen accumulation,nitrogen transport and nitrogen harvest index.The results showed that under the same nitrogen application level,the nitrogen accumulation of maize plants showed normal irrigation treatment>water stress in filling stage>water stress in jointing stage>water stress in tasseling stage.The water stress in tasseling stage seriously decreased the nitrogen accumulation in maize grains,which was also directly related to the reduction of maize grain yield under water stress in tasseling stage.Under each water and fertilizer treatment,the nitrogen accumulation in maize organs was grain>leaf>stem>core>bract,in which the proportion of nitrogen distribution in grain accounted for more than half of the total nitrogen accumulation of maize,which was determined by the characteristics of maize itself.In addition,under the nitrogen application treatment,the nitrogen transport capacity of maize after anthesis at jointing stage was significantly less than that of other water treatments under the same nitrogen application treatment,and with the increase of nitrogen application rate,the effect of water stress treatment at filling stage on nitrogen transport capacity of maize would gradually increase.(4)The response of soil inorganic nitrogen content to water stress at maturity of Maize under different nitrogen application treatments was analyzed.It was found that the change of soil nitrate nitrogen content with growth period decreased first,increased in grain filling period,and then decreased no matter whether water stress was carried out or not.The content of soil ammonium nitrogen showed an"m"curve,and the time when soil ammonium nitrogen increased was the time when nitrogen fertilizer was added.In addition,except for the treatment without nitrogen application,the contents of soil ammonium nitrogen and nitrate nitrogen in other nitrogen application treatments were higher than those in seedling stage. |
