Effects Of Water Deficit And Nitrogen Nutrition On Growth And Nitrogen Absorption Of Crop

In order to study the growth of crop and nutrition transport and use mechanism under water deficit and nitrogen nutrition,this thesis use the method of combination with experiments and theoretical analysis by taking the winter wheat of pot and maize of field. The winter wheat Xiaoyan 22 was selected as test materials. The pot experiment treatment consists of two factors: the water deficit and nitrogen lever in different growing stages of winter wheat. The water deficit which consist of 11 water treatment: A single growth stage water deficit and two growth stage water deficit.The former include water deficit at seedling stage,jointing stage,heading stage and filling stage.The latter include water deficit at seedling+ jointing stages,seedling+ heading stages,seedling+ filling stages,jointing+ heading stages,jointing+filling stages and heading+ filling stages. In addition the whole growth period with water normal supply treatment was set as control. The nitrogen lever consists of no nitrogen(N0,0 kg/hm2),low nitrogen(0.1 g/kg,N₁),middle nitrogen(0.3 g/kg,N₂)and high nitrogen(0.5 g/kg,N₃).The field maize experiment take liyu16 as test materials,which consist of two factors:moisture treatment and nitrogen levels.The moisture teatment include 7 levels:irrigation at the whole growth period ( CK ) ,irrigation at seedling + jointing stages,irrigation at seedling + heading stages,irrigation at seedling + filling stages,irrigation at jointing + heading stages,irrigation at jointing + filling stages and irrigation at heading + filling stages. The nitrogen lever consists of no nitrogen ZN(0 kg/hm2),low nitrogen LN(60kg/hm2)and high nitrogen HN(180kg/hm2). Systematic study and analyze the effect of maize and winter wheat's ecological indicators,yield and yield components,water use efficiency and mechanism of nitrogen absorption and utilization under water stress at different growth stages. The main results as follows:1. Water deficit at jointing stage,heading stage and jointing + heading stages significantly reduce the plant height and leaf area of winter wheat.Especially water deficit between jointing stage and heading stage which seriously supppress the plant's elongation,and the compensation effect after rewatering with water deficit is limited.With the increasing of nitrogen,the plant height,leaf area of winter wheat appeared increase firstly and then decrease,which the highest is in moderate nitrogen treatment.2. Water deficit at jointing stage,heading stage,seedling+ jointing stages and jointing + heading stages significantly reduce the upper and root system biomass,and the seedling+ filling stages has little influence of the upper biomass. Moreover the promotion of water and nutrient on upper growth of winter wheat is bigger than root.3. From the composition of winter wheat water consumption, with the advance of growth stage, water consumption of growth and daily water consumption intensity has a"low -high– low"trend,and the biggest water consumption of the whole growth period is water normal supply in moderate nitrogen treatment ,which is up to 44687.7 g / pot.Whether water normal supply irrigation or water deficit,before heading stage of winter wheat relatively largely affected mainly by water,after heading stage of winter wheat fertilizer plays a leading role. But with the increase of nitrogen,the water consumption is not always increase and decline when reaches a certain level.4. Water deficit at seedling stage under moderate nitrogen treatment always has the highest yeild and water use efficiency. Water deficit at jointing stages,jointing+ filling stages and jointing + heading stages are mainly decrease the effective ears and kernels of ear. Water deficit at jointing + heading stages significantly reduce the 1000-grain weight and grain yield. In no nitrogen conditions,water deficit at jointing stage,heading stage and two stages continuation are significantly reduce water use efficiency of winter wheat,and the biggest influence is water deficit at jointing + heading stages. With the increasing of nitrogen,the effective ears,kernels of ear,1000-grain weigh,grain yield and water use efficiency of winter wheat appeared increase firstly and then decrease.5. Water deficit at jointing stage,heading stage,seedling+ jointing stages,jointing + heading stages and jointing+ filling stages significantly reduce the root activity of winter wheat. Besides the root acticity of winter wheat under water deficit at seedling stage and low nitrogen treatment is higher than other nitrogen nutrition,the highest of root acticity of winter wheat under water deficit and nitrogen nutrition is in moderate nitrogen treatment,that is mean that the root acticity of winter wheat appeared increase firstly and then decrease with the increasing of nitrogen.6. With the increasing of nitrogen,the nitrogen content of stems and leaf and grain of winter wheat are increasing,but which appeared first increased and then decreased in root. Nitrogen accumulation showed: grain>stems and leaf>root.And with the increasing of nitrogen,the nitrogen accumulation of grain and stems and leaf of winter wheat has increase and decrease. But the nitrogen accumulation of root of winter wheat appeared increase firstly and then decrease.The nitrogen content and accumulation of water deficit at seedling stage is higher than the full water treatment.Water deficit at jointing stage,heading stage and jointing + heading stages significantly reduce the nitrogen content and accumulation of winte wheat.7. There were some effects of irrigation at different growth stages and nitrogen fertilizer levels on plant height,leaf area,dry matter accumulation,yield and water use efficiency of maize. Compared with irrigation at the whole growth period(CK),there was significantly reduction on the plant height,leaf area,dry matter accumulation,yield for irrigation at seedling +filling stage and irrigation at heading + filling stage,and the latter has the lowest water use efficiency .There was no significant decline in production maize yield with irrigation treatment at seedling + jointing stage,seedling + heading stage,jointing + heading stage,but irrigation water use efficiency is greatly improved.