Effects Of Water Deficit At Different Growth Stages And Nitrogen Nutrition On Growth And Water-nitrogen Movement And Utilization Of Maize

The paper relate water deficit at different growth stages and nitrogen styles,to explore the best irrigation indicator of crop highly use of water and nitrogen, to raise water and nitrogen coupling use efficiency,and realizes saving water,saving fertilizer and increasing efficiency. The pot experiment on water deficit at different growth stages and nitrogen was manipulated in place with waterproof of Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education, Northwest A &F University.The summer maize Liyu 18 was selected as test materials,four nitrogen treatments(no nitrogen fertilizer,low nitrogen,medium nitrogen,high nitrogen,they were 0,0.1,0.3,0.5g pure N kg -1 soil,represent as N₀,N₁,N₂,N₃) and eleven water deficit treatment(full irrigation,deficit at seedling stage,jointing stage,filling stage,maturity stage,seedling+jointing stages,seedling+filling stages,seedling+maturity stages,jointing+filling stages,jointing+maturity stages,filling+maturity stages) were provided to carry out the pot experiments to study the effect of water deficit irrigation at different growth stages and nitrogen nutrition on physiological and ecological Indicators of maize,the nitrogen content and nitrogen assimilation of root and stem-leaf,movement and use of soil nitrogen, and explore the most suitable water and nitrogen combination for the growth of maize.The paper obtained the following conclusions:(1) Water deficit at jointing stage,seedling+ jointing stages and jointing+filling stages have quite significantly reducing roles on the plant height and leaf areas of maize,the compensation effect after rewatering is little;Water deficit at filling stages,seedling+maturity stages,filling+ maturity stages have little effects on plant height and leaf area; Low nitrogen treatment has higher plant height and leaf areas than other nitrogen treatment under every water deficit condition.(2) Water deficit at different growth stages have reduced effects on root dry matter and shoot dry matter,water deficit at one growth stage has higher restraining effect to stem-leaf than root,and root/shoots ratio (RSR) increased, RSR increases or reduces under water deficit at two growth stages;The effect rules of nitrogen on root dry matter and shoot dry matter are N₀>N₁>N₂>N₃,but nitrogen has no uniform effect rules on RSR.(3) Water deficit at seedling stage,filling+ maturity stages have a larger promotive effect on root activity,water deficit at other growth stages decrease root activity;There is a greater promotive effect on medium nitrogen level and high nitrogen level than on no nitrogen fertilizer and low nitrogen after rewatering;The effects of nitrogen on root activity performe as: low nitrogen>no nitrogen>medium nitrogen>high nitrogen,there have significant differences between each nitrogen fertilizer levels. Root activity increases first and decreases later as the promotion of growth stages,(4) The effects of nitrogen on nitrogen contents of root performe as: N₀<N₁<N2<N3.Water deficit at different growth stages have a increasing effect on nitrogen contents of stem-leaf.The nitrogen assimilation of root and stem-leaf under any water deficit conditions are lower than full irrigation condition,and the nitrogen assimilation of root is higher under water deficit at one growth stage than water deficit at two growth stages. Under the soil fertility levels in the test, the nitrogen assimilation of stem-leaf under low nitrogen level (0.1g N/kg soil) is higher than other nitrogen levers.(5) Under water deficit at seedling stage,seedling+maturity stages,filling+maturity stages,WUE were higher than full irrigation condition.Under water deficit at maturity stage and low nitrogen treatment (0.1g N/kg soil),water and nitrogen use efficiency were the highest while water deficit at one growth stage.Under water deficit at seedling+maturity stages and low nitrogen treatment (0.1g N/kg soil),water and nitrogen use efficiency were the highest while water deficit at two growth stages.(6) Soil NO₃--N content of root zone increase as the increasement of soil depth and nitrogen rates. Soil NO₃^--N content of root zone decrease as the advancement of growth stages.Upper soil NO₃^--N content of root zone reduce quickly,the accumulation of NO₃^--N is larger under medium and high nitrogen levels. Under the soil fertility levels in the test, show that N₀ level can't meet with the demands of farm crop in the whole growth stages, N₁ level is the appropriatest nitrogen level, N2,N3 levels cause a large number of nitrogen cumulation in middle soil and subsoil.