Effect Of Irrigation At Different Growth Stages And Nitrogen Fertilizer Of Spring Maize And Soil Water And Nitrogen Transfer In Hexi Area

To study the effect of irrigation at different growth stages and nitrogen fertilizer on physiological and ecological index, yield, water use efficiency, the transport of water and fertilizer in root zone soil of spring maize in Hexi area, the field experiment was conducted in the Shiyanghe Experimental Station for Water-saving in Agriculture and Ecology of China Agricultural University, Wuwei, Gansu. Experiment was designed with irrigation at different growth stages (each growth stage with irrigation (contrast), no irrigation at seedling stage, no irrigation at jointing stage, no irrigation at heading stage, no irrigation at filling stage, no irrigation at seedling stage and filling stage, no irrigation at jointing stage and filling stage) and with different N levels (no nitrogen, low nitrogen, medium nitrogen, high nitrogen).The main results are shown as follows:1.Nitrogen level in the seedling stage is the primary factor that affects plant height and no irrigation treatment has little effect on plant height. In the jointing stage, no irrigation and fertilization have on significant effect on plant height. In low nitrogen and non-nitrogen conditions, the compensation effect of irrigation in seedling stage with no irrigation on plant growth is obvious. In heading and grain filling stages, water becomes the primary factor that affects the plant height of spring maize and no irrigation in the jointing stage has significant effect on plant height. Seedling stage with no irrigation will promote the expansion of leaf area, while the jointing stage with no irrigation will cause significant reduction on leaf area. In late growth stage of spring maize, no irrigation will result in leaves reduction quickly. In every water treatment, the leaf area increases with the increase of nitrogen rate and the difference among nitrogen levels was significant.2. The effect under different treatment of irrigation and nitrogen on shoot dry biomass of spring maize was different. The jointing stage was the sensitive time to accumulate the shoot dry biomass, no-irrigation during the jointing stage will cause the shoot dry biomass decreased significantly. The compensation of the treatment of resuming after no irrigation at seeding stage was apparent than the treatment of resuming after no irrigation at jointing stage. Single growing period with no irrigation effecting on shoot dry biomass was in sequence of: jointing stage>heading stage>filling stage>seedling stage. The effect of two growth stages with no irrigation on the biomass accumulation was greater than the effect of single growth stage with no irrigation.3. Biological yield, grain yield and irrigation water use efficiency have a trend with the increase of nitrogen rate. Compared with irrigation in all growth stages, no irrigation in any growth stages caused the reduction of biological and grain yield, while no irrigation in the growth stages increased the irrigation water use efficiency and no irrigation in two growth stages has the highest biological yield, grain yield and irrigated water use efficiency. In the growth stages of spring maize, no irrigation in the jointing, heading and filling stages has significant effect on the biological yield and no irrigation in the heading stage, no irrigation in both seedling and filling stages, no irrigation in both jointing and filling stages significantly affect the grain yield.4. In the seedling stage of spring maize, changes in photosynthetic rate under full water supply condition have trend of double peak, while no irrigation has a trend of single peak and reduces the leaf photosynthetic rate. Nitrogen is beneficial to the increase of photosynthetic rate. Transpiration rate under all treatments appears obvious single peak. The average transpiration rate of the day with irrigation is larger than that of no irrigation treatment. Fertilization has little effect on transpiration rate with irrigation, while inhibits the transpiration with no irrigation. No irrigation in seedling stage inhibits the leaf water use efficiency, while the leaf water use efficiency increases with the increase of nitrogen.5. The chlorophyll content at the late jointing or heading stage reached the maximum, and then began to decrease. During the whole growth period, the chlorophyll content increased with nitrogen application, irrigation didn't reduce the chlorophyll content. The effect of fertilization on chlorophyll was greater than the effect of no irrigation.6. Nitrogen fertilizer and irrigation significantly affected the accumulation and nitrate leaching. At various growth stages nitrate nitrogen accumulation of corn root zone 0~100cm increased with the nitrogen fertilizer. After fertilizing the surface soil nitrogen content significantly increased, nitrogen leached with the soil water infiltration resulting nitrogen content in lower layer soil increased. With the advance of the growing stage of spring maize, irrigation and rainfall gradually increasing, the residual nitrate decreased. The sequence of the reducing speed was high N treatment> low N treatment > medium N treatment > treatment without nitrogen. The important reason of nitrate nitrogen residue reduction was leaching out root layer.