Effects Of Different Irrigation And Nitrogen Application On Growth And Water Utilization Of Spring Wheat In Hexi Oasis

To study the spring wheat(Yongliang 4)at different growth stages of irrigation and nitrogen fertilization on ecological indicators,dry matter,yield,yield components and water use,a field plot experiment was conducted in Agricultural and Ecological Saving-water Station in China Agricultural University of Shiyang River Basin, Wuwei,Gansu from March 2010 to July 2010. Yongliang 4 was large-scale planted in Wuwei,Gansu province. The field experiment treatment consists of two factors: irrigation at different growth stages and nitrogen fertilizer levels of spring wheat,irrigation has 5 level:no irrigation at jointing(I1),no irrigation at tassel(I2),no irrigation at milky(I3) ,no irrigation at mature(I4)and full irrigation(CK);nitrogen fertilizer has 3 level:0kgN/hm² (N0),120kgN/hm² (N1) and 180kgN/hm² (N₂).Height,LAI,dry matter of spring wheat and distribution of soil water dynamics were measured at the middle of every stage,at the same time,yield,yield components of spring wheat and water use condition were analyzed. At last,water production function was set up in Hexi oasis. The main results are as follows:(1)Compare with full irrigation in the whole growth stage,there had been significantly effect on plant height, leaf area index with no irrigation in jointing stage, tassel stage and milky stage; no irrigation in milky stage and mature stage had significantly influence of canopy dry matter of spring wheat; nitrogen application on height and leaf area index of was significantly affected, there had also significantly effects on canopy dry matter in tassel stage , milky stage and mature stage. Irrigation at jointing stage after rehydration didn't have some compensation effect of plant height, but the compensation is limited.(2)Irrigation and nitrogen fertilizer were significantly affected on yield of spring wheat. In the appropriate water conditions, spring wheat yield increased with the amount of nitrogen increased; increase nitrogen fertilizer while poor soil water condition, spring wheat yield didn't increase significantly. Irrigation and nitrogen fertilizer have coupling. Full irrigation and high nitrogen treatment can obtain high yield; no irrigation in jointing stage, tassel stage and milky stage but high nitrogen fertilizer couldn't increase spring wheat yield. Full irrigation and no nitrogen fertilizer neither increase spring wheat yield. Through the rational field management of water and nitrogen, we can obtain higher production efficiency and ecological benefits.(3)Irrigation and nitrogen fertilizer were significantly affected on spike per ear and yield per ear. Otherwise, irrigation was much significantly affected on 1000-grain weight, nitrogen was significantly affected on number of ear per square meter. no irrigation at tassel or milky can significantly decrease 1000-grain weight, 1000-grain weight generally increased with the increasing of nitrogen fertilizer.(4)Irrigation and nitrogen fertilizer were significantly affected on water use efficiency (WUE) and irrigation water use efficiency (IWUE), nitrogen fertilizer can increase WUE and IWUE of spring wheat. Full irrigation can obtain the maximum yield and most higher WUE. In the nitrogen fertilizer condition, no irrigation at mature treatment obtain the maximum WUE and IWUE of spring wheat.(5)Path analysis between yield components and yield shows that,between yield, plant height, LAI, ear weight, the effective spike, spike length and grains per spike single relevant coefficients all reached the significant level. Plant height, LAI, ear weight, the effective spike, spike length and grains per spike interact each other,respectively.1000-grain weight has significantly relevant relationship with spike. There is a certain correlation between plant height,the effective spike, spike length, grains per spike and spike.(6)Under spring wheat irrigation experiment data of Agricultural and Ecological Saving-water Station in China Agricultural University of Shiyang River Basin, Wuwei,Gansu, established a Jensen water production function model, obtain under different nitrogen fertilizer conditions,the moisture sensitive stage of spring wheat Yongliang 4 is jointing stage,and then tassel stage,milky stage,mature stage.(7)Through formula water sensitive index was derived by yield components water sensitive index(include spike per ear,ear and 1000-grain weight)has theoretical feasibility, Most of the yield components of water sensitive index can reflect the real condition of spring wheat drought.(8)In the nitrogen fertilizer condition, the grain per ear has the highest water sensitive index, and it make up the main factor of yield cut, which is also consistent with the results of path analysis. Water deficit had no significant inhibitory effect on the spike, tassel and milky stage 1000-grain weight water sensitive index are higher than that of water sensitive jointing and mature stage, and more sensitive to water deficit.