The Mechanism Of Water And Nitrogen Effective Use For High-Yield Cultivation Of Spring Wheat In Hetao Irrigation Region

Took the field experiment respectively in Hangjinhouqi and Dengkou experiment stations in the city of Bayannaoer, Inner Mongolia ,from 2008 to 2009, study on the morphology, canopy structure, photosynthesis, material accumulation, grain filling, yield and the use of water and nitrogen and other aspects of spring wheat in different nitrogen in the patterns of water-saving irrigation(jointing and earing,2 water) and conventional full irrigation (tiller+ jointing + spiking + grouting, 4 water), defined physiological mechanism of efficient use of water and nitrogen of wheat, presented the theoretical basis to establish water-saving, fertilizer and high yielding cultivation technology system of spring wheat in Plain Loop. The main conclusions are as followed:1. The promotion of wheat higher was obviously under irrigation and nitrogen application, the length, width and area of clover especially flag leaf were increased. Transmittance of canopy central and the lower canopy in the treatment of 2 water was significantly higher than the treatment of 4 water after the completion of wheat groups, population extinction coefficient (K) showed that central> ground, and the K was decreased of canopy central and the lower canopy with the increase of nitrogen. It can balance the efficiency light interception of upper canopy and the losses leaky of lower in the condition of increasing amount of nitrogen of water-saving, this was the morphological basis to access high yield of wheat.2. The PSâ…¡activity (Fv/Fm) of Chlorophyll content(SPAD) and net photosynthetic rate of wheat flag leaf were relatively lower in the mode of water-saving irrigation, because of smaller leaf area and lower transpiration rate, water use efficiency (WUE) were significantly increased. At the same time, leaf relative water content (RWC) and Proline content were increased, osmotic adjustment were increased, water drought tolerance were improved significantly in the condition of increasing nitrogen of water-saving.3. The leaf area index and photosynthetic potential showed a single peak curve with the growth,and reached maximum from booting to flowering stage, then gradually declined until maturity in different irrigation and nitrogen treatments. In the conditions of increase frequency of irrigation and nitrogen, the leaf area and photosynthetic potential growth quickly before booting, but decline sharply in filling stage; correlation analysis showed that photosynthetic potential and economic yield were significantly correlated in different stages of growth. Therefore, it was an important guarantee to gain high yield of maintain higher green leaf area during the filling stage.4. Dry matter accumulation of wheat showed S-shaped curve with the growth in different irrigation and nitrogen treatments, colony growth rate (CGR) showed a single peak curve with the growth process, and reached maximum from booting to flowering stage. The difference of dry matter accumulation were no significant before jointing in different irrigation and nitrogen treatments, and dry matter accumulation showed that the treatment of 4 water>the treatment of 2 water, high nitrogen> low nitrogen, colony growth rate showed that the treatment of 2 water>the treatment of 4 water, high nitrogen> low nitrogen after jointing. It can promote the storage material transfer of stem and sheath after flowering, compensate the loss of weight reduced caused by photosynthetic performance degradation and maintain weight stability in the condition of decreasing amount of nitrogen of water-saving compared with full irrigation,.5. The peak of grain filling showed about 20d after flowering, the rate of grain filling showed that the treatment of 2 water>the treatment of 4 water, grain weight of low nitrogen faster than higher nitrogen before that; and it showed that the treatment of 4 water>the treatment of 2 water, the decrease of filling rate were slowly in the treatment of higher nitrogen, because of plant nutrient deficiency in the treatment of lower nitrogen, grain filling rate decreased rapidly. As the process of grain development, grain soluble sugar content decreased and starch content increased. Water conditions appropriate to reduce nitrogen, Efficiency of transfer from soluble sugar to starch had improved, grain weight and starch content increased in the condition of decreasing amount of nitrogen of water-saving.6. Except grains per panicle, spike per mu, grain weight and yield were no significantly between the patterns of water-saving irrigation (2 water) and conventional full irrigation (4 water),and water use efficiency (WUE) increase about 10 % than the conventional full irrigation. The wheat yield, water consumption and WUE simultaneously increases with the nitrogen increased in the lower range of nitrogen, the yield and WUE declined while the nitrogen exceed a certain range. In both of two irrigation modes, it could promote the absorption of nitrogen in the condition of increasing nitrogen, but the efficiency use of nitrogen decreased significantly. The efficiency use of nitrogen improved significantly in the treatment of 2 water compared with 4 water. Economic yield of wheat, efficiency of water use, efficiency agriculture use of nitrogen and total nitrogen showed a quadratic curve, to achieve water-saving, fertilizer and high yield of Plain Loop wheat, optimum amount of nitrogen (pure N) was 8-13kg/mu.