| 1 Effect of irrigation rate on water requirement characteristic, quality and grain yield of wheatTwo cultivar was studied in this experiment, they were Jimai 20, which has strong gluten potential and Taishan 22, which has medium gluten potential. Four irrigation rate treatment including no irrigation (expressed as W0 ), irrigation at before winter and jointing (expressed as W1 ), irrigation at before winter, jointing and anthesis (expressed as W2 ), irrigation at before winter, jointing, anthesis and filling stage (expressed as W3 ),the irrigation rate was 60mm every times. Physiological biochemistry measures were used to study the effect of different irrigation on WUE, grain yield and quality and its physiological mechanism. The results were as follows:1.1 Effect of irrigation rate on changes of soil water content in different soil layersAccording to the distribution and development of wheat roots, from the soil surface on, five soil layers were studied. They were 0～20cm,20～60cm,60～100cm,100～140cm,140～200cm. The results indicated that the effect of irrigation rate on grain yield can be achieved by influencing the soil water content in the soil layer of 0～140cm. In the condition that before sowing the soil water content in the soil layer of 0～20cm,20～60cm,60～100cm,100～140cm were 25.21%,23.11%,25.23%,24.63% high yield can be achieved. It was that in different growth stage the seemly soil water content in the layer of 0～20cm,20～60cm,60～100cm,100～140cm was 20.2%～21.1%,21.3%～21.5%,23.9%～24.1%,24%～24% before winter; 16.9%～17.4%,17.1%～17.5%,21.7%～21.7%,23.1%～23.5% at jointing; 15.4%～15.8%,18.4%～18.7%,22%～22.1%,23.4%～23.7% at anthesis; 12.93%～14.03%,13.47%～15.28%,15.51%～17.04%,23.11%～23.92% at maturity. From jointing to anthesis in the soil layer of 0～20cm,20～60cm and from anthesis to maturity in the soil layer of 20～60cm,60～100cm, the soil water contents maintained in high level which high yield was ensured.1.2 Effect of irrigation rate on water-use efficiency (WUE) of wheatThe water consumption rate of the treatment with high grain yield was 451.31mm～459.19mm, The percentage of irrigation rate to water consumption rate was 28.05%28.54%,the percentage of precipitation to water consumption rate was 26.59%39.20%,the percentage of soil water rate to water consumption rate was 32.75%44.87%.The WUE of different treatments was W0>W1>W2,W3. And there was no significant difference between W2 and W3 on WUE. The WUE of T22 was higher than J20. In the condition of W0,W1, the soil moist consumption amount of J20 was significantly higher than that of T22 which indicated that the capability of water utility of J20 in the condition of drought and waterless was higher than that of T22.1.3 Effect of irrigation rate on nitrogen cycle in plant and soil system of wheatUnder the treatment W0, soil NO3--N mostly deposited in the soil layer of 040cm before booting stage; and mostly deposited in the soil layer of 060cm from anthesis to maturity. The soil NO3--N content in the layer of 060cm moved deeper than treatment W0 under treatment W1,W2,W3.Compared with the treatment W0, irrigation increased nitrogen accumulation in anthesis and nitrogen transportation quantity from vegetative organs to kernels. Compared among the treatment W0,W1,W2, irrigation increased assimilation quantity of soil nitrogen and topdressing nitrogen, and decreased nitrogen quantity from fertilizer in kernels. The treatment W1 increased assimilation quantity of soil nitrogen and wheat kernel nitrogen accumulation.1.4 Effect of irrigation rate on protein components content and quality in kernel of wheatWith increasing of irrigation rate, theα- gliadin content,γ- gliadin content,LMW-GS content in kernels were increased until the irrigation rate of the treatment W2.ω-5 gliadin,ω-1,2 gliadin and HMW-GS content can be not significantly influenced by irrigation rate. Protein content,wet gluten content were increased until the irrigation rate of the treatment W1 for J20 and the treatment W2 for T22. Dough stability time and sedimentation value of the treatment W2 were the best.ω5- gliadin content,α-gliadin content,HMW-GS content,LMW-GS content,glutenin content and glu/gli,sedimentation value,Dough stability time of J20 were significantly higher than T22. 1.5 Effect of irrigation rate on nitrogen metabolism and enzyme activity of wheatCompared with the treatment W0 and W1, GS activity at middle filling stage and EP activity, free amino acid after anthesis in flag leaf were increased under the treatment W2. The treatment W3 decreased GS activity and EP activity at late filling stage in flag leaf which restrained protein hydrolyzing.1.6 Effect of irrigation rate on starch quality of wheatThe treatment W1 of J20 increased amylopectin content / amylose content by increasing amylose content and decreasing amylopectin content. Amylose content was increased with increasing of irrigation rate while amylopectin content was decreased. And the amylopectin content/ amylase content of J20 was higher than that of T22.1.7 Effect of irrigation rate on carbon metabolism and enzyme activity of wheatCompared with the treatment W0, the treatment W1,W2,W3 increased the Pn of flag leaf, prolonged the stage of higher Pn. Compared with the treatment W1, the treatment W2,W3 increased the Pn of flag leaf of T22. The proper irrigation rate increased SPS activity in flag leaf of J20. Irrigation too much restrained the transportation of sucrose from flag leaf to kernel.The treatment W1 decreased GBSS activity and increased SSS activity at middle filling stage in kernel. Irrigation was helpful for accumulation of GBSS, but not for SSS.1.8 Effect of irrigation rate on grain yield of wheatThe grain yield was increased with increasing of irrigation rate until the irrigation of the treatment W1 for J20 and the treatment W2 for T22. Under the condition of enough soil water, the grain yield of T22 was higher than J20, but under the condition of drought stress, the grain yield of J20 was higher than T22.2 Effects of nitrogen application rate on protein quality and starch quality of kernelJimai 20, a strong-gluten cultivar was used, the experiment was arranged four nitrogen application rate treatments, consisting of 0 kg·hm-2 (expressed as CK),96kg·hm-2 (expressed as N1),168 kg·hm-2 (expressed as N2),240kg·hm-2 (expressed as N3).Study the effects of nitrogen application rate on the forming mechanism of kernel protein quality, kernel starch quality and grain yield. The results were as follows:2.1 Effect of nitrogen application rate on protein components content of kernelAt the range of nitrogen application rate of 0～168kg·hm-2, increasing nitrogen application rate had no significant effect on glutenin content, the glutenin content increased greatly at the nitrogen application rate of 240 kg·hm-2. Gliadin content improved with the increasing of nitrogen application rate at the range of 0～168kg·hm-2, gliadin content had no significant difference between the nitrogen application rate of 168kg·hm-2 and 240kg·hm-2. The protein components contents were little effected by nitrogen application rate. The ratio of glutenin / gliadin was decreased with the increasing of nitrogen application rate until to a certain nitrogen rate. The results indicated that increasing nitrogen application rate could improve the kernel quality.2.2 Effect of nitrogen application rate on starch components content of kernelThe amylopectin content, amylose content and total starch content of nitrogen application treatments were significantly lower than that of CK. Compared with each other among the nitrogen application rate treatments, the contens of amylopectin and total starch was decreased with the increasing of nitrogen application rate, but there were no significant difference. There were no significant differences among the different nitrogen application rate treatments of amylose content.Suitable nitrogen application rate improved the ratio of amylopectin content / amylose content, treatment N2 had the highest ratio of amylopectin content / amylose content, the ratio of amylopectin content / amylose content was decreased when nitrogen application rate exceeding 168kg·hm-2 2.3 Effect of nitrogen application rate on grain yield Treatment N2 improved the number of earper ha,number of kernel per ear and weight per 1000 kernels,and got the highest grain yield. Was the optimal nitrogen application rate.
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