Effects Of Irrigation Times And Nitrogen Application Rates And Their Interactions On Grain Yield And Quality Properties Of Weak-gluten Winter Wheat

Field experiments were carried out at five sites, Zhengzhou, Xixian, Xiping, Xuchang and Xunxian County in growing season of 2003-2004, and in Zhengzhou in growing season of 2004-2005. Effects of different irrigation times and nitrogen application rates and their interactions on quality and yield were evaluated with four wheat cultivars, three weak-gluten cultivars (lines), Yumai 50, Zhengmai 004 and Taikong 5, and a strong-gluten cultivar Yumai 34 as control. The results were as follows:1. Both irrigation times and nitrogen application rates affected wheat population and leaf area index (LAI). The treatment of twice irrigations (at jointing stage plus grain filling stage)(W₂) with nitrogen application rate of 150 kg/hm² (N₁) significantly improved both population and LAI of Yumai 50, resulting in the highest spike number and grain yield. For Yumai 34, a weak-gluten cultivar, the treatment of W₂N₂ (nitrogen application rate was 270 kg/hm²) got the biggest values for those parameters.2. Both irrigation times and nitrogen application rates and their interactions affected chlorophyll content and fluorescence parameters in flag leaves. Significant differences were found among treatments of irrigation times, and of nitrogen application rates. Interactions between irrigation and nitrogen were also significant. In late grain filling stage, chlorophyll content was high, and reduction in Fv/Fo, Fv/Fm and qP was slow W₂N₁ for Yumai 50. ForYumai 34, the highest content of chlorophyll, Fv/Fo, and others were found in W₂N₂.3. Experiments conducted at five sites indicated that, for three weak-gluten wheat cultivars, the highest content of amylase was obtained in the treatment W₁N₂, and in W₂N₁ the highest content of amylopectin and total starch in grains was got. On the contrary, in the treatment W₂N₀ the lowest values of amylase, amylopectin and total starch content were observed. As for Yumai 34, in the treatments W₂N₂ and W₁N₀ the highest and the lowest values were obtained for contents of starch, respectively.Differences in starch pasting properties were significant (P<0.01) among sites. Increase in irrigation times resulted in decrease in breakdown of flour, but increase in nitrogen application rates got the opposite effects. For other pasting parameters such as peak...