施氮量和花后土壤含水量对小麦氮代谢特性和子粒蛋白质含量的影响

Effects of nitrogen fertilizer rate and post-anthesis soil water content on characteristics of nitrogen metabolism and grain protein content in wheat

在池栽条件下,研究了施氮量和花后土壤相对含水量对小麦氮代谢特性和子粒蛋白质含量的影响。结果表明,在同一施氮量下,旗叶和子粒硝酸还原酶(NR)和谷氨酰胺合成酶(GS)活性表现为花后土壤相对含水量(Soil relative water content,SRWC)在60%～70%时最高,过低(40%～50%)或过高(80%--90%)均降低NR和GS活性。旗叶蛋白酶活性随土壤相对含水量增加而降低;花后土壤相对含水量过低不利于叶片游离氨基酸含量的提高,过高则前期氨基酸合成少,后期向子粒转运不彻底。子粒游离氨基酸和蛋白质含量也随土壤相对含水量增加而降低;子粒蛋白质积累量以花后土壤相对含水量为60%～70%时最高,过高和过低均不利于子粒蛋白质积累。在同一土壤含水量下,旗叶和子粒NR和GS活性表现为随着施氮量的增加而升高,蛋白酶活性随着施氮量增加而降低;旗叶和子粒游离氨基酸含量、子粒蛋白质含量和积累量随施氮量增加而提高,但施氮量过多。蛋白质积累量增加幅度减小。试验表明,小麦生产中可以通过施用氮肥和控制花后土壤水分含量技术,调节植株氮代谢,提高子粒蛋白质含量。

With the ultimate goal of maximising productivity and quality of wheat, effects of soil water content （SRWC） and N fertilization rate on nitrogen metabolism and grain protein content in wheat was tested under proof-rainfall pool culture condition. The results indicated that the activities of nitrate reductase （NR） and glutamine synthase （GS） were the highest in flag leaves and grains of wheat at the same level of nitrogen fertilizer rate with suitable SRWC （60% - 70% ） after anthesis. High （80% - 90% ） and low （40% - 50% ） SRWC suppressed the activities of nitrate reductase （NR） and glutamine synthase （GS）. Protease activities decreased with the increase of SRWC after anthesis. Low SRWC after anthesis was unfavorable for the increase of free amino acid content in wheat leaves, while high SRWC resulted in low synthesis rate at early stages. Consequently, its transferring into grains was not complete at late stage. Moreover, free amino acid content and protein content decreased with the increase of SRWC in wheat grains after anthesis. Protein accumulation in grains was the highest under SRWC （60 % - 70 % ） after anthesis, whereas high （80 % - 90 % ） and low （40% -50% ） SRWC made against the protein accumulation in grains after anthesis. Under the same level of SRWC, the increase of nitrogen fertilizer rate resulted in an increase of the activities of nitrate reductase （NR） and glutamine synthase （GS） in flag leaves and grains whereas it lead to a decrease of protease activities. Free amino acid content, protein content and accumulation increased with the increase of nitrogen fertilizer rate in wheat leaves and grains after anthesis. Excessive nitrogen fertilizer rate reduced the magnitude of increased protein accumulation. It is considered that nitrogen metabolism might be regulated to maximizing grain protein content in wheat production by controlling nitrogen application rate and soil water content after anthesis.