Effects of nitrogen fertilizer rate on nitrogen metabolism and protein synthesis of superior and inferior wheat kernel

Chinese. 研究了施氮量对强筋小麦强势粒和弱势粒氮素代谢和蛋白质合成的影响。结果表明：强势粒的蛋白质含量和单粒蛋白质积累量在灌浆过程中均大于弱势粒，强势粒开花后21 d前的谷氨酰胺合成酶活性和花后28 d的游离氨基酸含量显著高于弱势粒，是强势粒蛋白质积累速率快的生理原因。成熟期，同一施氮处理强势粒的清蛋白、醇溶蛋白、谷蛋白和谷蛋白大聚合体含量大于弱势粒，而球蛋白含量小于弱势粒。适量施氮，籽粒中的蛋白质含量和积累量显著增加，强势粒和弱势粒的游离氨基酸含量、可溶性蛋白质含量、谷氨酰胺合成酶活性之间的差异减小，蛋白质含量和积累量的差异亦减小；当施氮量由150 kg/ha增至240 kg/ha，弱势粒蛋白质含量增加，而强势粒蛋白质含量无显著变化；随施氮量增加，籽粒的各蛋白质组分含量呈增加趋势，不同粒位不同蛋白质组分的增幅不同，以弱势粒中谷蛋白含量和谷蛋白大聚合体含量的增幅大，说明施氮量对籽粒蛋白质和蛋白质组分含量的调控主要是通过对弱势粒的调控实现的。

English. Effects of nitrogen fertilizer rate on nitrogen metabolism and protein synthesis of the superior and inferior wheat kernel were studied. The results showed that the protein content and accumulation amount of the superior kernel were higher than that of the inferior kernel during filling, and that GS (glutamine synthetase) activities during 21 days after anthesis and free amino acids content during 28 days after anthesis in super kernel were significantly higher than that of inferior kernel, which accounted for the faster protein accumulation in the superior kernel. At maturity, with the same nitrogen fertilizer rate, the content of albumin, gliadin, glutenin and GMP (glutenin macropolyer) of superior kernel was higher than that of inferior kernel, while the globulin content in superior kernel was lower. Appropriate application of nitrogen fertilizer increased the protein content and accumulation amount in kernel, and decreased the difference in free amino acids content, soluble protein content and GS activity between superior kernel and inferior kernel, and the difference in protein content and accumulation amount. With nitrogen supply increased from 150 kg/ha to 240 kg/ha, protein content of inferior kernel increased, but no significant difference occurred in protein content of superior kernel. With the nitrogen fertilizer rate increased, the content of protein components increased by different extents, and the content of glutenin and GMP of inferior kernel improved mostly, showing that nitrogen addition effects on the content of protein and its components occurred mainly on inferior kernel.