施氮对花后遮光条件下小麦产量与蛋白质含量的影响

为探讨施氮对花后弱光逆境下小麦籽粒产量和蛋白质含量的影响，选用2个对弱光敏感性不同的小麦品种（济麦22和济核916），设置3个施氮水平（0、120和240 kg·hm^-2），在花后遮去60%的自然光条件下研究了施氮量对小麦籽粒产量与蛋白质含量的调控效应。结果表明，增施氮肥可延缓花后遮光条件下两个小麦品种旗叶叶绿素下降，使PSⅡ实际光化学效率和净光合速率维持较高水平，促进旗叶可溶性糖含量合成，提高籽粒灌浆速率，增加穗数、穗粒数和籽粒产量。增施氮肥提高了遮光条件下两个小麦品种旗叶硝酸还原酶活性、籽粒谷氨酰胺合成酶活性和籽粒游离氨基酸含量，增加籽粒蛋白质含量。济麦22的籽粒产量以240 kg·hm^-2施氮处理最高，籽粒蛋白质含量在120 kg·hm^-2和240 kg·hm^-2施氮处理间无显著差异；济核916的籽粒产量和蛋白质含量均以120 kg·hm^-2施氮处理最高。由此可见，在花后遮光条件下适量施氮可提高小麦光合能力和促进碳氮代谢，最终增加籽粒产量和蛋白质含量。

Effect of Different Nitrogen Rate on Wheat Yield and Protein Content under Shading Conditions after Anthesis

To explore the effects of nitrogen application on wheat grain yield and protein content,two wheat varieties(Jimai 22 and Jihe 916) were selected as materials with different sensitivity to weak light and three nitrogen application levels of 0,120 and 240 kg·hm^-2were set up under low light conditions(shading 60% natural light after anthesis). The results showed that increasing nitrogen fertilizer under shading conditions delayed the chlorophyll degradation of flag leaves after anthesis,maintained a higher level of photosystem II actual photochemical efficiency and net photosynthetic rate,promoted the synthesis of soluble sugar content in flag leaves,increased the grain filling rate,increased the number of spikes and grains per spike,and increased the grain yield of two wheat varieties. Increasing nitrogen application under shading conditions increased nitrate reductase activities in flag leaves,glutamine synthetase activity in grains,free amino acid content in grains,and grain protein content of the two wheat varieties. The grain yield of Jimai 22 was the highest under 240 kg·hm^-2 nitrogen application,but there was no significant difference in protein content under the two nitrogen treatments(120 kg·hm^-2 and 240 kg·hm^-2 nitrogen application). The grain yield and protein content were the highest at 120 kg·hm^-2 nitrogen application for Jihe 916.Therefore,under the conditions of shading after anthesis,appropriate nitrogen application improved the photosynthetic capacity,promoted the metabolism of carbon and nitrogen,and ultimately increased the grain yield and protein content.