With Chinese chive as an experimental material ,four treatment factors including S (4 g/m 2 ) and ni-trogen intensity (0,12,24,36 g/m 2 ) were designed to study nitrate reduction and assimilation of Chinese chive in the experiment.The results showed that as the concentration of nitrogen rises ,the nitrate content and the activity of nitrate reductase increased,while the activity of glutamic-oxaloacetic-transaminase (GOT) and glutamate-pyruvate-transaminase (GPT),the content of free amino acids and soluble protein ,the dry content rate in Chinese chive in-creased at first and then descended .Sulphur can reduce nitrate accumulation and improve the activity of NR ,GOT and GPT in Chinese chive under different nitrogen concentration ,especially for 24 g/m 2 of nitrogen.The increase amplitudes of NR,GOT and GPT activity ,the content of free amino acids and soluble protein were 21.23%, 20.15%,17.74%,22.79%,25.27% respectively.In conclusion,S and suitable concentration of nitrogen improved nitrate reduction and assimilation ,which,meanwhile,brought transaminations into play vigorously ,and promoted turning NO-3 into free amino acid and dissolvable protein .% 以韭菜品种新世纪雪韭为供试材料，设不施氮（N）、低氮（N 12g/m 2，L）、中氮（N 24g/m 2，M）、高氮（N 36 g/m 2，H）4个氮素水平，结合4 g/m 2硫磺（S）对韭菜进行土施处理，分析氮硫互作对韭菜叶片硝酸盐（NO－3）累积及NO－3还原同化的影响。结果表明，随着施氮水平的提高，NO－3和硝酸还原酶活性（NRA）均呈现出逐渐增加的趋势，而谷氨酸草酰乙酸转氨酶（GOT）、谷氨酸丙酮酸转氨酶（GPT）活性、可溶性蛋白质、游离氨基酸含量以及干物率则表现出先增加后降低的变化趋势，且均在中氮水平达到最高。土施硫磺可降低不同氮水平下韭菜硝酸盐的累积，提高NA、GOT 和 GPT 的活性，各酶活性均以中氮水平下增幅最大，分别为21．23％，20．15％，17．74％；另外，施硫处理还显著提高了中氮水平下氮代谢产物游离氨基酸和可溶性蛋白含量，分别为22．79％，25．27％。综上所述，施硫和适量的氮素配合不但促进了氮素水平韭菜叶片氮代谢中硝酸盐的还原和同化，同时调动转氨作用的积极协同配合，促进了硝态氮转化为游离氨基酸和可溶性蛋白，降低了硝酸盐累积。
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