不同氮素水平对甜菜氮代谢酶和可溶性蛋白含量的影响

为了筛选合适的氮素施用量，研究氮素营养和氮素同化关键酶的关系，以尿素为氮源，采用HI003为试材，研究了不同的施氮水平对甜菜叶片、块根中可溶性蛋白含量、硝酸还原酶和谷氨酰胺合成酶活性的影响。结果表明：叶片中，硝酸还原酶的活性随着施氮水平的提高而增加，但是超过 200 kg/hm²酶活性下降；块根中硝酸还原酶活性在0~120 kg/hm²随着施氮量增加而上升，超过 160 kg/hm²酶活力下降。叶片、块根中，整个生育期施氮肥处理增加了谷氨酰胺合成酶活性。试验中发现施氮量和生育期早期的叶片中硝酸还原酶和谷氨酰胺合成酶活性呈显著正相关。施氮量和甜菜叶片可溶性蛋白含量在7月15日和9月15日呈显著正相关；在生育期内，氮素水平和块根中的可溶性蛋白含量呈极显著正相关。

Effect of Different Nitrogen Application Levels on the Content of Soluble Proteinand Key Enzyme Activities in Nitrogen Metabolism of Sugar Beet

Urea was used as soil nitrogen fertilizer and HI003 was selected as experimental sample. In order to select suitable levels of nitrogen and study the relationship between key enzyme activities in nitrogen metabolism and nitrogen application levels of sugar beet, studies on the content of soluble protein, activities of nitrate reductase and glutamine synthase were conducted in roots and leaves of sugar beet with different nitrogen levels. Results of this experiment were as following: in sugar beet leaves, activities of nitrate reductase increased with the increase of nitrogen levels, but nitrate reductase activities decreased when nitrogen levels were more than 200 kg/hm². Activities of nitrate reductase nitrogen levels increased with the increase of nitrogen levels in roots, and decreased with nitrogen levels more than 160 kg/hm². In the whole growth period, glutamine synthase activities increased with nitrogen application in roots and leaves. The studies found that nitrogen levels and activities of nitrate reductase and glutamine synthase had significantly positive correlation in the early growth stage. In sugar beet leaves, the content of soluble protein was positive correlated with nitrogen levels on July 15th and on September 15th. The content of soluble protein and nitrogen levels had significantly positive correlation in roots in the whole growth period of sugar beet.