不同氮肥施用量对甜菜蔗糖代谢关键酶和可溶性糖含量的影响

为了筛选合适的氮素施用量，研究氮素营养和甜菜蔗糖代谢的关系。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和块根可溶性糖含量、蔗糖磷酸合成酶、蔗糖合成酶活性的影响。结果表明：在生育期初期，叶片和块根中的可溶性糖含量随着施氮量的提高降低，后期糖分积累期，施氮量(40~160 kg/hm2)可以提高块根的可溶性糖含量，超过160 kg/hm2可溶性糖含量降低；叶片中，整个生育期施氮肥处理增加了蔗糖磷酸合成酶活性，蔗糖合成酶在生育期前期随着施氮量增加活性降低；甜菜块根中，氮素处理在生育期初期，降低了蔗糖合成酶、蔗糖磷酸合成酶的活性，适宜的施氮量(120~160 kg/hm2）可以提高甜菜生育期后期块根中的蔗糖合成酶、蔗糖磷酸合成酶活性；试验发现较高的施氮量不利于糖的积累，适合的施氮量为120~160 kg/hm2。

Effect of Nitrogen Application on the Content of Soluble Sugar and Key Enzyme Activities in Sugar Metabolism of Sugar Beet

In order to select suitable level of nitrogen and study the relationships between nitrogen nutrition and the sucrose metabolism of sugar beet, urea was used as soil nitrogen fertilizer and HI003 was selected as experimental sample, the effects of different nitrogen levels conditions on the content of soluble sugar, activities of sucrose phosphorus synthase and sucrose synthase were studied in roots and leaves. The results were as following: in the early growth stage, the content of soluble sugar was decreased with the increase of nitrogen levels in both roots and leaves. Nitrogen (40-160 kg/hm2) increased the content of soluble sugar in roots in the tuber sugar accumulation period, and decreased the content of soluble sugar with the increase of nitrogen levels more than 160 kg/hm2. Nitrogen application increased activities of sucrose phosphorus synthase in sugar beet leaves in whole growth period, and decreased activities of sucrose synthase with the increase of nitrogen levels in sugar beet leaves in the early growth stage. In sugar beet roots, activities of sucrose phosphorus synthase and sucrose synthase decreased with nitrogen application in the early growth stage, but suitable nitrogen levels (120-160 kg/hm2) increased activities of sucrose phosphorus synthase and sucrose synthase in later growth stage. The results showed that high nitrogen levels were not beneficial to sugar accumulation and the suitable levels of nitrogen were 120-160 kg/hm2.