中文摘要：

采用双丰16（偏丰产型）和甜单1号（偏高糖型）两个甜菜（Beta vulgaris L.）品种作为试材,在5个氮素水平（0、60、120、180和240 kg.hm^-2）下,研究甜菜功能叶片与块根中谷氨酸合成酶（glutamate syn-thase,GOGAT）在生育进程中的活性变化动态及其与块根产量、含糖率和产糖量的关系。结果表明：在不同氮素水平下,两个品种功能叶片和块根的GOGAT活性均呈双峰曲线变化,两峰值分别出现在6月下旬和8月下旬,其中,功能叶GOGAT前一峰值高于后一峰值;块根GOGAT则与之相反。在不同氮素水平下,功能叶片GOGAT活性表现为N180〉N120〉N240〉N60〉N0,块根GOGAT表现为N120〉N180〉N240〉N60〉N0。GOGAT的活性与块根产量及含糖率关系紧密,块根产量随GOGAT活性的增加而提高,但是GOGAT活性过高反而降低了块根含糖率,进而导致甜菜产糖量的降低。

英文摘要：

The effects of different nitrogen levels（0,60,120,180 and 240 kg·hm^-2）on dynamic changes of the activity of glutamate synthase in the functional leaf and root,and on beet yield,sucrose content and sucrose yield of the sugar beet variety（shuang feng 16 and tiandan 1）were investigated.The results showed that the activity of glutamate synthase of functional leaf and root were both expressed in double peak curve under the different nitrogen levels,the two peaks were observed in late June and August,and the activity of glutamate synthase of functional leaf in late June was obviously higher than in late August,but the order line of root was opposite.Under the different nitrogen levels the activity of the GOGAT of the functional leaf express that N180N120N240N60N0,and the root express that N120N180N240N60N0.There was a close relationship between GOGAT activity and beet yield,sucrose content.The beet yield increased steadily with increasing of enzyme activity,but the excessive high activity of GOGAT would lower sucrose content,which to cause the lower level of sucrose yield.