Abstract:

To study the effects of nitrogen fertilizer on activities of key enzymes of carbon and nitrogen metabolism of different varieties of flue\|cured tobacco, this paper carried out field experiment and determined the changes in activities of nitrate reductase (NR), glutamine synthetase (GS), glutamate dehydrogenase (GDH), sucrose phosphate synthase (SPS), sucrose synthase (SS) of 2 varieties of flue\|cured tobacco, Honghuadajinyuan (H) and K326 (K), under circumstances of N supplied and  without N supplied. The results showed that the applying nitrogen fertilizer for the same variety can increase activities of NR, GS at the early growth stage of flue\|cured tobacco; and the activity of GDH at the middle growth stage. At the same time, N supplying can increase the activity of SPS activity at early stage and activity of SS at the late stage. Under the same N supplying cases, activities of NR in K326 and SPS are higher than that in Honghuadajinyuan at early stage, so as the GDH activity in K326 during carbon metabolism period. Activity of GS in Honghuadajinyuan is higher than that in K326 at late growth stage. Nitrogen fertilizer can stimulate the nitrogen metabolism of different tobacco plant varieties. K326 utilizes nitrogen more than Honghuadajinyuan at the early stage, while at the late stage K326s reuse of nitrogen is less than Honghuadajinyuan. Therefore, in the process of flue\|cured tobacco growth and development, adequate supply of nitrogen fertilizer should be ensured according to nitrogen demands of different flue\|cured tobacco varieties.

Key words: nitrogen, Honghuadajinyuan, K326, carbon and nitrogen metabolism, enzyme activity

摘要：

为探讨氮肥对不同烤烟品种碳氮代谢关键酶活性的影响，采用大田试验测定了红花大金元(H)和K326(K) 两个烤烟品种在施氮和不施氮条件下,不同生育期硝酸还原酶（NR）、谷氨酰胺合成酶（GS）、谷氨酸脱氢酶（GDH）、蔗糖磷酸合成酶（SPS）和蔗糖合酶（SS）的活性变化。结果表明：对于同一品种，氮肥的使用在前期提高NR、GS活性，中期提高GDH活性；同时施氮提高前期SPS活性及后期SS活性。同一施氮处理情况下，K326的NR活性和SPS活性在前期高于红大，在碳代谢旺盛时期K326的GDH活性也要高于红大，在后期红大的GS酶活和SS活性高于K326。氮肥对不同品种烟株的氮代谢都起到促进作用；K326在前期利用氮素作用强于红大，后期氮素再利用作用却弱于后者，同时K326和红大在碳代谢过程中碳源向不同的碳水化合物分配的比例不同。因此在烤烟生长发育过程中，需根据不同品种氮素需求的特点，确保氮肥的供应充足。

关键词: 氮肥；红花大金元；K326；碳氮代谢；酶活性