外源水杨酸对韭菜硝酸盐累积及还原同化的影响

 针对韭菜生产中硝酸盐累积问题，研究了叶面喷施水杨酸(SA)对韭菜硝酸盐累积及还原同化的影响。在不同氮素水平下，叶面喷施3.0 mmol·L^-1SA后6～9 d可明显降低韭菜叶片硝酸盐含量15.9％～21.6％，而当SA水平达到10.0 mmol·L^-1时会加重硝酸盐的积累。叶面喷施3.0 mmol·L^-1SA后9 d，韭菜叶片硝酸还原酶(NR)和谷胺酰氨合成酶(GS)活性分别比对照增加了48.9%和40.3％、净光合速率(Pn)和可溶性蛋白含量分别提高了43.4%和21.3％；同时，韭菜叶片谷氨酸草酰乙酸转氨酶(GOT)活性和谷氨酸丙酮酸转氨酶(GPT)活性也均有增加。因此，叶面喷施的外源水杨酸显著提高了氮还原动力泵NR活性以及氮同化动力泵GS活性，同时调动光合作用和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，减少了硝酸盐进入液泡贮积。

Effects of Exogenous Salicylic Acid on Nitrate Accumulation and Reduction and Assimilation in the Leaves of Chinese Chive

In view of nitrate accumulation Chinese chive production, effects of exogenous salicylic acid on nitrate accumulation and reduction and assimilation in the leaves of Chinese chive were studied. The results indicated that the nitrate content of Chinese chives were significantly decreased from 15.9% to 21.6% with various concentration SA treatment after 6 to 9 days under different levels of nitrogen. Optimal concentration of SA is 3.0 mmol·L^-1, and SA concentration reached 10.0 mmol·L^-1, nitrate accumulation could be aggravated. After 9 days with spraying 3.0 mmol·L^-1 SA on leaves, the activity of nitrate reductase (NR) and glutamine synthetase (GS) were increased 48.9% and 40.3%; photosynthetic rate and dissolvable protein were increased 43.4% and 21.3%; However, the activity of GOT and GPT were slightly higher than the control. Therefore, activity of NR (which was named as 'N-reducing-driving-pump') and GS (which was called 'first driving pump') were significantly increased by spraying on leaves with exogenous SA, while photosynthesis and transaminations were played the positive role of coordination, and translation of nitrate into free amino acid and dissolvable protein were promoted and nitrate accumulating into the vacuole of Chinese chives were reduced.