Effects of Exogenous Salicylic Acid on Nitrate Reduction and Assimilation in Chinese Chive Under Weak Light

【Objective】The effect of exogenous salicylic acid(SA) on accumulation of nitrate,the key enzyme activity of nitrogen metabolism,the apparent electron transport rate(ETR) and the main amino acids and soluble protein was studied in Chinese chive under the weak light in order to understand the effects of exogenous salicylic acid on nitrate reduction and assimilation.【Method】With Chinese chive as an experimental material,two treatment factors including SA(3.0 mmol.L-1) and light intensity(the weak light and natural light) were designed in the experiment.【Result】Under the weak light,exogenous SA pretreatment reduced the decrease in the key enzyme activity of nitrogen metabolism(nitrate reductase(NR),glufamine synthetase(GS),glutamic-oxaloacetic-transaminase(GOT) and glutamate-pyruvate-transaminase(GPT)),while decreased nitrate accumulation.Compared with no SA treatments,NR and GS activities in SA treatments increased significantly,23.7% and 12.3%,respectively.Also,the content of chlorophyll(Chl),ETR,the content of free amino acids and soluble protein of weak light were enhanced after SA application.In addition,SA increased the content of most free amino acid components under weak light,with tryptophan and serine as the most effective,reaching 89.8% and 50.6%,respectively,and at the same time reduced the free amino acids and soluble protein ratio(A/P).【Conclusion】Weak light reduced the capacity of the nitrogen assimilation and material production,however,exogenous SA spraying on leaves obviously improved nitrate reduction and assimilation,which,meanwhile,brought transaminations into play vigorously,and promoted turning NO3-into free amino acid and dissolvable protein.Improvement of nitrate reduction and assimilation might be a key reason for reducing nitrate accumulating into the vacuole of Chinese chive under weak light.