Comparison Of Organic Acids Accumulation In Puccinellia Tenuiflora Under Salt Stress And Alkali Stress

The formation of salt-alkaline soil included salinization and alkalinization. The increase of salinity was the character of salinization and the increase of pH was the character of alkalinization. The environment of salinization and alkalinization includes two stresses - salt stress and alkali stress in fact for plant. The aim of this experiment was to show the characters and correlations between neutral salt stress and basic salt stress on plant. Seedlings of Puccinellia tenuiflora (Griseb.)Scribn. Et Merr. were stressed with neutral salt (NaCl:Na2SO4 = 1:1) and basic salt (NaHCO3:Na2CO3 = 1:1) when the seedling were 8 weeks old. Organic acids and proline in the shoots and roots of seedlings of P. tenuiflora such as citric acid, malate and oxalic acid were determined with Reversed-Phase High Pressure Liquid Chromatography, and the differences and characters of accumulation of organic acids were compared between two stresses.The results showed as follows. (1) The citric acid content increased obviously when the strength was higher than 60 mmol/L in alkali stress but decreased gently in salt stress. The accumulation of citric acid in P. tenuiflora was special physiological response to alkali stress which might correlate with pH adjustment. These showed that there were different responses mechanisms between salt stress and alkali stress. (2) The dominant factor in metabolic adjustment of organic acids was citric acid. The change degree of citric acid, malate, succinic acid and oxalic acid were obviously difference. Citric acid was occupied more than half in total organic acids and others were changed gently. As a result, change of total organic acids was rouse of content of citric acid. (3) In certainly degree (the stress was 0-300mmol/L), whether salt stress and alkali stress were arouse proline accumulated with increased strength. But proline was higher in salt stress than alkali stress. These showed salt stress and alkali stress were similar in certain aspects but not the same. They were raised by osmosis, ion toxicity and ion imbalance and alkali stress also resulted in high pH, which had been proved to be an important factor.The accumulation of organic acids, which citric acid played a dominant role in P. tenuiflora, was a special response to alkali stress. This phenomenon had important senses to enclose the mechanism of resistance to alkali stress for the natural alkali tolerant plants.