Effect Of Enhanced NH₄～+ On The Activity Of Nitrate Reductase, Glutamatesynthetas And Organic Acid Content In Tomato

The influences of enhanced ammonium nutrition on tomato growth, quality as well as the activity of nitrate reductase, glutamatesynthetas and organic acid content were studied. Also we founded a method that could extract 9 organic acids and determine together with one mobile phase by HPLC. The results were listed as follows.1. Organic acids were extracted from tomato fruit and Chinese cabbage leaves by distilled water directly (w), or by 80% ethanol (v: v=80:20) and then evaporation for concentration (E), or by distilled water for extraction and then frozen-evaporation concentration (WF). In terms of tomato fruits, the extracted amounts of fumarate and succinate were not influenced by extraction methods, while the amounts of oxalic acid, tartaric acid, malate and oxaloacetate extracted by W method were significantly higher than those extracted by the other two methods. E method could extract the highest amount of pyruvate and citrate. For Chinese cabbage leaves, no significant differences were found in oxalic acid, tartaric acid and fumarate extracted by the three extraction methods, whereas the amount of the other organic acids (except for oxaloacetate) extracted by W and WF method were significantly higher than those extracted by E method. There were no significant difference of pyruvate, malate, and succinate extracted by W and WF method while citrate amount extracted by WF was higher than that by W. Therefore, distilled water extraction (W) method was proposed to extract organic acids from tomato fruits when taking the extraction steps, working efficiency and extraction quality together into account.2. Twenty five percent of replacement of nitrate by ammonium led to a significant increase in fruit fresh weight. Also, the sugar content, the acidity and the protein content in fruits were higher in the treatment of enhanced ammonium nutrition than those in the treatment of pure nitrate. However the sugar/acid ratio, the amino acid content and the Vc content did not change a lot.3. The replacement of 25% nitrate with ammonium led to a significant increase in ammonium content in both leaves and fruits and soluble protein content in fruits, while...