Studies On Physiological And Biochemical Character Of Different Foliage Vegetable In Utilizing Nitrate

Different foliage vegetables were planted in nutrient solution with different concentration nitrate in the study. The biologic yield, nitrate, the nitrate reductase activity (NRA), nutrient quality and photosynthetic character were studied. We tried to select the cultivars with fewer nitrate Meanwhile, the result can help us to definite the physiological and biochemical character of nitrate accumulation in foliage vegetables and provide direction for the plant of the Green Vegetable. The mail results and conclusions were showed as follows.1. When the nitrogen supply was not enough, it was main limiting factor of vegetable yield. But increasing the nitrogen supply was not make the biologic yield increase unlimitedly; even make it decrease. It was the result possibly that there was overmuch carbohydrate consumed during superabundant nitrate was absorbed and transformed under extreme nitrate supply. At same time, it may affect the biologic yield that only increasing nitrate lead to nutrition unbalanced.2. Nitrate accumulation of Ribenxueyubaicai (B8) was lest, and that of changjiangqinggen (B4)was mast among 10 pakchoi cabbage cultivars in full nutrient solution (N2). The NO3 -N content ofLuomazhilishengcai (S4) was lest, and that of xianggangbolishengcai (S3) was most among 5 lettuce cultivars. But nitrate accumulation of Jinyouwuhaotiancaixin (C2) was most, and that of sijiushijiuhaocaixin (Cl) was lest among 4 flowering Chinese cabbage cultivars. So the several cultivars can be studied deeply to be the material in studying the gene related nitrate accumulation.3. When nitrate concentration in nutrient solution was 24mmol/L(N4), nitrate accumulation of Changjiangqinggeng (B4) was most, and NRA was lowest among 10 pakchoi cabbage cultivars. The biologic yield of Luomazhilishengcai (S4) was most; the NO3^--N content was lest, and NRA was lowest among 5 lettuce cultivars. The biologic yield was lest, and the NO₃^- -N content was most in Meiguodasushengcai (S1). All that is because of the dilution of increasing yield possibly. Among 4 flowering Chinese cabbage cultivars, the biologic yield was most, and the NO₃^{- N} content was lest, and NRA was highest in Sijiushijiuhaocaixin (Cl). The NO₃^--N content was most, and NRA was lowest in Jinyouwuhaotiancaixin (C2). There was negative correlation between its NO₃^--N contentand NRA. The cultivars mentioned hereinbefore were the good sample for studying the mechanism of nitrate accumulation in the superfluous nitrate supply.4. There was positive correlation very significantly between NRA and the nitrate concentration in nutrient solution. The positive correlation was significant between NRA and the NO₃^--N content of vegetable. It showed that the NO₃^--N content did not decrease with the increase of NRA in vegetable, perhaps because of the different position of NR and NO₃^- in the plant cell.5. With the increasing of nitrate concentrate in nutrient solution, the change of every nutrient character index did not showed a coincident. The contents of soluble sugar in pakchoi cabbage and flowering Chinese cabbage were decreasing, but the decreasing degrees were not same in different vegetables. The content of soluble sugar in lettuce decreased after increasing. The soluble sugar in 5 lettuce cultivars is different significantly in same treatment, which rest mainly with the cultivars. And the full nutrient solution was in favor of the accumulation of soluble sugar in lettuce. With the increase of nitrate concentrate in nutrient solution, the content of protein of Chongqingdaqiqing (B7) decreased, which decreased after increasing in other 9 pakchoi cabbage cultivars, lettuce and flowering Chinese cabbage. The content of amino acid in pakchoi cabbage and lettuce basically decrease after increasing. The Vc content of flowering Chinese cabbage decreased after increasing. But the change of amino acid in 4 flowering Chinese cabbage cultivars was not coincident. So does the change of Vc in pakchio cabbage and lettuce. The mechanism is waiting for deeply studying.6. In full nutrient solution, the NO₃^--N content of Ribenxueyubaicai (B8) among the 10 pakchoi cabbage cultivars was lest, the soluble sugar and Vc was most, and protein was more; among the 5 lettuce cultivars the NO₃^--N content of Luomazhilishengcai (S4) was lest, the soluble sugar and amino acid was most, the biologic yield and Pn. was most. But the biologic yield of Jinyouwuhaotiancaixin (C2) was lest, and the NO₃^--N content was most, and the protein and Vc was lest.7. With the increase of nitrate concentration in the nutrient solution, the Chl. content increased accordingly. There was positive correlation very significantly between the Chl. content and the nitrate concentration in the nutrient solution. It was showed that superfluous nitrate was advantaged with the forming of Chlorophyll, which maybe have relations to that nitrogen is a constitution of Chlorophyll. There was positive correlation significantly between the content of protein and its apparent photosynthetic rate. With the increase of nitrate concentration in the nutrient solution, the Pn. of Xiawangqinggeng (B6), Shanghaiqibaoqing (B10) and Jinyouwuhaotiancaixin (C2) increased accordingly. There was positive correlation between apparent photosynthetic rate and stomatal conductance in Shanghaiqibaoqing (B10) and Jinyouwuhaotiancaixin (C2). It showed that their apparent photosynthetic rate was limited mainly by un-stoma factors, such as the Chl. Content. But there was positive correlation between the apparent photosynthetic rate and stomatal conductance of...