Primary Studies On Nitrate Content In Radish (Raphanus Sativus L.)

Vegetable and drinking water contribute to the main source of nitrate in human. Nitrate can be reduced into nitrite which is harmful to human. Different vegetables have different nitrate content and the root vegetable have more nitrate content than others.Radish belongs to cruciferae and originates from China. It has been wildly cultivated in China. As root vegetable, radish has relatively high nitrate content. So selecting low nitrate content radish cultivars is an important objects and has the most important practical significance.Four male sterile lines and their hybrids, ten F1 radish varieties and their F2 populations were employed for nitrate content analysis. The results showed that the nitrate content of F1 hybrids of male sterile lines populations was near to that of male sterile lines . It suggested that male sterile line took a crucial effect on their F1 hybrids' nitrate content. Nitrate contents in ten hybrid cultivars were high and has the distinct difference among them. F2 populations separated greatly and the variation coefficient was 11.46%~44.23%; the range of nitrate content of intra-cultivars broadened accordingly, lower or higher nitrate content single lines which never occurred in their F1 populations having been detected. It showed good prospects to use hybrid cultivars in low nitrate content breeding. Nitrate contents in the root and leaf from one plant had been analyzed. The results indicated that the nitrate content of root was four to five times higher than that of the leaf from one plant, and a remarkable positive correlation existed between the leaf and the root. So the nitrate content in leaves could be used as one drogue to show that of the roots to help select low nitrate content radish.Nitrate reductase (NR) is a crucial enzyme in the process of nitrate metabolizing and can be induced by nitrate. Different nitrate concentrations and inducement time had been employed to determine nitrate reductase activity (NRA) in four varieties of radish. The results showed that NRA ascended with the increase of nitrate concentration (under 0-50 mmol/L KNO3), then descended after the peak value. Different varieties had different peak values due to different genotypes. Under 30 mmol/L concentration of KNO3,NRA appeared and then ascended under the conditions of(K 2, 4, 6, 8, 10, 12 h inducement, and the peak value emerged at 6-8 h. Differentvarieties had different peak values due to different genotypes.Correlation between the nitrate content and characteristics of photosynthesis of radish had been analyzed. The results showed that there were almost no correlation between nitrate and Photo., Cond., Trmmol. But the nitrate content had some negative correlation with Ci.