Studies On Genotypical Difference Of Nitrate Content And The Physiological Mechanism In Pak-Choi

Vegetables, not served as main course, are indispensable in our daily life. It not only provides a variety of vitamin, minerals and cellulose, but also is rich in nitrate, potentially hazardous to human health. Economical nitrogenous fertilizer utilization, vegetable ecology improvement, optimizing harvest season, storage and processing before cooking are all adopted to decrease the percentage of nitrate in vegetables. Because of the increasing tendency of nitrogenous fertilizer utilization, nitrate hazard, especially in leaf-vegetables is still deteriorating.The selection of vegetables that have low density of nitrate could become possible after Cantliffe (1972) claimed that remarkable differences of nitrate possession had been found among vegetables. After choosing pak-choi as research object, research objectives had been defined as following: figuring out the differences of nitrate in different genotype, physiologically and hereditarily discussing the mechanism brought by genotypic mechanism, providing theoretical and technical instructions to reduce vegetable nitrate contamination.Research results:After comparison of 32 kinds of pak-choi in three seasons, research results are: significant difference of nitrate possession have been found in various pak-choi, the difference between maximum and minimum is 2500mg?kg^-1FM. Obvious difference has not been found in three seasons, which indicates that contents of nitrate in pak-choi is hereditable. ABCD were discovered as the pak-choi that have the least percentage of nitrate. The percentage of nitrite in these four categories keeps stable no matter season changes or not. Therefore, they could be brought to market as low nitrite possession pak-choi straightaway. Another thing found in the research was that although the rank of nitrite possession in different pak-choi does not change during research, the very content of nitrite does fluctuate in the period of research. Normally, the percentage of nitrate in pak-choi is mg?kg^-1FM higher in first two quarters than the rest time a year. Thus, nitrate content of pak-choi is not only hereditable, but also influenced by environment. Accordingly, in order...