Physiological Characters Changes During Vernalization Or Bolting In Different Cultivars Of Chinese Cabbages

Premature bolting of Chinese cabbage is the most important factor that confines its production in spring. To provide a theoretically basic proof and identification index for breeding of late bolting or bolting-resistant cultivars, vernalization and bolting characters as well as the relation with biochemical and physiological index were studied in this research.1. Effects of vernalization on physiological Characters of Chinese cabbage: To compare and analyze physiological Characters between vernalized(2～4℃,15 d) and unvernalized Chinese cabbage seedlings, six different cylindrical and ovate Chinese cabbage cultivars were studied . As a result, the contents of soluble protein has no difference between cylindrical and ovate Chinese cabbage whether it is vernalized(2～4℃,15 d) or unvernalized; However, Soluble sugar contents and peroxidase (POD) activity of vernalized ones are obviously higher than that of unvernalized ones; catalase (CAT) and nitrate reductase (NR) activity in vernalized cylindrical Chinese cabbage cultivars is remarkably lower and higher than that of unvernalized ones respectively, at the same time, differences of the two enzymes in ovate Chinese cabbage cultivars are not very significant. In addition to CAT, physiological index of prematured-ones is varied greater than mid-maturity ones, and that of mid-maturity ones is varied greater late-maturity ones. Therefore, vernalization can cause changes on soluble sugar contents, POD,CAT and NR activity of Chinese cabbage cultivars especially of prematurity and mid-maturity ones.2. Correlative analysis of bolting tolerance and physiological index: By analyzing correlations of bolting tolerance and soluble protein contents, soluble sugar contents, POD activity, CAT activity, NR activity during bolting in nine cylindrical and ovate Chinese cabbage cultivars whose bolting tolerance character are remarkably different, the result shows that soluble protein contents, CAT activity, NR activity have a significant positive correlation with bolting tolerance, while soluble sugar contents, POD activity have a significant negative correlation with bolting tolerance. Therefore, soluble protein contents, soluble sugar contents, POD activity, CAT activity and NR activity can all be used as identification indexes for bolting tolerance.