Study On The Bolting Tolerance In Chinese Cabbage And Its Identification

In order to solve the problem of premature bolting that exists in spring Chinese cabbage production. The certified method of bolting tolerance in Chinese cabbage was studied.Six Chinese cabbage cultivars were studied for the effect of temperature and photoperiod on flower bud differentiation and bolting and the changes of the soluble protein contents and peroxidases activity during flower bud differentiation. The relation between their morphology indexes and bolting tolerance were analyzed with these cultivars.The main results as shows as follows:The Chinese cabbage went to sex development earlier and fast after seed vernalized under the treatment of 3~9℃. At 11℃, Chinese cabbage can be vernalized, but relatively longer time of vernalization is needed.There is an inheritant difference of flower initiation and bolting among Chinese cabbage varieties which bolting dates are different. After treated with vernalization 17 days, plant can not bolting at 3~9℃, when plants are vernalized at 11 ℃ for 30 days, late bolting cultivar can not bolting. The late bolting Chinese cabbage presents the character of late differentiation of bud and the slowest development.With the index of flower bud differentation at 7℃ for 20 days was easy to tell the different bolting tolerance of cabbages clearly. Therefore keeping seed at 7℃ for 20 days was opeimum for testing the bolting tolerance of Chinese cabbage.The correlation analyses among the data of fiowere bud differentiation critical days, flowral initiation days, bolting days, flowering days, stem length flower bud differentiation index and bolting tolerance showed that the six morphyology indexes had a significant correlation with bolting tolerance. Therefore they all could be used as a identificated and evaluated methods for bolting tolerance.Flower bud differentiation index and stem length could identificate varieties bolting tolerant degree accurately and quickly than other.The soluble protein contents in Chinese cabbage seedling with vernalization treatment for 20 days were suggested to be physiology index for the evalation of bolting tolerance. The soluble protein contents of high bolting-tolerant genotype was lower than those of poor bolting-tolerant genotype.The developing process of the flower bud differentiation of Chinese cabbage is divided into six stages, no differentitation phase, prepared differentiation phase, flower bud initiation, sepal differentiation phase, stamen differentiation phase and pistil differentiation phase, petal differentiation phase.The top flower of the inflorescence differentiated earlier than lateral flower.