Study On The Morphological Development And Physiological Changes Of Floral Bud Differentiation In Radish (Raphanus Sativus L.)

Floral bud differentiation is the basis of flowering. In the present study, the morphological characteristics and the influence of vernalization on bolting and flowering of radish with various cultivars, and some physiological changes occurring during floral bud differentiation in radish were studied. The results are showed as followings:The result showed that sowing time had a distinct influence on the floral bud initiating, bolting and flowering and there were great difference among cultivars. There were differences in acclimatization to environment between four cultivars. These four cultivars can be attributed into three kinds based on the characteristics of their floral bud differentiation. 'Bai-Yu-Chun' and 'Zao-Chun-Da-Gen' could be classified to strong winter variety, 'Yi-Dian-Hong' was a winter variety, and 'Duan-Ye No. 13' was a spring variety. 'Yi-Dian-Hong' and 'Duan-Ye No. 13' were suitable to study the floral bud differentiation according to their characteristics.The result also demonstrated low temperature treatment could promote floral bud differentiation. It was found that the promoting effects were better at lower temperature and the longer treatment duration in floral bud differentiation. The condition of vernalization varied greatly with cultivars. Vernalization had an evident restraint in the plant growth. Based on the morphological characteristics of vegetative cone in stem apex, the process of floral bud differentiation could be divided into 5 stages.The contents of total sugar and reducing sugar in stem apex were increased during the former stages of floral bud differentiation, and then decreased. The content of reducing sugar was responsible for the increasing content of total sugar during the floral bud differentiation. The contents of sucrose and starch in stem apex were increased during floral bud differentiation. The contents of starch in stem apex and leaves show a similar tendency. The starch content of stem apex, which could be the indirect identification of some early flowering varieties, could be substituted with that of leaves.The level of soluble protein of stem apex was increased steadily during the whole development, while that of leaves was reversed. The soluble protein content of stem apex, which could be the indirect identification of some early flowering varieties, could be substituted with that of leaves. Some specific bands were detected44during the floral bud differentiation.Less esterase isozyme bands were detected during the various development stages and the difference between every development stage was not distinct. The esterase activities of stem apex were higher than that of leaves. The a -amylase isozyme bands were rather rich. The a -amylase isozyme bands during floral bud differentiation were more than those during reproductive stage, but the activities of a -amylase were no significant difference between these different development stages. The activities of a -amylase of stem apex were higher than those of leaves during the various development. The cytochrome oxidase isozyme (COD) bands were nearly the same as the peroxidase isozyme (POD) bands during floral bud differentiation. The activities of COD were declined and the COD band could not be examined in reproductive stage. The activities of POD were increased and the POD bands were enriched in reproductive stage. The POD band of A4 variety had a mostly band and three subordinate bands which could not be examined in A3 variety.