Effect of chlormequat chloride (CCC) on the growth of new shoots of one-year-two-harvest Kyoho grapevine.

[Objective]The experiment was conducted to study the effect of chlormequat chloride (CCC) on the growth of new shoots of Kyoho grapevine in order to provide technical guidance for one-year-two-harvest cultivation of Kyoho grapevine. [Method]The 6-year-old Kyoho grapevine which is used to cultivate two crops per year with pergola, was used to observe the effects of CCC (300 times dilution) spraying (once and twice), and water was used as the control. The length of strong new shoots, number of node in new shoots (above 2 cm), diameter of 6 t h node and length of 6 t h, 8 t h and 10 t h internodes were investigated. [Result]Spray of CCC significantly inhibited the growth rate of new shoots at 3 r d week after treatment. The inhibitory effects of CCC spray on growth rate were more pronounced at 4 t h week after treatment, compared to control. Spray of CCC significantly inhibited the increase in number of nodes in new shoots, while diameter of 6 t h node of new shoots was not affected significantly. The length of 6 t h and 8 t h internode was little affected in CCC treated plants. However, the length of 10 t h internode was significantly inhibited after 2 weeks of CCC treatment. [Conclusion]Spray of CCC showed significant inhibitory effects on the growth of strong new shoots of Kyoho grapevine, especially the growing point of new shoots. It may be concluded from the results that CCC could control the vegetative growth of fast growing Kyoho grapevine and reduce the labor cost. It is an effective measure to obtain high quality and yield of Kyoho grapevine harvested two times a year. It may be recommended for commercial production of Kyoho grapevine.