The Effect Of CPPU On Growth Development And Endogenous Hormones In Cucumber

Cucumber(Cucumis sativus L.) in protected cultivation are mainly of parthenocarpy, and need artificial pollination or daubing growth regulator to set fruit. Artificial pollination is only on the bloom day, and difficult under bad weather condition. External application of growth regulator could change the level of endogenous hormones, meet the need of fruit setting, enhance the ability of allocation and transportation the nutrition in ovary in the process of fruit development, and replace artificial pollination partly or completely.CPPU【N-(2-chloro-4-pyridyl)-N'-phenylurea】belonging to phenyl urea cytokinin is a new and efficient plant growth regulator. Physiological activity of CPPU is higher than other Purine cytokinin, and the effect in the development of fruit, especially in promoting the fruit expanding is very obvious, better than other growth regulator found.In this study, we treated cucumber with 10 mg/L CPPU in bloom day, and separately sampled in 2,4,6,8,10,12 days. The nutrition transportation and the changes of endogenous hormones in cucumber samples were analysed, the results were as below:1. According to the analysis of fresh weight, the development can be divided into three periods:it grows slowly in 2-4 day, fast in 4-8 days, and slowly in 10-12 days, shows single-S style. This study showed that 10 mg/L CPPU could promote the increase of cucumber growth and enlargement, and heavy the weight of single fruit, shortened the growth cycle, and riped in advance to merchantable fruit. Vc2.10 mg/L CPPU could promote the content of soluble sugar, sucrose, and fructose, alleviate the descending of the content of sprotein, Vc, total nitrogen, total phosphorus and total potassium.Generally, it was beneficial to improving the quality treated by CPPU.3.10 mg/L CPPU could make the POD activity decline to promote setting fruit, and improve the content of the enzyme related to N reaction and the absorptive capacity. And at the same time the activity of SOD and POD were improved, especially in the metaphase and anaphase of growth.4. There was a negative effect of exogenous CPPU against the endogenous IAA in cucumber, the content of IAA was lower than the CK at the same time, but it made the peak of IAA advance two days. CPPU made the content of ZR lower than CK because there may be competitive inhibition to ZR. But CPPU could directly advance the content of GA3 in cucumber in every period. Exogenous CPPU improved the balance of ABA and IAA, which was more significantly in stimulating fruit enlargement and improving development.5. Through making paraffin section, we could see that CPPU could make the cells bigger in volume and less in number than CK in the same field.