Physiological Effects of CCC on the Growth of Grapevine

Abstract

Physiological effects of CCC on the growth of grapevine inflorescence differentiation, cytokinin activity in the xylem sap, and photosynthetic and respiratory activities of grape leaves were investigated by the application of CCC as a soil drench.
1. Shoot elongation and dry weight of shoot were not affected by CCC treatment. However, CCC caused an increase in dry weight of roots without changing any external features of the roots.
2. The top/root ratio of CCC-treated plants was reduced to about one-half that of the control plants. The volume of xylem sap of CCC-treated plants exceeded about two times that of controls.
After separation of xylem sap by Sephadex LH-20 column chromatography, at least five cytokinin-like substances including zeatin and zeatin riboside were present in the sap of control plants. The main peak of cytokinin-like activity (Compound 1) in the sap was depressed by CCC treatment, whereas the sixth cytokinin-like substance (Compound 5) appeared in the chromatograms of the sap examined.
3. Number of inflorescence differentiation in the lateral bud of CCC-treated plants was larger than that of controls. The number of inflorescence differentiation of lateral buds from the 3rd to the 5th node of the shoot was larger than that of the 8th to the 10th node of the shoot.
4. Chlorophyll content of the leaves of CCC-treated plants was higher than that of controls, especially in young leaves. Photosynthetic activity of mature grape leaves was stimulated by CCC treatment, though dark respiration was not affected by the treatment. Photorespiration rate (PIB-1) and PR/DR ratio of mature leaves were increased by CCC treatment.