SYNTHETIC CYTOKININ - 1-(2-CHLORO-4-PYRIDYL)-3-PHENYLUREA (CPPU) - PROMOTES FRUIT-SET AND INDUCES PARTHENOCARPY IN WATERMELON

Applying a 200 ppm solution of CPPU to pollinated ovaries of watermelo n (Citrullus lanatus Matsum) at anthesis increased fruit set from 26.9 % (control) to 95%. Applying CPPU solutions to nonpollinated ovaries a t anthesis induced parthenocarpy, yielding 65% and 89.5% fruit set, re spectively with 20 and 200 ppm applications. However, 64% of the 20 pp m CPPU-treated parthenocarpic fruit stopped growth 10 days after treat ment. Growth of CPPU-treated, pollinated, and nonpollinated fruit incr eased significantly compared,vith growth of control fruit during the f irst 10 days after treatment, but, except for the 20 ppm CPPU partheno carpic fruit, growth subsequently slowed, resulting in fruit equal in size to the control by harvest. CPPU application did not affect solubl e solids content of pollinated fruit, but reduced content of parthenoc arpic fruit treated with 20 ppm. Fructose content was generally higher than glucose and sucrose at harvest. However, in pollinated fruit tre ated with 20 ppm CPPU, sucrose levels were higher than glucose and fru ctose. These results suggest that CPPU is practical for promoting frui t set and seedless fruit without adversely affecting fruit quality and development.