Effect of Ethephon and Boa on Ethylene Evolution and Maturation of Tokay Grapes. I Vines Sprayed at Stage Ii.

Ethephon (2-chloroethylphosphonic acid at 500 ppm and auxin BOA (benzothia-zole-2-oxyaceticacid) at 50 ppm were applied as spray to Tokay grapevines at the start of stage II. Natural ethylene production was found low during stage II and declined as berries ripened. Both ethephon and BOA caused an increase in ethylene production but they had varying effect on ripening. Ethephon increased berry weight and improved the quality of fruits in terms of an increase in TSS/acid ratio and development of colour in berries without affecting the time of ripening while BOA retarded ripening as evidenced by a decrease in TSS/acid ratio and colour development.