Abstract
Further studies were conducted in 1971 and 1972 to reaffirm the effects of SADH and CCC on berry set and shoot growth of grapes when applied directly to clusters before anthesis.
In Kyoho grape, the direct application of SADH to clusters by dipping at 500ppm or by spraying at 2500ppm was as effective as the shoot spraying at 2500ppm for increasing set of seeded berries, but only the latter treatment had the inhibitory effect on shoot elongation during blooming and set stages.
The same trend was detected in Muscat of Alexandria grape to which CCC was applied at 200ppm by cluster dipping or shoot spraying. These results were completely in agreement with those obtained in our previous investigation. Shoot pinching before anthesis was also applied to the grapes as a comparative treatment, but it did not significantly increase the berry set. The leaf development was depressed only by the shoot spray treatment. Further, in no case the pollen germination was affected.
The mechanism of promoting set of grapes by the applications of growth retardants was discussed in relation to their effect on shoot growth.
