The effects of shoot pinching before anthesis on shoot elongation, berry set and bunch growth of GA treated Delaware grape were examined in reference to the timing and intensity of pinching and also to the number of laterals elongating from the distal portion of pinched shoots.
Experiment I. Among the weak pinching(shoot tip removal) treatments applied at the 8th, 10th and 14th leaf stage, the treatment at the 8th leaf stage when the 8th leaf on shoot had unfolded resulted in the highest berry number per bunch.
However, the strong pinching leaving 8 leaves per shoot at the 14th leaf stage was as effective for berry set as the weak pinching at the 8th leaf stage. The pinched shoots having two laterals were larger in total leaf area per shoot than those having on lateral, but no difference was detected between them as to berry set and other bunch qualities.
Experment 2. Three intensities of shoot pinching were applied at the 11 th leaf stage on vines grown in a vinyl film house. Bunch weight, berry number per bunch and berry number per a unit bunch length(cm) were siginficantly larger in shoots pinched at the 6th or 8th node than in non-pinched controls. Difference in the number of laterals elongating from the pinched shoots had no effect on bunch qualities as same as in the former expenriment.