Application of growth regulators markedly affected fruit-set in grapes.
GA3 increased set in 'Concord' grapes, and SADH markedly increased set in 'Himrod'. GA3 effectively reduced set in Vitis vinifera grapes, and morphactins, CEPA, and ABA may prove useful for this purpose.
Size of seedless grapes was strikingly increased by both 4-CPA (4-chlorophenoxyacetic acid) or GA3. GA3 induced formation of seedless berries in 'Delaware', and eliminated berry shrivel in 'Emperor' and 'Calmeria'.