Response of Certain Varieties of Grapes to Plant Growth-Regulators

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Abstract
Dip applns. of 4-chlorophenoxyacetic acid, alpha-(1-naphthoxy) propionic acid, 2,3,5-triiodobenzoic acid, N-2-chlorophenylphthal-amic acid, N-1-naphthylphthalamic acid, and N-phenylphthalimide to flowering clusters of Black Corinth grapes resulted in some compact clusters with some large berries containing seeds. Clusters of Black Corinth were immersed in 4-chlorophenoxyacetic acid at full bloom or 4 days later. With the higher concns. of acid used, correspondingly heavier clusters developed. A higher % of berries of the first treatment contained seeds than did those of the later one; clusters given the later treatment were heavier. Black Corinth vines at full bloom were sprayed with 4-chlorophenoxyacetic acid at 25 ppm. Average wt. of fruit per vine for ungirdled but sprayed, girdled but unsprayed, and ungirdled and unsprayed was 17.3, 22.4, and 1.8 lb., respectively. Flowering clusters of White Corinth and Black Monukka grapes dipped in 4-chlorophenoxyacetic acid at 5 or 50 ppm. developed compact clusters. Similar applns. to Sultana, Thompson Seedless, Muscat of Alexandria, and Hunisia induced the setting of many "shot" berries. Thompson Seedless vines sprayed with 4-chlorophenoxyacetic acid at 5 or 20 ppm. after the shatter of berries developed larger berries than did the ungirdled, unsprayed vines.