Increasing the Size of Thompson Seedless Grapes by Means of 4-Chlorophenoxyacetic Acid, Berry Thinning and Girdling

Abstract

Girdling has been practiced for years to produce large berries of Thompson Seedless grapes intended for table use. The operation, however, is expensive and occasionally results in the death of the girdled cane. In an effort to discover a better means of attaining results similar to girdling, applications of 4-chlorophenoxyacetic acid have been made (4, 5). These tests embraced separate and combined treatments of applications of 4-chlorophenoxyacetic acid, berry thinning (a practice usually employed to overcome compactness of cluster, 6), girdling, and girdling and berry thinning.Use was made of an irrigated vineyard located about one mile west of Davis, California. Mature vines of Thompson Seedless were pruned to four or five canes each of which had 9 to 12 buds. Each cane was tied horizontally on one wire of a 3-wire, flat-top trellis. Immediately after fruit set, the crop was reduced to five clusters per cane in tests made in 1950, and six in tests made in 1951.In 1950 an oil emulsion of 4-chlorophenoxyacetic acid was prepared, by dissolving 1 gm. of the compound in 5 ml. of an oil-base carrier (4), and then diluting to 1000 ml. with distilled water. This stock emulsion was diluted with water to make the desired concentrations. Aqueous solutions of 4-chlorophenoxyacetic acid were prepared in 1951 by adding sufficient ammonia to dissolve the compound. Dreft was used each year as a wetting agent.Clusters of berries were immersed momentarily into one of the formulations; clusters on one cane constituted a unit in these dipping experiments. Replicate canes were selected at random among the vines used. Berry thinning consisted of cutting off the apical half of the cluster, leaving five or six mnain branches of the rachis. Girdling consisted of removing a strip of bark three sixteenths of an inch in width near the base of canes with girdling pliers. For the spray applications of the growth regulator, each vine was divided into equal parts; one half was sprayed with a Craftsman sprayer, and the other half served as the untreated control. Cardboards were used to confine the spray to the intended area.At harvest, berries removed from the same parts of the clusters were thoroughly mixed and the weight of 100 or 200 was obtained in duplicate to indicate the size of the berry. . The remaining berries were crushed, and the percentage of total soluble solids in the juice was determined with a Balling hydrometer. Total acidity was determined by diluting 10 ml. of the juice

Response of “Red Globe” (Vitis vinifera L.) to cane girdling

“…Total titratable acidity percentage (TA%) was measured by titrating the berry juice with 0.1 N NaOH. The TA% was expressed as grams of tartaric acid per 100 ml of juice [18]. The experimental design was randomized parcels with three replicates.…”

A comparison of soil quality and yield parameters under organic and conventional vineyard systems in Mediterranean conditions (West Turkey)

“…Titratable acidity (g l 21 ) was assigned by diluting 10 ml of the juice with 10-ml distilled water and titrating it with 0.1 N NaOH, using phenolphthalein as an indicator. The results were expressed as grams of tartaric acid per 1000 ml (Weaver & Winkler 1952).…”

Effect of gibberellin on seedlessVitis vinifera

“…The procedure for measuring the amount of pull required to remove a pedicel from its berry has been previously described (Weaver and Winkler, 1952).…”

“…(Photographed September 2, 1958. ) ter at harvest (Weaver and Winkler, 1952). The present experiment sought additional information.…”