A bunch position effect on response to CCC in Cabernet Sauvignon grapevines

Abstract

CCC ((2-chloroethyl) trimethylammonium chloride) was applied to whole vines at the rates of 0, 300, 600, 1200, or 2400 p.p.m. three and two weeks before flowering and its effects on bunch and berry characteristics of both proximal and distal bunches observed. CCC increased berry number per bunch and bunch weight despite reduced berry weights. Rachis weights were generally decreased, although they increased with the 300 p.p.m. treatment. Fruit maturation, expressed as skin pigment concentration, juice soluble solids, and acidity were delayed. No differences occurred due to time of spray application. Unsprayed proximal bunches carried larger berries, which matured earlier than those on distal bunches. Despite the larger berries on untreated proximal bunches, the skins weighed no more than those on distal bunches and contained similar pigment concentration. Following CCC application, the proximal bunches set more berries, which were no larger than those on distal bunches, so that proximal were heavier than distal bunches (expressed in absolute terms or as a percentage increase). Treatment reduced the soluble solids of proximal but not distal bunches. It also tended to increase proximal rachis weight at concentrations of 300-1 200 p.p.m., but decreased it at 2400 p.p.m. It had no effect on distal bunch rachises when applied at 300 or 600 p.p.m., but decreased the weight at 1200 and 2400 p.p.m.