Effects of GA and CCC on setting, splitting, yield and quality of Zante currant (<i>Vitis vinifera</i> var.)

Abstract

Ten-year-old Zante currant vines (Vitis vinifera var.) were sprayed in two seasons with GA at 1 ppm+ CCC at 100 ppm or GA at 1 ppm+ PCPA at 20 ppm as soon as capfall was complete. The average number of flowers per bunch for a random selection of primary bunches was 568 in 1967 and 574 in 1968. Natural setting without treatment on these bunches was 66 per cent in 1967 and 44 per cent in 1968.
Berry deve1opment is the main problem in the production of Zante currant. Susceptibility to splitting was associated in this trial with amount of rain that fell during the 3 weeks prior to harvest and with berry size. Ten mm of rain caused 52 per cent splitting on untreated vines in one season while 2 mm of rain caused 9 per cent splitting in the other. Treatments with GA+ CCC or GA+ PCPA, although both improving berry setting, differ in their effects on the final quality and dried yield of these berries. GA+ CCC produced acceptably sized berries with high sugar content, and of advanced maturity and colour, with less tendency to split, and high dried yield, while GA+ PCPA produced excessively large sized berries with low sugar content and retarded maturity and colour, which split more readily, resulting in 22 per cent dried yield reduction over two years.