Effects of girdling and covering mesh on ripening, colour and fruit characteristics of 'Italia' grapes

The effect of single and double girdling, and covering by mesh on the ripening, colour and fruit characteristics of 'Italia' grapes was examined. Three types of girdling were studied: girdling after fruit set, girdling at the beginning of ripening (veraison) and double girdling (girdling at fruit set + girdling at veraison). Girdling after fruit set significantly increased both berry weight and yield. Girdling at the beginning of ripening significantly increased soluble solids, the maturity index and berry colour, decreased titratable acidity and advanced fruit ripening by 5 d. Double girdling significantly increased berry weight and yield and produced the best results as regards soluble solids, maturity index, berry colour and earliness. Covering the vine with mesh delayed ripening by 9 d, decreased soluble solids, the maturity index and berry colour, although the yield was higher than that of the control because bunches were bigger and had more berries. Analysis of covariance showed that the delay in fruit ripening caused by mesh was not only due to an increase in yield but to other unmeasured factors probably associated with changes in microclimate.