Effect of thinning and of trunk girdling on growth, production and quality of Japanese plums

Abstract

In the production of plums (Prunus salicina Lindley) for in natura consumption the fruit size is a very important feature. Fruit thinning is traditionally used to increase fruit size. Girdling is a practice which is deserving renewed attention, since in many situations is useful to improve fruit size and to advance harvest. This study seeks to evaluate the effect of manual fruit thinning at intensities of 0, 25, 50, and 75% associated or not to trunk girdling (4 mm wide) on the growth, production and quality of plum cv. Amarelinha. The experiment was carried out at the Universidade Federal do Rio Grande do Sul Experimental Research Station (Southern Brazil), during the growth season of 1995-96 (August - June). Thinning was applied on October 16, 1995, 36 days after full bloom, and girdling seven days after thinning. Thinning decreased total fruit yield proportionally to the applied intensity. Trunk girdling anticipated harvesting, decreased fruit firmness, titratable acidity and increased the ratio total soluble solids: titratable acidity of fruits, but decreased the vigour and vegetative growth of the trees. None of treatments affected significantly the mean fruit weight.