Effects of Fruit Thinning on the Development and Sugar Accumulation by the Fig Syconia on Different Nodal Positions

Abstract

Effects of fruit thinning on characteristics and sugar accumulation by the 'Masui Dauphine', Common fig (Ficus carica L. var. hortensis Shinn), syconia on different nodal positions were investigated. Fruits from the 1st to the 7th nodes on all shoots were thinned when they were 4mm in diameter ; fruit development and characters of the second crop on the 8th and 13th nodes were compared with those on an unthinned tree. 1. On thinned and unthinned trees, the fruit development period from budbreak to harvest of the second crop on the 8th and 13th nodes was 73∿74 days. Fruit thinning had little or no effect on the final weight and diameter of fruits on the 8th node, whereas the fruits on the 13th node were larger and heavier. 2. On the unthinned trees, the diameter and weight of the fruits on the 3rd node were significantly larger than those on the 8th and 13th nodes at harvest. Peel coloring and Brix values of fruitlets and receptacles of fruits on the 3rd node were higher than those on the 8th and 13th nodes. No difference in firmness of fruits located on different nodal positions was detected. 3. Diameter and weight of the fruits on the 13th node on thinned trees were larger than those on unthinned trees at harvest ; the weight of receptacular tissue was markedly heavier than those of fruitlets. The thinning treatment fostered better peel color of fruits on the 8th node but not those on the 13th node ; it had no effect on fruit firmness. 4. On the thinned trees, the fruitlets and receptacles of the fruits on the 8th and 13th nodes had higher glucose and fructose contents than had comparable organs on unthinned trees ; the total sugar contents, on fruit weight basis, consequently, were also higher. Fruit thinning treatment accelerated growth (weight) as well as sugar accumulation by the receptacles of fruits on the 13th node.