Effects of defoliation and fruit thinning on occurrence of watercore fruit in Japanese pear (Pyrus pyrifolia Nakai) 'Hosui'.

摘要

Defoliation significantly reduced the occurrence of water core. At harvest, the fruits were small, had a green ground colour, had lower specific gravity and concentration of soluble solids, and had firmer flesh than controls. Trees which were excessively thinned, leaving only 2, 4 or 8 fruits/m2 of canopy, had a higher incidence of water core. At harvest, fruits from these trees were larger than those of the controls (which had 12 fruits/m2 canopy), but they had lower specific gravity and a greenerground colour. Water core occurred especially around the stalk cavity and below the skin, similar to symptoms in fruits produced under abnormal climate conditions such as a cool summer. It is suggested that water core of Japanese pear cv. Hosui is related to source-sink ratios of the trees.