Physiological and Chemical Changes Associated with Watercore Development Induced by GA in Japanese Pear 'Akibae' and 'Housui'

Abstract

We examined physiological- and chemical-characteristics of watercored fruits induced by gibberellin (GA) paste treatment in Japanese pear (Pyruspyrifolia Nakai) 'Akibae' and 'Housui'. 'Akibae' was more susceptible to the development of watercore induced by GA treatment during fruit maturation than was 'Housui'. 'Akibae' fruit accumulated sucrose during its fruit maturation, reaching a level two times higher at maturity than did 'Housui'. Analyses of watercore tissues in two cultivars showed marked drops of firmness and total lipid contents concomitant with increases in electrolyte leakage and sugar content in both cultivars. Ethanol insoluble solids (EIS) contents in watercore fruit consistently decreased with the extent of the disorder in 'Akibae' but they remained nearly constant in 'Housui'. The amount of water- and trans-1, 2-cyclohexanediamine-N, N, N', N'-ielra-acetic acid (CDTA)-soluble pectic polysaccharides increased as watercore extended in both cultivars. 'Akibae' had more hemicellulose and cellulose (FW basis) fractions than did 'Housui', their weights decreased continuously as the watercore zone expanded. Therefore, we conclude that the physiological and chemical changes, corresponding to watercore development, induced by GA treatment progressed faster in 'Akibae' than they did in 'Housui'.