PECTIN FLUCTUATION DURING NECTARINE FRUIT DEVELOPMENT

Cell wall is of paramount importance in determining the quality of the fruit, influencing as it does the texture of the pulp, some other components of the taste and the storage ability of the fruit. Similarly to what was done with other species (Jona et al., 1983), an investigation was performed to analyze the various cell wall components of nectarine and their change during the development of the fruit. As the main components of cell wall material are pectins only these have been plotted together with the total polysaccharides. The cultivar examined (which will later be compared with another) was 'Silver Lode!. From May 7th (i.e. about one month after flowering) the levels of both total polysaccharides and pectins increased at two periods: once in middle June and later after middle July with a sharp decrease in between in late June and early July. These periods of increase correspond to the two periods of rapid cell growth as was reported for grape berry (Jona et al., 1983) and with the double sigmoid curve of growth reported for peach. Ripening and storage, on the other hand, correspond to an increasingly rapid decrease of total polysaccharides and pectins in the cell wall. Since only insoluble pectins were measured it is possible that the decrease was caused by the solubilisation of the pectins in the pulp cell walls.