Abstract

Starch is the main form in which plants store carbohydrates reserves, both in terms of amounts and distribution among different plant species. Carbohydrates are direct products of photosynthesis activity, and it is well know that yield efficiency and production are directly correlated to the amount of carbohydrates synthesized and how these are distributed among vegetative and reproductive organs. The objective of this research work was to study the behavior of carbohydrate reserves, considering mainly starch, in fruits and leaves of ‘Abbé Fétel’ pear trees, at different physiological stages during two consecutive growing seasons (2012 and 2013), trained at Spindle system and grafted on two rootstocks, Sydo® and Quince C. Moreover, the starch degradation evolution in fruit was evaluated in order to correlate it with the main fruit quality parameters, soluble sugars and organic acids. Starch in fruit was accumulated at early stages, from 50 days after full bloom (DAFB), and reached a maximum concentration during the middle phase of fruit development, approximately at 110 DAFB, several weeks before harvest. As starch degradations begin, a steady increase of soluble carbohydrates occurs. As far as the rootstocks concern, no significant differences were reported for starch concentrations in the comparison between them; however, for soluble carbohydrates a slight effect was observed. Moreover, the starch degradation in fruits was highly related to fruit weight, soluble solids content, flesh firmness and IAD index. Regarding, the specific soluble sugars and organic acids, being glucose, fructose, sucrose and quinic acid were related to starch hydrolysis, during fruit maturation,