Dinâmica da dormência e conteúdo de carboidratos em pessegueiros em clima subtropical úmido

Abstract

The South region of Brazil grows temperate fruit species, especially peaches, apples, vines and plums trees with relative success. However, the production is strongly linked to the rest-breaking chemicals technique, once prohibit in importing countries receiving Brazilian fruits. There is a necessity to know better the dynamics of dormancy of these fruit trees, mainly the peach, for the development of new techniques and cultivars adapted to subtropical regions. The aim of this work was to evaluate and to comprehend the mechanisms of entry and interruption of dormancy of the fruit buds, as well as to evaluate the carbohydrates content in branches and buds of peach trees cultivars Santa Áurea e Tropic Beauty, which have intermediate and low cold necessity, respectively. In this regard, it were investigated the dormancy status evolution using the isolated nodes and Tabuenca tests, the tissues hydration, the alpha-amylase enzyme activity and the sugars concentration in several portions of productive branches collected from April to August. No endodormence period was observed on the buds of Tropic Beauty e Santa Áurea; also, no typical ecodormence period was observed, whereas the observed downtime is attributed to paradormence. The biologic tests (isolated nodes and Tabuenca tests) were efficient on the cultivars division due to their dormancy status. The distal portion of the branches has the higher or equivalent soluble sugars concentration (sucrose, hexoses) than the base, suggesting that they may be related to acrotomy, mainly in Santa Áurea. No real relation among carbohydrates content and dormancy, varying according to the changes in the ambient temperature.