Dormancy breaking of peach and plum trees in subtropical region

Abstract

Peach and plum trees originate from regions with a temperate climate, where low temperatures occur during the winter. They developed a mechanism denominated dormancy, as a strategy to overcome the period of low temperatures. Cultivation in mild winter regions is possible, thanks to the development of cultivars with less cold requirements. Even though, it is necessary to use chemical chemicals to artificially break dormancy, to start a new productive cycle. Thus, the objective of this work was to evaluate alternative products to hydrogenated cyanamide for breaking dormancy of peach and plum trees in subtropical regions. The experiments were carried out in a place located at 22º22‟S, 43º77‟W and 1,173 m above sea level, Cwa climate. In 'Kampai' peach trees and 'Reubennel' plum trees, the treatments were applied: 1) negative pattern only by water (control); positive standard composed of 2) hydrogenated cyanamide (CH) in the 1.5% dosage (commercial product Dormex®) plus 4.5% mineral oil; 3) Erger G® organomineral fertilizer plus calcium nitrate at a dosage of 3%; 4) potassium nitrate at a dose of 5%, and; 5) 0.3% copper sulfate. It is observed if the chemical products influence changes in the capacity of budding, flowering and reduction of the productive cycle, as well as in the production, in the quality of the fruits. It was concluded that, in peach trees, hydrogenated cyanamide and the organomineral fertilizer Erger G® promote anticipation of flowering and in the production cycle; hydrogenated cyanamide and copper sulphate stimulate increased flower opening and peach production. In the case of plum trees, the chemicals used only change in phenology. For both experiments, an application of copper sulfate may be an option to break the dormancy of peach and plum trees in the subtropical region.