ABSTRACT
Apple shows two distinct phases that characterizes its annual cycle: dormancy and vegetative/ reproductive growth. The importance of knowing the influence of climate conditions on tree reproductive processes and furthermore, developing technologies that minimize the future effects increases upon the global warming predictions becomes concerning. The goal of this study was to characterize the behavior of the main phenological events of apple, from bud break to harvest, on different fruiting habits under the subtropical climatic conditions of the South of Brazil. The experiments were carried out on nine year old ‘Gala’ and ‘Fuji’ apples in the Experimental Station of EPAGRI (Brazil - 26°50’S, 50°58’W, altitude 950m) during two different growing seasons, 2011/12 and 2013/14. Date and days after dormancy breaking treatment and heat requirements of the main phenological stages from bud break to harvest were evaluated. Evaluations were performed on each fruiting habit: spur buds, terminal and axillary buds on long shoots. Differences found on the onset of bud break and flowering among fruiting habits greatly depended on climate conditions of the particular year. High temperatures conditions after the dormancy breaking treatment induced to a phenological synchrony among fruiting habits, and vice versa. From dormancy breaking treatment, spur buds, especially ‘Gala’ buds, required less heat accumulation to bud break. Terminal buds of long shoots required higher amount of heat than spur buds to start flowering
Index terms
Malus domestica Borkh.; degree-days; bud break; flowering
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