June 2022

Abstract

The cultivation of apple tree is highly dependent on meteorological variables, especially temperature. The link between accumulation of degree-days (DD) and accumulation of chilling hours (CH) are determinant to field success, in the context of climate change. The objective of this study was to quantify the accumulation of DD necessary during the reproductive phenological stages for cultivar IAPAR 75 Eva, considering the accumulation of CH during the period of dormancy. The study was carried out at the Experimental Station from the Rural Development Institute of Paraná IAPAR-EMATER, in the municipality of Palmas, Paraná State, Brazil. The evaluations were from 2013 to 2019, showing for each three days, the phenological phases and the value of DD and CH. The results were submitted the simple and multiple correlation by the R® software. We verified the influence of the increase in temperature on the cycle acceleration, in addition, it was verified a tendency of less requirement for DD to advance the cultivar cycle. Were verified the value of chilling hours as 281, 156, 84, 326, 96, 76 and 11 hours of chill, respectively, and the consequent accumulation of DD to breaking dormancy was appointed as 1093 , 1156 , 1574 , 1157 , 1834 , 1096 and 1838 We concluded that CH causes impact in DD accumulation to development of apple tree. Higher temperatures accelerate the apple tree development. With the information of CH accumulation in dormancy, it is possible estimate the quantity of DD to develop the phenological phases. This information contributes to agricultural planning for cultivar Eva farmers.