The progression of endo and para dormancy in apple buds as affected by different climatic regions

In order to determine whether delayed foliation problems are related to the paradormancy component of dormancy, the endo and paradormancy components of dormancy were determined for Granny Smith and Royal Gala shoots from three climatic regions during the dormancy periods of 2011 and 2012.

The results showed that cultivars varied in their depths of dormancy and that the depth of dormancy of both cultivars increased with increased chilling. However, there were no differences between the general patterns of endo and paradormancy for each cultivar in relation to climatic region or year. It is therefore evident that climatic conditions do not influence the paradormancy component of dormancy independently of the endodormant component.

However it should be noted that in relative terms, Granny Smith shoots exhibited a high paradormancy in the lower sections of the shoot late in the season. This phenomenon could possibly play a part in the susceptibility of the Granny Smith cultivar to blind wood.