Evaluation of biennial bearing of apple genotypes with columnar tree growth habit
Columnar growth habit of apple cultivars is characterized by the central tree axis with short fruiting spurs. The columnar growth habit is controlled by the dominant allele of Co gene discovered in 'McIntosh Wijcik', a branching sport of cultivar 'McIntosh'. Hypothesis of the existence of genotypes with high annual crop were confirmed in this work. Biennial bearing occurred both in apple genotypes carrying the Co gene, and in genotypes originating from 'James Grieve Super Compact' characterized by extremely weak growth. The number of fruits harvested was approximately at the same level in genotypes carrying the Co gene for columnar tree growth habit and in genotypes with extremely low growth originating from 'James Grieve Super Compact' proving that biennial bearing is not connected with the Co gene. Regular annual bearing was recorded approximately at the rate of 5% both in group of genotypes of group A (10 crosses and 2 cultivars) carrying the Co gene and in genotypes of group B (2 crosses and 1 cultivar) originating from 'James Grieve Super Compact'.
Vávra, R., Blažek, J., Vejl, P. and Jonáš, M. 2017. Evaluation of biennial bearing of apple genotypes with columnar tree growth habit. Acta Hort. (ISHS) 1172:395-398
Co gene, regular annual bearing, tree architecture