Effect of heading cuts on branch growth of ‘Encore’ mandarin

Pruning can be used for various purposes in citriculture: to control the size and shape of the trees; improve fruit size and quality; manage alternate bearing and control diseases and pests. However, the physiological response of the tree to heading cuts is not well documented. To supplement the lack of studies on the effect of pruning on branch growth, a trial was conducted on ‘Encore’ mandarin, in the Algarve region, the main citrus-growing area of Portugal. Twenty-five sets of two branches that had completed growth and had similar characteristics in terms of vigor and position on the tree were selected. In July, one branch was left unpruned (control) and the other was pruned to half its length (pruned). New shoot growth (position in the branch, number, length, and type) was recorded from July to December. While control branches grew in the summer months and stopped in September, pruned branches grew more gradually and stopped in November. Pruned branches had a higher percentage of new growth (52%), compared to the control branches (25%). The pruning treatment also had a higher percentage of branches with new shoots (36%), compared to the control treatment (16%). In both treatments, the number of new shoots in the bud was higher at the branch tip and decreased towards the branch base. However, the pruned branches had more new shoots per bud at the tip of the branch than the control branches. There were no significant differences in total length of new shoots between control branches and pruned branches.