Effect of heading and its timing on flowering and vegetative shoot development in Clementine mandarin (Citrus reticulateBlanco)

SummaryYoung, unbranched, resting stems (bearers) produced during the previous autumn or summer growth flush were headed to below the intercalation between these and their subtending intercalary units at different times from floral induction to after budbreak. This was done on Clementine mandarin trees to investigate the effects on flowering of removing apical control from bearers. Treatments imposed before bud sprouting did not affect yield, fruit size distribution or fruit internal quality. Heading significantly increased sprouting, new shoot production, production of vegetative shoots and the inflorescence leaf:flower ratio, but not the proportion of axillary sites producing reproductive shoots. The time of heading affected the response; the earlier apical control was removed by heading the greater the response differed from the control. Heading during winter may be used to rejuvenate trees or to increase their complexity and inflorescence leafiness, without affecting the proportion of sprouting axillary sites producing inflorescences.