Pg. 9-15 Flowering and fruit retention of Mauritius litchi as affected by post-harvest pruning and pre-flowering treatments to stimulate bud-development

Trees were subjected to light (30 cm) and more severe (45 cm) post-harvest heading in early March, the withdrawal of irrigation in late March followed by its reinstatement in mid-July, potassium nitrate/kelp extract spraying in early July, or soil paclobutrazol application in late March. The effects, where applicable, on shoot maturation stage on May 5, extent of bud activity on July 15, course of bud-development on October 8, advancement of inflorescence development on October 8, and fruit retention on November 31, were assessed. Terminal shoot maturation stage on May 5 was less
advanced, active buds on July 15 were less prevalent, flowering intensity on October 8 was reduced, stage of inflorescence development on October 8 was less advanced, and number of fruit retained per inflorescence on November 31 was less, in the pruned as opposed to the un-pruned trees. In the un-pruned trees, the effects of the treatments on these aspects were either non-apparent or were unclear. A highly significant positive relationship was
found between the percentage of terminal buds developing on a tree on July 15 and tree flowering intensity. Buds on terminal shoots having matured by May 5 were more inclined to be active on July 15 than buds on terminal shoots that were immature or were developing on May 5. Inflorescences development occurred on both terminal shoots that had
matured by May 5, or were immature or developing on May 5. On November 31, the number of fruits retained per inflorescence strongly correlated with inflorescence stage of development on October 8, the more advanced inflorescences retaining more fruits. T he study strongly supports the contentions that the level of bud activity when conditions are most inductive during the winter months determines the intensity of flowering, that the terminal
shoots are required to be sufficiently mature during winter for the likelihood of good flowering to be maximized, and that the time of inflorescence development in spring, as influenced my shoot maturation stage when flowering commences, bears a strong bearing on the number of fruits retained by the inflorescences.

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