ISHS Acta Horticulturae 665: II International Symposium on Lychee, Longan, Rambutan and other Sapindaceae Plants
A PHASE APPROACH TOWARDS FLORAL FORMATION IN LYCHEE |
| Authors: | H.B. Huang, H.B. Chen |
| Keywords: | dormancy, millet stage, flushing, soil moisture stress, chilling temperature, shoot maturation, floral induction |
| Abstract:
This paper discusses the current knowledge on floral formation in lychee, clarifying some crucial issues and conceptual controversies. The sequence of floral formation in lychee exhibits obvious phase changes and different requirements. Cease growth brought on by moisture stress is the prerequisite for shoot maturation and the ensuing floral induction under chilling temperatures. The amount of chilling required for floral induction varies among cultivars. Chilling as a continuous spell is more effective than appearing in a scattered manner. Soil moisture stress cannot replace chilling over the induction process. The chill-induction effect cannot be reversed by soil moisture increase after the beginning of floral initiation during the late winter. Floral induction occurs when the apical meristem is quiescent whereas floral initiation starts from the ‘millet stage’ when cell division in the apical meristem becomes active. The newly introduced notion of ‘whitish millet’ symbolizes the “demarcation” separating floral induction and floral initiation. The slow growing buds in the leaf axils appearing as ‘whitish millets’ have acquired the potential for further differentiating and developing into flowering panicles under ascending air temperatures and moderate moisture. Exposing lychee plants to excessively high temperatures during panicle differentiation will cause the leaves on the panicles to develop and flowers to atrophy, especially when the induction phase has been suspended with insufficient exposure to chill-inductive temperatures. | |
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