荔枝花芽分化研究进展

亚热带常绿果树荔枝(Litchi chinensis Sonn.)经济栽培区域局限于南、北半球17°—32°两个狭窄的纬度带内。在基于多品种的产业结构中,几乎所有荔枝品种均出现过成花障碍。文中从品种成花状况、花芽分化阶段性表现、影响花芽分化的因素、成花机理及成花调控等方面做了综合评述。认为:荔枝必须具备完全成熟的末端枝梢,在停长状态下接受为时相当长的冬季低温成花诱导,之后在冬末或初春气温回升和解除水分胁迫时发生花发端,在暖和而不酷热(表现为昼温高而夜温低)的天气下才能完成花穗与花的分化;花芽分化过程表现明显的阶段性和节奏性,任一阶段条件不满足均可导致花芽分化失败;影响荔枝花芽分化的外因主要包括末端枝梢状态、温度和水分;梢内碳水化合物积累、内源激素含量影响成花。为解决生产中成花不稳定问题,确保在极端和边缘天气条件下实现良好的花芽分化,应研究荔枝花芽分化中各因素作用的分子生理机制,并对嫩梢不能接受成花诱导、低温诱导信号的感受与传导及促进成花和花性分化的机制加强研究,探索针对荔枝花芽分化不同阶段的营养、水分、生长物质及物理调控措施。

Progresses in Research of Litchi Floral Differentiation

The commercial production of litchi (Litchi chinensis Sonn.), a subtropical evergreen fruit tree, has been restricted in the two narrow areas of 17o-32o latitude in the north and south hemispheres. Within the multiple cultivars-based industrial structures, unreliable flowering has taken place in almost all litchi cultivars. The flowering status of varieties, flower bud differentiation stage performance, influence factors, flower bud differentiation mechanism and flowering regulation are reviewed in this paper. It is considered that, litchi trees must have fully matured terminal shoots in autumn and be florally induced under chill conditions for a quite long period during the winter. Primordial inflorescence initiated upon the ascending temperatures and with release of water stresses during late winter or early spring, the inflorescence and flowers developed at mild conditions with warm days and cool nights. Any one unsatisfactory factor during the phase changes might cause failure of flower formation. The major factors influencing litchi floral development are state of terminal shoots, temperatures and water. Carbohydrate accumulation in shoots and the endogenous hormones affect flowering. In order to solve the instability problem in production of flowering and ensure good flowering under extreme and marginal conditions, the molecular mechanism about litchi floral differentiation and why young shoots and leaves could not be florally induced with chills, how the chill signals perceived and transduced, stimulate the floral transition of the terminal buds, when and how the flower sex is determined should be studied, and to explore nutrient, water management, growth regulators and other mechanical measures according to the phase changes of floral differentiation.