杜鹃属的抗寒性

杜鹃属按其抗低温的能力可分为极抗寒、抗寒、不完全抗寒与敏感四个组,就杜鹃各器官与组织而言,抗低温能力依营养芽、叶和皮层最强,木质部与花原基最弱。杜鹃属在抗寒性上的明显差异与其地理分布密切相关,这一特点显示出抗寒性的自然选择与气候的变异方式相应发生。认为“冰洞”作用,“超冷”能力是抗寒杜鹃花芽和木质部薄壁细胞藉以回避冰冻的机制。

THE FREEZING RESISTANCE OF THE PLANT OF RHODODENDRON

Rhododendron species can be divided into 4 hardihess divisions: very hardy, hardy, semihardy, and tender, following its low-temperature resistance ability. In all the hardinessdivisions, the vegetative beds, leaves, and stem cortex are the hardiest, the flower bud and xylem are the least hardy. The peculiarity that the difference in freezing resistance of Rhododendron relates well with their geographic distribution suggests that the natural selection of freezing resistance may have occurred corresponding to the climatic variation pattern. It is considered that 'ice sink' function, 'supercooling' ability are physiological mechanism of freezing avoidance in Rhododordron flower bud and xylem.