极小种群野生植物波叶杜鹃的花部特征和繁育系统研究

Research on Floral Syndrome and Breeding Systems of Rhododen-dron hemsleyanum,a Plant Species with Extremely Small Populations

[目的]研究极小种群野生植物波叶杜鹃(Rhododendron hemsleyanum)的花部特征和繁育系统,为其作为乡土园林树种推广提供遗传育种理论基础。[方法]对四川峨眉山波叶杜鹃野生居群资源现状进行深入调查,研究其花部形态、花粉—胚珠比、杂交指数和昆虫访花行为等,并结合人工控制授粉试验对其繁育系统展开研究。[结果]5月中旬为波叶杜鹃的盛花期;其杂交指数为5,花粉—胚珠比为640.93±65.52;自然对照结实率为56.67%,异株异花传粉结实率为86.67%;主要访花者是中华蜜蜂(Apis cerana)和排蜂(A.dorsata)。[结论]波叶杜鹃的最佳授粉时期为盛花期(开花第3~6天),其繁育系统是倾向于异交的混合交配系统,自然条件下有效传粉者为中华蜜蜂和排蜂。

[Purpose]To study the floral syndrome and breeding system of Rhododendron hemsleyanum,a plant species with extremely small populations,and to provide a genetic breeding theoretical basis for the promotion of R.hemsleyanum as a native garden tree.[Methods]The status of the R.hemsleyanum wild population in Emei Mountain,Sichuan,were investigated,and its floral syndrome,pollen-ovule ratio, hybridization index and insects’ flower-visiting behavior were studied, as well as its breeding system in combination with artificial controlled pollination tests was researched. [Results]The blooming period of R. hemsleyanum was mid-May;the hybridization index was five, the pollen-ovule ratio was 640.93±65.52;the fruiting rate of the natural control was 56.67%, and the fruiting rate of heterogeneous pollination was 86.67%;the main flower visitors were Apis cerana and A. dorsata. [Conclusion]The best pollination period for R. hemsleyanum is at the peak of flower-ing (the 3rd-6th day of flowering), its breeding system is a mixed mating system that tends to be het-erozygous, and the effective pollinators are A. cerana and A. dorsata.