太白山5种杜鹃属植物叶片光合特性及解剖结构的生态适应性研究

对分布于太白山海拔2 000～3 700 m的5种杜鹃属植物的叶片光合特性和形态解剖结构进行了研究.结果显示:头花杜鹃分布于高山灌丛,光饱和点、光补偿点高,强光适应性好,耐荫性差;爬枇杷分布于3 000～3 400 m的太白红杉林下,光饱和点较低,光补偿点最高,利用强光能力较弱,生态幅较窄;金背杜鹃、药枇杷、秀雅杜鹃分布于2 000～3 200 m的红桦、牛皮桦林下,光补偿点低,耐荫性强,生态幅宽.在形态结构上,5种杜鹃的栅海组织比均远小于1,属耐荫植物.头花杜鹃叶表密被鳞片,栅栏组织发达,通气组织发达;爬枇杷栅栏组织发达,排列紧密;金背杜鹃叶下表皮密被毛,气孔密度最高,海绵组织排列疏松;秀雅杜鹃叶上下表皮密被鳞片;药枇杷的栅栏组织厚度最小,栅海组织比最低.研究表明,5种杜鹃属植物叶片结构特征的形成是对生境条件长期适应的结果.

Photosynthetic Characteristics and Anatomical Structure of Five Species of Rhododendron in the Taibai Mountain

We studied the photosynthetic characteristics and morphological and anatomical structure of five species of Rhododendron between 2 000 m and 3 700 m elevation in the Taibai Mountain.The results showed that:R.capitatum distributed in alpine shrub,has high light saturation point and light compensation point,high light adaptability and poor shade tolerance.R.taibaiense found in 3 000～3 400 m under Larix chinensis forest,has lower light saturation point and higher light compensation point,weak light adaptability and narrower ecological amplitude.R.clementinae subsp.aureodorsale,R.purdomii and R.concinnum distributed in the 2 000～3 200 m under Betula albo-sinensis and Betula utilis forest,was low light compensation point,strong shade-tolerant and wide ecological amplitude.In morphological structure,the ratio of palisade tissue and spongy tissue of five species of Rhododendron were much less than 1,they were shade-tolerant plant.Leaf epidermis of R.capitatum densely covered scales,with well-developed palisade tissue and aerenchyma;Palisade tissue of R.taibaiense arranged closely and developed well;lower leaf epidermis of R.clementinae subsp.aureodorsale was densely puberulous,with highest stoma density and loosely arranged spongy tissue;Lower leaf epidermis of R.concinnum densely covered scales;Palisade tissue of R.purdomii was as low as the ratio of palisade tissue and spongy tissue.The formation of these structures was the results of adaptation to habitat in long-term.