濒危植物暖地杓兰的叶解剖结构和光合特性

Leaf Anatomical Structure and Photosynthetic Characteristics of the Endangered Plant Cypripedium subtropicum

关键词:  暖地杓兰  濒危植物  光合特性  叶解剖结构  光合色素

Key words:  Cypripedium subtropicum  endangered plant  photosynthetic characteristic  leaf anatomy  photosynthetic pigment

摘要:

暖地杓兰(Cypripedium subtropicum)是兰科(Orchidaceae)杓兰属(Cypripedium)目前已知的唯一一种多年生常绿草本植物，其野生资源遭受严重破坏，野外居群数量急剧减少，已被列为我国一级重点保护野生植物。为探讨暖地杓兰不同生长期叶片的解剖结构和光合生理特性的差异，本研究对其叶表皮特征、叶解剖结构、光合特性以及光合色素含量展开研究，以期为暖地杓兰的保育和引种驯化提供科学依据。结果表明：(1)暖地杓兰叶片上、下表皮的形状不规则，呈波状，并且气孔和表皮毛仅分布于下表皮；叶片结构由表皮、叶肉和叶脉组成，叶肉无栅栏组织和海绵组织的分化。结实植株的气孔面积、叶片厚度和叶主脉厚度均极显著大于幼苗。(2)暖地杓兰结实植株和幼苗的最大净光合速率(P_max)、光补偿点(LCP)、表观量子效率(AQY)均较低，且结实植株极显著大于幼苗，说明其具有阴生植物的特征。(3)暖地杓兰结实植株叶片的光合色素含量极显著大于幼苗。(4)暖地杓兰叶片的P_max、LSP、AQY、暗呼吸速率(R_d)与Chl(a+b)、叶主脉厚度呈极显著相关。暖地杓兰为典型的阴生植物，其光适应范围窄，对光能的利用能力低下，结实植株的光合能力强于幼苗，因此在引种驯化过程中需对其幼苗进行较高程度的遮阴。

Abstract:

Cypripedium subtropicum is the only known perennial evergreen herb in Cypripedium of Orchidaceae.Its wild resources have been severely damaged,and the number of wild populations has decreased dramatically.It has been listed as a first-class protected wild plant in China.In order to explore the differences in anatomical structure and photosynthetic physiological characteristics of leaves at different growth stages of C.subtropicum,the leaf epidermal characteristics,leaf anatomical structure,photosynthetic characteristics and photosynthetic pigment content were studied in this study.It was prospected to provide scientific basis for the conservation,introduction and domestication of C.subtropicum.The results showed that:(1) The shape of the upper and lower epidermis of C.subtropicum leaves was irregular and wavy,and the stomata and epidermal hairs were only distributed in the lower epidermis.The leaf structure was composed of epidermis,mesophyll and veins,and the mesophyll had no differentiation of palisade tissue and spongy tissue.The stomatal area,leaf thickness and leaf main vein thickness of fruiting plants were significantly larger than those of the seedlings.(2) The maximum net photosynthetic rate (P_max),Light Compensation Point (LCP) and Apparent Quantum Efficiency (AQY) of fruiting plants and seedlings were lower,and fruiting plants were significantly higher than the seedlings,indicating that it had the characteristics of shade plants.(3) The photosynthetic pigment content of leaves from fruiting plants was significantly higher than that of the seedlings.(4) The P_max,LSP,AQY,R_d of C.subtropicum leaves were significantly correlated with both Chl(a+b) and leaf main vein thickness.C.subtropicum is a typical shade plant.Its range of light adaptation and its ability to utilize light energy are relatively low.Furthermore,the photosynthetic capacity of fruiting plants is stronger than that of seedlings.Therefore,it is necessary to shade the seedlings to a higher degree during the introduction and domestication process.