Page 118 - 广西植物2024年1期
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1 1 4                                  广  西  植  物                                         44 卷
              ( 1. College of Tourism and Landscape Architectureꎬ Guilin University of Technologyꎬ Guilin 541006ꎬ Guangxiꎬ Chinaꎻ 2. Guangxi Institute of
                   Botanyꎬ Guangxi Zhuang Autonomous Region and Chinese Academy of Sciencesꎬ Guilin 541006ꎬ Guangxiꎬ Chinaꎻ 3. College of
                         Pharmacyꎬ Guilin Medical Universityꎬ Guilin 541004ꎬ Guangxiꎬ Chinaꎻ 4. Guangxi Yachang Orchid National
                                      Nature Reserve Management Centerꎬ Baise 533209ꎬ Guangxiꎬ China )

                 Abstract: To explore leaf anatomical structures and photosynthetic characteristics of Geodorum plantꎬ the anatomical
                 structure of leavesꎬ daily variation of photosynthesisꎬ light response curveꎬ CO response curveꎬ chlorophyll content and
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                 other indexes of the narrowly endangered Geodorum eulophioides and widely spread G. densiflorum and G. attenuatum
                 were measured. The results were as follows: (1) Three species of Geodorum did not have spongy and fenestrated tissue
                 differentiation in their chloroplastsꎬ and stomata were distributed only in the lower epidermis. Compared with G.
                 densiflorum and G. eulophioidesꎬ G. attenuatum had a greater leaf thickness and smaller stomatal densityꎬ exhibiting
                 structural characteristics that were more adaptable to low light environments. (2) The daily changes of net photosynthetic
                 rate (P ) of three species of Geodorum showed a “bimodal” curveꎬ and the photosynthetic “lunch break” was mainly
                      n
                 caused by non ̄stomatal limitation. The daily mean values of P and water use efficiency ( WUE) showed that G.
                                                                 n
                 attenuatum > G. densiflorum > G. eulophioidesꎬ which indicated that G. eulophioides had a weaker ability of accumulating
                 photosynthesis productsꎬ and its adaptive capacity to the arid environment was probably poorer. (3) Three species of
                 Geodorum were all shade plants. G. densiflorum had the smallest light compensation point (LCP) and the largest light
                 saturation point (LSP)ꎬ and had a wider range of adaptation to light intensityꎻ G. attenuatum had a high maximum net
                 photosynthetic rate (P  ) and apparent quantum efficiency ( AQY)ꎬ and its photosynthetic capacity was strongerꎻ
                                 max
                 G. eulophioides had the smallest P  and the potential maximum net photosynthetic rate (A  )ꎬ and its photosynthetic
                                          max                                       max
                 capacity and CO utilization capacity were weaker. (4) The chlorophyll a (Chl a)ꎬ chlorophyll b (Chl b) and total
                             2
                 chlorophyll (Chl) contents of G. densiflorum and G. attenuatum were significantly ( P < 0.05) higher than those of
                 G. eulophioide. (5) There were significant (P<0.05) correlations between the leaf thicknessꎬ mesophyll thicknessꎬ
                 chlorophyll contentꎬ and P  of three species of Geodorum. It was concluded that the photosynthetic capacity and
                                     max
                 adaptability of G. eulophioides were poorer compared with G. densiflorum and G. attenuatumꎬ which might be greatly
                 related to its endangermentꎻ appropriate shading and increased CO concentration favored photosynthesis in three species
                                                                 2
                 of Geodorum. The results of this study provide a reference for the analysis of the endangered causes of G. eulophioides and
                 the conservation of germplasm resources of three Geodorum species.
                 Key words: Geodorumꎬ stomatal characteristicsꎬ daily variation of photosynthesisꎬ light response curveꎬ CO response
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                 curveꎬ chlorophyll



                光合作用是大部分植物进行物质积累的基                             物的内在濒危机制ꎮ 濒危植物与近缘非濒危植物
            础ꎬ也是植物生长的重要生理过程ꎬ其特征可预先                             相比ꎬ具有较低的光合速率、水分利用率和生物量
            确定和解释植物所需的重要生态需求( Adamecꎬ                          积累( Ge et al.ꎬ2003)ꎮ Wei 等(2018) 研究表明ꎬ
            1997)ꎮ 植物在生长过程中的竞争力和适应力等                           不管是 野 外 种 群 还 是 栽 培 种 群ꎬ 濒 危 种 金 花 茶
            综合生存能力和环境因子间的相互作用可揭示其                              (Camellia nitidissima)的光合、呼吸、蒸腾等生理代
            内在规律(Zhang et al.ꎬ1999)ꎬ光合能力的强弱能                   谢速率均低于同属广布种茶树( C. sinensis)ꎬ并且
            很大程度上反映植物在种群中的竞争地位和适应                              金花茶喜欢潮湿、遮阴的环境ꎬ不喜欢强烈的阳光
            能力ꎮ 研究濒危植物的光合作用及其影响因素ꎬ                             直射ꎬ而茶树在半阴和强光的地方都能很好地生
            是正确评估最优栖息地条件的重要方法( Smith et                        长ꎮ 裂 叶 沙 参 ( Adenophora lobophylla) 的 光 合 速
            al.ꎬ1993)ꎬ能够判断其生长所需的最适宜光照、水                        率、呼吸速率、蒸腾速率及水分利用率等均低于广
            分等 环 境 条 件ꎬ 选 择 最 优 的 栽 培 地 ( Smith &              布近缘种泡沙参( A. potaninii) ( 祖元刚等ꎬ1999)ꎮ
            Houpisꎬ2004)ꎮ 将濒危植物和广布近缘种作为对                       另外ꎬ有研究表明ꎬ植物的叶片解剖结构受长期自
            照进行光合特性比较研究ꎬ能更好地揭示濒危植                              然环境的影响ꎬ叶片中的表皮细胞厚度、栅栏组织
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