外来入侵杂草薇甘菊及其伴生种基本光合特性的比较

COMPARISON OF BASIC PHOTOSYNTHETIC CHARACTERISTICS BETWEEN EXOTIC INVADER WEED MIKANLA MICRANTHA AND ITS COMPANION SPECIES

摘要:

以LCA4光合蒸腾测定系统测定了植物叶片的气体交换过程,比较分析了薇甘菊与周围其它藤本、草本和阔叶速生木本植物之间光合速率的差异.结果表明:(1)匍匐攀援草质藤本薇甘菊Mikaniamicrantha具有较高的CO₂固定能力,净光合速率21.56μmol CO₂m^-2S^-1,高于草质藤本野葛Puerarialobata(16.97),草质缠绕藤本五爪金龙Ipomoea cairica(14.55),与一年生鬼针草Bidens bipinnata(24.32)接近,但低于多年生粗壮草本五节芒Miscanthus floridulus(33.77)；(2)正午12:00后薇甘菊净光合速率和气孔导度出现一定程度的下降,降幅分别约为30%和47%,下降的起始时问滞后于林下灌木,光合作用光饱和点1 002 μmol m^-2s^-1,表明薇甘菊为喜阳植物；(3)当林内光强低至70 μmol m^-2s^-1时,薇甘菊仍然维持2 μmol CO2m^-2s^-1左右的净光合速率,且其光合作用的光量子效率(QUE)高于五节芒,光补偿点则相反,提示薇甘菊具有适应阴生环境的能力或特性。这些信息有助于解释薇甘菊生长迅速、高生物量和生产力及其在自然界中的分布形式,并可作为进一步研究调控其生长发育的部分依据。

Abstract:

Gas exchange in leaves of selected plants was measured by using LCA-4 portable photosynthesis and transpiration system (ADC, England). Analysis of the difference in net photosynthetic rate (Pn) between Mikania micrantha and its companion species was also made. Results were as follows : (1) Mikania micrantha, a herbaceous vine, had a strong capacity for CO2 fixation, the Pn being 21.56 μmol CO₂ m^-2S^-1, which was higher than that in the accompanying somewhat woody twiner Pueraria lobata (16.97) and climbing herb