Photosynthesis of Submerged and Surface Leaves of the Dwarf Water Lily(Nymphoides aquatica)Using PAM Fluorometry  

作　　者：Tharawit Wuthirak Raymond J.Ritchie 

机构地区：[1]Department of Biology,Faculty of Science,Prince of Songkla University,Hat Yai,90112,Thailand [2]Tropical Plant Biology Unit,Faculty of Technology and Environment,Prince of Songkla University,Phuket,83120,Thailand

出　　处：《Journal of Botanical Research》2022年第3期25-43,共19页植物研究（英文）

摘　　要：Dwarf Water Lilies Nymphoides aquatica(J.F.Gmel)Kuntze have floating and submerged leaves.Some submerged aquatic vascular plants have a form of CAM(Crassulacean Acid Metabolism)called Submerged Aquatic Macrophyte(SAM)metabolism.Blue-diode based PAM technology was used to measure the Photosynthetic Oxygen Evolution Rate(POER:1O_(2)≡4e^(-)).Optimum Irradiance(E_(opt)),maximum POER(POER_(max))and quantum efficiency(α_(0))all vary on a diurnal cycle.The shape of the POER vs.E curves is different in seedling,submerged and surface leaves.Both E_(opt) and POER_(max) are very low in seedling leaves(E_(opt)≈104μmol photon m^(-2) s^(-1),PPFD;POER_(max)≈4.95µmol O_(2) g^(-1) Chl a s^(-1)),intermediate in mature submerged leaves(E_(opt)≈419µmol photon m^(-2) s^(-1) PPFD,POER_(max)≈38.1µmol O_(2) g^(-1) Chl a s^(-1))and very high in surface leaves(E_(opt)≈923µmol photon m^(-2) s^(-1) PPFD,POER_(max)≈76.1µmol O_(2) g^(-1) Chl a s^(-1)).Leaf titratable acid(C4 acid pool)is too small(≈20 to 50 mol H+m^(-3))to support substantial SAM metabolism.Gross daily photosynthesis of surface leaves is≈3.71 g C m^(-2) d^(-1) in full sun and as much as 1.4 gC m^(-2) d^(-1) in shaded submerged leaves.There is midday inhibition of photosynthesis.

关 键 词：CAM photosynthesis SAM photosynthesis Submerged aquatic macrophyte Carbon fixation Diurnal cycle Photosynthetic oxygen evolution rate(POER) Light curves PAM fluorometry Photosynthetic photon fluence rate(PPFD) Primary productivity 

分 类 号：R28[医药卫生—中药学]