水网藻附着对亚洲苦草光合特性的影响

Changes of photosynthetic characters of Vallisneria asiatica adhered by Hydrodictyon reticulatum

运用水下饱和脉冲荧光仪(Diving-PAM)测定附着了水网藻的亚洲苦草(Vallisneria asiatica)叶片的荧光参数和快速光响应曲线．在水网藻主要附着的苦草叶片上部,15 d后F_v/F_m显著下降,光系统(PS)的光化学效率显著降低;附着水网藻的叶片通过热的形式耗散掉的能量极显著增加(P＜0．01),有效荧光产量、光化学淬灭系数和相对光合电子传递速率(rETR)、Chl．a、类胡萝卜素(Car)、Chl．a/Chl．b和Car/Chl．a均显著降低;在快速光响应曲线中,当光照强度高于104μmol/ (m^2·s)后,随光照强度的增加,附着水网藻的苦草叶片的rETR显著低于对照,光合作用能力下降;且其饱和光强为248μmol/(m^2·s),显著低于对照叶片的685μmol/(m^2·s),表明水网藻附着苦草叶片后导致叶片光响应能力显著下降．

Chlorophyll fluorescence characters and rapid light curves （RLCs） of Vallisneria asiatica adhered by Hydrodictyon reticulatum were measured by a submersible, pulse-amplitude modulated fluorometer： Diving-PAM. Results indicated that on the top of the leaves, Fv/Fm decreased apparently after 15 days, and Photosystem photochemical efficiency was reduced remarkably. Dissipated heat of the leaves adhered by H. reticulatum increased in high significant level （P 〈 0. 01 ） after 15 days. The efficient quantum yield, photochemical quenching, relative Electron-transport rate （rETR）, chlorophyll a （abbreviation, Chl. a）, carotenoid （abbreviation, Car）, the ratio of Chl. a and Chl. b, the ratio of Car and Chl. a of these leaves decreased significantly. It was observed from RLCs that when photosynthetically active radiation excess 104μmol/（ m2· s）, rETR of V. asiatica leaves with H. reticulatum in irradiance were less notablely than that of the control, and photosynthetic ability of these leaves decreased, Meanwhile, the saturating irradiance （ 248μmol/（ m2 ·s ） ） of leaves in the experimental pool was significantly less than 685 μmol/（m2 · s）of the control. This indicated that after H. reticulatum adhered to V. asiatica, light responding capacity of V. asiatica＇s leaves decreased notablely in 15 days.