洱海沉水植物的光合特性与分布水深的关系

THE MEASUREMENT OF PHOTOSYNTHETIC PARAMENTERS OF SUBMERSED MACROPHYTES WITH AIMS TO EXPLORE THE PLANT DISTRIBUTION DEPTH IN ERHAI LAKE

为研究沉水植物光合特性与其分布水深的关系,选取黑藻(Hydrilla verticillata)、苦草(Vallisneria natans)、水蕴草(Egeria densa)、大茨藻(Najas marina)、微齿眼子菜(Potamogeton maackianus)、光叶眼子菜(Potamogeton lucens)和穿叶眼子菜(Potamogeton perfoliatus)等15种洱海常见沉水植物,测定其光合作用参数。结果表明:光合速率为2.8—18.1μmol O_(2)/(g DW·h)、暗呼吸速率为0.3—2.0μmol O_(2)/(g DW·h)、光补偿点为6.3—63.8μE/(m^(2)·s)、光饱和点为55.6—441.5μE/(m^(2)·s),不同沉水植物间光合作用参数存在显著差异。结合洱海全湖沉水植物分布水深调查结果,沉水植物的光补偿点和光饱和点与分布水深呈显著负相关;苦草与其他物种比较具有更低的光补偿点6.3μE/(m^(2)·s)、光饱和点55.6μE/(m^(2)·s),更适宜在深水或弱光条件下生长,可作为沉水植被修复的先锋物种。

Photosynthesis is vital physiological process producing carbohydrate for the growth and distribution of submersed macrophytes,and thus may closely relate to the plant distribution depth.To clarify the differences of photosynthetic parameters and their relevance to the colonization depths of submersed macrophytes,we measured the light compensation and saturation points,photosynthetic rate and dark respiration of 15 submerged macrophytes,using a liquidphase oxygen electrode,and investigated the plants distribution depth in Erhai Lake,China.The results showed that the photosynthetic rate ranged from 2.8 to 18.1μmol O_(2)/(g DW·h),the dark respiration rate ranged from 0.3 to 2.0μmol O_(2)/(g DW·h),the light compensation point ranged from 6.3 to18.1μE/(m^(2)·s),the light saturation point ranged from 55.6 to 441.5μE/(m^(2)·s).The plants had significant differences in the photosynthetic parameters.Based on a field survey of the plant distribution depth,the light compensation and saturation points of the submerged macrophytes were negatively correlated with their distribution depths.V.natans had the lowest light compensation and saturation points,and were more suitable to grow in deeper water where the experienced low light stress,and thus V.natans could be taken as a pioneer species for the restoration of submerged macrophytes in eutrophic lakes.