摘要
浮游植物大量生长引起的遮光通常被认为是导致富营养湖泊中沉水植物的衰退的主要原因,但是藻类对沉水植物的竞争抑制作用还包括化感作用和无机碳竞争等重要方面,它们可能产生很大影响．为了验证这一观点,本文测定了除遮光以外浮游植物对沉水植物的抑制作用．在相似遮光下(10%-33%),对比研究了不同遮光方式(黑塑料网的物理遮光/浮游绿藻的生物遮光)对苦草(Vallisneria natans)生长和光合作用的影响．结果表明在遮阳网作用下苦草的生长指标(叶数、叶长、叶片叶绿素含量和生物量)和净光合速率都显著高于浮游绿藻作用下苦草,且后一种处理下苦草叶片上端有腐烂现象．由此可见,浮游绿藻对沉水植物生长除了通过遮光抑制生长外,还有较遮光更加严重的抑制作用．这可能是由于浮游绿藻通过化感作用和对可利用光合有效辐射光能和溶解无机碳的竞争优势抑制了苦草的光合作用．
Shading of phytoplankton on submersed macrophytes in eutrophic waters is considered to be one of the main causes for the decline of the macrophytes. However, growth inhibition of submersed macrophyte by phytoplankton may be also due to other important factors including alleloph and DIC competition of phytoplanktion. In order to study whether or not shading is the major effect of phytoplankton inhibiting submerged macrophytes, a laboratory experiment was carried out with a submersed macrophyte VaUisneria natans grown in dense phytoplankton water. Similar shade levels were created either by dark fabric screens or by phytoplankton dominated by chlorophyta （irradiation in the water was 10% -33% that in the air）. Growth indices of both number and length of leaves, and biomass of V. natans were measured during the experiment. Chlorophyll a ＋ b concentration and net photosynthesis rate in leaves were also monitored. Growth and photosynthesis of V. natans under the shade screens were significantly higher than the plants grown with the chlorophyta, even the leave tips of the plant were found decay in later treatment. The results indicated that chlorophyta suppressed the growth of V. natans in ways other than shading. Allelopathic inhibition of chlorophyta on the net photosynthesis rate of V. natans, competitive advantages for photosynthetic active radiation （PAR） and dissolved inorganic carbon （DIC） of chlorophyta over V. natans were suggested .
出处
《湖泊科学》
EI
CAS
CSCD
北大核心
2007年第2期111-117,共7页
Journal of Lake Sciences
基金
国家重点基础研究发展规划"973"项目(2002CB412300)
国家自然科学基金项目(30570280)联合资助
