水体泥沙对黑藻幼苗生长发育的影响

用粒径小于100μm的泥沙分别配置浊度为30、60NTU和90NTU的浑浊水体,将黑藻(Hydrilla verticillata)幼苗分别种植于上述水体中,水深约60cm,定期统计植株的节间距、株高、分枝数、叶宽、叶长、鲜重和泥沙附着量,利用水下饱和脉冲荧光仪(DIVING-PAM)测定叶片的Fv/Fm,并测定附着泥沙叶片和未附着叶片快速光响应曲线。结果表明,前40d随着水体浊度的增加黑藻植株的节间距、株高呈显著的增加趋势,而分枝数和生物量增长速率呈显著降低趋势。植株生长接近水面后接受的光照强度增加,第60天时株高和叶宽增长受到显著抑制,但植株上层的分枝受到促进,生物量显著增加。同时,随着水体浊度的增加植株上的泥沙附着显著增加,第100天时在30、60NTU和90NTU水体中植株的叶宽分别比对照宽71.4%、57.1%、48.6%,叶长分别为对照的113.0%、85.5%和75.1%,差异极显著(P0.01);在高浊度(60NTU和90NTU)水体中,水体下部生物量显著降低,冠层叶片的Fv/Fm分别仅降低了5.5%(P0.05)、2.9%(P0.05),rETRmax分别降低了2.0%(P0.05)、16.8%(P0.01)。表明在水深较浅的泥沙水体中可以适当引种黑藻幼苗,植株可以正常生长发育。

Influence of silts on growth and development of Hydrilla verticillata's seedling in silt waters

Seedlings of Hydrilla verticillata (SHV) were planted in the waters with turbidity of 30NTU, 60NTU or 90NTU. The turbidity of the water was controlled by sand particles smaller than 100μm, and the effect of water turbidity on the growth (such as intemode length, stem height, branch number, leaf width, leaf length, fresh weight and sediment adhesion) of SHV was examined. The photosynthetic fluorescence characteristics of the leaves were determined in situ by a developed, submersible, pulse-amplitude modulated (PAM) fluorometer (diving-PAM). The rapid light responding curves of the leaves were also determined. The experimental results indicated that intemede length and the stem height of SHV increased significantly, whereas branch number and growing rate of biomass decreased remarkably as the water turbidity increased after planted in turbid water for 40 days. When the plants grow to water surface, the light intensity is inceasing. The plants development were restricted on the 60~(th) day. But the growth of upper branch was promoted, and biomass of H. verticillata was enhanced remarkably. At the same time the silts amount attached on H. verticiUata observably were added with water turbidity increasing. Compared with plants in the control water, the leaf width of H. verticillata leaves were wider 71.4%(P< 0. 01), 57. 1% (P < 0. 01) and 48.6% (P < 0. 01) with turbidity of 30 NTU, 60NTU or 90NTU respectively on 100~(th) day, and their leaf length were 113.0% (P < 0.01), 85.5% (P < 0. O1) and 75.1% (P < 0.01) of the control leaves, respectively. The plant biomass under the high silts turbid water decreased significantly. F_v/F_m of Canopy leaves in the turbid waters with turbidities of 60NTU and 90NTU only reduced 5.5 % (P < 0.05) and 2.9% (P > 0.05), and their rETR_(max) only reduced 2.0% (P > 0.05) and 16.8% (P < 0.01). It was shown that SHV can grow and develop normally when they are introduced into shallow silt water.