【作者】 王文林；

【导师】 王国祥；

【作者基本信息】 南京师范大学 ， 自然地理学， 2006， 硕士

【摘要】 沉水植物是浅水湖泊生态系统的关键种群，对水环境质量及水生生态系统结构有重要影响。然而，污染、水土流失等原因使得许多浅水湖泊水质混浊，水下光照严重不足，沉水植物消失，水体处于严重的“藻型富营养化”状态。探讨水体混浊度对沉水植物生长发育的影响，可以为水环境生态修复提供理论依据。 用粒径小于100μm的悬浮泥沙，模拟不同混浊度的水体，将菹草、亚洲苦草栽种于其中，观测水体浊度对两种沉水植物萌发及生长的影响。并利用水下饱和脉冲叶绿素荧光仪(DIVING-PAM)原位、无损伤测定水体浊度对沉水植物光合作用的影响。 研究结果表明：①水体浊度对菹草石芽的萌发速度有一定的影响，但对其萌发率没有显著影响，菹草萌发苗及幼苗的生长发育对光照的需求不高，在浅水(水深≤70cm)，水体浊度不超过90NTU时，其正常生长发育及光合作用将能得到保证，而当水体浊度超过120NTU时，其也能存活较长时间，但超过一定时间(80～120天)，叶片的PSII系统将会受到破坏，植株大规模死亡。②而在浅水(水深≤70cm)，水体浊度对亚洲苦草幼苗的生长影响显著，当水体浊度大于60NTU，苦草幼苗不易存活，随水体浊度增加和时间延长(≥18天)，幼苗光合能力不断降低，PSII系统最终损坏；而水体浊度不超过90NTU时，亚洲苦草成株能保持存活，并能正常的生长，水体浊度对叶片的PSII系统无显著影响，植株能正常的进行光合作用。③在混浊水体中，菹草与亚洲苦草幼苗均会出现低光抑制现象，叶片光化学效率下降，但植株叶片通过增加热耗散(qN)以保护光合结构PSII，但随着植株受试时间的增长，高浊度水体中菹草(≥120NTU)与亚洲苦草(≥60NTU)叶片的光化学效率明显下降，同时热耗散(qN)能力下降表明光合结构PSII已经开始损坏，而这一变化与植株的存活变化明显相关。 叶绿素荧光分析方法简便、灵敏、实时、无破坏、无干扰的优点，使得其能即时诊断沉水植物体内光合机构运转状况、分析沉水植物对逆境的响应机理，因而可作为沉水植物恢复重建的评价指标。更多还原

【Abstract】 Submerged macrophytes is key community in shallow lake ecosystem. It plays important role in water environmental quality and aquicolous ecosystem structure. However, many reasons such as contamination, soil erosion and so on make water turbid in many shallow lake, underwater light is serious insufficient, submerged macrophytes die out, water body is in great algae eutrophic state. Therefore, studying influence of water turbidity on growth of submerged macrophytes can offer academic method and measurement for ecological restoration of water environment. Different turbidity water were simulated with suspended substance which was less than 100 microns in diameter. Potrmogeton cripus and Vallisneria asiatica were planted in the turbid water. The influence of water turbidity on growth of two submerged macrophytes were investigated and the influence of water turbidity on photosynthesis of submerged macrophytes were measured with natural and undamaged means by pulse-amplitude modulated fluorometer (PAM). The results showed that: ① the germination speed of Potrmogeton crispus’s buds was influenced by suspended substance, but germination rate were not influenced by suspended substance. The growth of germination seedlings and seedlings of Potrmogeton crispus didn’t need high underwater light, in the water with depth of 70cm, when water turbidity under 90NTU, the growth and photosynthesis of them could be natural. However , when water turbid overrun 90NTU, 80~120 days later, structure of PSII was destroyed, plants died in a large scale. ② The growth of seedlings of Vallisneria asiatica were influenced by water turbidity markedly, when water turbidity overrun 60NTU, seedlings of Vallisneria asiatica couldn’t live, the ability of photosynthesis with the increasing of water turbidity and experimental time(≥18 days) decreased, structure of PSII was destroyed finally. Whereas, with the same condition, mature plants of Vallisneria asiatica could live, grow, propagate naturally. Structure of PSII of leaves were not influenced markedly. ③ In turbid water, the seedlings of Potrmogeton cripus and Vallisneria asiatica were restrained by low light, photochemical efficiency of leaves decreased, but the leaves protected PSII by increasing heat dissipating(qN). With the increasing of experimental time, Potrmogeton cripus in high water turbid(≥120NTU) and Vallisneria asiatica in high water turbid( ≥60NTU) whose photochemical efficiency decreased markedly, meanwhile the decreasing of heat dissipating(qN) indicated that structure of PSII had been destroyed. The changes of chlorophyll fluorescent parameters was connected with the livability of plants.The method of chlorophyll fluorometer analysis showed simple and convenient, sensitive, moment, undestroyed, undisturbed advantages in this experiment, which make this method diagnose photosynthesis situation of submerged macrophytes and analyze responsive mechanism of submerged macrophytes instantaneously. So this method can become index of assessment for restoration and reconstruction of submerged macrophytes.更多还原