富营养底质对沉水植物的胁迫研究 Ι.乙酸对伊乐藻和菹草萌发与幼芽生长的影响

Stresses of Eutrophic Lake Sediment on Submersed Macrophytes Ι.Effects of Acetic Acid on Germination and Bud Growth of Elodea nuttallii and Potamogeton crispus

湖泊底质中有机物的厌氧代谢产生多种有机酸,其中主要成分是乙酸。研究了暴露于不同浓度的乙酸溶液后伊乐藻(Elodea nuttallii)和菹草(Potam ogeton crispus)无性繁殖体的萌发和幼芽的生长状况。1 mmol/L的乙酸能显著抑制伊乐藻幼芽的生长(p<0.05),但对其繁殖体的萌发无明显影响。在4 mmol/L的乙酸影响下,菹草幼芽仍有明显的生长;菹草繁殖体的萌发受到显著抑制(p<0.05),但在随后的培养中可全部萌发。4 mmol/L以上的乙酸暴露3 d或6 d导致伊乐藻全部死亡,8 mmol/L的乙酸处理6 d或16 mmol/L的乙酸处理3 d或6 d导致菹草全部死亡。研究表明厌氧底质中的乙酸可能是阻碍沉水植物生长的重要因素之一,菹草比伊乐藻能耐受较高强度的乙酸胁迫,更适合作为先锋物种用于富营养化湖泊中的沉水植物恢复。

Anaerobic digestion of organic matters will produce organic acids, in which acetic acid is dominant. Propagules and buds of Elodea nuttallii and Potamogeton crispus were exposed to acetic acid concentrations from 1 to 16 mmol/L for 3 or 6 days, and then they were subsequently cultured in absence of acetic acid. Results showed P. crispus was more tolerant to acetic acid than E. nuttallii. At acetic acid concentration of 1 mmol/L, E. nuttaUii propagules germinated normally, but the buds was significantly inhibited （p 〈 0.05 ） in growth and the recovery in the subsequent culture was slow. Exposures to 4 mmol/L or higher caused death of E. nuttallii. In contrast, at concentration of 4 mmol/L, all P. crispus buds survived with significant growth and had a good recovery in the subsequent culture; P. crispus turions were remarkably reduced in gerimination rate, but all sprouted in the subsequent culture. However, exposures to 8 mmol/L for 6 days or to 16 mmol/L for 3 or 6 days led to death of P. crispus. The study showed that presence of acetic acid in sediment might cause great difficulties in reestablishing submerged macrophytes in eutrophic lakes, and that P. crispus was more suitable than E. nuttallii to be established as pioneer species.