Factors on seed germination, tuber sprout and plant growth of <i>Vallisneria </i> species in China

由于人类生产生活对众多淡水水体的扰动、污染,我国苦草属(Vallisneria)植物的种群规模出现了严重的退化.明确苦草属植物萌发和生长的影响因素,阐明苦草属植物退化的原因,是保护和恢复该属植物亟需解决的科学问题.通过对已发表的文献进行收集和分析,总结了影响苦草属植物萌发和生长的主要因素,并通过挖掘文献中的数据,对重要环境因子与苦草属植物萌发和生长参数的关系进行了分析.结果表明:(1)涉及苦草(V.natans(Lour.)Hara)的研究较多,而涉及刺苦草(V.spinulosa Yan)和密刺苦草(V.denseserrulata Makino)的研究较少;(2)苦草属植物种子的萌发受到温度、光照强度、水深、掩埋深度、基质情况和储存方式等因素的影响;(3)苦草属植物生长受到光照强度、水深、水体营养水平、底泥营养水平、底泥有机质和动物牧食等因素的影响;(4)其他条件适宜时,苦草和刺苦草种子在20~30℃都保持较高的萌发率(均值> 50%);(5)苦草种子萌发率随着掩埋深度的增加而快速下降;(6)苦草的相对生长率随光照强度的增加而升高,随水深增加而下降;(7)苦草的相对生长率随着氨氮浓度增加而下降;(8)水体和底泥中高含量的总氮和总磷对苦草属植物生长的抑制作用主要是通过促进浮游植物和附着藻生长导致的遮光,而不是直接毒害作用.未来需要进一步加强苦草属植物萌发、生长参数与环境因子关系的定量研究,更好地服务于该属植物的保护和恢复.;The abundance of the Vallisneria species has declined in many freshwater bodies in China, as their habitats were disturbed and polluted by human activities. The restorations of these species, however, have had limited success. This review aims to determine which factors and how these factors regulate the seed germination, tuber sprout and plant growth of the Vallisneria species, thus providing insights for the protection and restoration of the Vallisneria species in China. The factors which affect the seed germination, tuber sprout and plant growth of the Vallisneria species were summarized and the quantitative relationships between some key environmental factors and seed germination, tuber sprout and plant growth of the Vallisneria species were re-analyzed based on the data from the literature. The results showed that: (1) studies for V. natans (Lour.) Hara were much more than those of V. spinulosa Yan and V. denseserrulata Makino in literatures; (2) seed germination of the Vallisneria species was affected by factors including temperature, light availability, water depth, burial depth, growth medium and store conditions; (3) the growth of the Vallisneria species was affected by factors including light availability, water depth, water nutrient, sediment nutrient, sediment organic matter and herbivory; (4) seed germination rate of V. natans and V. spinulosa was high (>50% in average) at 20-30℃; (5) seed germination rate of V. natans rapidly decreased with burying depth; (6) the relative growth rate of V. natans increased with light availability and decreased with water depth; (7) the growth of V. natans decreased with ammonia nitrogen concentration and (8) the negative effect of high total nitrogen and total phosphorus in water column or sediment on Vallisneria species was from shading by phytoplankton and epiphyton induced by nutrient enrichment other than direct toxicity. More studies are needed to reveal the quantitative relationship between the environmental factors and the growth of Vallisneria species in the further.