三种泌盐红树植物对盐胁迫的耐受性比较

Comparisons of tolerances to salt stress among three salt-secreting mangrove species

在盐度 0、5、15、2 5和 35 (% )下种植泌盐红树植物老鼠 (Acanthus ilicifolius)、桐花树 (Aegiceras corniculatum)和白骨壤(Avicennia marina)的繁殖体 ,以繁殖体萌发、幼苗生长、叶片泌盐量、叶片组织液盐含量和蒸腾蒸发量为指标 ,比较其对盐胁迫的耐受性。盐度提高对胎生种类桐花树和白骨壤的萌根速率无显著影响 ,但高盐度明显抑制非胎生种类老鼠的萌根。白骨壤的萌苗率不受盐度影响 ,但 2 5以上的盐度导致桐花树和老鼠的萌苗率下降。在盐度范围 5～ 35内 ,白骨壤幼苗的茎高生长随盐度的增加而减少 ,但减少量比桐花树小 ,而老鼠的减少量最大。老鼠因盐度提高而导致的叶片长度的减少量最大。在盐度提高的情况下 3种植物均具有泌盐量增加的效应 ,在任一盐度下泌盐能力的顺序均为白骨壤 >桐花树 >老鼠。淡水培养时 ,3种红树植物的叶片组织液盐含量 (约 2 % )均高于环境盐度 0。在盐度范围 5～ 35内 ,白骨壤的叶片组织液盐含量维持在较稳定的水平 (4 .3%～ 5 .0 % ) ,桐花树的变化范围为 2 .4 %～ 4 .5 % ,老鼠 2 .3%～ 5 .3%。淡水培养时 ,3种植物的蒸腾蒸发量类似 ,但盐性条件下白骨壤的蒸腾蒸发量显著高于桐花树和老鼠。随着盐度的增加 ,老鼠的蒸腾蒸发量下降最多。这些结果均表?

Propagules of three salt-secreting mangrove species, Acanthus ilicifolius, Aegiceras corniculatum, and Avicennia marina, were germinated at salinities 0, 5, 15, 25 and 35. Their tolerance to salt stress was evaluated in terms of propagule germination, seedling growth, salt secretion from leaves and salt content in leaf tissue water, evaporation and transpiration. Root initiations of the two viviparous species, Aegiceras and Avicennia, were not significantly influenced by increased salinities but root initiations of the non-viviparous species (Acanthus) were significantly delayed at high salinities. Salinity also affected seedling establishment, the unfurling of the first pair of leaves, and the effects were species specific. The seedling establishment percentages in Avicennia were not significantly affected by salinities up to 35 while salinities over 25 significantly reduced the establishment of Aegiceras and Acanthus. Although increasing salinity seemed not to affect propagule germination and seedling establishment of Avicennia, its stem height decreased as salinities increased from 5 to 35. Nevertheless, the range of stem height decreases in Avicennia was less than that in Aegiceras, and Acanthus showed the largest reduction in height as salinities increased from 0 to 35. Acanthus also had the largest reduction in maximum leaf length due to high salinity. All of the three species secreted more salts as salinities increased but their salt secretion capacity differed, followed the descending order of Avicennia>Aegiceras>Acanthus at any given salinity. When seedlings were cultured in tap water, all three mangrove species had the salt concentrations in the leaf tissue water (about 2%) higher than the environmental salinity 0. Under saline conditions (salinities 5～35), salt concentrations in leaf tissue water of Avicennia were maintained at a steady level, around 4.3% to 5.0% with little changes. On the contrary, salt concentrations increased from 2.4% to 4.5% in Aegiceras and the corresponding increases in Acanthus were from 2.3% to 5.3%. The evaporation and transpiration rates of these three species were similar under the tap water condition (salinity 0); however, Avicennia had significantly higher rates than Acanthus and Aegiceras under saline conditions (salinities 5～35). The decline in evapo-transpiration rates was most significant in Acanthus. These parameters all indicated that salt tolerance among the three salt-secreting mangrove species was in the descending order of Avicennia>Aegiceras>Acanthus.