两种红树植物白骨壤(Avicennia marina)和桐花树(Aegiceras corniculatum)的耐淹性

Studies of the tolerance of Avicennia marina and Aegiceras corniculatum to seawater immersion in Guangxi,China

以两种红树植物白骨壤（Avicennia marina（Forsk.）Vierh.）和桐花树（Aegiceras corniculatum （L.） Blanco）幼苗为材料,在梯度海面高程的野外人工平台上开展了为期1a的淹水胁迫实验。3座平台作为重复,每座设置8个梯度,相邻梯度间高度相差10cm,幼苗立地基质平面的海面高程320~390cm。实验1a后测定1a幼苗的生长状况及与一些生理指标。结果表明：小高程生境对两种幼苗茎的纵向生长均有显著促进作用,但白骨壤幼苗茎生长高度是桐花树的7.5倍。与白骨壤相比,桐花树幼苗有较高的叶片保存率。白骨壤幼苗生物量在各器官分配为：茎〉根〉叶,3个器官平均所占比例分别为56.7%,25.7%和17.6%;桐花树则为：叶〉根〉茎,3个器官平均所占比例分别为49.6%,33.0%和17.4%。小高程生境对白骨壤幼苗全株生物量有较强的促进效果,桐花树幼苗则在中等高程生境中有较大生物量。在任一高程组,桐花树幼苗叶片叶绿素含量均大于白骨壤幼苗,但两种幼苗叶绿素a/b比值差异不显著。无论在叶片还是根系中,桐花树幼苗的活性氧清除酶类活性均高于白骨壤幼苗,表明在相同高程生境中桐花树幼苗比白骨壤幼苗面临更大的困难。综合实验结果和野外观察，可看出白骨壤耐淹水能力高于桐花树；仅从植物本身的生理特性考虑，可确定北部湾沿海白骨壤造林滩面高程不宜低于平均海面30cm，桐花树不应低于当地平均海面。

From October 2004 until October 2005 water logging experiments on two mangrove species Avicennia marina （Forsk.） Vierh. and Aegiceras corniculatum （L.） Blanco, were carried out on the tidal flat of Yingluo Bay （109°43′E, 21°28′N） in Guangxi, China. Three replicate artificial platforms were set up for seedling cultivation. Eight sea level altitude （SLA） treatments on each platform were created, each 10 cm above the neighboring treatment. The surface planes of the seedling substrates equaled the SLAs and ranged from 320 to 390 cm. 359 cm was the altitude of the local mean sea level. After one year of cultivation under the SLA treatments the growth characteristics and some physiological parameters of the seedlings were measured. The results showed that the lower SLA treatments significantly promoted longitudinal development of stems of both species, while the mean height of A. marina seedlings was 6.5 times higher than that of A.corniculatum seedlings. Compared with A. marina seedlings, A. corniculatum seedlings had a higher conservation rate in the existing leaves. The order of biomass allocation for A. marina seedlings was stem 〉 root 〉 leaf, and mean percentages of the three organs to the total biomass were 56.7%, 25.7% and 17.6% respectively. But the order of biomass allocation for A. corniculatum seedlings was leaf 〉 root 〉 stem, and the mean percentages of the three organs were 49.6%, 33.0% and 17.4% respectively. A strong promoting effect of the lower SLAs could be seen in the total biomass of A. marina seedlings. However, the moderate SLA treatments were the favorite conditions for higher biomass in A. corniculatum seedlings. At the same SLA the chlorophyll content of A. corniculatum seedlings was higher than that of A. marina seedlings, but there was no significant difference between the ratios of Chl-a to Chl-b for the two species. In both the leaves and the roots the activities of enzymes processing active oxygen in A. corniculatum seedlings were higher than those in A. marina seedlings, indicating a more stressful condition for the former than the latter. Our experimental results and field observations indicate that the tolerance of A. marina to seawater immersion was greater than that of A. corniculatum. If only physiological characteristics were considered the most favorable SLA for forestation in Beibu Gulf region should not be 30cm lower than the local mean sea level for A. marina, and roughly equal to local mean sea level for A. corniculatum.