以海桑属(Sonneratia Linn. f.)红树植物无瓣海桑(S. apetala Buch. -Ham.)、海桑[S. caseolaris (Linn.) Engl.]、杯萼海桑(S. alba Smith)、卵叶海桑(S. ovata Backer)、拟海桑(S. × gulngai N. C. Duke et B. R. Jackes)和海南海桑(S. × hainanensis W. C. Ko et al.)为研究对象,比较了根际土壤和叶片中离子含量以及叶片光合和叶绿素荧光参数、叶绿素含量、抗氧化酶活性和 O₂^·- 产生速率的差异,并分析了叶片中 Na+和 Cl^-含量与部分生理生化指标的相关性。 比较结果表明:海桑和拟海桑叶片中 K⁺含量最高、Na⁺和 Cl^-含量均显著低于其他种类,但它们的根际土壤中Na⁺和 Cl-含量却较高。 供试 6 种植物中仅海桑叶片对 Cl-的富集系数小于 1,各供试种类对 K⁺、Na⁺、Cl^-、Ca²⁺和Mg²⁺的富集系数均大于 1;无瓣海桑对离子的富集系数由大至小依次为 Mg²⁺、K⁺、Ca²⁺、Na⁺、Cl^-,其他种类对离子的富集系数由大至小均依次为 K⁺、Ca²⁺、Mg²⁺、Na⁺、Cl^-。 无瓣海桑和海桑的 chla、chlb 和总叶绿素含量差异不显著,但均高于其他种类;供试种类的 chla / chlb 比值均约为 3,可能与海桑属植物为阳生植物有关。 无瓣海桑的 Pn、Tr 和Gs 均最高,而杯萼海桑的 Pn、Tr 和 Gs 均最低,但 6 种植物的 Ci 无明显差异。 供试种类的 Fv / Fm、qP、ETR 和 ФPSⅡ均无显著差异,仅部分种类间的 NPQ 差异显著。 无瓣海桑叶片中 SOD、CAT 和 POD 活性均显著高于其他种类,但O₂^·- 产生速率最低;而卵叶海桑叶片中 O₂^·- 产生速率最高,其 APX 活性也均显著高于其他种类。 相关性分析结果表明:供试 6 种植物叶片中 Na⁺和 Cl^-含量与 Pn、qP、ФPSⅡ和 ETR 负相关,与 NPQ 及 SOD、CAT、APX 和 POD 活性正相关。 其中,Na+含量与 qP、ФPSⅡ、ETR 和 SOD 活性极显著相关,与 NPQ 和 CAT 活性显著相关;Cl^-含量与 SOD 活性极显著相关,与 qP、ФPSⅡ和 ETR 显著相关。 研究结果表明:供试海桑属植物对高盐生境有不同的耐性机制,其中,海桑和拟海桑通过拒吸 Na⁺和 Cl^-抵御盐胁迫的伤害;供试 6 种植物对海岸潮间带生境的适应性有明显差异,无瓣海桑最适宜在此生境中生长。

 

Taking mangrove plants of Sonneratia apetala Buch. -Ham., S. caseolaris ( Linn.) Engl., S.alba Smith, S. ovata Backer, S. × gulngai N. C. Duke et B. R. Jackes and S. × hainanensis W. C. Ko et al. in Sonneratia Linn. f. as investigation objects, differences in ion content in rhizosphere soil and leaf and differences in photosynthetic and chlorophyll fluorescence parameters, chlorophyll content, antioxidant enzyme activity and O₂^·- production rate in leaf were compared, and correlations of Na⁺ and Clcontents in leaf with some physiological and biochemical indexes were analyzed. The comparison results show that K⁺ content in leaf of S. caseolaris and S.× gulngai is the highest and Na⁺ and Cl^- contents in their leaf are significantly lower than those of other species, but Na⁺ and Cl^- contents in their rhizosphere soil are higher. In these six species, enrichment coefficient of leaf to Cl^- is lower than 1 only in S. caseolaris, while that of leaf to K⁺, Na⁺, Cl^-, Ca²⁺ and Mg²⁺ in all species are higher than 1. Order of enrichment coefficient of S. apetala to ions from big to small is Mg²⁺, K⁺, Ca²⁺, Na⁺, Cl^-, while that of other species is K⁺, Ca²⁺, Mg²⁺, Na⁺, Cl^-. Differences in chla, chlb and total chlorophyll contents between S. apetala and S. caseolaris are not significant but are higher than those of other species. Ratios of chla / chlb of all species all are about 3, it may be related to Sonneratia species belonging to heliophyte. Pn, Tr and Gs of S. apetala all are the highest, while those of S. alba all are the lowest, but there is no obvious difference in Ci among all species. There is no significant difference in Fv / Fm, qP, ETR and Ф PSⅡ among all species, there is significant difference only in NPQ among some species. SOD,CAT and POD activities in leaf of S. apetala all are significantly higher than those of other species, but its O₂^·- production rate is the lowest; while O₂^·- production rate of S. ovata is the highest, and its APX activity is also significantly higher than that of other species. The correlation analysis results show that Na⁺ and Cl^- contents in leaf of six species are negative correlated to Pn, qP, ФPSⅡ and ETR, and positive correlated to NPQ and SOD, CAT, APX and POD activities. In which, Na+ content is extremely significantly correlated to qP, ФPSⅡ, ETR and SOD activity, and significantly correlated to NPQ and CAT activity; Cl^- content is extremely significantly correlated to SOD activity, and significantly correlated to qP, ФPSⅡ and ETR. The research results show that there are different tolerant mechanisms of tested Sonneratia species to high salt habitat, in which, S. caseplaris and S. × gulngai can resist damage of salt stress through refusing to absorb Na⁺ and Cl^-. There are obvious differences in adaptability of six tested species to coast intertidal zone habitat, and S. apetala is the most suitable to grow in this habitat.