盐度对乡土红树海桑和引进种无瓣海桑离子吸收的影响

Effect of salinity on ion absorption of native mangrove Sonneratia caseolaris and introduced S. apetala

在不同NaCl盐度(0、5、10、15、20、30、40、50)处理下培养海桑(Sonneratia caseolaris)和无瓣海桑(S.apetala)苗木4个月,测试分析叶、茎和根的Na^(+)、K^(+)、Ca^(2+)、Mg^(2+)和Cl^(-)等离子含量,探讨盐度对海桑和无瓣海桑离子吸收的影响,揭示海桑属这两种乡土和外来红树植物维持离子平衡的机理差异。结果表明:(1)随着盐度升高,Na^(+)和Cl^(-)含量快速增加,根部的增速快于茎和叶,盐度超过20海桑茎和叶的Na^(+)和Cl^(-)含量下降;海桑全株平均含量在盐度50处理比在盐度0处理分别增加了210.2%和248.2%,无瓣海桑分别增加了204.1%和246.1%;K^(+)和Ca^(2+)含量先升后降,海桑和无瓣海桑K^(+)含量分别在盐度15和20达到最高值,全株Ca^(2+)含量在盐度20达到最高值;Mg^(2+)含量变化平缓,在盐度30~50略有增加。(2)各盐度处理全株Na^(+)和Cl^(-)含量主要为无瓣海桑高于海桑,海桑在盐度20处理的Na^(+)含量、盐度15~30处理的Cl^(-)含量分别高于无瓣海桑;2种红树植物的K^(+)含量差异小;全株Ca^(2+)平均含量无瓣海桑高于海桑,Mg^(2+)含量低于海桑。(3)盐胁迫下海桑各器官Na^(+)和Cl^(-)含量、无瓣海桑各器官Na^(+)、Cl^(-)和Mg^(2+)含量相互间相关程度高,表明这些离子在植物吸收过程中相互影响,K^(+)和Mg^(2+)含量在2种红树植物各器官没有相关关系。(4)随着生境盐度变化,海桑和无瓣海桑离子吸收和在各器官分配的变化规律基本一致,说明这2种红树植物在盐胁迫下维持离子平衡的机理相同;无瓣海桑耐盐胁迫能力略强于海桑。

In order to explore the effect of salt stress on ion absorption of mangrove Sonneratia caseolaris and S.apetala,and reveal the mechanism of maintaining ion balance in these two plant species,saplings were treated at different NaCl salinities(0,5,10,15,20,30,40,50)for 4 months and sampled to analyze the concentration of Na^(+),K^(+),Ca^(2+),Mg^(2+),Cl^(-)in stems,leaves and roots.With the increase of salinity,the concentration of Na^(+)and Cl^(-)in all organs increased and increased fastest in roots;the Na^(+)and Cl^(-)concentrations in stems and leaves decreased with the salinity over 20 for S.caseolaris;the average concentration values of Na^(+)and Cl^(-)at salinity 50 increased by 210.2%and 248.2%compared with the treatment of salinity 0 for S.caseolaris,and 204.1%and 246.1%for S.apetala,respectively.The concentration of K^(+)and Ca^(2+)increased first and then decreased,peaking K^(+)concentration was found at salinity 15 and 20 for S.caseolaris and S.apetala,respectively,and peak value of average Ca^(2+)concentration of all organs at salinity 20 for both plants.The Mg^(2+)concentration increased slightly under salinities varying between 30 and 50.Under most salinity treatments the Na^(+)and Cl^(-)concentrations in S.apetala were higher than those in S.Caseolaris except Na^(+)concentration at salinity 20 and Cl^(-)concentration at salinities between 15 and 30.K^(+)concentration between these two species varied little.Ca^(2+)concentration in S.apetala was higher than that in S.caseolaris while Mg^(2+)concentration was lower.Under salt stress,Na^(+)and Cl^(-)in S.caseolaris,Na^(+),Cl^(-)and Mg^(2+)in S.apetala were highly correlated among their concentration values in all plant organs,indicating that these ions influencing each other during plant absorption.There was no correlation between concentration values of K^(+)and Mg^(2+)in all organs of these two plants.With the change of salinity,the rules of ion absorption and allocation among organs were similar for these two mangrove species,indicating that they have a similar mechanism of ion balancing under salt stress.S.apetala was slightly more salt tolerant than S.Caseolaris.