A regulation of calcium ion on jerusalem artichoke(JA) seedlings under seawater salt(SWS) and NaCl with the same salt content was made with three calcium ion concentration of 5 mmol/L

10 mmol/L and 20 mmol/L.The effects of calcium ion on biomass

SOD activity

MDA content

relative conductivity

chlorophyll content and net photosynthetic were studied.The results indicated that: normal metabolism of JA was markedly inhibited by 1.0% SWS and 1.0% NaCl.However

addition of Ca~(2 ) could alleviate the effects of SWS and NaCl stresses on JA in different degree

so higher biomass

SOD activity

chlorophyll content and net photosynthetic rate

lower content of MDA and relative conductivity were maintained

especially 10 mmol/L Ca~(2 ).Above 10 mmol/L the alleviation decreased.As a result

appropriate concentration Ca~(2 ) could significantly protected JA from oxidative damage caused by SWS and NaCl stresses.Therefore

higher SOD activity

chlorophyll content and net photosynthetic rate

lower content of MDA and relative conductivity were maintained.These were propitious to the dry matter accumulation so that the fresh weight was increased significantly.At Ca~(2 ) concentration of 5 mmol/L

10 mmol/L the effect of Ca~(2 ) on alleviation of SWS stress was superior to NaCl stress significantly

whereas the two treatments did not have pronounced difference when the concentration was 20 mmol/L.