Toxicity and tolerance in Samanea saman (JACQ.) Merr. to some metals (Pb,Cd,Cu and Zn)

In this study toxicity and tolerance of samanea saman (jacq.) merr. was investigated for pb,cd,cu and zn under lab conditions. germination rate of s. saman showed that increased concentration of different metals from 25 to 100 ppm,significantly (p<0.05) reduced germination which was more prominent for pb treatments. seedling growth variables i.e. root and shoot length,seedling size,root/shoot ratio,seedling fresh and dry weights also declined significantly (p<0.05). seedlings growth of s. saman gradually reduced with increasing in concentrations of metals especially pb and cd compared to cu and zn. the inhibitory effects of metals had the following order pb>cd>cu>zn of sequence at different concentrations. tolerance indices determined for different metal illustrated that increasing concentrations of metals reduced the tolerance of s. saman but this reduction was more prominent for pb and cd as compared to cu and zn treatments.