the effects of lead on the proline content and dry weight of leaves and roots were investigated in two canola cultivars (brassica napus l.) grown in the hoagland solution. the growth of treated plants was inhibited under lead stress. lead induced differential accumulation of proline in canola grown in solution with the addition of 0, 100 and 200 mgl-1 of pb. hyola308 cultivar showed low biomass...