CS (a), NADP
+-IDH (b) and MDH (c) specific activities. The seedlings were grown for 14 days in a Hoagland modified complete nutrient solution (0) and treated for the last 2 days with HS concentrations of 0, 1 and 5 mg C L−1. The specific activities were expressed unit per milligramme protein. For CS, 1 U corresponds to the reduction of 1 μmol Ac-CoA per minute; for NADP+-IDH, 1 U corresponds to 1 μmol of NADPH reduced per minute and for MDH to 1 μmol of NAD+ formed per minute at assay conditions. Values are means of three independent determinations (±SE). Letters above bars indicate significant differences (P < 0.05).