Field experiments were conducted to study the effect of lead (Pb) in different
concentrations (0, 100. 200 and 300 ppm) on vegetative growth, flowering, chemical
constituents and seed yield of Borago officina/is. The study tests also the ability of the
antioxidants Ethylenediurea (EDU), Ascorbic acid (AA) and Salicylic acid (SA) to
overcome the harmful effects of Pb on the growth and physiological behavior of the
polluted plants. Results showed that Pb treatments negatively affected plant growth
represented by shoot length. number of branches and dry weight. Flowering date,
flower dry weight. seed yield and fixed oil percentage were also negatively affected by
Pb pollution. The endogenous Pb concentration in the analyzed plants increased
following the increase in Pb levels in the growth medium. Chl.a, b, and carotenoids
were sharply reduced by Pb treatments. Nitrogen, phosphorus and potassium
concentrations were decreased dramatically especially at high Pb levels. The activity
of peroxidase was positively correlated with the concentration of Pb in leaves and
roots. In all cases, EDU. AA and SA treatments seemed to be useful in counteracting
the harmful effects exerted by Pb contamination on borage plants by r~lating
certain enzymes. The results suggested that the measurements of enzyme activities
(peroxidase) could serve as early bio-markers to asses the phytotoxicity of Pb polluted
soils on Boragro officinalis.