Water lettuce plants were exposed to various concentrations (0, 0.01,0.1, 1.0 and 10.0 ppm) of
nickel as
nickel sulphate in nutrient medium. The effect of graded
nickel (Ni +2) concentrations on visible symptoms of toxicity, pigments (
chlorophyll a, b and total) and antioxidative attributes were evaluated. Plants exposed to high
nickel (1.0 and 10.0 ppm) showed visible toxicity symptoms, such as wilting,
chlorosis in young leaves, browning of root tips and broken off roots, observed at 6 days
after treatment.
Nickel was accumulated more in root (863.3 microg g-1 dry weight) than leaves (116.2 microg g-1 dry weight) at 6 days of treatment.
Nickel exposure decreased
chlorophyll a, b and total
chlorophyll contents. Relative water content decreased at high
nickel (1.0 and 10.0 ppm).
Antioxidants, such as
proline content and
peroxidase activity increased with increase in
nickel concentrations, whereas, other
carotenoids and
protein contents at 1.0 ppm and activity of
catalase at 10 ppm of
nickel were decreased. The low level of
nickel stimulates photosynthetic pigments and antioxidative attributes. The study may be helpful in phytoremedial strategies and
biological indication of
nickel toxicity in aquatic plants.