Photosynthesis in copper mediated plant is affected due to oxidative damage caused by reactive oxygen species (ros) generation

Abstract

Rice Oryza sativa cv. Jaya grown in vermiculite and irrigated with the range of Cu treatments (0 to 3.0 mmol l sup(-1)) in Hoagland solution were studied for its effect on photosynthesis and oxidative damage in twenty days old plants. Gradual decrease in plant growth and biomass was observed with the increase in Cu treatment. Treatments with 3 mmol l-1 Cu led to 69 times more accumulation of Cu in root than in leaf tissue. Quantum efficiency of photosystem II measured as Fv/Fm ratio and photochemical quenching (qP) decreased significantly with increase in non-photochemical quenching (qNP) as the Cu treatment increased. Accumulation of proline an indicator of osmotic stress increased considerably in Cu treated plants. Inverse relationship between increasing Cu treatment and photosynthetic rate, transpiration rate and stomatal conductance was observed. Photosynthetic pigments such as Chlorophyll a, chlorophyll b, Neoxanthine, Violaxanthine, Antheraxanthine, beta Carotene and Lutein showed significant linear decrease with the increasing Cu treatment. Progressive enhancement in the H2O2 level at 1, 2 and 3 mmol l sup(-1) Cu treatments was observed which was coupled with greater level of lipid peroxidation measured as MDA. Superoxide dismutase (SOD), an antioxidant enzyme exhibited significant activity only at highest Cu treatment.