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Response of rice seedlings to copper toxicity and acidity

Mahmood, T., Islam, K.R.
Journal of plant nutrition 2006 v.29 no.5 pp. 943-957
rice, seedling growth, oxidative stress, copper, phytotoxicity, Oryza sativa, seedlings, lipid peroxidation, cations, hydroponics, potassium, nutrient solutions, soil pH, chlorophyll, roots, leaves, shoots
Metal toxicity and soil acidity affect plant growth. A hydroponic experiment was conducted to simulate effects of pH and copper concentration [Cu] on early growth and biomass production of high-yielding rice seedlings (Oryza sativa L. cv. 'NIAB 6'). The rice seedlings were allowed to grow in Yoshida nutrient solution with 1 (control), 8, 16, and 32 μM Cu at buffered pH levels of 4.5, 5.0, and 5.5, respectively. Shoot and root growth, leaf chlorophyll content, and root lipid peroxidation and K+ leakage of 15-day-old rice seedlings were determined. Results show that [Cu] had significant adverse effects on rice seedlings. Shoot height and root length were reduced by 18%-60% and 7%-69%, respectively, compared with the control, and shoot and root weight decreased by 26%-56%, and 25%, respectively, in response to progressive increases in [Cu]. Similarly, leaf chlorophyll content decreased by 150%-245% compared with the control treatment. Rice seedling roots suffered from significant increases in lipid peroxidation followed by K+ leakage (> 8-23 times) in response to increasing [Cu]. Averaged across [Cu], seedling growth and biomass were greater at pH 5.5 than at other pH treatments. In some instances, increasing pH minimized the adverse effects of Cu at low concentrations on rice seedlings.