Effects of Lead Toxicity on Plant Growth and Biochemical Attributes of Different Rice (Oryza Sativa L.) Varieties

Abstract

Rice (Oryza sativa) is one of the principal foods for a large part of the worlds human population, but its productivity is reduced by the toxic effects of heavy metals such as lead. In the present study seeds of the rice cultivars KSK-133, NIAB-IR-9, Basmati-385 (B-385) and Shaheen Basmati (SB) were treated with different concentrations of lead chloride (PbCl2) (0, 250, 500, 1000 and 2000 ppm) to evaluate the effect on germination, seedling growth and some biochemical attributes. Lead had no effect on germination percentage, except cv. SB at 2000 ppm. Germination rate, root and shoot length and dry weight decreased with increasing lead concentrations. A sand culture experiment was conducted to measure the ion contents (Na, K, Ca), photosynthetic pigments, total protein and nitrogen contents. Chlorophyll a, chlorophyll b and carotenoids decreased with the increasing concentration of lead. Three varieties (NIAB-IR-9, KSK-133 and SB) had a decreasing trend in potassium and calcium ions and increasing in lead ion concentration. There was an increase in sodium ion concentration with the increase in lead concentration but B-385 showed contrary results. Results confirm that lead has an inhibitory effect on plant growth and development.