Effects of lead salts on growth, chlorophyll contents and tissue concentration of rice genotypes

Abstract

Lead (Pb) is one of the most abundant heavy metal pollutants and readily absorbed by plants that exerts toxic effects and also gets entered into human food chain. There are very few examples of genetic differences being exploited to produce low Pb rice food through decreased metal uptake from Pb-polluted environment. In this regard, solution culture screening has been proposed as a rapid technique for the identification of prospective rice genotypes. In a hydroponics study, fourteen rice genotypes were tested against varying rates of applied Pb, to investigate the effects of chloride, sulfate and nitrate salts of Pb on growth, chlorophyll contents and tissue concentration of rice genotypes. The plants were exposed to 0, 100 and 200 μM Pb as PbCl2, PbSO4 and Pb(NO3)2, separately for 42 days. Thus, there were seven treatments arranged in completely randomized design each with four replications. The results showed that at a certain defined Pb rate (100 or 200 μM), the toxic effects of Pb as Pb(NO3)2 to rice plants were found significantly (p = 0.05) higher than PbCl2 and PbSO4 treatments. At all applied Pb treatments, the Shaheen Basmati and KS-282 were found tolerant to Pb because of higher growth, total chlorophyll contents, low root and shoot Pb concentration. Therefore, these both genotypes were found to be a good source for future rice breeding programs or grown by the farmers for Pb risk-free rice production in Pb polluted environment.