Cadmium accumulation and its effects on metal uptake in maize (Zea mays L.)

The effects of different concentrations of Cd on growth of maize (Zea mays L.) and metal uptake were investigated. Cd accumulations in roots and shoots and the interactions among other metals (Mn, Fe, Cu and Zn) were analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES). The concentrations of cadmium chloride (CdCl(2).2.5H2O) used ranged from 10(-4) M to 10(-6) M. Cd had stimulatory effects during the first 5 days on root length of Nongda No. 108 at 10(-6) M and 10(-5) M Cd concentrations. Seedlings exposed to 10(-4) M Cd solution exhibited substantial growth reduction, and root growth even stopped. Root growth of Liyu No. 6 was stimulated at concentrations of 10(-5) M and 10(-6) M Cd during the entire experiment (15 days). Cadmium inhibited root growth of Liyu No. 6 at 10(-4) M Cd after 10 days of treatment. The Cd accumulation in roots and shoots of the two cultivars increased significantly (P < 0.05) with increasing Cd concentration and duration of treatment. Cadmium concentrated mainly in the roots, and small amounts were transferred to shoots. The proportion of Cd in the roots of Nongda No. 108 decreased with increases in Cd concentrations and duration of treatment, except for the group exposed to 10(-4) M Cd. In Liyu No. 6, the proportion of Cd in the root decreased progressively with an increase in Cd concentrations. Liyu No. 6 has a greater ability to remove Cd from solution and accumulate it when compared with Nongda No. 108. Liyu No. 6 can be considered a Cd-hyperaccumulator, according to the current accepted shoot concentration that defines hyperaccumulation as 0.01% (w/w) for cadmium. This cultivar, producing many roots and a high biomass and with great ability to accumulate Cd can play an important role in the treatment of soils stressed by Cd.