Zinc Tolerance and Accumulation in Eight Oil Crops

Although zinc (Zn) is an essential element for normal plant growth, it is phytotoxic at high concentrations. To identify oil crops that can be cultivated in Zn-contaminated soil for biodiesel production, the ability of Zn tolerance and accumulation of eight oil crops were evaluated under 200–800 mg Zn kg−1 sand substrates (DW) conditions. Results showed that all crops, except sunflower, could grow quite well under 400–800 mg kg−1 Zn stress. Among them, hemp, flax, and rapeseed showed small inhibitions in plant growth and photosynthetic activities, indicating these crops had a strong tolerance to high Zn concentrations and could be cultivated in Zn-contaminated soils. Peanut and soybean exhibited higher Zn concentrations in shoots, higher bio-concentration factor, and higher total Zn uptake, as well as higher biomass. These crops, therefore, are good candidates for the implementation of the new strategy of cultivating biodiesel crops for phytoremediation of Zn-contaminated soils.