Influence of Heavy Metals on Seed Germination and Early Seedling Growth in Eruca sativa Mill.

Abstract

Heavy metals present in soil and water naturally or as contaminants from human activities can cause bioaccumulation affecting the entire ecosystem and pose harmful health consequences in all life forms. Some famous non-food hyperaccumulators such as Thlaspi caerulescens, Sedum alfredii, Pteris vittata, Arabidopsis halleri and Athyrium yokoscense are of very little economic value, making it difficult for them to be used for phytoremediation. In this paper, the influence of heavy metals Cu, Ni, Zn, Hg, Cr, Pb and Cd on seed germination and early seedling growth in oil crop Eruca sativa was evaluated under laboratory conditions. Our results indicated that among the 7 heavy metals tested, only Ni at higher concentrations (1 mM and above) significantly decreased the Eruca seed germination in a dose-dependent manner. All heavy metals except Zn and Ni decreased the root length first, then the shoot length or the fresh seedling weight, and seed germination was always the last to be influenced. With Ni, the root length, shoot length and fresh seedling weight were stimulated when Ni concentrations were under 1 mM; with Zn, the root length, shoot length and fresh seedling weight were increased by all concentrations tested (0.20 - 5.0 mM). Our results indicated that Eruca is tolerant or moderately tolerant to Cu, Hg, Cr, and Cd and highly tolerant to Pb, Ni and Zn, and can be developed as an industrial oil crop for phytoremediation of soils contaminated by heavy metals.