Risk-spreading strategies of two dwarf bamboos in heterogeneous Pb (lead) environments

Abstract

As a typical clonal plant, dwarf bamboo has potential applications in the remediation of Pb (lead) -contaminated soils; however, the environmental risk-spreading strategies of dwarf bamboo in heterogeneous Pb-contaminated environments are not known. To this end, we conducted hydroponic experiments on two species of groundcover bamboo, Sasa fortunei (Van Houtte) Fiori (SF) and Sasa auricoma (Mitford) E.G. Camus (SU), with seven treatments including two environments, homogeneous and heterogeneous. The results showed that SF protected the distal ramets (DRs) and that SU did the opposite in a homogeneous Pb environment. In the heterogeneous Pb environment, the NTR of both bamboos (RSISF = 0.64/0.44, RSISU = 0.40/0.33) was higher than that under the heterogeneous high-concentration environment (RSISF = 0.15/0.28, RSISU = 0.26/0.26). Moreover, the total Pb concentration of SF was as high as 80123.5 mg/kg and that of SU was as high as 53333.33 mg/kg, and in general, SF was more capable of absorbing Pb. In the heterogeneous low-Pb environment, the ascorbic acid and proline levels of the TRs (Pb-treated ramets) were elevated to alleviate oxidative stress; in contrast, antioxidant enzyme activities of SU were all reduced due to the damage caused by Pb absorption. The results of the experiments showed that SF had a greater risk-spreading capacity and higher Pb concentrations than SU in heterogeneous environments, and therefore, SF had better Pb bioenrichment and tolerance than SU. We proposed a novel metric (RSI) to assess the ability of plants to spread risk, and the results of the study provid a basis for dwarf bamboo phytoremediation in heterogeneous Pb environments.