Sn. Whiting et al., Hyperaccumulation of Zn by Thlaspi caerulescens can ameliorate Zn toxicityin the rhizosphere of cocropped Thlaspi arvense, ENV SCI TEC, 35(15), 2001, pp. 3237-3241
Citations number
20
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
The metal hyperaccumulating plant Thlaspi caerulescens is effective in depl
eting plant-available metals from the soil. We hypothesized that this reduc
tion of toxic metals in the rhizosphere of T caerulescens would increase th
e growth of less metal-tolerant plants with their roots permitted to interm
ingle and develop coincident rhizospheres. The extent of rhizosphere intera
ction between T caerulescens and a coplanted nonaccumulator species, Thlasp
i arvense, was controlled using barriers. Two media with elevated concentra
tions of water-extractable Zn were prepared by enriching one soil with zinc
oxide (ZnO) or zinc sulfide (ZnS). The shoot mass of T arvense was increas
ed by 30% when its roots were permitted to intermingle with those of T. cae
rulescensin the ZnO treatment. The concomitant 2-3-fold reduction in shoot
Zn concentration in T arvense confirmed that its improved growth was associ
ated with reduced uptake and phytotoxicity of Zn. Thlaspi arvense also show
ed increased growth and reduced metal uptake when cocropped with T caerules
cens in the ZnS treatment. We conclude that the strong Zn accumulation by T
caerulescens might enhance the establishment and development of surroundin
g less-tolerant species on soils that are naturally- or anthropogenically-e
nriched with metals.