C. Schwartz et al., Root development of the Zinc-hyperaccumulator plant Thlaspi caerulescens as affected by metal origin, content and localization in soil, PLANT SOIL, 208(1), 1999, pp. 103-115
Penetration into and exploitation of contaminated soils by roots of hyperac
cumulator plants is a prerequisite for efficient removal of heavy metals, i
.e. efficacy of phytoextraction. This work was undertaken to study the deve
lopment of roots of the Zn-hyperaccumulator Thlaspi caerulescens under vari
ous conditions of soil contamination. Rhizoboxes were constructed with a re
movable plastic front cover, and filled with soils containing different amo
unts and forms of metals (Zn, Cd and Pb). Treatments were: homogeneous soil
profile, superposition of three layers, inclusion of contaminated soil int
o uncontaminated soil, or inclusion of uncontaminated soil into uniformly c
ontaminated soil. Four seedlings were transplanted into each rhizobox, and
development of the root system was periodically recorded for 133 days. At h
arvest, the biomass and size of the rosette of aerial parts were determined
. The aerial biomass/root length fraction as well as the kinetics of root d
evelopment varied according to the presence and localization of Zn. The dis
tribution and morphology of roots at harvest were strongly dependent upon t
he metal content and form in soil. Roots exhibited a high affinity for the
Zn-contaminated patches and showed two distinct morphologies according to t
he concentration of Zn in soil.