Page 226 - Plant-Based Remediation Processes

218 M. Griga and M. Bjelkova ´

transport and accumulation in order to find biochemical/molecular markers
connected with low/high retention of HMs in roots and their easy/hard transport to
above-ground plant parts, thus reflecting both hygienic and phytoremediation aspect,
respectively. As the laboratory analyses of HMs content are very expensive, such
markers may speed the selection of genotypes of interest (Penner et al. 1995).
Existence of variation in the uptake, translocation and accumulation of heavy metals
by flax is a prerequisite for selection and further breeding both low- and high-
accumulating genotypes.
The field screening of Linum germplasm resources (AGRITEC Flax Collection;
location with natural background of heavy metals in soil) for a trait Cd/Pb/Zn
accumulation has not been finished yet (in 2010–2011, ca. 350 accessions
analysed—Bjelkova ´, unpublished results)—the variation exists, nevertheless it is
not large enough to select hyperaccumulating genotypes (Cd stem range:
1 1
0.05–3.49 mg Cd kg DW; Pb stem range: 0.15–2.72 mg Pb kg DW; Cd seed
1 1
range: 0.34–2.22 mg Cd kg DW; Pb seed range: 0.23–4.62 mg Pb kg DW; Zn
1 1
stem range: 1.46–96.42 mg Zn kg DW; Zn seed range: 40.82–84.23 mg Zn kg
DW). In contrast to flax/linseed, there is no evidence in available literature on
genetic differences in heavy metal uptake and accumulation by hemp plants as
majority of papers were dealing only with one variety or even the experimental
material was not described (Table 11.4). The following hemp cvs were studied as
related to HMs in the course of last 20 years: Bialobrzeskie, Beniko, Juso 31,
Kompolti, Fibranova, Silistrinski, Carmagnola (Jasiewicz 1991; Jurkowska et al.
1990; Gorlach and Gambus ´ 1992; Gorlach 1994; Baraniecki and Mankowski 1995;
Baraniecki et al. 1995, 2001; Kozlowski et al. 2002; Linger et al. 2002;Lo ¨ser et al.
2002; Citterio et al. 2003, 2005; Angelova et al. 2004). Only Baraniecki et al. (1995,
2001) and Kozlowski et al. (2002) used in on site experiments two hemp varieties
for comparison (cvs Beniko and Bialobrzeskie). Despite the absence of statistical
evaluation, there were negligible differences between these two varieties in the
accumulation of Cu and Pb in the seeds, stems and fibre—the only exception was
the accumulation of Pb in stems (cv. Beniko accumulated more than 2.5 times more
Pb than cv. Bialobrzeskie; 3.20 versus 1.20 mg Pb kg 1 DW) (Baraniecki et al.
1995). However, later experiments of the same group showed more or less similar
accumulation of Cu, Pb, Zn and Cd by both cvs with dominating year-to-year effect
or the fluctuating data did not show any clear tendency (Baraniecki et al. 2001;
Kozlowski et al. 2002). Our experiments (Bjelkova ´ et al. 2005 and unpublished
results) designed to compare four hemp cvs (Beniko, Glera, Juso, Silesia) showed
minimal differences in Cd uptake in geogenic Cd concentrations.
The analysis of published data results in two conclusions (1) The genetic
variation for HMs accumulation in above-ground biomass in flax/linseed is limited
(even in germplasm resources) and thus, the original expectations have not been
fulfilled (i.e. finding genotypes with the level of HMs accumulation close to wild
hyperaccumulators); (2) There are no data in literature on genetic variation for HMs
accumulation in hemp—the screening of genotypes/lines/cultivars must be still
done to obtain first view of the problem. It is a question, if would be reasonable
to start conventional breeding for HMs tolerance and accumulation and what would