Page 228 - Plant-Based Remediation Processes

220 M. Griga and M. Bjelkova ´

elevated in orders of magnitude (10 times, 100 times higher; Broadley et al. 2001;
Bjelkova ´ et al. 2011a). Thus, it is interesting to know, what is the behaviour of flax
and hemp plants in such “drastic”, more or less non-physiological conditions? It
means—are there any negative effects on plant growth and development, yield and
quality of final harvestable product (fibre, seeds)? Gaudchau and Marquard (1990)
did not find any negative effect of increased soil Cd concentration on the yield of
seeds, oil content and fatty acid composition of two linseed varieties. In general, the
natural content of Cd (or other heavy metals) did not influence growth and devel-
opment of flax plants as well as their yield parameters (Moraghan 1993;
Mankowski et al. 1994; Baraniecki et al. 1995, 2001; Jankauskiene 1998). Sligthly
elevated concentrations of some heavy metals had even stimulatory effect; only
significantly increased soil concentrations led to yield reduction, primarily in seeds,
less in the stem (Moraghan 1993; Mankowski et al. 1994; Jankauskiene 1998)or
even resulted in plant death (Linger et al. 2005). Grzebisz et al. (1997b) also
reported minor effect of heavy metals on flax yield in the soils polluted by industrial
activity (copper smelting), and the key significance was considered to sufficient
nutrient supplementation and proper agrotechnology. Jankauskiene (1998)—based
on the field experiments with fibre flax—did not find yield depression up to the
following soil levels of heavy metals (mg kg 1 soil): Cr—24, Cd—1, Pb—16, Ni—
14, Cu—8, Mn—200.
Our recent data (Bjelkova ´ et al. 2011a) showed that even very high Cd
concentrations (1,000 mg Cd(NO 3 ) 2 kg 1 soil) did not have visible effect on flax/
linseed plants growth and development. The soil Cd concentrations over 100 mg Cd
(NO 3 ) 2 kg 1 soil resulted in dramatic increase of Cd retention in roots and very
slow Cd transport to above-ground organs. Such elevated Cd soil concentrations
helped to distinguish between flax/linseed cvs as related to distribution of Cd from
root to shoot (or above-ground plant parts) (e.g. cv. Jitka—low Cd retention in root,
high root-to-shoot transport; cv. Escalina—high Cd retention in root, low root-to-
shoot transport). Such contrasting models may contribute to understanding of
mechanisms HMs tolerance and transport by searching for specific markers—
PCs, HMW complexes with HMs (Vrbova ´ et al. 2009; Najmanova et al. 2012).
Up to date results show that flax/linseed is able to tolerate elevated concentrations
of some heavy metals in soil without evident yield depression or decrease of quality
of harvested product—this fact has a crucial significance for further industrial
processing of harvested biomass (stem—fibre, seed—oil).
The distribution/accumulation of HMs in hemp organs is summarised in
Table 11.4. The early studies distinguished only between roots and above-ground
biomass (Jurkowska et al. 1990, 1992; Jasiewicz 1991; Gorlach and Gambus ´ 1992;
Gorlach 1994); as compared to flax early studies, more metal elements were studied
in hemp, namely Fe, Mn, Zn, Cu, Mo, Cd, Pb, Ni and Cr. The content of heavy
metals in roots and above-ground biomass was determined as influenced by N-, P-
or Cu fertilisation and liming. In general, roots retained usually more Fe, Mn, Zn,
Ni, Cu, Cd and Pb than above-ground biomass, while concentration of Mo was on
similar level. Later on, Baraniecki et al. (2001) and Kozlowski et al. (2002)
compared stem and seed concentrations at on site experiments and they found