ISSN 10214437, Russian Journal of Plant Physiology, 2013, Vol. 60, No. 2, pp. 295–299. © Pleiades Publishing, Ltd., 2013.
The contamination of soils with metals is a major
environmental problem throughout the world .
Cadmium (Cd) is a highly toxic metal, and it has been
ranked number 7 among the top 20 toxins mainly due
to its negative influence on the enzymatic systems of
the cells [2, 3]. Large areas of land in many countries
have been contaminated by Cd due to the application
of sludge or urban composts, pesticides, fertilizers,
emissions from waste incinerators, waste water irriga
tion, residues from metalliferous mining, and the
metal smelting industry [4, 5].
Maize is one of the major crops cultivated through
out the world, and China is the second largest maize
producer and consumer after the United States .
Maize may be exposed to heavy metal stress during
their growing period. The accumulation of Cd in the
seeds and other aboveground parts of maize became a
serious problem for agriculture and human health. Cd
retained in stems, leaves, and other crop parts are
either used as fodder or recycled when the inedible
crop residues are returned to the soil .
This text was submitted by the authors in English.
Cd excess may stimulate the formation of free rad
icals and reactive oxygen species, perhaps resulting in
oxidative stress [8, 9]. The chlorophyll content is used
to assess the impact of environmental stresses on
plants. Moreover, proline accumulation, accepted as
an indicator of environmental stresses, is also consid
ered to have important protective roles .
The objectives of this study were (i) to examine the
growth response and Cd accumulation in maize seed
lings at different external Cd supply levels under
hydroponic conditions; (ii) to determine the effect of
external Cd stress on the physiological traits, such as
chlorophylls, carotenoids, and proline in the leaf
blades of maize seedlings.
MATERIALS AND METHODS
Plant materials and experimental design.
L.) cultivar were offered by Chinese
Academy of Agricultural Sciences. Seeds were germi
nated in a perlite medium and under intermittent mist
until the development of the first true leaf. Then the
plants were grown in a greenhouse under natural light
and temperature conditions (daytime,
). Seedlings were watered with deionized water
or 0.25strength Hoagland solution . At the two
The Response of Maize Seedlings to Cadmium Stress
under Hydroponic Conditions
C. X. Wang
, L. Tao
, and J. Ren
College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
School of Environmental and Municipal Engineering and Institute of Environmental Ecology, Lanzhou Jiaotong University,
Lanzhou 730070, China;
Received February 2, 2012
—The effects of cadmium (Cd) supply level in nutrient solution (0, 12.5, 25, 50, 100, 200, 400, and
M) on growth, Cd accumulation ability, and the related physiological indices of maize (
seedlings were studied under hydroponic conditions. The results showed that the increments in the shoot
height and biomass were stimulated at relatively low external Cd supply levels (<100
M), while they were
inhibited at Cd supply levels over 200
M. Cd accumulation ability of the maize seedlings also showed the
similar stimulation/inhibition pattern as shoot growth, and the Cd contents in the shoots and roots reached
the peaks (389.5 and 505.5 mg/kg dry wt, respectively) at 50
M Cd. The contents of chlorophyll
, and carotenoids in the maize leaf blades decreased with increasing external Cd supply level. At the
highest Cd supply level (800
M), the contents of chlorophyll
, and carotenoids in the leaf
blade were only 38.9, 46.0, and 29.7% of the control plants, respectively. Moreover, chlorophyll
sensitive to the Cd stress than chlorophyll
. The increased proline content in the leaf blade of maize seedlings
resulted from external Cd stress indicates that maize can adapt to the adversity menace via changing the con
tent of proline.
Keywords: Zea mays
, cadmium, chlorophylls, carotenoids, proline