C - Lublin

OXYGEN STRESS IN THE ROOT ZONE AND PLANT RESPONSE
(SOME EXAMPLES)
Balakhnina T.I., Bennicelli R.P., Stępniewska Z., Stępniewski W.
One of the essential negative consequences of the soil flooding is oxygen
deficiency in the tissues of the submerged plants. Oxygen deficiency effects the
intensity and the direction of a number of physiological and biochemical reactions
and induces oxidative stress in the plant cells ( Bennicelli et al. 1998, Blokhina et
al., 1999; Hunter et al., 1987; Yan et al., 1996, Zakrzhevsky et al. 1995).
Under optimal conditions the content of reactive oxygen species (ROS)
maintains, with the help of antioxidative defence system, at a level which is safe
for the organism (Larson, 1988). Enzymes of superoxide dismutase and ascorbate –
glutathione pathway eliminate the excess of Н 2 О 2 in chloroplasts, in the cytoplasm
and in non photosynthesizing tissues (Foyer and Halliwell, 1976). Under stress
conditions the formation of ROS can exceed the antioxidative potential of the cell
and cause an oxidative damage (Halliwell, 1984).
The plant capability to activate the defense system against oxidative
destruction may be a key link in the mechanism of plant tolerance to unfavorable
conditions. Changes in the activity level of one or more antioxidative enzymes are
connected with the plant resistance to stressor action (Allen, 1995). The aim in this
paper was to shown response of stomatal resistance (R d ) on the examples of some
plants: Triticum aestivum L., Triticale L., Zea mays L.,Pisum sativum L.reaction
planted on unfavorable soil conditions through hypoxia to anoxia conditions. As
the indicators of soil aeration conditions Oxygen Diffusion Rate (ODR) and redox
potential (Eh) were used as described by Gliński and Stępniewski (1985).
MATERIALS AND METHODS
The experiments were performed with the use of Triticum aestivum L.,
Triticale L., Zea mays L.,Pisum sativum L under growth chamber in plastic pots,
5.9 dm 3 in volume, filled with soil material from the Ap horizon of a brown loess
soil (Orthic Luvisol) of pH in H 2 O - 7.3 (pH in KCl - 7.1) containing 0.89% C org ,
15% of 1 -0.1m fraction, 80% of 0.1-0.002 mm fraction, and 5% clay. Each pot
contained 6.2 kg of soil (dry mass basis) packed to a bulk density 1.35 Mg m -3
corresponding to total porosity 48% v/v .
The air temperature was kept at 23±2 о C and 12±2 о С during the day and
night, respectively. The day period was 12 hours with the light intensity of 190
Wat m -2 . The relative air humidity in the growth chamber was 45±5% during the
day and 70±5% during the night.
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