Stress responses of spring rape plants to soil flooding

Abstract

A b s t r a c t. Stress responses of spring rape to soil hypoxia were investigated during 8-days flooding. Soil air-filled porosity decreased from 25-30% to 0%, oxygen diffusion rate -from 2.6-3.5 to 0.34 µmol O 2 m -2 s -1, and redox potential -from 460 to 150 mV within few hours. Alcohol dehydrogenase activity in roots increased up to 7-fold after one day of flooding and then decreased to 170% of control. Superoxide dismutase activity in roots increased by 27% during first 3 days and then dropped to 60% of control; in the leaves superoxide dismutase activity increased in average by 44%. Ascorbate peroxidase activity in leaves increased by 37% during first 3 days and then decreased to control value. Glutathione reductase activity increased by 45% in roots of flooded plants but did not change in leaves. Proline concentration in leaves increased up to 4-fold on the 3d day of flooding and then decreased to control value. Thus soil flooding induces increase of alcohol dehydrogenase activity and subsequent increase of superoxide dismutase and glutathione reductase activities in roots while the leaves display a few days increase of free proline concentration and ascorbate peroxidase activity, and a long-term increase of superoxide dismutase activity.K e y w o r d s: spring rape, flooding, oxygen diffusion rate, redox potential, enzyme activity INTRODUCTION Soil flooding changes subsurface plant gas exchange. The low diffusion rate of oxygen in water-filled pore space of the soil results in limitation of oxygen availability for plant roots and soil microorganisms and leads to a switch of aerobic metabolism of plant roots into less efficient anaerobic fermentation, causing a fast depletion of carbohydrate reserves. Hypoxic conditions in soil cause also a decrease of Eh (Balakhnina et al., 2009(Balakhnina et al., , 2010 Gliñski and Stêpniewski, 1985;Bailey-Serres and Voesenek, 2008). This, in turn, stimulates evolution of carbon dioxide, molecular hydrogen, hydrogen sulphide, ethylene, and methane and accumulation in the soil of reduced phytotoxins (Fe 2+ , Mn 2+ , sulfide and, at high concentrations, ammonium) which can have a negative impact on plants, causing, among others, growth retardation, reduction in leaf size, wilting of shoots and necrosis (Lucassen et al., 2002; Smith and Restal, 2006). Plant adaptation to soil hypoxia includes series of interconnected reactions directed to survival during the periods of hypoxic and anoxic conditions and to the homeostasis maintenance. Anatomical and morphological changes help to provide oxygen to the plant tissues (Colmer, 2003;Pederson et al., 2009;Vartapetian et al., 2003).In connection with the specificity of the effect of hypoxia on plants, of special interest are compensatory changes connected with transformations of respiration pathways. Under oxygen deficiency most plants exhibit intensification of glycolysis accompanied with accumulation of lactate and ethanol (Rocha et al., 2010). Under prolonged and deep hypoxic stress the formation of ethanol prevails. Pr...

Plant Responses to Soil Flooding

“…Under drought conditions, soil moisture decreased up to 30 % and lower; under the full soil flooding, it increased up to 120 % of TWC by the volume (Kalashnikov et al 1994). The availability of oxygen to roots of plants changed under flooding during a few hours as following: E g decreased from 25-30 to 0 % (Balakhnina et al 2009); ODR in the root zone decreased from 120 to 6 μg m À2 s À1 (Zakrzhevsky et al 1995) or from 2.28-3.44 to 0.09-0.28 μmol O 2 m À2 s À1 ; Eh decreased from 543 to 70 mV (Balakhnina et al 2009(Balakhnina et al , 2012. The soil measurements performed during the period of drainage showed that the soil parameters in the flooded treatment variants returned to the control values already after 2 days of free drainage (Balakhnina et al 2010).…”

Effect of soil bulk density on forest tree seedlings

“…Too compacted a soil loses its ability of infiltration and prevents rainwater storage, which causes fast water flow and soil erosion (Cudzik et al, 2010). Soil compaction caused by multiple tractor units passing through the farm fields can cause shallow rooting of the plants and changes in roots morphological features (Bartholomew and Williams, 2010;Głąb, 2013;2012a,b;Powałka, 2008), while oxygen deficit in the soil is a reason of plants growth suppression (Balakhnina et al, 2012). The intensity and kind of cultivation which affect soil structure have also a significant meaning for microbiological activity or organic compounds content in the soil (Blouin et al, 2008;Gajda and Przewłoka, 2012;Sławiński et al, 2012).…”

Photosynthetic gas exchange, chlorophyll fluorescence, antioxidant enzymes, and growth responses of Jatropha curcas during soil flooding

“…oxygen and carbon dioxide in plants. The slow rate of gas diffusion in water limits the oxygen supply (Visser and Voesenek, 2004;Tan et al, 2010;Balakhnina et al, 2012). Soil flooding due to excess rains or seepage from large reservoirs may damage crops completely as it causes a dramatic impact on biochemical activities viz., aerobic respiration and photosynthesis in stagnant or slow-moving water (Armstrong and Drew, 2002;Islam et al, 2008;Jackson, 2008;Else et al, 2009).…”