Sanam Ghanepour, Mohammad-Reza Shakiba, Mahmoud Toorchi, Shahin Oustan
Department of Plant Ecophysiology, Faculty of Agriculture, University of Tabriz, Iran
Department of Plant Breeding and Biotechnology, Faculty of Agriculture, University of Tabriz, Iran
Department of Soil Science, Faculty of Agriculture, University of Tabriz, Iran
Key words: electrolyte leakage, growth, malondialdehyde, relative water content, stomatal conductance, Zn deficiency.
Under controlled conditions four common bean genotypes (KS21486, D81083, Akhtar, and COS16) were exposed to drought by reducing soil moisture content from 100±5 % FC to 55±5 % FC, which supplied whether with 4.5 mg Zn kg-1 soil, or did not receive Zn. Superoxide dismutase activity; SOD, malodialdehyde content; MDA, membrane stability index; MSI, relative water content; RWC, stomatal conductance, gs; and growth parameters (fresh weigh; FW, and dry weight; DW of shoot, and root DW) were measured. Dehydration caused a small change in SOD activity. RWC and gs fell down due to water stress which was in accordance with lipid peroxidation and solute leakage. MDA content and hydration status of Zn- fed leaves tend to be less adversely affected by water shortage than those grown at adequate Zn. Under Zn deficiency, decreased SOD activity and RWC, as well as, partial stomata closure contributed to damages on membranes lipids and integrity. Furthermore, such plants exhibited remarkable stunted growth. With the exception of root biomass, other growth-related traits were hampered by soil dryness. Drought- induced reductions in growth were associated with increments in MDA content and consequently MSI and in parallel to decrease of RWC. Enhanced the extent of lipid peroxidation and solute leakage in COS16 was in accordance with lower SOD activity and gs, due to greater water loss from leaf tissues caused by reduced available water. In conclusion, Zn application would help the crop to cope with drought during early growth stages, through mitigating of drought- induced oxidative stress and maintenance of leaf water status.
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