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Protective Antioxidant Enzyme Activities are affected by Drought in Quinoa (Chenopodium Quinoa Willd)

Journal of Biology, Agriculture and Healthcare 01/2013; 3(4):62-68.

ABSTRACT Changes in water availability are responsible for a variety of biochemical stress responses in plant organisms. Stress induced by this factor may be associated with enhanced reactive oxygen species (ROS) generations, which cause oxidative damage. In the present study we investigated the activities of antioxidant enzymes superoxide dismutase (SOD), polyphenoloxydase (PPO), peroxidase (POD) and catalase (CAT), measured at flowering in quinoa, subjected to varying levels of drought stress. Drought levels were 100, 50 and 33% of evapotranspiration (ETc), and rainfed. Compared to full water supply (100%ETc), the activities of SOD under dry conditions (33%ETc) increased significantly by 39 and 90%, in 2011 and 2012, respectively. Under rainfed conditions, the activities of SOD increased by 178.71 and 322.42 %. The CAT activity in rainfed treatment increased significantly by 103.15% (2011) and 87.4% (2012) compared to the full water supply treatment. Compared to the control, POD activity in both essays increased significantly by 50.2% in 33%ETc of 2012 assay and increased by 72.8 and 115.6% in the rainfed treatment of 2011 and 2012 assays respectively. In comparison to the full watered treatment, the PPO activity increased in all treatments. These results suggest that antioxidant enzymes play important roles in reducing oxidative stress in quinoa plant exposed to drought stress.

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Available from: Said Wahbi, Jun 13, 2015
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    ABSTRACT: Water shortage is a critical problem touching plant growth and yield in semi-arid areas, for instance the Mediterranean region. For this reason was studied the physiological basis of drought tolerance of a new, drought tolerant crop quinoa (Chenopodium quinoa Willd.) tested in Morocco in two successive seasons, subject to four irrigation treatments (100, 50, and 33%ETc, and rainfed). The chlorophyll a fluorescence transients were analyzed by the JIP-test to translate stress-induced damage in these transients to changes in biophysical parameter’s allowing quantification of the energy flow through the photosynthetic apparatus. Drought stress induced a significant decrease in the maximum quantum yield of primary photochemistry (ΦP0 = Fv/Fm), and the quantum yield of electron transport (ΦE0). The amount of active Photosystem II (PSII) reaction centers (RC) per excited cross section (RC/CS) also decreased when exposed to the highest drought stress. The effective antenna size of active RCs (ABS/RC) increased and the effective dissipation per active reaction centers (DIo/RC) increased by increasing drought stress during the growth season in comparison to the control. However the performance index (PI), was a very sensitive indicator of the physiological status of plants. Leaf area index, leaf water potential and stomatal conductance decreased as the drought increased. These results indicate that, in quinoa leaf, JIP-test can be used as a sensitive method for measuring drought stress effects.
    Chilean journal of agricultural research 02/2015; 75(2):174 - 183. DOI:10.4067/S0718-58392015000200006 · 0.45 Impact Factor