Effect of Water Stress on Photochemical Activity of Chloroplasts during Greening of Etiolated Barley Seedlings |
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Authors: | Bhardwaj, Ravindra Singhal, Gauri S. |
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Affiliation: | School of Life Sciences, Jawaharlal Nehru University New Delhi-110067, India |
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Abstract: | Water stress retards accumulation of chlorophyll and chlorophylla/b protein complex during greening of barley seedlings in light.The rate of 2,6-dichlorophenol indophenol (DCPIP) photoreductionin isolated chloroplast which decreases under water stress isenhanced significantly in the presence of electron donors, diphenylcarbazide (DPQ) and Mn2+. Under water stress, the decrease ofthe rate of oxygen evolution measured in continuous white lightwas 4073% and that of oxygen uptake (as a measure ofelectron transport through PS I from reduced DCPIP) was onlyabout 20%. During greening, under water stress, (i) a differentialinhibition of PS II biosynthesis as compared to PS I occurs,(ii) the site of electron donation by DPC seems to be closerto the reaction center ofPS II, (iii) the oxidizing side ofPS II near the oxygen-evolving system is affected maximallyby water stress. (Received March 11, 1980; Accepted November 13, 1980) |
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