Sana Physiological responses of two grapevine (Vitis vinifera L.) cultivars to CycocelTM treatment during drought |
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Authors: | S Abdi N Abbaspur S Avestan A V Barker |
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Institution: | 1. Horticulture Department, Faculty of Agriculture, University of Urmia, Sero Road 11 km, Urmia 57561-51818, Iran;2. Biology Department, Faculty of Biology, University of Urmia, Sero Road 11 km, Urmia, 57561-51818, Iran;3. Horticulture Department, Faculty of Agriculture, University of Guilan, Tehran Road 5 km, Guilan 43653-41998, Iran;4. Stockbridge School of Agriculture, University of Massachusetts, 201 Natural Resources Road, Amherst, MA 01003, USA |
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Abstract: | The plant growth regulator CycocelTM (2-chloroethyl)trimethylammonium chloride] can be used to produce drought tolerance in grapevine (Vitis vinifera L.) due to a reduction in the ratio between vegetative growth and fruit production. To evaluate the physiological responses of two grapevine cultivars to drought and CycocelTM treatment, a factorial experiment was conducted in a greenhouse. The factors included irrigation frequency (at 5-, 10-, or 15-day intervals corresponding to no, mild, or severe drought stress), CycocelTM concentration (0, 500, or 1000 mg l–1), and cultivar (‘Rasheh’ or ‘Bidane-Sefid’). Stomatal conductance (gs) the net rate of CO2 assimilation (Anet), the rate of transpiration (Tr), and chlorophyll a and b concentrations decreased in plants exposed to mild or severe water-deficit stress, whereas carotenoid, proline, and total soluble sugar concentrations increased compared to plants with no drought stress. The relative water content (RWC) of leaves declined only under severe drought stress. A reduction in intercellular CO2 concentrations (Ci) occurred under mild drought stress; however, under severe drought stress, Ci values increased. Under mild drought stress, the reduction in the net rate of photosynthesis was related to stomatal closure, whereas under severe drought stress, non-stomatal factors were dominant. Water-use efficiency (WUE) improved under mild drought stress relative to non-stressed plants, but under severe drought, it declined. Foliar applications of CycocelTM resulted in increased Anet, gs, Tr, and WUE values, as well as proline and soluble sugar concentrations. ‘Rasheh’ was more tolerant to drought stress than was ‘Bidane-Sefid’. Foliar applications of CycocelTM, particularly at 1000 mg l–1, mitigated the negative effects of drought stress by increasing Anet, WUE, RWC, compatible solute concentrations, such as proline, soluble sugar, and chlorophyll a and b concentrations. |
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Keywords: | Grapevine Vitis vinifera drought stress Cycocel |
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