Effect of different levels of sodium nitroprusside on some morphological and physiological characteristics of three grapevine cultivars under drought stress conditions

This study was conducted in 2015 as a factorial randomized complete block design with four replications to assess the effects of sodium nitroprusside on reducing the drought damage on morphological and physiological parameters of three grapevine cultivars (Yaghooti, Askari and Bidane sefid). Water deficit treatments were applied at four levels including: full irrigation (100% FC), moderate stress (60% FC), severe stress (30% FC) and re-irrigation after severe stress treatment and foliar application of sodium nitroprusside (SNP) (at 0, 0.5 and 1 mM). Water stress decreased plant height, stem diameter, chlorophyll content, relative water content and membrane stability, whereas significantly enhanced total soluble sugars, carotenoids, proline content, guaiacol peroxidase, ascorbic peroxidase and catalase activities. Based on the responses of cultivars to different levels of drought stress, it can be concluded that Yaghooti seems to be a more resistant cultivar to water stress compared to Askari and Bidanesefid cultivars. Foliar applications of SNP significantly decreased the negative effects of water stress in grapevine cultivars and increased plant height, stem diameter, chlorophyll content, relative water content, membrane stability, total soluble sugars, carotenoids, proline content, guaiacol peroxidase, ascorbic peroxidase and catalase activity. Therefore, application of SNP (especially at 0.5 mM) can reduce adverse effects of drought stress and improve growth in grape cultivars.