Assessing saffron response to salinity stress and alleviating potential of gamma amino butyric acid, salicylic acid and vermicompost extract on salt damage

Detailed information on response of saffron, one of the most economical medicinal plants, to high levels of saline (NaCl) water irrigation is not available. In this study, effect of spraying Gamma amino butyric acid (GABA), salicylic acid (SA) and vermicompost extract (VCE) on root structure, corm and flower production, K+ and Na+ allocation, physiological and photosynthesis aspects along with antioxidant enzymes activity of saffron were evaluated under saline water irrigation. The treatments consisted of adding four salinity doses to irrigation water (0, 5, 10 and 15 dS m−1 of NaCl) as main plot and four exogenous foliar applications (control, distilled water; GABA, 10 mM; SA, 1.5 mM and VCE, 5%) as subplot. The results illustrated that increasing root density; generating larger and heavier corms; and promoting Na+ exclusion and K+ accumulation were the main tolerance mechanisms which help saffron produce a satisfactory economical yield under salt stress conditions. All the foliar application treatments, especially VCE, could nullify the detrimental impacts of salinity. VCE remedied the nutrient deficiency caused by reducing soil osmotic potential and improved aerial K+/Na+ ratio in salinity conditions. Triggering antioxidant defense system was the most notable mechanism of GABA and SA that led to alleviation of adverse effect of salt stress. In conclusion, the results demonstrated that saffron can be introduced as a salt-tolerance crop and exogenous foliar application of VCE, GABA and SA are suggested for minimizing negative effects of salinity on saffron.