Physiological responses of Black cumin (Nigella sativa L.) to calcium silicate under drought and salinity stresses with iso-osmotic potential

To investigate physiological responses of black cumin to calcium silicate under salinity and drought stress condition with iso-osmotic potentials, a factorial experiment carried out based on the completely randomized design with three replications in research greenhouse of Faculty of Agriculture, Yasouj University, Iran in 2018. The first factor consisted of seven levels (salinity and drought stresses with iso-osmotic potentials of -2.4, -4.9 and -7.4 bar and control treatment) applied in Hoaglandchr('39')s solution. Salinity was applied with sodium chloride (NaCl) and drought with polyethylene glycol 6000 (PEG 6000). The results showed that at calcium silicate levels, salinity and drought stresses increased catalase and peroxidase activity, proline soluble sugars and malondialdehyde and also decreased leaf relative water content and leaf chlorophyll content. Silicate application mitigated the stress effects so that increased catalase and peroxidase activity, chlorophyll, proline and soluble sugars and decreased malondialdehyde content. In iso-osmotic potentials of drought compared with salinity, relative water content decreased but proline content, soluble sugars content, malondialdehyde content and catalase activity increased, indicating that black cumin sensitivity to drought is more than salinity based on physiological traits.