Alleviation of Salt Stress in Nigella Sativa L. By Gibberellic Acid and Rhizobacteria

Salinity is one of the extremely serious abiotic stresses for plants, affecting other subsequent consequences such as oxidative stress, which finally leads to cell death. A pot experiment was performed during 2014 / 2015 and 2015/ 2016 at Sakha Agricultural Research Station, to elucidatethe alleviation of salinity effects by spraying gibberellic acid (GA3), Azospirillum sp. and Azotobacter sp. Rhizobacteria (PGPR) and the combination between GA3+(PGPR) and their effects on the vegetative growth, yield characters, chemical composition and fixed oil percentage of black cumin plant. Salinity concentrations were 1000, 2000, 3000 and 4000 ppm sea water diluted compared with fresh water as control, GA3 was used at 100 ppm and PGPR at10%. Salinity treatments significantly decreased plant height, number of branches, plant dry weight, number of capsules, number of roots per plant, root volume, roots fresh and dry weights, capsules yield, seed yield /plant and 1000 seeds weight compared with control. Salinity also decreased chlorophyll content, fixed oil percentage and relative water content. However, proline content, peroxidase and catalase activities, membrane permeability and total soil soluble salts were increased relative to the control. GA3 or PGPR treatments alleviated the above mentioned undesirable effects of salinity. The increment of enzymes activities and proline accumulation due to GA3 or PGPR treatments are suggested to involve as part of the defense versus salinity on Nigella sativa L plants. To reduce the unfavorable salinity influences, treatment of GA3 at 100 ppm or PGPR at10% was recommended.