Seed priming improves seed germination and reduces oxidative stress in black cumin (Nigella sativa) in presence of cadmium

Seed priming is a technique which is potentially able to promote rapid and more uniform seed germination and plant growth. In order to study the effects of seed priming treatments on some physiological and biochemical parameters, black cumin seeds were subjected to hormopriming and halopriming. The results indicated that germination percentage and rate were not impressed by cadmium. Radicle length was reduced more than plumule length and was expressed as the sensitivity index. Hormopriming (100 mg/L of salicylic acid) improved the germination, radicle elongation and dry weight (30.74, 42, and 31.57%, respectively) in compared with the control under cadmium stress (30 mg L-1). The maximum plumule elongation and plumule dry weight were related to the seeds primed with KNO3 about 48.61 and 25%, respectively. Increase in cadmium concentration until 30 mg/L increased electrical conductivity, malondialdehyde (MDA) and proline content for the all priming treatments and unprimed seeds, although in primed seeds was lower than that unprimed seeds. In highest cadmium concentration (30 mg/L), POX activity significantly increased in SA, KNO3 and KCl treatments about 56.25, 50 and 40.62% as compared with control, respectively. The reduction in soluble protein was observed in unprimed and primed seedlings with SA, KNO3 and KCl under highest cadmium concentration. In conclusion, the seed priming with SA due to improve germination performance of black cumin in different Cd levels can enhance tolerance of seedlings to toxic metals stress in the irrigation water. (C) 2015 Elsevier B.V. All rights reserved.