Study of germination and seedling growth of black cumin (Nigella sativa L.) treated by hydro and osmopriming under salt stress conditions

The objective of the study was to determine the responsible factors for germination and early seedling growth due to salt toxicity or osmotic effect and to optimize the best priming treatment for these stress conditions. To study the effect of osmopriming and hydropriming on germination and seedling growth of black cumin (Nigella sativa L.) under salt stress conditions this experiment was conducted at Torbat-Heydariyeh University, Torbat, Iran. The treated seeds (control, hydropriming and ZnSO4) of black cumin were evaluated at germination and seedling growth for tolerance to salt (NaCl and Na2SO4) conditions at the same water potentials of 0.0, -0.3, -0.6, -0.9 and -1.2MPa. Electrical conductivity (EC) values of the NaCl solutions were 0.0, 6.5, 12.7, 18.4 and 23.5 dSm-1, respectively. Results showed that hydropriming increased germination and seedling growth under salt stress. Germination delayed in both solutions, having variable germination with different priming treatments. In NaCl treatment, germination percentage, root and shoot weight, shoot and root length were higher but mean germination time and abnormal germination percentage were lower than Na2SO4, at the same water potential. The root / shoot weight and R/S length enhanced with increase of osmotic potential in both NaCl and Na2SO4 solutions. NaCl had less inhibitor effect on seedling growth than the germination. It was concluded that inhibition of germination at the same water potential of NaCl and Na2SO4 resulted from salt toxicity rather than osmotic effect. The findings of this experiment can be useful and applied to achieve best germination and uniform emergence under field conditions for farmers of medicinal plants