Germination Responses of Black Cumin (Nigella sativa L.) Seeds to NaCl Induced Osmotic Stress Expressed

Salinity is one of the major environmental stress factors limiting agricultural production. The objective of this study was to determine the effects of different NaCl concentrations on seed germination and early seedling development in the Çameli variety of black cumin (Nigella sativa L.). The experiment was conducted using NaCl concentrations of 0, 50, 100, 150, and 200 mM NaCl concentrations, which corresponded to osmotic potentials of 0, -0.244, -0.487, -0.731, and -0.974 MPa, respectively. Germination rate, seedling and root length, fresh and dry weights, and various germination and vitality indices were determined. The results of the study showed that the germination rate, which was 93% in the control treatment, decreased to as low as 14% with increasing salt-induced osmotic stress. While low and moderate levels of osmotic stress did not statistically significantly alter the germination rate, high levels of osmotic stress markedly inhibited germination and seedling development. Seedling and root fresh weights and dry weights decreased depending on the stress level. MGT values, which were 4.47 days in the control treatment, increased to 12.06 days under the -0.976 MPa treatment. T50 values increased from 3.83 days to 12.06 days. In particular, the fact that root and shoot development did not occur despite germination taking place under the -0.974 MPa condition demonstrated that early seedling development can be completely suppressed under high osmotic stress. In conclusion, it was determined that the Çameli nigella variety can largely maintain its germination performance under low and moderate levels of NaCl stress; however, germination and, in particular, early seedling development are significantly adversely affected at high salinity levels.