Study of Effective Methods to Break Seed Dormancy of Henbane (Hyoscyamus reticulatus L.)

Henbane Hyoscyamus reticulatus L. is a plant species in solanaceae family that seeds hardly germinate because of seed dormancy. In order to determine the best methods for seed dormancy breaking in henbane, a experiment was conducted as a completely randomized design with three replications. The treatments included moist pre-chilling (at 4 °C) for 7, 14, 21 and 28 days, combined treatment of gibberellic acid (500 ppm) and moist chilling at 4 °C for 7, 14, 21 and 28 days, soaking the seeds in hormones gibberellic acid, kinetin, auxin (250, 500, 750 and 1000 ppm) for 24 h, KNO3 (0.1, 0.2 and 0.4%), Hot water (70 and 90 °C) for 5, 10 and 15 minutes, soaking seeds under running water for 24 and 48h, soaking the seeds in sulfuric acid 70% and 90% (5, 10 and 15 minutes) and mechanical scarification with sandpaper. The results showed that seed dormancy in henbane is physiological since the highest germination percentage (96%) was obtained by using the combined treatment of gibberellic acid (500 ppm) and pre-chilling (for 25 days). In addition, moist chilling and gibberellic acid treatments -by itself- on breaking seed dormancy were remarkable in this plant as germination increased up to 40 and 81%, respectively. Effects of hormones were also statistically significant on increasing seed germination but compared with the salient effect of combined chilling with gibberellic acid treatment and gibberellic acid treatment was not so remarkable. On the other hand, other applied treatments (Hot water, sulfuric acid and mechanical scarification with sandpaper) had no effects on breaking seed dormancy in henbane which indicates that the type of seed dormancy in henbane is not physical or it is due to the accumulation of inhibitory substance in seed coat.