Effects of plant growth regulators on Orobanche coerulescens seed germination

, used in traditional medicine and as a nutraceutical, requires external chemical stimuli for seed germination, similar to other Orobanchaceae species. This study aims to explore the effects of plant growth regulators conditioning and non-conditioning on its seed germination. Seeds collected from mature plants parasitizing A. capillaris were stored at 4 °C to induce dormancy and sterilized with NaOCl. Seeds were sterilized with NaOCl and Tween 20, and preconditioned on agar with gibberellic acid (GA3), fluridone, norflurazon, or brassinolide, and incubated at 4–18 °C for 3–7 days in darkness. Afterward, seeds were transferred to GR24 or SD H2O agar, and incubated at 23 ± 2 °C. Non-conditioned sterilized seeds were directly germinated on agar with various substances and incubated for 180 days. Seeds exhibited a viability of 39.23% at the fifth day after TTC-staining. Fluridone and norflurazon significantly promote germination during conditioning with SD H2O or GR24. The highest germination rate occurred with fluridone-conditioned seeds at 18 °C for 5 days, followed by SD H2O stimulation. However, GR24 may act as an inhibitor rather than a stimulant. These findings enhance our understanding of seed germination in this parasitic species, which can aid in conservation efforts.