Breaking seed dormancy in Daphne mucronata and assessing the modulatory effect of its hydroalcoholic extract on dicot plants germination

Daphne mucronata is an important medicinal plant used in traditional medicine, but its limited habitats and low regeneration rates make propagation challenging. This study aimed to enhance D. mucronata seed germination using gibberellic acid (GA3), potassium nitrate, and seed scarification. The highest germination was achieved with GA3 at 1000 ppm, reaching 77.7% in shelled seeds and 66.6% in unshelled seeds. Results confirmed that the seeds exhibit physical-physiological dormancy due to the seed coat’s stiffness and hormonal balance, possibly due to germination inhibitors or the lack of promoting substances. Moreover, this plant is recognized for its allelopathic and stimulatory effects on other plants. This study aimed to assess these effects by investigating the influence of different concentrations of D. mucronata leaf hydroalcoholic extract (DMLE) on the germination of three dicot plants: Lepidium sativum, Amaranthus retroflexus, and Portulaca oleracea. As DMLE concentration increased, the germination of A. retroflexus and L. sativum decreased, with zero germination at 2%. In contrast, DMLE enhanced P. oleracea germination, reaching 54.66% at 2% concentration, compared to 6.66% in the control. The allelopathic effects of D. mucronata leaves could be attributed to their high phenolic content (766.9 mg/100 g DW), showing species-specific stimulatory effects on P. oleracea.