Germination and dormancy-breaking of Diren (Melastoma dodecandrum) seeds

Melastoma dodecandrum (Melastomaceae) is a tropical and subtropical sub-shrub that grows in South China and North Vietnam. In this project, we studied the effect of various chemical pretreatments and short-term storage on its seed germination. Seeds were germinated at temperatures from 10 to 35 degrees C, and 25 and 30 degrees C were found to be the optimum temperatures for germination. Light provided by cool white fluorescent lamps at 800-1000 lux for 12h every day significantly improved seed germination. Soaking for 24 hours in 250-1000 mg/L gibberellic acid (GA(3)), 50-200 mg/L 6-Benzylaminopurine (6-BA) or 10%-30% potassium nitrate (KNO3) all significantly increased GP (germination percentage) and GI (germination index), while 10% hydrogen peroxide (H2O2) did not significantly improve GI, but increased the GP. Indole-3-butyric acid (IBA) at 50-200 mg/L and 20%-30% H2O2 solution did not significantly affect GP or GI. Dormancy was also relieved by after-ripening. Storage at 5, 10 and 25 degrees C for 30-120 days all accelerated germination compared to the control, and GP and GI both increased more rapidly at 10 and 25 degrees C than at 5 degrees C as storage durations increased from 30 to 90 days. However at -10 degrees C, GP and GI decreased with increased duration when stored for 30-120 days. To propagate seedlings of this sub-shrub, the seeds should be stored for 90-120 days at 15-25 degrees C to ensure the completion of after-ripening. In addition appropriate application of chemical pretreatments can enhance germination.