Effect of different treatments on dormancy-breaking and germination of perennial pepperweed (Lepidium latifolium) (Brassicaceae).
The purpose of our study was to better understand the seed-germination ecology of the invasive plant Lepidium latifolium, which grows in orchards and among cool-season crops in Iran. The seed dormancy of this weed was studied using soil burial, scarification, cold stratification, constant temperatures, flooding, and potassium nitrate (KNO3) and gibberellic acid (GA3) treatments. The results showed that the seeds' dormancy can be broken most effectively by scarification, KNO3, flooding and after-ripening. The highest seed-germination percentage was achieved from physical scarification (66%), while chemical scarification had a comparatively low effect (35%). KNO3 could induce the seed germination (61%) in 0.02 M concentration. waterlogging resulted in 60% germination, and the seeds survived in the flooding conditions for more than 90 days. Constant temperature increased the seeds' germination and promoted its percentage (37%). Soil burial had a positive effect on the germination of L. latifolium during the first 30 days of warm conditions, with germination rates of 34.5% for 1 cm soil-burial depth, and 26% for 10 cm. Increasing GA3 concentration to 20 ppm resulted in 29% germination; greater GA3 concentrations did not increase the germination percentage significantly.