Isabgol (Plantago ovata Forsk) seed germinationand emergence as affected by environmental factorsand planting depth

Isabgol (Plantago ovata Forsk) seed germination and emergence in response to drought (Polyethylene glycol 8000) and salinity stress (NaCl), temperature, pH and planting depth were studied in laboratory and greenhouse experiments. Base, optimum and ceiling germination temperature were estimated as 3.35, 21.24 and 35.04 oC, respectively. Isabgol seed is rather tolerant to low water potential and high salt stress. Salinity stress up to 200 mM had no effect on Isabgol seed germination, but the germination decreased by increasing the salt concentration. The drought and salinity required for 50% inhibition of maximum germination were 328 mM and -1.24 MPa, respectively. High percentage of seed germination ( > 93%) was observed at pH=4-6 and declined to 52-58% at alkaline (pH 7-9) pH. Maximum seedling emergence occurred when the seeds were planted on the soil surface and decreased with increasing the depth of planting; no seed emerged from depth of 3 cm.