Isabgol (Plantago ovata Forsk) seed germination and emergence as affected by environmental factors and planting depth

Isabgol (Plantago ovata Forsk) seed germination and emergence in response todrought (Polyethylene glycol 8000) and salinity stress (NaCl), temperature, pH andplanting depth were studied in laboratory and greenhouse experiments. Base,optimum and ceiling germination temperature were estimated as 3.35, 21.24 and35.04 oC, respectively. Isabgol seed is rather tolerant to low water potential and highsalt 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 andsalinity required for 50% inhibition of maximum germination were 328 mM and -1.24 MPa, respectively. High percentage of seed germination (>93%) was observedat pH=4-6 and declined to 52-58% at alkaline (pH 7-9) pH. Maximum seedlingemergence occurred when the seeds were planted on the soil surface and decreasedwith increasing the depth of planting; no seed emerged from depth of 3 cm.