Water Stress and Temperature in Relation to Seed Germination of Pearl Millet and Sorghum
Pearl millet [Pennisetum glaucum (L.) R. Br.] is a potentially productive high-quality grain crop that appears superior to sorghum (Sorghum bicolor L. Moench) in establishment under limited soil moisture. Our objectives were to compare sorghum and pearl millet seed germination under moisture stress conditions at two temperatures. Drought resistance was tested by germinating seeds in polyethylene glycol solutions with osmotic pressures of 0, 0.4, 0.8, and 1.2 MPa at 15 and 30 °C. At both temperatures pearl millet germination was less affected by increasing osmotic pressure (OP) than sorghum germination. At 30 °C sorghum germination decreased steadily as OP increased above 0 while pearl millet germination decreased significantly above an OP of 0.8 MPa. At 15 °C, pearl millet germination was always significantly higher than sorghum germination although the germination of both decreased steadily as OP increased. No germination occurred in either species at an OP of 1.2 MPa at 15 °C. The median germination time (MGT) at 30 °C for pearl millet was less than the MGT of sorghum under osmotic stress. There were no differences between sorghum and pearl millet MGT at 15 °C except at an OP of 0.4 MPa. The average MGT was higher at 15 °C than at 30 °C. Median germination time increased with each rise in OP, except for pearl millet between osmotic pressures of 0 and 0.4 MPa at 30 °C. The results indicate that pearl millet seed germinates better than sorghum seed under drought and lower temperature. The ability to germinate under stressful conditions could give pearl millet an advantage in stand establishment under the less than ideal conditions that frequently occur in the field.
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