Time, Temperature and Germination of Pearl Millet (Pennisetum typhoidesS. & H.): III. INHIBITION OF GERMINATION BY SHORT EXPOSURE TO HIGH TEMPERATURE

Abstract

Seeds of pearl millet were germinated on wet filter paper at temperatures up to 50 °C. In one experiment, the temperature was held at 50 °C during imbibition and was then lowered to 32 °C or 25 °C. Germination rate and the maximum fraction of seeds germinating (Gm) both decreased as the time of exposure to 50 °C increased. In contrast, exposure to 50 °C after imbibition for 8 h slowed germination but did not significantly reduce Gm. When the 'high' temperature imposed after imbibition was reduced from 50 °C to 45 °C, there was a small reduction in the rate of germination but not in Gm. The responses have implications for the optimum time of sowing in the tropics when maximum daytime soil temperature at the depth of sowing is in the range of 45-50 °C.