Effects of Grain Development and Thermal History on Grain Maturation and Seed Vigour of Pennisetum americanum

Studies were made of the viability and vigour of seeds of pearl millet (Pennisetum americanum) harvested at different stages of grain development and from different controlled-temperature environments. Seed viability and vigour of the next generation were dependent on the extent of grain development at harvest. Where grain had developed for only one-third of the potential grain-filling period before harvest, seed viability and vigour were greatly reduced. Harvest at or after the middle of grain-filling did not reduce seed viability or vigour. The temperature at which the grains had developed did not affect seed viability, but grains that had developed at 21/16 °C (day/night) produced seedlings of greater height and dry weight than those from grains which had developed at higher temperatures