To address the poor seed viability problem of pearl millet in Ghana, the influences of time of harvesting, some seed physical characteristic and moisture content relations on viability were evaluated. Harvesting was done on day 1, 3, 5, 7 and 14 from the physiological maturity or the hard-dough stage. The seeds were also fractionated into <2, >2 and 1-3 mm grades. Data on seed moisture content, bulk density and thousand seed weight were determined. Standard germination tests were carried out and counting was done from day 3 to 9. An analysis of the physical environment revealed that the extreme dry conditions (Temperature~18-42°C, RH%~20-54) which prevail during the period of seed storage may provide opportunity for seed drying. Gradual increases in seed weight, bulk density and thousand seed weight occurred from day 1 to 5 and peaked by 7 days after hard-dough stage. Consistently high germination rates were attained by harvesting at 7 days after hard-dough. The seeds harvested at day 1, 3 and sometimes 5 showed abysmal performances for most vigor traits evaluated. Within 9 months of storage, low germination rate of 53.3-65.8% was recorded. Four varieties, Arrow millet, Bongo short head, Bristle millet and Tongo yellow, which exhibited large seed characteristics consistently showed higher germination rates compared with their counterparts Salma-1, Salma-3, Indiana-05 and Langbensi millet. Across varieties, large seeds recorded higher germination rates compared with other grades. Seed vigor traits such as incidence of seedling abnormalities and days 3 to 5 leaf stages were positively related to early harvesting and large seed size.
I. Sugri, S.K. Nutsugah and J. Yirzagla, 2011. Effect of Some Seed Physical Characteristics on Viability of Pearl Millet (Pennisetum glaucum (L.) R. Brown). Research Journal of Seed Science, 4: 181-191.