Seed-bank characteristics in a group of tropical weeds.
The response of seeds of 15 common Nigerian weeds to a set of standard treatments was followed during a 15-month period of burial in the soil. Monthly records were made of changes in dormancy and ability to germinate in light and darkness. These data were interpreted in relation to the periods of natural field emergence. Several spp. underwent a decline in resistance to germination at certain times of the year which generally coincided with peaks of seedling emergence in the field. Other spp. either underwent physiological changes soon after burial and then maintained that state for the rest of the period of the experiment or underwent little change. The seeds of several spp. lost viability rapidly when buried, especially the composites; the seeds of 2 of them all died within 1 month of burial. The significance of the results in planning weed control programmes are discussed in relation to changing agricultural practice in West Africa.