THE DECREASE IN SEED-GERMINATION OF STRIGA-HERMONTHICA IN BENIN IN THE COURSE OF THE RAINY-SEASON IS DUE TO A DYING-OFF PROCESS

Germination rate and viability of Striga hermonthica seeds in the fiel d in the Republic of Benin decreased steadily in the course of the rai ny season. The percentage of germinating seeds decreased from 82% on A pril 13, 1993 to 16% on October 13, 1993. The percentage of viable see ds, according to the tetrazolium colour test, decreased in the same pe riod from 90% to 15%. In the subsequent rainy season these values furt her decreased and it was concluded that the seeds do not enter a stage of secondary dormancy. This implies that if host plants (including wi ld hosts) are consistently kept away from infested fields for one or t wo year periods, this will lead to a dramatic decrease in the number o f viable S. hermonthica seeds in the soil.