EFFECT OF TEMPERATURE, LIGHT, AND SIMULATED DROUGHT ON THE GERMINATION OF SOME WEED SPECIES FROM THE SUDAN

The effect of temperature, light, and simulated drought on the germina tion of Sorghum arundinaceum, Ocimum basilicum, Brachiaria eruciformis , Dinebra retroflexa, and Ischaemum afrum was studied. All weed specie s failed to germinate at 5-degrees-C. Gemination of Sorghum arundinace um occurred at 10-degrees-C, but other weed species germinated at 15-d egrees-C. Ungerminated seeds, however, were able to germinate after be ing transferred to 30/20-degrees-C. Indiscriminately, the maximum temp erature for germination of all weed species was 40-degrees-C. The opti mum consistant temperature, however, varied between species (20 - 35-d egrees-C). The alternating temperature 30/20-degrees-C (12/12 hr light /dark) was the optimum for all species. All species germinated when ex posed to light. Germination of Sorghum arundinaceum, Ocimum basilicum, Brachiaria eruciformis, Dinebra retroflexa,and Ischaemum afrum at 30/ 20-degrees-C in the dark was 97,4,50, 2, and 89%, respectively. The co rresponding figures for 12/12 hr light/dark were 94, 100, 87, 97, and 98%. Seed germination decreased with decreasing osmotic pressure. At - 10.3 bar only Sorghum arundinaceum and Dinebra retroflexa were able to germinate. The significance of these findings is briefly discussed.