Abstract
Seeds of Urena lobate L. cv. ‘Ex-Mokwa’ and a local strain termed ‘Indigenous’ were sown at four-weekly intervals from 1 May to 14 November. Some seed was set by all ‘Ex-Mokwa’ crops and by those ‘Indigenous’ crops clown on or before 18 September. Highest seed yield was obtained with 1 May sowings and was progressively lower with later sowing dates. A reduction in the period of vegetative growth before flowering was a major cause of reduced seed yield from late-sown crops. Results suggest that the onset of flowering is under photoperiodic control. U. lobata behaving as a short-day plant. Between May and July, sowing date had little effect on the date of flowering seed harvest of ‘Indigenous’ crops, although both flowing and harvest were delayed somewhat with ‘Ex-Mokwa’. Growth of late-sown crops was further reduced by crops unfavourable conditions of the dry season which prevented or seriously reduced seed production by crops sown in October or November.
