Seed viability, dormancy, and field emergence of Urena lobata L. in Sierra Leone

Abstract

The percentage field emergence from seeds of two cultivars of Urena lobata L. sown as a fibre crop in Sierra Leone was found to be low. In the case of seeds from indigenous plants, poor emergence was primarily due to seed dormancy and was markedly improved by scarification. In contrast, a low percentage viability was the major cause of poor emergence from seeds of the introduced cv., 'Ex-Mokwa'. Although initially high the percentage viability of embryo from this cv. declined during development. The insect pest Dysdercus superstitiosus F. was implicated in the loss of embryo viability. The percentage field emergence from scarified seed of both cv was considerably less than the percentage viability determined in laboratory tests, indicating a significant failure of emergence due to environmental factors.