The role of temperature in the germination of subterranean and aerial seeds of Commelina benghalensis L.

Information on the temperature requirements for germination of weed seeds can be used to predict the soil temperature required for weed emergence. The germination behaviour of the two types of mature C. benghalensis seeds, ie. subterranean and aerial, were studied to establish whether differences in seed germination provide these plants with an apparent competitive advantage over other weed species. Seeds of aerial and subterranean types were placed separately on germination towels and put inside plastic bags. The subterranean seeds germinated significantly faster than the aerial seeds, indicating greater thermal sensitivity of the former type of seed. The dormancy displayed by aerial seeds could inter alia be attributed to delayed germination and not to loss of viability. The optimum germination temperature for subterranean seeds was 21/28°C, and for aerial seeds 18/25°C. This broad adaptability may require continuous C. benghalensis management efforts and supports the need for an effective residual herb...