Dormancy patterns in accessions of caryopses from savanna grass species in South Eastern Botswana

Caryopsis dormancy patterns of indigenous grass species from South Eastern Botswana were studied. Observed dormancy patterns in accessions from Aristida congesta, Aristida stipitata, Chloris virgata, Eragrostis superba, Eragrostis rigidior, Heteropogon contortus, Rhyncelytrium repens, Schmidtia pappophoroides, and Tragus berteronianus, indicated a drought avoidance dormancy syndrome while caryopses from Cynodon dactylon did not show dormancy. Under room storage conditions, most accessions lost at least part of their dormancy within 6 to 12 months. For some species differences in dormancy pattern were observed between accessions from the same season, as well as for accessions from different seasons. As the type of dispersal unit of the plant may influence its dormancy mechanisms, it is argued, that studies of dormancy patterns and mechanisms of indigenous grass species should include information on the seed dispersal strategy of the species and be based on the comparison of more than one accession.