The role of fruit traits on the germination of Mesosphaerum suaveolens and Cantinoa americana (Lamiaceae), two pesticidal plant species

Mesosphaerum suaveolens (L.) Kuntze and Cantinoa americana (Aubl.) Harley & J.F.B.Pastore are two former congeneric Hyptis species used by farmers in West Africa as pesticidal plants for crop protection. This study investigated the nutlet dormancy and thermal requirements for germination of both species to support their cultivation. Our results allowed the identification of non-deep physiological dormancy for both species and the need for further studies to clarify water imbibition uptake for nutlets of C. americana. Both species showed a positive photoblastic response with optimal seed germination temperatures well adapted to tropical climates (27.2 and 31.3˚C for M. suaveolens and C. americana, respectively). However, while seed germination responses to light and temperature environments were similar in the two species, differences in morphology of the nutlets displayed distinct patterns of water imbibition. For their cultivation, nutlets of both species should be sown in the light at temperatures above 25°C with a pre-germinative scarification treatment applied in the case of C. americana.