Germination of the exotic Calotropis procera (Aiton) W.T. (Apocynaceae) in Mexico

Abstract

Background: Seed germination strategies are important for exotic species to identify the factors that control seed germination and establishment. Questions and /or Hypotheses: Temperature and light germination requirements for seeds of Calotropis procera do not change neither in its native regions nor in lands where it is exotic. Calotropis procera show germination traits that may increase their probability of colonization. Studied species: Calotropis procera is a perennial plant native to some desertic areas in Asia and Africa and now naturalized in America. Study site and dates: Mature fruits were collected in Oaxaca in September 2019 to test germination parameters. The last experiment was conducted in September 2021. Methods: We determined the effect of different temperatures, photoblastic response, and loss of viability of seeds kept at laboratory conditions for two years. We performed several sowings under controlled conditions and achieved germinability, t50 and the time to germinate. Results: Seeds were non-dormant, neutral photoblastic and did not lose viability after two years of dry storage. Temperature affected germinability and t50. Optimum germination temperature was 30 °C with no germination above 40 °C. Conclusions: Germination requirements of seeds of Calotropis procera studied were similar to those reported worldwide. Though seed germination was affected by maximum mean temperatures, seeds germinated fast and at high percentages under a wide range of temperatures, which together with other attributes, may confer C. procera great chances for successful colonization.