Tratamientos de semillas para mejorar la germinación de Guazuma ulmifolia bajo estrés hídrico y calórico: comparación entre árboles tropicales pioneros

Abstract

Pioneer tropical trees constitute an important functional group in the succession and restoration processes of forests. However, very little is known about its germination mechanisms under stress conditions, and less about the possible pregermination treatments to improve the performance of the seeds. In the present work the effects of hydration-dehydration treatments and conditions of water and heat stress on the germination of Guazuma ulmifolia , pioneer tree of the Neotropic were examined. The germination of G. ulmifolia (seeds treated or not) was also compared with that reported for other tropical pioneer species ( Cecropia schreberiana , Trichospermum lessertianum and Hibiscus elatus ) with similar seed treatments and planting conditions. The final germination and start germination time of G. ulmifolia was significantly affected by stress conditions, although they were able to germinate under very critical conditions of water stress (-1.46 MPa) and heat stress (25/50 oC). However, germination was significantly increased when the seeds underwent hydration-dehydration cycles, the most effective treatment being a partial hydration cycle in water. This pregermination treatment also improved the germination of C. schreberiana , T. lessertianum and H. elatus under stressful conditions, but its effectiveness depended on the species. The germination behavior of G. ulmifolia was correlated with its wide distribution and habitat characteristics, but this pattern is not clear in the other species. There was no significant relationship between the seed mass and the response to water stress. The ecological role of hydration-dehydration cycles is discussed. Citation: Sanchez, J.A., Pernus, M. & Martinez, J. 2020. Tratamientos de semillas para mejorar la germinacion de Guazuma ulmifolia bajo estres hidrico y calorico: comparacion entre arboles tropicales pioneros. Revista Jard. Bot. Nac. Univ. Habana 41: 93-108. Article history: Received: 25 April 2020. Accepted: 15 August 2020. Online: 4 November 2020. Editor: Jose Angel Garcia-Beltran.