Efecto del choque térmico en la germinación y establecimiento temprano de cinco especies de leguminosas de un bosque seco tropical

Abstract

Fire is a natural or anthropic disturbance present in different ecosystems around the world. In response to this disturbance, plants have generated traits that allow them to either resist or recover from fire events. Among these traits, the germination capacity of the seeds stands out when exposed to derivatives of fire such as heat, smoke or ashes. Although in the tropical dry forests of Colombia this disturbance is considered a threat, very little is known about the post-fire germination capacity of the vegetation. One of the families of plants that has a generalized persistence to fires, particularly through fire-stimulated germination, are Legumes, which is highly dominant in these ecosystems. Thus, the objective of this research was to evaluate the effect of heat on the germination and early establishment of seeds of five species of legumes: Albizia niopoides, Piptadenia cf. uliginosa, Pseudosamanea guachapele, Chloroleucon mangense and Enterolobium cyclocarpum. In order to fulfill this purpose, seeds of each species were collected and exposed to nine treatments, product of the combination of three temperatures (ie 80 ° C, 100 ° C and 140 ° C) and exposure times (ie 1 , 3 and 5 minutes). After exposure, the seeds were put to germinate in Petri dishes with moistened filter paper for the next two months. The germinated seeds were transplanted into ripening trays to evaluate their survival. Likewise, the viability of ungerminated seeds was evaluated with a tetrazolium test. The results show that the seeds of Albizia niopoides (small-seeded species) and Piptadenia cf. uliginosa (medium-sized seeds) are sensitive to heat and did not tolerate temperatures above 100 ° C for one minute. Pseudosamanea guachapele, Chloroleucon mangense and Enterolobium cyclocarpum (of different seminal sizes) were considered heat-tolerant species, since they germinated in almost all treatments and presented high levels of viability after being exposed to thermal shocks.In general, it is possible to affirm that heat-sensitive species can lose their populations to recurrent fire events, while tolerant species require heat to be able to recruit and to remain more successfully in the seed bank. Finally, the weight of the seeds does not influence heat tolerance.