Efecto de la luz y micorrizas en la germinación de semillas de árboles de selvas secas

Abstract

Germination is a fundamental process in natural regeneration of tropical forest. In dry forest, germination is affected by the pronounced seasonality, which causes a high heterogeneity in understory light availability, as well as the biological interactions with soil microorganism, i.e. micorrhizae. The germination of three tree species of dry Tecoma stans (L.) Juss. ex Kunth, Senna racemosa (Mill.) H.S. Irwin y Barneby, y Bauhinia forficata Link. subsp. pruinosa (Vogel) Fortunato & Wunderlin was studied. Under a factorial design with three soil treatments: control (forest soil + nutriments), micorrhizae (Glomus intrarradices) and chemical control (Triple 17: Nitrogen + Phophorous + Potassium); and four light treatments (10%, 30%, 50% and 70%), the germination process was evaluated taken nine response variables. Both factors affected germination responses in an independent form. Interactive effects were only found in mean germination rate of T. stans, and uncertainty of the germination synchrony of B. forficata. Low and intermediate light levels availability increased the mean germination rate and germination value of T. stans. In addition, percentages of germination of S. racemosa were higher in intermediate and high light levels. In B. forficata we found no effects produced by light availability on germination process. The addition of micorrhizae produced positive effects on mean germination rate of T. stans, and highest percentages of germination in S. racemosa and B. forficata, although assynchronically. Adequate light availability and addition of micorrhizae to the substrate would cause benefits to germination in situ of important tree species used in restoration tropical dry forest programs, although with certain restriction.