Effect of environmental conditions on the growth of pau-brasil (Caesalpinia echinata Lam.) seedlings

Abstract

Toe effects of different conditions of light and temperature on the initial growth of "paubrasil" plants were observed at Botanical lnstitute, in São Paulo, SP. Four environmental conditions were tested with an arrangement of three light levels (0%, 50%, and 80% of shade) and two temperature leveis (ambient and greenhouse conditions). Seedlings were grown under the following conditions: a) in a greenhouse covered by a 50% shade screen; b) direct sunlight, outdoors; e) outdoors covered by a 50% shade screen and d) outdoors covered by a 80% shade screen. Plant height, stem diameter and number of leaves per plant were evaluated at 17 (initial), 29 and 41 months of age. The results showed that seedling growth was accelerated by both shading (up to 50%) and increased temperature (greenhouse conditions). However, growth was more equally distributed among the evaluated characteristics for seedlings growing under 50% shading at greenhouse conditions. Seedlings growing under 50% shading at ambient temperatures (outdoors) showed a increase in plant height greater than inother structures as stem diameter and number of leaves per plant. Seedlings growing under 80% screen shading experienced the slowest growth rates for all three parameters measured.