Crescimento de mudas de pau-ferro sob diferentes níveis de sombreamento

Abstract

Obtaining native seedlings requires information about seeds harvest time, storage and luminosity conditions, germination and types of substrate, among others. This study aimed at evaluating the luminosity demands for the initial growth of Caesalpinia ferrea Mart. ex. Tul. var. leiostachya Benth (Fabaceae-Caesalpinioideae) seedlings submitted to different shading levels, at 60 days after transplant (DAT). The experimental design was completely randomized, in 3x5 factorial scheme (three shading levels: 0%, 50% and 70%; and five evaluation times: 60, 90, 120, 150 and 180 DAT), with four replications of 10 seedlings per experimental unit. Plants grown under the shading level of 70% presented the highest contents for total chlorophyll (38.79 µg cm-2), leaf area ratio (51.54 g cm-2), relative growth rate (0.0322 g g-1 day-1) and leaf weight ratio (0.2708 g g-1). The highest values for stem height (110.34 cm) and base diameter (9.3 mm), and root (11.13 g), leaf (5.59 g) and shoot (16.05 g) dry matter, as well as leaf area (705.25 cm2), were observed in the plants cultivated under the shading level of 50%. No differences were observed for root growth, specific leaf weight, net assimilation rate and specific leaf area, concerning the different shading levels tested (averages of 9.3 cm, 0.0082 g cm-2, 0.0006 g cm-2 day-1 and 186.24 g cm-2, respectively). The Caesalpinia ferrea seedlings presented a better growth rate when cultivated under the shading level of 50%.