Specific leaf area and leaf anatomy traits of signalgrass (Brachiaria decumbens cv. Basilisk) and forage peanut (Arachis pintoi cv. Amarillo) were evaluated in response to levels of artificial shades (0, 50 and 70%) with the objective of determining the acclimation of these forage species to changes in the luminous environment. It was used a complete random block design, with three replicates. Three and two harvests were performed for evaluation of signalgrass and forage peanut, respectively. Specific leaf blade of the two species increased linearly as a function of the increasing levels of shading. In signalgrass, the increase on specific leaf area was followed by a linear reduction in leaf thickness, with the increasing levels of shade. On the other hand, forage peanut leaf thickness was not significantly altered by shade. Stomatal density on adaxial and abaxial leaf surfaces decreased linearly with the increase on levels of shade. In spite of increase of the proportion on intercellular spaces in forage peanut leaves, the area occupied by different tissues was not significantly affected by shade levels. Signal grass leaves presented a quadratic increase in the area occupied by the vascular bundle sheath in the first harvest. The area occupied by vascular bundle and by bulliform cells was reduced in the second and third harvest, respectively, with the increasing shade. The forage species evaluated showed a good acclimation to variations on light intensities, and they are good alternatives to use in environments with low solar radiation levels
Arachis pintoi; Brachiaria decumbens; leaf tissues; luminosity; stomatal density
