Phenotypic plasticity as indicator of no pioneer trees more tolerant to intense irradiance

Abstract

The occurrence of Cariniana legalis (Mart.) Kuntze (Lecythidaceae) in secondary forests in different levels of regeneration suggests that this species is more resistant to full sun in relation to Paratecoma peroba (Record. & Mell) Kuhlm. (Bignoniaceae) found in dense primary forest. The aim of this study was to characterize the plasticity of growth, anatomical and structural cell wall variables of C. legalis and P. peroba. As the stem is strong drain on tree, it was proposed the hypothesis that plasticity of lignin and hemicelluloses monosaccharides are higher than of growth and anatomical variables, especially with C. legalis that is more resistant to full sun as suggested by its ecological habit. Young plants with 14 months of age were subjected to 20 and 100% of solar light for 60 days. Unlike expected, the plasticity of lignin was lower than plasticity of growth and anatomic variables for both species. Hemicellulose composition of C. legalis was not affected by light. Proportion of arabinose was lower in P. peroba under full sun. We conclude that the indication of higher resistance of C. legalis to full sun was associated with plasticity index of net assimilation rate and relative growth rate (≥ 0.6), stomatal density (≥ 0.3) and lignins (≤ 0.2).