Morphophysiological comparison of Schizolobium parahyba varieties seedlings cultivated under different shading levels

Abstract

Schizolobium parahyba varieties are found in both Atlantic and Amazon Forests, being considered suitable raw material for pulp, paper, pharmaceutical, and bioenergy industries. Hence, seeking to exploit the production of native seedlings adapted to adverse environments, this work aimed to evaluate seedlings growth of two S. parahyba varieties under three different shading conditions (full sunlight, 30%-shading screen, and 70%-shading screen). We carried out the experiment in full sunlight, 30% shading screen and 70% shading screen and used a commercial substrate Tropstrato Florestal ® in a factorial scheme 2x3, for 90 days. Growth and physiological (gas exchange and pigments content) parameters were assessed at the end of the experiment. In contrast to the results found for this analysis, verified by means of the IRGA measuring device, most of the growth traits differed among treatments while the photosynthetic pigments were strongly influenced by shading levels regardless of varieties. S. parahyba var. amazonicum ‘Paricá’ presented better fitting and growth under 70%-shading screen, since it displays a close physiognomy of ‘terra firma’ regions, thus being suitable for reforestation in closed-canopy forests. On the other hand, S. parahyba var. parahyba ‘Guapuruvu’ presented better responses on growth parameters under the 30%-shading screen, with potential for open forests. S. parahyba varieties present some phenotypic variation to shading levels wherein this information can be useful for this species management.