Efeito do substrato na emergência, crescimento e comportamento estomático em plantulas de mangabeira

摘要

This study was carried out in greenhouse aiming to evaluate the germination, initial growth and water relations in mangaba seedlings. The experimental design was a completely randomized with fifty replicates and three substrates: autoclaved sand, local soil of the plants native region and a mixed of humus, sand and vegetal soil (2:4:4, v/v/v). The following variables were studied: germination and emergence velocity (IVG) rates, seedling height, number of leaves, leaf temperature (LT), transpiration (E) and diffusive resistance (Rs). Also some climate variables were measured: air temperature (Tar), relative humidity (UR) and photosynthetic active radiation (PAR). The larger values of germination and IVG were observed in autoclaved sand substrate. Both plant height and number of leaves hadn't been influenced by substrates. There were significant differences among treatments in relation to E and Rs. Leaves of seedlings cultivated in native soil have transpired more than mixed substrate (9.59 and 2.59 mmol.m-2.s-1, respectively). Leaves cultivated in autoclaved sand showed intermediate value (4.63 mmol.m-2.s-1). There were variations on Rs of leaves for sand substrate and for native soil substrate (2.2 and 0.9 s.cm-1, respectively). Inverse and significant effect for correlations among LT and E was verified. Positive effect was observed among LT and Rs. Effects of E x Rs were inverse and significant for all treatments. LT, E and Rs, as well as seedling height and number of leaves were not influenced by Tar, UR and PAR.