Análise anatômica e quantificação de taninos de stryphnodendron adstringens (Mart.) coville em diferentes estratos da copa e entre períodos de coleta

Abstract

Stryphnodendron adstringens (Mart.) Coville, popularly known as "barbatimão", is a native species and its leaves and bark are important sources of vegetal tannin of great commercial importance. The aim of this work was to compare contents of total phenols, residual phenols, tannin, flavonoids, chlorophylls a, b and a/b relation between crown heights and periods considering February, May, September and December, to compared tannin extraction by folin-ciocalteu and radial diffusion methods and by biometric characteristics (height, crown diameter and IAF) and to verify possible anatomical modifications in the folios. The collections were carried at Lavras, South of Minas Gerais. The experiment was conducted in an entirely randomized design disposed in a 3 x 4 factorial scheme, being position the first factor and (base, middle and top) and months the second factor (February, May, September and December). The data was analyzed through analysis of variance and Tukey test both with significance level at 5%. To evaluate correlation between height, diameter and leaf area index, Person correlation coefficient was used. The results showed that S. adstringens leaves produce higher concentrations of total phenols and tannin in top (23.05% and 18.23%) and base positions (21.42% and 16.61%) in May (25.79% and 20.85%) and September (25.57% and 20.50%) months respectively. However, there was no difference for residual phenols and flavonoids between crown positions and collection months. Tannin content obtained by radial diffusion method was lower than those extracted by Folin-Ciocalteu method, which occurred because the methods are based on different chemical properties of tannin. Biometric characteristics such as height and diameter are not related to tannin production and are affected only by leaf area index. Para-dermal sections revealed a higher stomata number in the abaxial face, being the leaf classified as amphi hypostomatic. The α chlorophyll concentration was higher in top (9,799 mg/100mL) and base (10,428 mg/100mL) leaves. Chlorophyll β had higher value in the middle of the crown (3,472mg/100mL).