Aspectos ecofisiológicos de Palicourea racemosa (Aubl.) Borhidi em função da sazonalidade

Abstract

Due to its shaded habitat, P. racemosa is a species of understory belonging to the Rubiaceae family that may be affected by seasonal changes in the environment. The aim of the present study was to evaluate the effects of seasonality on ecophysiological aspects of P. racemosa. For this, the variables were measured monthly in 10 individuals over ten months. The environmental variables analyzed were leaf area index (IAF), photosynthetically active radiation (RFA), visible sky fraction (FCV), precipitation, soil moisture, soil surface temperature (0 cm), soil temperature (20 cm), and air temperature. The ecophysiological variables evaluated were stomatal conductance, photosynthesis rate, transpiration, internal carbon, water use efficiency, intrinsic water use efficiency, instantaneous carboxylation efficiency, chlorophyll a, chlorophyll b and total chlorophyll. For data analysis, a Canonical Correlation Analysis (ACC) and Principal Component Analysis (ACP) were performed to verify associations between group I (environmental variables) and group II (ecophysiological variables). Then, the ecophysiological data were subjected to analysis of variance and the Tukey test was used to compare the means. It was observed a strong association of soil moisture, precipitation and LAI with ecophysiological variables. Except for the intrinsic water use efficiency and instantaneous carboxylation efficiency, all ecophysiological variables showed significant differences over the months. Therefore, the influence of seasonality on the ecophysiological responses of P. racemosa.