“Fava-atanã” (Parkia gigantocarpa) sob alagamento: respostas ecofisiológicas, bioquímicas, morfoanatômicas e de crescimento

Abstract

Parkia gigantocarpa is a Neotropical tree that occurs naturally in the woods of solid ground and high floodplain. To characterize the morphological and anatomical responses, growth, physiological and biochemical young plants of P. gigantocarpa were experimentally subjected to two water regimes. Flooding was imposed on the blade approximately 5 cm above the soil surface using vasel with 14 kg of substrate capacity. Non-flooded plants (control) were irrigated daily, close to field capacity. Plant height, stem diameter, number of leaves and leaflets, shoot dry matter (SDM), root dry mass (RDM), total dry matter (TDM), root shoot ratio (R/PA), lenticels hypertrophic, adventitious roots, air gaps, predawn water potential (Ψam), leaf water potential of the xylem (Ψx), stomatal conductance (gs), transpiration (E), hydraulic conductivity (KL), nitrate concentration, nitrate reductase (NR), free ammonia, glutamine synthetase (GS), total soluble amino acids (TSA), total soluble proteins (TSP), starch, proline, glycine betaine (GB), alcohol dehydrogenase (ADH), lactate dehydrogenase (LDH), and sucrose total soluble carbohydrates (TSC) were assessed at 0, 4, 8, 12 and 16 days. Flooding significantly reduced plant height from the 8th day, but stem diameter did not differ between treatments. The largest reduction in the number of leaves and leaflets, SDM, RDM, TDM and R/PA occurred at 16 days in flooded plants. From the 4th day was displayed to hypertrophic lenticels at the stem base of flooded plants. However, the adventitious roots at the stem base were only observed at 16 days in plants under flooding. In this same period, parenchyma cells of the cortex of the root samples of secondary treatment wetland began the process of training schizogenous small air gaps. A significant reduction in Ψx and KL was continued until the 8th day flooded plants. gs and E decreased continuously until the 16 days the plants under flooding. Nitrate concentration, NR, free ammonia, GS, TSA, TSP, starch significantly reduced, especially in the leaves of flooded plants, reaching the highest values at 16 days. GB proline and sharply increased both in leaves and in the roots of the plants saturated with water. ADH activity was higher in root and LDH was more pronounced in the leaves of plants under water saturation. Flooding significantly reduced the sucrose concentration in the leaves, but after 4 days, there was substantial increase of this sugar in the roots of flooded plants. The concentration of TSC increased, especially in wetland plant roots. All plants survived until the end of the experiment. Growth responses, morphological and anatomical, physiological and biochemical presented by young plants of P. gigantocarpa under flooding during sixteen days, suggesting a tolerance to this type of stress.