Morphophysiological responses of Ormosia arborea (Fabaceae) seedlings under flooding and post-flooding conditions

The success of restoration practices in areas subject to seasonal flooding is associated with the selection of plant species tolerant to both flooding and post-flooding conditions. Morphophysiological changes of Ormosia arborea (Vell.) Harms (Fabaceae) seedlings were studied to evaluate the plasticity related to the water regime. O. arborea seedlings were flooded for 0, 15, 30, 45 and 60 days. At the end of each flooding period, the seedlings were removed from the pools to assess seedling survival at 75 days after completion of the flooding regime. The seedlings survived under the flooding and post-flooding regime and expressed lenticel hypertrophy. During longer periods of flooding, the seedlings exhibited a reduction in the quantum efficiency of PSII and gas exchanges (except for the internal concentration of CO2, which increased during this period). During the reestablishment, the metabolism was resumed, however, when plants was submitted to more prolonged flooding (60 days), the photosynthetic rates and carboxylation efficiency were not completely recovered. Stomatal conductance and water use efficiency was not recovered at the level of the control independent of the flooding period. These morphophysiological adjustments indicate phenotypic plasticity and potential for survival in temporarily flooded areas.