Recovery capacity and morphophysiological responses of Sapindus saponaria L. to water stress

Water stress is characterized by the lack or excess of water for a certain period, which can hinder the establishment and growth of different tree species. Thus, this study aims to evaluate growth and physiological changes in young Sapindus saponaria plants subjected to flooding, drought, rehydration and post-flooding recovery. For flooding, plants were kept in pots containing water 2 cm above the soil; for drought, plants were not irrigated for 25 days. At the end of the period, growth, height, dry and fresh mass of leaves, stem, and root measurements were assessed. Photosynthetic pigments and total soluble carbohydrate contents were also analyzed. Young S. saponaria plants showed reduced growth rates under drought conditions, and did not recover when rehydrated. In addition, drought caused a decrease in the chlorophyll a/b ratio and an increase in the total soluble carbohydrates content in the roots. Plants kept under flooding and post-flooding conditions did not show differences in growth and chlorophyll content, but a higher total soluble carbohydrates content was observed in the root of flooded plants. The study revealed young S. saponaria plants are intolerant to drought periods, showing low recovery capacity, but are tolerant to flooding and post-flooding periods.