Respostas fisiológicas e bioquímicas de plantas de jurema-preta (Mimosa tenuiflora (Willd.) Poiret) submetidas ao déficit hídrico e reidratação.

Abstract

When subjected to water stress conditions, depending on their intensity and duration, the plants may suffer a negative effect on their water status, promoting stomata closure and, consequently, a reduction in photosynthesis, limiting growth, which may lead to the death of plants. The objective of this work was to evaluate the physiological and biochemical responses of juremapreta plants submitted to variable water availability conditions during the nursery stage. Twelvemonthold plants kept in plastic pots containing 5 kg of the substrate composed of the subsoil soil mixture and bovine manure (2:1) were submitted to two treatments: irrigated (control) and water deficit, which was imposed through the suspension of irrigation. After 7 days of stress, the plants were rehydrated. The relative water content (RWC), stomatal parameters and organic solutes contents were evaluated. The plants responded quickly to the irrigation suspension, promoting stomata closure, reducing stomatal conductance, transpiration and photosynthesis. The instantaneous efficiency in water use of plants under water deficit remained high only until the middle of the period when irrigation was suspended, and then declined until the last day of the water deficit. The water deficit promoted soluble sugars and total amino acids accumulations, providing osmotic adjustment and maintenance of RWC at acceptable levels. After rewatering, the plants showed recovery in all evaluated parameters, demonstrating that the level of stress imposed did not cause irreversible damages in the cells and tissues.