WATER AND SODIUM CHLORIDE EFFECTS ON Mimosa Tenuiflora (WILLD.) POIRET SEED GERMINATION

Abstract

Water shortage and saline soils of the Brazilian semi-arid northeastern region are limiting factors to the development of many plants. Jurema preta (Mimosa tenuiflora (Willd.) Poiret) is a small, multiple use tree that abundantly colonizes unfavorable sites, including environments with severe water stress. This work had the objective of investigating the tolerance of jurema preta seeds to water and salt stresses during germination. Seeds germination in polyethylene glycol (PEG-6000) and sodium chloride (NaCl) solutions was analyzed under five different osmotic potentials (0.0; -0.3, -0.6, -0.9 and -1.2MPa), in order to simulate water and salt stress, respectively, in four 100-seed replications for each treatment. Seeds were placed into 10cmx10cmx4cm boxes, and germination accomplished in BOD germinator adjusted to 30oC. The number of germinated seeds was monitored every 24 hours, and percentage and speed of seed germination were generated from these data. Mean percentage germination in the control treatment was ~95%, reducing to 63-53% at -0.9 to -1.2-MPa PEG solutions, and to 27- 9.5% at NaCl solutions at equivalent osmotic potentials. Velocity of germination index was more affected, and decreased up to 1/8 of the control, at -0.6 MPa. Jurema preta seeds showed lower tolerance to NaCl than to water stress, and this species can be classified as a glycophyte.