Estresses abióticos em sementes de Piptadenia moniliformis Benth

Edaphoclimatic changes, increase in temperature, water deficit, and soil salinization are remarkable characteristics of the Brazilian semiarid region and may also affect plantlet germination and development of many species. This way, we aimed to evaluate germination and seed vigor of P. moniliformis undergone to water and saline stress under different osmotic potential and temperatures. For water stress, a polyethylene glycol (PEG 6000) solution was prepared and used to dampen the germination-test substrate, in a completely randomized experimental design, 2x5 factorial scheme, with four replicates of 25 seeds each. First factor referred to the temperatures of 25 and 20 °C, and the osmotic potential [0.0 (control), -0.2, - 0.4, -0.6, e -0.8 MPa] as the second factor. Saline stress was simulated with NaCl, in completely randomized design, 2x4 factorial scheme, with two temperatures (25 and 20 °C) and four salinity levels (0.0, 1.5, 3.5, and 5.5 dS.m-1). The following parameters were assessed: germination, index of germination rate, length and dry matter of plantlets. Tolerance limit for P. moniliformis seeds to water stress is about -0.4 to -0.6 MPa at 25 °C, with no germination in the -0.8 MPa or greater for both temperatures. The species was sensitive to saline stress, significantly reducing its germination and seed vigor in 5.5 dS.m-1.