Hydropriming of seeds of <i>Piptadenia moniliformis</i> Benth. and its effects on the tolerance to the saline stress conditions

Abstract

Salinity is one of the main abiotic stresses affecting the germination and growth of plants in arid and semiarid regions. In this context, some alternative techniques can be used to mitigate the negative effects of the exposure to salts, including seed hydropriming, which consists in the controlled imbibition of the seeds, sufficient to promote the activation of the initial stages of the germination (stages I and II) without leading to primary root protrusion. This study aimed to evaluate the effect of hydropriming on the germination and vigor of Piptadenia moniliformis seeds subjected to salt stress. Hydropriming time was determined based on the construction of an imbibition curve, and the time chosen was 38 hours. To simulate the salt stress during the seed germination, solutions were prepared with sodium chloride (NaCl) at potentials of -0.3, -0.6, -0.9 and -1.2 MPa. The germination test was performed with hydroprimed and non-hydroprimed seeds, sown on Germitest® paper sheets moistened with saline solutions and kept in a B.O.D. (Biochemical Oxygen Demand) germination chamber at 25°C for 21 days. The experimental design was completely randomized in a 2 x 4 factorial scheme, with four replicates of 25 seeds, in which the first factor was formed by hydroprimed and non-hydroprimed seeds, whereas the second factor corresponded to the salt stress potentials (-0.3, -0.6, -0.9 and -1.2 MPa). The variables analyzed were: germination, germination speed index, seedling height, root length and seedling dry mass. Hydropriming reduces the negative effects of salt stress on the vigor of Piptadenia moniliformis seeds, up to the limit of -0.9 MPa.