Hidrocondicionamento em sementes de piptadenia moniliformis benth. e efeitos em condições de estresse salino

Abstract

The physiological conditioning consists of the controlled hydration of the seeds, enough to promote the activation of the initial stages of germination, without the emission of the primary root. This technique has presented advantages to the seed performance after exposures to saline stress, however, still little used for forest species. The objective of this study was to evaluate the effect of hydrocondicionamento on germination and seed vigor of Piptadenia moniliformis Benth. submitted to saline stress. For this, seeds were collected in the city of Areia Branca-RN, in October 2014 and conditioned in plastic bottles in a controlled environment (± 17 ° C, 50% RH) until the experiment was carried out. To determine the time of hydrocondicionamento, two replicates of 25 seeds were used, placed between two sheets of blotting paper conditioned in a gerbox box, with weighings done every one hour, in the first 14 hours, with interval of 9 hours and in then weighed every one hour until the appearance of the radicle in at least 50% of the seeds. To simulate saline stress during seed germination, solutions were prepared with sodium chloride (NaCl) at potentials -0.3, -0.6, -0.9 and -1.2 MPa. The germination test was performed with hydrocondycin and non-hydrocondylated seeds, seeded on germitest® paper sheets, moistened with saline solutions and kept in a B-type germ-type B.O.D (Biochemical Oxygen Demand) 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, the first factor being hydrocondicionadas and non-hydrocondicionadas seeds and the second one to potentials of saline stress (-0.3, -0, 6, -0.9 and -1.2 MPa). The analyzed variables were: germination, germination speed index, seedling height, root length and seedling dry mass. The hydrocondicionamento reduces the negative effects of saline stress on the vigor of P. moniliformis seeds up to the limit of up to -0.9 MPa.