Water stress and seed water content can affect the first germination stages and disturb the full pasture establishment. This study aimed at evaluating the effect of substrate water availability and seed water content on the germination of Urochloa ruziziensis seeds, as well as verifying any harmful effect of seed imbibition. The treatments consisted of seeds with 9.5%, 11.3% and 14.6% of moisture content, subjected to substrate water availability simulated with aqueous solutions of polyethylene glycol 6000 (PEG 6000) of 0.0 MPa (PubMed control), -0.1 MPa, -0.2 MPa, -0.3 MPa and -0.4 MPa. The following characteristics were used to evaluate the seeds physiological quality: germination percentage and first counting, aerial and primary root length and seedlings fresh weight. The experimental design was completely randomized, with four replications of 50 seeds. All the evaluated characteristics were negatively influenced by the water potentials reduction, however, the U. ruziziensis seeds with 11.3% and 14.6% of moisture content showed a higher germination rate and seedlings growth at low water availability. Despite the reduction in the indexes evaluated for water deficiency, the damage extension in seeds was determined by seeds moisture content and water stress severity.
Tropical forage; polyethylene glycol; seeds physiologic quality
