Priming and stress under high humidity and temperature on the physiological quality of Brachiaria brizantha cv. MG-5 seeds

Condicionamento fisiológico e stress sob alta umidade e temperatura na qualidade fisiológica de sementes de Brachiaria brizantha cv. MG-5

ABSTRACT.

Palisade grass is a forage plant that is widely used in pasture cropping in the Brazilian savannah. The aim of this experiment was to evaluate palisade grass (Brachiaria brizantha cv. MG-5) seeds subjected to priming and stress at high humidity and temperature (before and after conditioning). The experimental design was completely randomized in a 2x5 factorial arrangement. Seeds were exposed to stress under high humidity and temperature (before and after conditioning) and five priming treatments [Water (Control), potassium nitrate (KNO₃) at 0.2%, calcium nitrate Ca(NO₃)₂ at 0.2%, gibberellin (GA₃) at 0.2% and glucose at 10%] with four replications. Two experiments were performed: Experiment I - seed with chemical scarification using H₂SO₄ and Experiment II - without scarification. The stress on the seed was applied using artificial aging at 41°C for 96 hours. Seed priming was accomplished by immersion at 25°C for 2 hours. Thereafter, the seeds were oven-dried at 35°C until they regained hygroscopic equilibrium. Seed germination and vigor were evaluated. Priming using KNO₃ and Ca(NO₃)₂ produced seeds with high tolerance to stress under high temperature, and this process is efficient to overcome dormancy.

Keywords:
palisade grass; seed deterioration; expression of vigor; nitrate