Efficiency of thermal and chemical treatments on overcoming dormancy three species of Brachiaria

Abstract

This study was conducted in 2011 at the Universidade Estadual de Mato Grosso do Sul, Unidade Universitária de Aquidauana, and aimed to evaluate the effect of chemical and thermal treatments to overcome dormancy in seeds of different Brachiaria species. The experimental design was completely randomized 3 x 4 factorial with five replications and composed by the combination of three Brachiaria species - B. decumbens, B. humidicola and B. ruziziensis - and four seed pre-treatments - control, thermal, H₂SO₄ and KNO₃. The total germination in three periods (7, 14 and 21 days) was evaluated, according to seed pre-treatment, and the comparison between germination and tetrazolium test, performed in the control, was done. The values found by the tetrazolium test did not correspond at all with those obtained by germination test, revealing inefficiency of the seed pre-treatments used. B. decumbens showed higher total percentage of germination, but B. ruziziensis showed better seed viability. The sulfuric acid treatment was more efficient than the other, which did not differ for the total germination of seeds of tropical forages.