Tratamentos térmico e químico de sementes de feijoeiro: eficiência na erradicação de Curtobacterium flaccumfaciens pv. flaccumfaciens e efeitos na qualidade fisiológica das sementes

The effect of thermo and chemotherapy on the eradication of Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) and on the physiological quality of seeds of common bean (Phaseolus vulgaris) cv. Perola were tested. Soaking times (30 min, 1 and 2 h) in water and in AGRIMAICIN 500 solutions (copper sulphate, 500 g + oxytetracyclin, 30 g/kg of the product) in concentrations of 5 and 10 g/L of water; dry heat (60 and 70 oC for 1, 2, 3, 6 and 12 h); and heat of 60 oC/3 h on previously soaked seeds for 30 min, 1 and 2 h were tested. The vigor of seeds soaked in water for more than 1 h was affected. Soaking the seeds (30 min, 1 and 2 h) in solution with 10 g of AGRIMAICIN 500/L of water affected the length of the rootlet and the stem, whereas germination was affected only with 2 h. The treatment eliminated the bacterium from naturally infected seeds; however it was not effective in inoculated seeds (108 ufc/mL). Dry heat (60 and 70 oC) for more than 3 h reduced significantly the vigor of the seeds and did not eliminate the bacterium. Soaking the seeds for 30 min and 1 h + 60 oC/3 h affected the length of the stem and rootlet but did not eliminate the bacterium. Two hours of soaking the seeds in water ± 60 oC/3 h reduced significantly the germination and the vigor; it also reduced significantly the Cff in inoculated seeds, whereas it eliminated the bacterium in naturally infected ones.