Salicylic acid in the induction of resistance to beet seedling damping-off and antifungal activity against Fusarium sp., in vitro

<p>The damping off is the main disease that affects the beet crop during the seedling production. The aim of this study was to evaluate different salicylic acid (SA) concentrations for resistance induction against damping-off in beet seedling and its antifungal activity against <em>Fusarium </em>sp., <em>in vitro </em>condition. Treatment of beet seed was with SA solution by immersion during 5 minutes in the 0.5, 1.0, 1.5 and 2.0 mM concentrations and control (distilled water). It was used four replications with 20 cells by experimental unit. The experiment was carried out for 14 days in cultivate chamber with temperature (23 oC ± 2°C), lighting (12 hours photoperiod) and humidity (70% ± 10%) controlled. After this time, the germination, damping off incidence, seedling length and fresh mass matter weight were evaluated. It was evaluated also in the seedling tissue the phenylalanine ammonia-lyase (PAL), ?-1.3 glucanase and chitinase level enzymes. In the <em>in vitro </em>the SA was putted in PDA (potato-dextrose-agar) medium, where the <em>Fusarium </em>sp. mycelial growth was evaluated. The SA applied for seeds treatment didn’t had effect significant on damping off of beet seedlings, but it induced the activity of ?-1.3 glucanase enzyme, it being this higher in nine times when compared the treatment control. The SA acted in the <em>Fusarium </em>sp. <em>in vitro </em>control with fungitoxic action, suppressed mycelial growth in 28% if compared to control.