Chitosan beads combined with Terminalia nigrovenulosa bark enhance suppressive activity to Fusarium solani

Chitosan beads (CTB) and Terminalia nigrovenulosa bark (TNB) were prepared using chitosan powder combined with T. nigrovenulosa powder (TNP) and T. nigrovenulosa extract (TNE) to obtain CTB + TNP (0, 1, 3, and 5%) and CTB + TNE (0, 0.1, 0.3, and 0.5%), respectively. The chitosan beads combined with TNB were tested for their antifungal activity against Fusarium solani. In vitro studies indicated that a mixture of 20 chitosan beads and 3-5% TNP inhibited F. solani mycelial growth the greatest. Mixtures of 10-20 chitosan beads and 0.3-0.5% TNE showed the greatest inhibition of F. solani mycelial growth. Total inhibition of F. solani mycelial growth was achieved with CTB and 5% TNP and CTB and 0.5% TNE after a 6 day incubation. Induction of pathogenesis-related proteins such as chitinase, β-1,3-glucanase, and guaiacol peroxidase were tested in cucumber seedlings. Enzyme accumulation was significantly higher in CTB and 0.5% TNE treated cucumber plants compared to that in control plants. We effectively demonstrated the biological activities of the CTB and TNP and CTB and TNE treatments. These results suggest that applying chitosan beads combined with TNB could be useful to control soil-borne diseases of cucumber seedlings.