Symptoms expression of bakanae disease following seed treatment with phytohormone and metabolites

Gibberellic acid (GA3) phytohormone responsible for bakanae disease development is well-known and identified. But a number of secondary metabolites along with GA3, produced by the causal pathogen in relation to bakanae symptoms expression were unknown. Therefore, the aims of this research were to evaluate the symptoms expression analysis of bakanae disease by pre-seed treatment with pure (synthetic) phytohormones and metabolites in susceptible rice variety MR 211. The typical bakanae symptoms were evaluated by applying pure GA3, FA and MON either singly or in mixtures. It was confirmed that higher concentration of GA3 singly or with higher concentration of GA3 and MON in mixtures, caused unusual elongation of internodes. Plants became stunted when high concentration of FA was applied. Browning of leaves and stems, crown rot, root necrosis occurred and root length was decreased when mixtures of higher concentration of FA *MON*GA3 were used as pre-treatment. Similar observations were noted in plants inoculated with F. proliferatum at different score levels. The mechanisms of bakanae disease development through different symptoms expression in susceptible variety infected with F. proliferatum were identified.