Effects of Paclobutrazol Seed Priming on Seedlings Quality, Physiological and Bakanae Disease Index Characteristics of Rice (Oryza sativa L.).

Rice (Oryza sativa L.) is one of the most important cereal crops in the world. Bakanae disease is a significant rice disease widely distributed in rice-growing regions worldwide. Therefore, the present investigation aimed to assess the optimal concentrations of paclobutrazol (PBZ) as a treatment for rice grains (cv. Sakha 108) to control bakanae disease, also evaluating its impact on grain germination, seedling growth parameters as well as disease index. Paclobutrazol concentrations had no significant impact on seed germination, regardless of whether the seeds were incubated with Fusarium fujikuroi or not. Application of PBZ, either alone or in combination with fungal pathogens, negatively impacted the rice seedlings' height. Paclobutrazol at 25, 50 and 100 mg/L, combined with the fungal pathogen positively impacted root length. Paclobutrazol at 3 and 6 mg/L mitigated the adverse impact on chlorophyll pigments content in infected seedlings. The highest proline contents were achieved by 100 mg/L PBZ alone or in combination with fungal pathogens. It has been observed that the application of PBZ, either alone or in combination with a fungal pathogen, leads to the enhancement of catalase, peroxidase, and polyphenol oxidase activities. The median lethal concentration of PBZ was 0.874 mg/L; applying low concentrations of paclobutrazol effectively increased the percentage of fungal growth suppression. Application of PBZ, at higher concentrations (50 and 100 mg/L), decreased infection percentage and disease severity index (DSI) significantly. These findings suggest that PBZ can be an effective treatment for controlling bakanae disease and enhancing resistance in rice plants. [ABSTRACT FROM AUTHOR]