Synthetic Resistance Inducers: an Alternative to Fungicides for Controlling Gaeumannomyces Graminis in Rice

Abstract Two field experiments were conducted to assess the effects of individual and combined resistance inducers (RIs) sprays on disease severity, physiological performance, and yield components to control crown sheath rot caused by Gaeumannomyces graminis in rice. In the first experiment, individual applications of cinnamaldehyde (CA), botanical extract (BE), nano-silicon (SiNPs), and chitosan (Chi) were compared with fungicide treatment and an untreated control. The second experiment focused on the efficacy of RIs combinations. Disease severity, area under the disease progress curve (AUDPC), leaf gas exchange properties, chlorophyll fluorescence parameters, and agronomic variables were measured in both the experiments. The results showed that individual and combined RIs treatments reduced disease severity [~3.3 and ~3.4%, respectively] and AUDPC [~85 and ~95, respectively] compared to the untreated control ((individual: 5.20 and 198); (combined: 5.40 and 178)), with RIs efficiency similar (35%) to that of fungicide treatment. RIs application improved leaf photosynthetic rate, photosystem II efficiency, and relative chlorophyll content under biotic stress conditions. Grain yield and efficiency per unit area (EUA) were also enhanced by the RIs treatments, particularly BE (10812 kg · ha −1 ; 83.99 kg rice paddy · m −2 · d −1 ) and SiNPs + Chi + BE + CA (~9600 kg · ha −1 ; ~73 kg rice paddy · m −2 · d −1 ) in comparison with untreated plants [(E1:8283 kg · ha −1 ; 62.42 kg rice paddy · m −2 · d −1 ) and (E2:7475 kg · ha −1 ; 54.32 kg rice paddy · m −2 · d −1 )]. These findings suggest that the foliar application of synthetic RIs during the vegetative stage can be an effective component of integrated disease management strategies for crown sheath rot in rice, potentially reducing the reliance on fungicides while maintaining crop productivity and promoting sustainable disease control.