Control ofSeptoria tritici in durum wheat: Genetic evaluation of seven traditional genotypes and assessment of antifungal potential of five plant-derived essential oils

Abstract

Effective management of Septoria tritici blotch (STB) remains a major challenge in durum wheat-growing regions, particularly as Triticum durum production continues to suffer from increasing disease pressure. The reduced effectiveness of previously resistant cultivars highlights the urgent need to identify new genetic resources and alternative control strategies. This study evaluated both genetic resistance and biological control approaches to improve STB management. Seven Tunisian durum wheat genotypes, including six previously abandoned due to low productivity, were assessed for their response to STB. Analysis of variance of area under disease progress curve (AUDPC), transformed AUDPC, and percentage of infected leaf area revealed highly significant differences among genotypes, enabling clear discrimination of resistance levels. Across all disease parameters, mean comparisons showed that Beskri, Chetla, and Rommani exhibited consistently high tolerance to STB, whereas Chili and Swabaa Algiaa exhibited a moderate tolerance. In contrast, Jneh Kottifa and Karim were classified as susceptible genotypes, displaying the highest levels of disease severity and disease development. In parallel, the antifungal potential of six plant-derived essential oils was investigated using fumigation and contact bioassays. Essential oils derived from Thymus capitatus, Rosmarinus officinalis, Eucalyptus camaldulensis, Artemisia herba-alba, and Cinnamomum bark were evaluated at three concentrations (2, 5, and 10 µL for fumigation assays and 20, 40, and 80 µL for contact bioassays) to assess their antifungal activity. In fumigation assays, inhibition of mycelial growth varied depending on oil type and dose. Cinnamomum and Thymus oils achieved complete inhibition at 2 µL, whereas Eucalyptus reached a maximum inhibition of 69% at 10 µL. Artemisia herba-alba showed moderate activity, while Rosmarinus officinalis displayed the lowest effectiveness. In contact bioassays the antifungal activity assessed after 12 days, confirming significant inhibitory effects. Cinnamomum oil caused total inhibition at 20 µL. Eucalyptus oil produced inhibition rates ranging from 63.5% to 100% at volumes between 20 and 80 µL. Artemisia herba-alba exhibited a dose-dependent response, with inhibition between 32.92% and 67.46%, whereas Thymus oil showed limited activity, not exceeding 20.7%. The identification of STB-tolerant Tunisian durum wheat genotypes provides promising new sources of resistance that may offset the declining performance of previously reliable cultivars. Their integration into breeding programs, combined with plant-based antifungal agents, represents a valuable strategy for sustainable and long-term control of Septoria tritici.

Keywords

Septoria tritici Blotch / durum wheat / genetic resistance / essential oils / biological control / antifungal activity / plant-derived compounds / disease management

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