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Background Fusarium crown rot is one of the major diseases that cause significant yield losses of wheat, and Trichoderma strains were known as an effective biocontrol agent. Main body The aim of this study was to evaluate the potential of coating durum wheat seeds of the cultivar “Karim” with 3 different Tunisian strains of Trichoderma sp. (S.INAT, SIO1, SIO2) and the Trichoderma-based commercial product Trianum-T22 on seed germination, seedling growth, and plant defense response against the pathogen Fusarium culmorum. The strains were identified using molecular tools based on sequencing ITS region of ribosomal DNA. The results confirmed at 99% of homology that the strains were T. harzianum. Under controlled conditions, the coating seeds were released with 400 μl of spore suspension at 107 spores/ml. The seed coating with Trianum-P, and S.INAT showed the highest seed germination rates ranging from 85 to 90% while S.IO1 and S.IO2 presented the lowest germination rates with 66 and 68%, respectively. At 20 days post-infection (dpi) with F. culmorum, the treated plants with S.INAT and Trianum-T22 reduced the disease incidence by 53.59 and 51.79%, respectively than the control. Besides, S.INAT induced two-folds the phenolic compounds level compared to infected control. Further, the peroxidase activity was enhanced by 50% in average since 10 dpi in plants treated with S.INAT and SIO2 than the control. Conclusion The results suggest that seed coating with T. harzianum S.INAT was a promising tool for crop production and protection under field conditions due to both direct antagonist activity and the indirect growth promotion. This strain seems to induce the systemic resistance of plants against foot crown rot disease.

Description of the subject. Drought is one of the major abiotic factors affecting growth and productivity of plants by imposing certain morphological, physiological and biochemical changes at different growth stages. Objectives. The objective of this work is to study key morphological, physiological and biochemical responses of faba bean (Vicia faba L. var. 'minor') to soil water deficit stress and to assess the contribution of genetic factors in improving faba bean tolerance to water deficit. Method. Plants of 11 faba bean cultivars were grown in the greenhouse and subjected to three levels of water deficit (90, 50 and 30% of field capacity [FC]) in a simple randomized design for 20 days. Water deficit effects on plant growth, relative water content (RWC), gas exchange, chlorophyll a (Chla) and chlorophyll b (Chlb) content, osmoprotectant accumulations (such as proline and soluble sugars), antioxidant enzyme activities and grain yield were determined. Results. Soil water deficit stress reduced growth and affected physiological parameters, especially antioxidant enzyme activities. Water deficit also increased proline, soluble sugars and protein contents. The studied cultivars significantly differed in their responses to water deficit stress. Photosynthetic parameters were less affected in the 'Hara' cultivar. Furthermore, this cultivar produced the highest value of grain yield at 30% FC, and showed higher antioxidant enzyme activities (CAT, GPX and APX), osmoprotectant accumulations, Chlb and RWC. The 'Hara' cultivar was found to be more tolerant to water deficit stress than the other cultivars. Conclusions. Our methodology can be used for assessing the response of faba bean genetic resources to soil water deficit. The identified tolerant cultivar can be utilized as a source for water stress tolerance in faba bean breeding programs aimed at improving drought tolerance.