Exploring the agronomic traits, antioxidant and antifungal properties of Hermetia illucens frass extract in durum wheat (Triticum durum Desf.).

BACKGROUND: Wheat (Triticum spp.), the most cultivated species worldwide, is threatened by various stresses. Among these, the biotic stresses caused by phytopathogenic fungi, like Fusarium sporotrichioides, are responsible for food losses and mycotoxins poisoning. The green strategy based on recovery and use of frass deriving from Hermetia illucens reared on the standard Gainesville diet was applied, involving durum wheat (Triticum durum Desf. var Simeto) seed priming with 10% frass extract, alone or combined with T. afroharzianum T22 (T22), in pot/soil experiment. For this purpose, the agronomic traits, reduction of damping-off due to F. sporotrichioides, and activity of the pool of antioxidant enzymes involved were evaluated. In addition, the presence of microorganisms in the frass extract with possible plant growth promoting and/or protection activity, was searched. RESULTS: Seed priming determined enhanced wheat growth performance and, in the meantime, a control of the development of disease symptoms, allowing a reduction of damping-off of almost 40% when frass extract and T22 were used together. This was accompanied by an increased antioxidant activity in seedlings derived from primed seeds, enabling them to face stresses in a proper way. In addition, in order to address which component of frass extract was responsible for these effects, Paenibacillus polymyxa was isolated from frass extract, and tested for its antifungal activity in vitro, resulting effective against F. sporotrichioides and also the phytopathogenic fungi Fusarium oxysporum f.sp. lycopersici and Botrytis cinerea. CONCLUSIONS: This finding demonstrated that seed priming with frass extract, together with T. afroharzianum T22, could be used as an effective and environmentally friendly strategy to promote wheat growth and, at the same time, effectively control the development of F. sporotrichioides disease. The insights gathered from this research, confirmed the ability of frass to be used in priming technique, opening the door to promising solutions to harness the potential of sustainable agricultural practices and green technologies circular economy-based.