Antagonisme de Trichoderma spp. contre Fusarium oxysporum f.sp. ciceris et leur rôle dans la promotion de la croissance du pois chiche

Abstract

This study evaluates the antagonistic potential of Trichoderma spp. against Fusarium oxysporum f. sp. ciceris and their ability to promote chickpea growth. Four Trichoderma strains were characterized morphologically and their antagonistic activity was evaluated in vitro. All strains tested showed significant mycoparasitic activity on a scale of 0 to 4. In the greenhouse, the batch of chickpea seedlings inoculated with the parasite (FOC 132) and the batches inoculated with Trichoderma strains showed a significant difference, both in terms of fusarium wilt and the ability to promote seedling growth. In fact, the two Trichoderma strains used in the test confirmed their partial antagonistic power compared to the control batch of seedlings inoculated with Foc 132. The AUDPC calculation showed that strain T13 delayed the development of fusarium wilt in the batch of seedlings inoculated with a mixture of parasite spores and T13 spores (FOC+T13) compared to the control treated with strain FOC 132. In terms of growth promotion, agronomic parameters such as seedling height and biochemical indicators measured using an optical sensor (Dualex®™) showed an improvement in the growth and nutritional status of plants treated with Trichoderma spp. The NBI, Chll, and Flavonols indices were recorded at 7, 14, 21, and 28 days after inoculation. The NBI index remained more stable in plants treated with Trichoderma T13 and I, suggesting improved nitrogen availability, likely related to the interaction between the fungi and the roots. The Chll index shows that strain T13 contributes more to chlorophyll preservation, which could reflect protection against oxidative stress induced by infection. The Flav index highlights a differential regulation of flavonoids depending on the treatment. Strain T13 maintains a more balanced level of these antioxidant compounds. Spectrophotometric analysis of AIA hormone levels revealed that Trichoderma T13 produced the highest amount, reaching 15 μg/ml. Next came FOC 132 with 13.8 μg/ml and Trichoderma I with 12.6 μg/ml. The cellulolytic activity of isolate T13, tested on CMC medium, shows a hydrolysis index of 0.46 compared to I, where it is equal to 0, thus reinforcing its interest as a biological control agent.