Résumé:
Four Trichoderma strains isolated from soils in Sétif and El Tarf were morphologically characterized. Their in vitro antagonistic capacities were evaluated, and all tested strains exhibited significant mycoparasitic activity.
To confirm these results, two strains (T5 and T16) were selected for in vivo antagonism tests. Chickpea seedlings were subjected to four treatments: one group was inoculated with Fusarium oxysporum f.sp. ciceris (FOC 132) by root immersion in a spore suspension (10⁶ spores/ml) for 30 minutes; two other groups were inoculated with a mixture of FOC 132 and either T5 or T16 in equal volumes; the control group was treated with sterile distilled water. AUDPC calculations revealed a significant difference: the T5+FOC 132 treatment delayed disease progression. Although T5 did not eliminate the disease, it slowed its rapid development.
The growth-promoting abilities of T5 and T16 were also assessed. Parameters such as plant height and root development were measured. Biochemical indicators obtained via Dualex® optical sensor showed improved growth and nutritional status in Trichoderma-treated plants. NBI, Chl, and flavonol indices were recorded at 7-, 14-, 21-, and 28-days post-inoculation. T5 significantly preserved nitrogen balance (NBI), suggesting enhanced nitrogen uptake or utilization. It also reduced flavonoid production, indicating reduced plant stress. Conversely, T16 showed no protective effect on NBI and performed similarly to controls. Regarding chlorophyll index (Chl), neither strain prevented degradation. FOC 132 treatment showed the least decline. T5 behaved similarly to the healthy control, while T16 caused the most significant chlorophyll loss.
Spectrophotometric analysis of AIA hormone levels revealed the highest production in FOC 132 (13.84 mg/ml), followed by T5 (7.13 mg/ml) and T16 (6.94 mg/ml). Cellulolytic activity of T16 on CMC medium showed a hydrolysis index of 0.95, unlike T5 which had zero activity—highlighting T16’s potential as a biocontrol agent.
