Field Performance of Trichoderma harzianum AAUT14 and Bacillus subtilis AAUB95 on Faba Bean (Vicia faba L.) Growth Promotion and Management of Chocolate Spot (Botrytis fabae Sard.)

Aims: This study was done to evaluate the effects of T. harzianum AAUT14 and B.subtilis AAUB95 on chocolate spot (B. fabae) and growth promotion of faba bean.

Study Design: A completely randomized block design was utilized.

Place and Duration of Study: The study was conducted at Kulumsa Agricultural Research Center, 8º2'N and 39º10’E, Kulumsa, June-November, 2018.

Methodology: Two trails (Trial-1 Ashebeka and Trial-2 Hachalu) were employed. We included T1-Control (B.f only); T2-T. harzianum AAUT14+ B.f; T3-B. subtilis AAUB95+B.f; T4-T. harzianum AAUT14+B. subtilis AAUB95+B.f; T5- MORE 720 WP+B.f; T6- ORZEB+B.f as treatments of the study. The disease development was assessed together with yield and related parameters.

Results: In trail 1, a reduction that varied from 31-61% for disease incidence and 13-33% of severity over T1 upon 70 days after sowing. Upon 90 days, the disease incidence and severity was reduced to 20-50% and 36-51%, respectively. Trichoderma harzianum AAUT14+B.subtilis AAUB95 (T4) reduced the disease incidence and severity showing no significance difference (P=.05) with the chemical fungicide, MORE 720 WP (T5) upon 70 and 90 days of sowing. In trial 2, the microbial inoculants reduced the disease incidence and severity to 28-63% and 17-30% upon 70 days. Likewise, the disease incidence and severity was reduced to 23-51% and 37-54% upon 90 days. In addition, the AUDPC ranged from 1586.1-2250.0%DSU in trial 1 and 1382.0-2454.5%DSU in trial 2. Moreover, leaf area of 68.95cm2 was displayed by T4 in trial 1 and 54.14cm2 in trial 2. In addition, T 4 indicated, 62% and 49% increment of hundred seed dry weight and grain yield estimate in trial 1, and 56% and 55%, increase in trial 2 compared to the uninoculated control. The percentage of healthy pods was 90% and 88.87% in trial 1 and 2, respectively, in the treatment that received T4 and followed by T2 that showed 70.40 and 78.86% in trial 1 and 2, respectively. T4 resulted 4391.45kg/ha and 4378.12kg/ha, that followed by T2 with 3764.58kg/ha and 3654.17kg/ha of yield estimate in trial 1 and 2, respectively. 27-42% and 26-41% of harvest index was exhibited in trial 1 and trial 2, respectively. Furthermore, the seed nitrogen content increased from 33-70% in trial 1 and 29-62% in trial 2. The seed nitrogen content showed 33-70% and 29-62% increment in trial 1 and 2, respectively. Even though the fungicides (T5 and T6), protected the faba bean plants from chocolate spot, there was <10% of seed nitrogen and crudeprotein content increment over the untreated control plants in both varieties.

Conclusion: The mixture of T. harzianum AAUT14 and B. subtilis AAUB95 or in some cases T. harzianum AAUT14 performed best on controlling chocolate spot, growth promotion and yield increment of faba bean.