The effects of Arbuscular mycorrhizal Fungus and Trichoderma harzianum Rifai against basal rot disease (Fusarium oxysporum F.sp. cepae W.C. Snyder &H.N Hansen) on onion

In the study, the effects of Arbuscular Mycorrhizal Fungi (AMF) and Trichoderma harzianum were investigated against basal rot agent by Fusarium oxysporum f.sp. cepae W.C. Snyder &H.N Hansen which has been known as an important problem of onion with no reasonable chemical control. Firstly, isolations were made from the onion plants collected in Ankara - Polatlı district. As a result of both classical and molecular diagnostic methods, the fungus isolated has been identified as F. oxysporum f.sp. cepae. In a climate chamber under controlled conditions, two different AMF application (Glamus mosseae and commercial AMF isolate), T. harzianum and F. oxysporum f.sp. cepae were inoculated to the susceptible onion variety with different combinations (as single, double and triple). The rates of colonization, spore density and mycorrhizal dependency of AMF species on onion plants were found to be 8.91% -24%, 16.4-50.4 spore / 10 g soil and 18.3% -51.9% respectively. The best colonization, mycorrhizal dependency and spore density were determined as G. mosseae + F. oxysporum f.sp. cepae and G. mosseae applications respectively. It was found that AMF species and T. harzianum were effective by suppression of disease between 13.5% - 23.5% and the highest suppression was performed by G. mosseae. In addition, it has been found that G. mosseae increases some morphological development parameters and phosphorus content of the plant compared to control plants.