Evaluating individual and mixed arbuscular mycorrhizal fungi for controlling Rhizoctonia root rot in lupine.

Lupin is an economically and ecologically important legume crop. However, it is susceptible to infection with Rhizoctonia solani, which causes damping off and root rot diseases. Arbuscular mycorrhizal fungi (AMF) as a biological control agent has emerged as a promising alternative to chemical fungicides. Four species of AMF, namely Entrophospora etunicata, Rhizophagus clarus, Rhizophagus intraradices, Entrophospora lutea and their mixture were evaluated to determine their compatibility with lupine plants, also as a biocontrol agent against damping-off and root-rot diseases in comparison with the chemical fungicide Rizolex-T. All mycorrhizal treatments significantly reduced damping-off disease and increased the surviving plants under greenhouse and field conditions. The most effective isolates were Entrophospora lutea, followed by R. intraradices. Alongside their biocontrol activity, they positively enhance the uptake of macro- and micronutrients, promoting nodulation, and boosting nitrogenase enzyme activity. Additionally, they improved various plant growth parameters, increased yield, and stimulated the activity of peroxidase (PO), polyphenol oxidase (PPO), and elevated phenolic compounds. Moreover, greater accumulations of proline, chlorophyll, and carotenoids were observed. However, Entrophospora lutea treatment was effective as Rizolex-T in disease reduction and superior in enhancing plant growth and yield.