Evaluation of Bioproducts and Mycorrhizal Inoculation in Asian Soybean Rust Control, Nutrient Leaf Contents and Yield Under Field Conditions

Asiatic Soybean Rust (ASR), caused by the fungus Phakopsora pachyrhizi, is the main disease affecting soybean crop, generating high losses each year, with insurgence of fungicide resistance. One strategy to decrease the fungus resistance is to use natural antimicrobial compounds to control ASR. Therefore, the objective of this work was to evaluate the potential for ASR control of a fraction produced during secondary metabolism by a Pseudomonas aeruginosa LV strain, inoculating plants with Rhizophagus clarus, an arbuscular mycorrhizal fungus (AMF) produced in vitro, evaluating the treatments effect on grain yields. Plants were treated with two doses of F4A semi- purified fraction (1 mu g mL(-1), 10 mu g mL(-1)), mixed or not with commercial fungicides (Unizeb Gold (R) or Sphere Max (R)). Scanning electron microscopy (SEM) and light microscopy images showed that the association between F4A in both doses plus Sphere Max (R) provided protection, similarly to Unizeb Gold (R) or Sphere Max (R), against ASR, causing ultrastructural changes in P. pachyrhizi hyphae and spores. Mycorrhizal colonization, plant growth and height increased in plants treated with F4A10 + Sphere Max. Plants treated with F4A1 compound produced 4.64 ton ha(-1), followed by F4A1 + Sphere (4.51 ton ha(-1)), F4A10 + Sphere (4.44 ton ha(-1)) and Unizeb+Sphere (4.36 ton ha(-1)).