Comparison between Some Biotic and Abiotic Inducers in Controlling Peanut Pod Rots and Aflatoxin Contamination

Peanuts are the fourth most widely cultivated oilseed in the world. Peanut pod rots disease and aflatoxin contamination are significant challenges that affect both production and quality, leading to considerable yield losses and complicating control efforts. Applying fungicides is one of the management techniques that are crucial for preventing peanut pod rot, but it also poses a risk to the health of people and animals and contributes to environmental contamination, thus it is imperative to discover alternatives to fungicides. To follow this path, the efficacy of biotic inducers (Pseudomonas fluorescens and Bacillus subtilis) and abiotic inducers (bion at concentrations 2, 4, and 8 mM and chitosan at concentrations 1, 2, and 3 mM) in lowering the incidence of pod rots and aflatoxin contamination was evaluated in comparison to fungicide (check control). All tested inducers led to significantly reduce the incidence of pod rot disease and aflatoxin contamination compared to untreated controls, whether under artificial or natural inoculation conditions. In general, chitosan at a concentration of 3 mM, followed by chitosan at a concentration of 2 mM and P. fluorescens had the most significant effect in reducing pod rot diseases and aflatoxin contamination, under greenhouse conditions or during the 2022 and 2023 consecutive seasons. Increasing the chemical inducers concentration enhanced their effectiveness in reducing disease incidence. The study also showed a positive relationship between induced resistance and some biochemical changes in peanut pod tissues. These changes included increased phenolic compound, activity of oxidative enzymes (PO, PPO and CAT), content of crude protein and total free amino acids. Furthermore, there was an increase in the activity of various classes of pathogenesis-related (PR) proteins. The data obtained clearly showed that some inducer treatments were able to achieve efficiency close to that of fungicides in reducing peanut pod rot and amount of aflatoxin, this encourages the use of these inducers instead of fungicides.