Effects of Arbuscular Mycorrhizal Fungi on Maize Growth, Root Colonization, and Root Exudates Varied with Inoculum and Application Method

The use of arbuscular mycorrhizal (AM) fungi is considered as an effective approach to enhance plants’ growth; nevertheless, its efficacy may vary with the type of inoculum and its application method. The present study, for the first time, investigates the effects of different mycorrhizal species applied through different methods on morpho-physiological growth, root system architecture, nutrient uptake, and root exudates of maize. Four AM fungi species viz., Claroideoglomus etunicatum (C.E), Rhizophagus intraradices (R.I), Funneliformis mosseae (F.M), and Diversispora versiformis (D.V) were applied to maize through seed coating, soil application, or seed coating+ soil application. A control without AM fungi was maintained for comparison. All the thirteen treatments were arranged in completely randomized design with three replications. Application of C.E, R.I, F.M, and D.V through different methods triggered the growth performance of maize by improving morpho-physiological characteristics and root morphology, modulating AM fungi colonization, enhancing the nutrient (N, P, K) uptake, and reducing the root exudates (oxalic, malonic, fumaric, malic, citric, and T-aconitic) compared with control. Among the different mycorrhizal species, F.M applied particularly through seed coating+ soil application was more effective in regulating maize growth as compared with C.E, R.I, or D.V species owing to better root system, higher root colonization, and greater nutrient uptake in this treatment. Interestingly, seed coating of F.M recorded statistically similar or higher shoot and root growth attributes compared with soil application particularly at 30 days after sowing. In crux, F.M applied through seed coating + soil application performed better than that of other mycorrhizal species. The obtained results also suggest that seed coating can be a cheap, viable, and efficient delivery system of AM fungi particularly for large scale application, as AM fungi seed coating had faster and greater effect on maize growth compared with soil application during early growth stages.