Effects of selenium (Se) application and arbuscular mycorrhizal (AMF) inoculation on soybean (Glycine max) and forage grass (Urochloa decumbens) development in oxisol

Abstract

Fertilizer application can enhance the nutritional value of plants, such effects being influenced by the presence of arbuscular mycorrhizal fungi (AMF). Nutrients × AMF interactions are well-known for variety of elements but very little has been addressed on biofortification of selenium (Se) in plants grown in tropical soils. The purpose of this study was to evaluate the effect of Se application and AMF inoculation on growth and micronutrient contents on soybean plants as forage grass. The experiments were conducted in a completely randomized factorial design with five Se doses (0.0, 0.5, 1.0, 2.0 and 3.0 mg kg-1 for soybean plants, and 0.0, 0.5, 1.0, 3.0 and 6.0 mg kg-1 for forage plants), with and without AMF inoculation in three replicates. The results showed that soil Se had only slight effect on soybean growth but it caused a two-fold increase on grain yield. However, the growth of forage grass was enhanced by Se application when AMF was present. The AMF inoculation reduced benefit for soybean growth and yield but marked positive effect on forage grass at high doses of Se. Selenium contents in both plants were increased by its application in soil, being such effect proportional to soil applied doses. Selenium application and AMF inoculation had marked effects on micronutrients contents in both soybean plants and forage grass and they may contribute to Se and micronutrient biofortification.