Vegetative growth and acquisition of nutrients for the alfalfa in response to mycorrhiza and levels of phosphorus

Abstract

With the purpose of evaluating the influence of arbuscular mycorrhizal fungi and phosphorus fertilization on the yield and quality of alfalfa (Medicago sativa L.) cv. Crioula, in a soil of low natural fertility, an experiment was conducted under greenhouse conditions. The experimental design utilized was completely randomized, in a 5 x 3 factorial arrangement, with 5 replications, with 5 levels of P (P) (30, 60, 120, 180 e 240 mg of P/dm³ of soil) and 3 soil conditions (natural soil; fumigated soil; fumigated and inoculated soil with the arbuscular mycorrhizal fungus (AMF - Glomus etunicatum). The dry matter production of the aerial part, the yield of crude protein, the accumulated amounts of P, K, Ca, Mg and S, and the mycorrhizal colonization rate was evaluated. It was verified that the interaction between P doses x soil conditions influenced significantly all the studied variables. The phosphorus fertilization increased the dry matter production of the aerial part, the yield of crude protein, the accumulated amounts of P, K, Ca, Mg and S, and the results were more pronounced in the soil inoculated with AMF. The rates of mycorrhizal colonization decreased with the increase of P doses, and explain the differences in the results observed between fumigated and inoculated soils. In the conditions of this study, it was verified that alfalfa is highly dependent on the mycothrofic condition to maximize its yield.