Influence of Arbuscular Mycorrhizal Fungi and Nitrogen Concentrations on Carica papaya Plant Growth

Although the Carica papaya plant is a mycotrophic species that requires high nitrogen (N) concentration to obtain high yield, the effect of interaction between inoculums and nitrogen doses has not been studied thoroughly for this species. In this work we evaluated the effect of interaction between five inoculums (a native inoculum denominated Agua Dulce; commercial inoculum containing Glomus spp; Glomus claroideum; Acaoulospora spinosa and without inoculum) and four N concentrations (0, 0.5, 1.5 or 4.0 mM of N) on C. papaya cv, Maradol. plant growth. Plants treated with different inoculums of AM fungi showed significant differences (P<0.05) in plant growth. The Agua Dulce inoculum obtained 65.23 cm(2) of leaf area, 10.17 g of total fresh weight and 56.67% of root colonization percentage. Also, the plant growth was affected by N concentration supply, concentrations up to 1.5 mM increased the growth and concentrations of 4 mM of N decreased the plant growth and the root colonization percentage. In regards to the interaction between factors, the Agua Dulce treatment inoculum and 1.5 mM N recorded the major values in the growth variables on C. papaya plants. The fact that we have obtained better results with Agua Dulce inoculum could be due to the diversity of AMF in this inoculum that promotes the root growth as shown by the increased volume and root length. This would allow increased N uptake by the plant, which was reflected, in higher growth. In conclusion, the use of Agua Dulce (native inoculum) and 1.5 mM N may be recommended to obtain good quality plants at the nursery. (C) 2015 Friends Science Publishers