Assessing nutritional status and development of Pereskia aculeata Mill. affected by inoculation of Azospirillum brasilense combined with nitrogen rates

The interactive effect of Azospirillum brasilense inoculation and nitrogen (N) rates on Ora-pro-nobis (Pereskia aculeata Mill.) is poorly understood. Ora-pro-nobis (OPN) could be an important horticultural plant to promote a diverse and healthy diet to combat macronutrients and micronutrients deficiencies, particularly in developing countries. The objectives of this research were to assess the effect of inoculation with A. brasilense combined with N rates on OPN development, yield and leaf nutrients content under greenhouse conditions. Treatments were tested in a randomized completely block design with four replicates, arranged in a full factorial design 2 x 5 and included: i) two inoculations (with and without A. brasilense) and iii) five N application rates (0, 50, 100, 150 and 200 kg ha(-1) applied in two split application as ammonium sulfate source). Inoculation with A. brasilense benefited OPN growth and development, leading to a greater leaf biomass, even combined or not with N application rates. In addition, A. brasilense inoculation increased OPN nutrition with increased leaf N, P, K, Ca, Mg, S, Fe and Zn concentrations. Azospirillum brasilense combined with 150 kg N ha(-1) increased leaf biomass by 40% in sampling 1, and in sampling 2, A. brasilense inoculation increased leaf biomass by 8.8% regardless N application rates. Therefore, A. brasilense inoculation could be an important practice to increase OPN cultivation, development, nutrition and yield. Ora-pro-nobis showed high nutrient content in leaf tissue, therefore, OPN plant can be an interesting source of nutrients to human consumption. Nitrogen application rates benefited OPN growth and development leading to a greater leaf biomass. In addition, N application rates increased OPN nutrition with increased leaf N, P, Ca, Mg, S, Cu, Mn and Zn concentrations. However, increasing N rates decreased leaf K concentration. Therefore, long-term studies are required to better understand the role of A. brasilense under different N management and their effects on OPN development and nutritional properties, aiming to reduce N application rates and improve N management in OPN cultivation.