Agronomic Performance and Mineral Composition of Prickly Pear Cactus (Opuntia ficus-indica L. Mill.) Inoculated with Native Rhizobacteria

Abstract

Prickly pear cactus (Opuntia ficus-indica) is widely consumed fresh due to its nutritional value, functional properties, and recognized health benefits. Although traditionally considered a low-input crop, the increasing dependence on chemical fertilizers has raised production costs and environmental concerns, prompting the exploration of sustainable alternatives such as plant growth-promoting rhizobacteria (PGPR). These microorganisms can enhance plant performance through multiple mechanisms, including phytohormone production, biological nitrogen fixation, nutrient solubilization, and improved nutrient use efficiency. This study aimed to evaluate agronomic traits, quality attributes, and mineral composition of cactus cladodes inoculated with native PGPR under reduced chemical nitrogen fertilization. The experiment was conducted under open-field conditions using a randomized complete block design arranged in a 3 ? 2 factorial scheme. Enterobacter bugandensis (C1), Achromobacter xylosoxidans (C2), and Pseudomonas putida (C3) were applied individually and in combination at 10? CFU mL?¹, with nitrogen fertilization supplied at 50% and 100% of the standard dose. Inoculation with E. bugandensis (C1) and the C1 + C3 combination was associated with a higher number of cladodes per plant, suggesting stimulation of vegetative growth under field conditions. Regarding mineral composition, treatments including P. putida showed higher concentrations of phosphorus, potassium, magnesium, and iron in cladodes, indicating improved nutrient acquisition and internal nutrient balance. Additionally, the combination of A. xylosoxidans + P. putida under reduced nitrogen fertilization was associated with increased sugar accumulation in cladodes, reflecting potential metabolic adjustments related to carbon allocation. Overall, the results indicate that inoculation with PGPR can contribute to maintaining agronomic performance and improving the nutritional quality of Opuntia ficus-indica while reducing chemical nitrogen inputs, supporting their use as a sustainable strategy for cactus production in arid and semi-arid environments.