Ex vitro standardization enables evaluation of phosphorus-use strategies in Pampa biome grasses

Native grasses of the Pampa biome are essential for ecosystem functioning and restoration, yet understanding of how native species respond to nutrient availability remains limited by challenges in standardizing plant material for controlled experiments. To address this, we developed a reproducible ex vitro propagation protocol to standardize native grass materials and applied it to three representative Pampa biome grasses, Paspalum notatum, Andropogon lateralis, and Axonopus affinis. Using a minimally disturbed soil column system, we evaluated species-specific responses to contrasting phosphorus (P) availability through measurements of plant growth, P dynamics, and phosphatase activity. Propagation was assessed using successive tiller transplants over 60 days, followed by a soil experiment to quantify plant growth, P dynamics, and phosphatase activity. The propagation protocol enabled rapid production of uniform plant material, generating up to 1197.9, 131.4, and 39.4 viable plantlets per initial plant for A. affinis, P. notatum, and A. lateralis, respectively. Results indicate contrasting P-use strategies among species. Paspalum notatum showed strong increases in biomass and leaf P concentration under P addition, consistent with a resource-acquisitive strategy, and reduced phosphatase activity under high P availability. In contrast, A. lateralis exhibited limited growth response to P addition but maintained greater P-use efficiency under low P conditions, indicative of a resource-conservative strategy. These findings demonstrate that native grasses differ in their physiological responses to P availability, reflecting trade-offs between productivity and nutrient-use efficiency. The propagation protocol provides a standardized platform for controlled studies, while the identified functional differences support trait-based species selection under contrasting soil P conditions.