Key role of root trait combinations and plasticity in response to phosphorus forms on phosphorus-acquisition in agroecosystems

Phosphorus (P) in soil comprises both organic P (OP) and inorganic P (IP), but efficiency of plant P-acquisition strategies for accessing various IP or OP from soil is unclear.

We examined the response of P-acquisition root traits in eight plant species in the presence of IP or OP sorbed onto various soil minerals.

We highlighted contrasting trait plasticity for three distinct P-acquisition strategies: mining, foraging, and intermediate. Species with mining and foraging P strategies showed significant plasticity in root traits across P-forms. Species with P-mining strategy had greater physiological root traits and P-acquisition from OP, while species with a P-foraging strategy had greater morphological and architectural root traits and P uptake from IP. In contrast, species with intermediate P strategy showed lower trait plasticity among P forms and similar P acquisition from all P forms. Results show that each strategy presented a specific trait combination, with greater degree of P acquisition for the intermediate strategy that combined morphological and physiological traits. Mineral-P interactions also influenced plant strategies, with OP desorbing more from clays (kaolinite) than from Fe/Al oxides.

The present findings highlight the importance of both plasticity and combinations of root traits for each P-acquisition strategy and allow to improve our understanding of P dynamic in the soil-plant system while presenting new knowledges for modelling P acquisition.