The crop mined phosphorus nutrition via modifying root traits and rhizosphere micro‐food web to meet the increased growth demand under elevated CO ₂

Abstract

Elevated CO₂ (eCO₂) stimulates productivity and nutrient demand of crops. Thus, comprehensively understanding the crop phosphorus (P) acquisition strategy is critical for sustaining agriculture to combat climate changes. Here, wheat (<i>Triticum aestivum</i> L) was planted in field in the eCO₂ (550 µmol mol^-1) and ambient CO₂ (aCO₂, 415 µmol mol^-1) environments. We assessed the soil P fractions, root morphological and physiological traits and multitrophic microbiota [including arbuscular mycorrhizal fungi (AMF), alkaline phosphomonoesterase (ALP)-producing bacteria, protozoa, and bacterivorous and fungivorous nematodes] in the rhizosphere and their trophic interactions at jointing stage of wheat. Compared with aCO₂, significant 20.2% higher shoot biomass and 26.8% total P accumulation of wheat occurred under eCO₂. The eCO₂ promoted wheat root length and AMF hyphal biomass, and increased the concentration of organic acid anions and the ALP activity, which was accompanied by significant decreases in calcium-bound inorganic P (Ca-P_i) (by 16.7%) and moderately labile organic P (by 26.5%) and an increase in available P (by 14.4%) in the rhizosphere soil. The eCO₂ also increased the growth of ALP-producing bacteria, protozoa, and bacterivorous and fungivorous nematodes in the rhizosphere, governed their diversity and community composition. In addition, the eCO₂ strengthened the trophic interactions of microbiota in rhizosphere; specifically, the eCO₂ promoted the associations between protozoa and ALP-producing bacteria, between protozoa and AMF, whereas decreased the associations between ALP-producing bacteria and nematodes. Our findings highlighted the important role of root traits and multitrophic interactions among microbiota in modulating crop P-acquisition strategies, which could advance our understanding about optimal P management in agriculture systems under global climate changes.