Microbially mediated rhizospheric phosphorus turnover promotes wheat yield by enhancing phosphorus bioavailability

Wheat is the most important and widespread grain crop. However, the influence of cultivars released in different decades of modern breeding on the rhizospheric microbial community involved in phosphorus (P) cycling, including phoD- and pqqC-harboring microorganisms, remains poorly understood. The objective of this study was to examine the influence of different P fertilization levels (0 and 100 kg ha⁻¹) and soil moisture conditions (well-watered and drought stress) on five major wheat varieties cultivated in Shaanxi, China, which were released between the 1940s and 2010s. We quantified the key indices of rhizospheric P turnover and analyzed the influences of soil P bioavailability on yield and P accumulation. Our results revealed that the newest variety (Changhan 58) accumulated more P and produced more grain yield than the oldest variety (Mazha) did (by up to 79.4 % and 92.6 %, respectively), as the concentration of rhizospheric labile P (resin-P, NaHCO₃-Pi and NaHCO₃-Po) increased by 1.33–2.03-fold. Correlation analysis of key microbial biomarkers with environmental factors revealed that among them, OTU1486, OTU16602, and OTU9370 were significantly positively correlated with the labile P pool and significantly negatively correlated with NaOH-Po. These findings suggest their potential role in supporting the microbial community assembly and further promoting P mobilization. The results of the PLS[sbnd]PM model revealed that the soil labile-P pool is mainly directly regulated by the phoD-harboring microbial community and the moderately labile-P pool. Moreover, the pqqC-harboring microbial community indirectly regulates the soil labile-P pool by influencing the moderately labile-P pool. This study provides valuable insights for improving P management in wheat production, emphasizing the importance of modern wheat varieties and microbial dynamics in optimizing P use efficiency.