Breeding Milestones Correspond with Changes to Wheat Rhizosphere Biogeochemistry That Affect P Acquisition

Breeding wheat (Triticum aestivum L.) has resulted in small gains in improved nutrient acquisition and use as numerous traits are involved. In this study, we evaluated the impact of breeding on P-acquisition and identified both plant and soil variables that could be used to inform the selection of germplasm with increased P acquisition efficiency. We previously screened a historic panel of winter wheat cultivars for root system architecture and root tip organic acid content when grown in P-deficient solution/agar and used these characteristics together with breeding history to develop a predicted P extraction potential (PEP). We tested the validity of the PEP classification by growing cultivars under sufficient and insufficient soil P conditions. Old, wild-type cultivars had the greatest P utilization efficiency (PUtE) when grown under insufficient P, likely a result of the chemical potential of wild-type (with respect to Rht-B1) cultivars (greater organic acid production) rather than root system size. Wild-type plants had differences in rhizosphere microbial community structure, rhizosphere bicarbonate-extractable P, and bulk soil Fe and Al, indicating the utilization of typically less available P pools. The PEP classification based on the presence of dwarfing allele and era of release offers a path forward for breeding for improved P acquisition.