Characterization of root architecture in an applied core collection for phosphorus efficiency of soybean germplasm

In the present study, we constructed an “ap- plied core collection” for phosphorus (P) efficiency of soy- bean germplasm using a GIS-assisted approach. Systematic characterization and comparative analysis of root architec- ture were conducted to evaluate the relationship between root architecture and P efficiency and its possible evolution- ary pattern. Our results found that: i) root architecture was closely related to P efficiency in soybean. Shallow root archi- tecture had better spatial configuration in the P-rich culti- vated soil layer hence higher P efficiency and soybean yield; ii) there was a possible co-evolutionary pattern among shoot type, root architecture and P efficiency. The bush cultivated soybean had a shallow root architecture and high P efficiency, the climbing wild soybean had a deep root architecture and low P efficiency, while the root architecture and P efficiency of semi-wild soybean were intermediate between cultivated and wild soybean; iii) P availability regulated root architec- ture. Soybean roots became shallower with P addition to the topsoil, indicating that the co-evolutionary relationship be- tween root architecture and P efficiency might be attributed to the long-term effects of topsoil fertilization. Our results could provide important theoretical basis for improving soy- bean root traits and P efficiency.