ABSTRACT
The development of genotypes and fertilizer management practices that facilitate high phosphorus (P) use efficiency is needed given the depleting phosphorus ore deposits and increasing ecological concerns about its excessive use. Root system architecture (RSA) is important in efficiently capturing immobile P in soils, while agronomically, localized P application near the roots is a potential approach to address this issue. However, the interaction between genetic traits of RSA and localized P application has not been examined. Near-isogenic lines (NILs) and their parent of rice (qsor1-NIL, Dro1-NIL, and IR64, with shallow, deep, and intermediate root growth angles (RGA), respectively) were grown in flooded pots in a uniform and P-sufficient condition (Pinco), and with localized P application by dipping seedling roots into P-enriched slurry at transplanting (P-dipping). The P-dipping created an available P hotspot at the soil surface and substantially improved applied P-use efficiency (equivalent biomass at one fifth of application rate of the Pinco). Further, the qsor1-NIL had significantly greater biomass and P uptake than the other genotypes in the P-dipping. The qsor1-NIL consistently had a greater root biomass and surface area in the 0–3 cm soil layer, despite that there were no genotype differences in total values and that the other genotypes also reduced their RGAs responding to the P hotspot in the P-dipping. The shallow root system of qsor1-NIL facilitated P uptake from the P hotspot. P-use efficiency in crop production can be further increased by combining genetic traits of RSA and localized P application.
Footnotes
Author contributions: A.Z.O., and Y.T. designed research and analyzed data; A.Z.O., Y.T., M.M., and T.N. performed research; A.Z.O., and Y.T. wrote the article with contribution of all authors; Y.U. developed and provided plant materials; All authors reviewed, revised and approved the articles; Y.T. agrees to serve as the author responsible for contact and ensures communication.
One sentence summary: A combination of a micro-dose, localized phosphorus (P) application and a shallow root system improves rice P uptake which can increase crop production with reduced environmental impacts.
Funding: Science and Technology Research Partnership for Sustainable Development (SATREPS), Japan Science and Technology Agency (JST)/Japan International Cooperation Agency (JICA) (Grant No. JPMJSA1608); CREST, Japan Science and Technology Agency (JST) (Grant Number JPMJCR17O1)