Large Crown Root Number Improves Topsoil Foraging and Phosphorus Acquisition.

Area of Science:

• Plant Science
• Agronomy
• Genetics

Background:

• Suboptimal phosphorus (P) availability is a major limiting factor for plant growth globally.
• Maize (Zea mays) productivity is often constrained by low soil P levels.

Purpose of the Study:

• To test if maize genotypes with a large crown root number (CN) exhibit shallower rooting and enhanced P acquisition in low-P soils.
• To evaluate the physiological and agronomic benefits of large CN under P stress.

Main Methods:

• Maize recombinant inbred lines with contrasting CN were grown under suboptimal P conditions in greenhouse mesocosms and field trials.
• Root architecture, P concentration, photosynthesis, stomatal conductance, biomass, and yield were measured.

Main Results:

• Large CN maize showed significantly shallower rooting depth and increased topsoil root length density under P stress in both environments.
• Plants with large CN exhibited higher leaf P concentration, improved photosynthetic rates, greater stomatal conductance, and increased biomass and yield.
• Specifically, large CN improved shoot biomass by 44% in mesocosms and 23% in the field, and yield by 28% in the field.

Conclusions:

• A large crown root number (CN) enhances P acquisition from low-P soils by promoting topsoil foraging and reducing rooting depth.
• The large CN phenotype is a promising selection target for improving P use efficiency and yield in maize and potentially other cereal crops.