Winter rye root growth and plasticity in response to nitrogen and phosphorus omission under field conditions

Nitrogen (N) and phosphorus (P) deficiencies can significantly reduce crop yield. Despite their importance, the impacts of N and P deficiencies under field conditions on cereal roots, particularly winter rye, remain poorly understood. This study investigates the effects of N and P deficiencies on winter rye growth and root architecture under field conditions. A sampling campaign was conducted during the 2022 season at the long-term fertilizer experiment Dikopshof, Germany. Four fertilizer treatments were chosen: (1) fully fertilized with manure (NPKCa+m+s), (2) fully fertilized without manure (NPKCa), (3) N omitted (_PKCa), and (4) P omitted (N_KCa). Shoot biomass was assessed at five growth stages, alongside with topsoil root biomass, number of nodal roots and tillers, and root angle. The results showed that shoot and root biomass were highest in the NPKCa+m+s treatment and lowest under N omission. Although the treatment ranking of root traits varied between dates, a trend for an enhanced number of roots in the N and P omission treatments was observed around flowering. P omission fostered an increased number of tillers and N omission caused steeper root angles compared to other treatments. These findings demonstrate the strong impact of the environment and development stage on root phenotypic plasticity.