PhD Candidate Institute of Bio-and Geoscience: Agrosphere (IBG-3), Forschungszentrum Jülich GmbH Frechen, Nordrhein-Westfalen, Germany
Body of Abstract: Agricultural practices often rely on the excessive use of mineral fertilizer. Phosphorus (P) is an essential macronutrient and is required for plant growth. Within the next years, the availability of rock phosphate, the current main P-fertilizer source, will decline. Especially forZea mays it is known that yield declines and canopy development is inhibited by P-deficiency. However, it remains unclear how various P-limitation levels affect structural properties and the depending life-sustaining processes like water uptake. We conducted a greenhouse rhizotron experiment with Zea mays cv. B73 in agriculturalsoil at four P fertilization levels, from strongly to not P-deficient. 2D RGB-imaging of shoot and root-systems was conducted on a daily basis. The resulting timeline data were analyzed, using a neural network-supported and mostly automated analysis pipeline, to obtain architectural parameters of all plant organs. Our observations revealed that the leaf area was maintained for plants with higher P-supply and sharply decreased at the two lowest P-levels. Total root length sharply decreased when P was below the highest level and stagnated at the three lowest P-levels. We also observed a reorganization of the root systems resulting in more seminal roots and shorter and thinner basal roots at lower P-supply. We used the measured architectural and anatomical parameters to calibrate thefunctional-structural plant model CPlantBox.We simulate empirically the growth ofZea maysatthe four P-supply levels andmechanistically the resulting waterflow.Zea mays with the highest P-supply had a significantly higher total root conductance (Krs) compared with the Krs for the three lower P-supply levels, indicating that for maize under P deficiency a lower plant water potential is required to maintain water uptake. In the next steps, we will evaluate how this affects the plant fitness and water flow in the soil-plant-atmosphere continuum.