**5. Conclusions**

We illustrated that gel and liquid cultures rapidly deliver quantitative plant biometrics, and tomography a more qualitative outcome. The study revealed a large diversity of root morphologies and variability of N uptake capacities. These traits can be introgressed into one performant NUpE genotype possessing large root surface (e.g, HER cultivar), great N uptake rate per root mass (e.g., AVI, CLO) and reducing the adverse impact of N products on root uptake.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/10 .3390/nitrogen2040033/s1, Figure S1: Inter-trait phenotypic correlations in 55 winter oilseed rape cultivars grown in vitro, Figure S2: Inter-trait phenotypic correlations in 12 winter oilseed rape cultivars grown in hydroponics, Figure S3: Correlation between nitrate influxes and leaf area and total root length in 10 oilseed rape cultivars grown in hydroponics, Table S1: List of oilseed rape cultivars used in the study, Table S2: Statistical treatment for the data set measured in vitro, Table S3: Statistical treatment for the data set measured in hydroponics.

**Author Contributions:** Conceptualization and original draft preparation: C.H., L.K.; Investigation, methodology: C.H., C.J.S., H.D.G., J.L., L.K., M.B., P.N., P.T., T.R.M.; editing, C.C., L.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Fonds de la Recherche Scientifique (F.R.S.-FNRS) (MIS and PDR T.0116.19), and by European Plant Phenotyping Network (EPPN) (Grant Agreement No. 284443).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** L.H. and C.H. are, respectively, PhD fellow and research associate from F.R.S.-FNRS.

**Conflicts of Interest:** The authors declare no conflict of interest.
