نبذة مختصرة : Root system architecture contributes to crop performance under biotic and abiotic stresses but is, at the same time, considerably affected by adverse conditions. It is therefore receiving increasing attention from the scientific community, which is developing root system ideotypes for given environmental constraints and evaluation tools for breeders. The challenge is fraught with many practical difficulties, however, which comprise the observation and the quantification of root system architecture. This thesis was conducted in the frame of the RootOPower EU project that aims to develop a suite of tools to enhance agronomic stability and sustainability of crops under combined abiotic stresses. We used a novel high throughput phenotyping platform in aeroponics to investigate the genetic determinism of root growth and development in tomato (Solanum lycopersicon) under nitrogen deficiency, in relation with biomass production. A segregating population of 144 recombinant inbred lines generated from an interspecific cross between S. lycopersicum and S. pimpinellifolium has been used for the QTL analysis of root system architecture and biomass production under control and nitrogen deficient conditions. To achieve the required throughput, we evaluated different optical methods to assess plant nitrogen content and we validated near-infrared microscopy to estimate the nitrogen content of small leaf samples. We also deployed a model-based formalism of root system architecture to perform in-depth analysis of genetic correlations between traits. The RIL population, used as rootstock, revealed interesting shoot responses to the root genotype. QTLs were observed for three major processes which shape root system architecture, viz. root growth rate, root branching and root tropism. ; (SC - Sciences) -- UCL, 2017
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