## 2 Material and Methods  
### Plant Material  
Genotypes selected from 3 plant species belonging to the _Brassicaceae_ family were chosen based on previous studies showing their differences in their glucosinolates profile and trace elements concentration: _Brassica rapa_ L. (turnip greens and top greens), _Eruca vesciaria_ L. (rocket) and _Sinapis alba_ L. (white mustard). Turnip greens are the young leaves harvested in the vegetative growth period, and turnrip tops are the fructiferous stems with flower buds and the surrounding leaves that are consumed before opening and while still green. These plant species are well adapted to Mediterranean environmental conditions and have been obtained by the Plant Breeding Group at the Institute for Sustainable Agriculture (IAS-CSIC) after several generations of breeding for seed yield and glucosionate content. This material was sown and cultivated during two seasons, 2018-2019 and 2019-2020, in two Farms (I and II) in Southern Spain (see Figure 1). The Farm I land (37\({}^{\circ}\)51\({}^{\prime}\) N, 4\({}^{\circ}\)48\({}^{\prime}\) W) is located in Cordoba, next to the Guadalquivir River, in a position of the first terrace (altitude of 106 m), with a deep soil (Typic Xerofluvent) of sandy-loam texture with high pH (around 8), intermediate organic matter content (1.6%), and high carbonate content (17%). The experimental plot size for conventional cultivation of _Brassicaceae_ species on Farm I was 25 \(\times\) 25 m. The climate is typically continental Mediterranean (Csa in [PERSON]'s climate classification), with relatively cold winters, intensely hot dry summers and mean annual precipitations of 650 mm. On this Farm, the three Brassicaceae species were only grown under conventional conditions with herbicides and mineral fertilization being applied. In pre-sowing, an herbicide with trifularin as its active matter was used at a dose of 1.5 L/ha. Moreover, before sowing, a basic dressing with 8-15-15 bottom fertilizer was applied at a rate of 600 kg/ha. A top dressing (cover fertilization) with 300 kg/ha of Ammonium Nitrate was applied after the winter stop at the resumption of vegetative growth. Farm II is located in the municipal district of Alcala la Real (Jaen) (37\({}^{\circ}\)27\({}^{\prime}\) N 3\({}^{\circ}\)55\({}^{\prime}\) W, Spain) in the Sub-Baetic zone, next to the Velillos River (altitude 920 m) with a moderately stony structure and clay loam texture (Xerofluvent-Fluvisol calcareous) with high pH (8.2), high organic matter content (3%), and high carbonate content (16%). The experimental plot size for conventional and ecological cultivation of _Brassicaceae_ species in Farm II were 25 \(\times\) 25 m each. Both experimental plots were close together and separated only by a 2-m-wide border. The climate is typically continental Mediterranean (Csa in [PERSON]'s climate classification), with short summers, very hot, arid and mostly cloudless, winters are long, very cold and partially cloudy and mean annual precipitations of 650 mm. In this Farm, the three _Brassicaceae_ species were grown both under conventional and organic conditions. The conventional cultivation conditions on Farm II were similar to those of the Farm I. In organic cultivation, neither herbicides nor mineral fertilizers were applied. Instead, only treatment with a mixture of goat and sheep manure was applied at a rate of 3 kg/m\({}^{2}\). When plants from the different species reached their optimal moment of consumption (from 3 to 5 months after sowing), leaf samples from individual plants of each species were harvested, pooled, and processed for chemical analysis. The number of analyzed plants throughout the two-years duration of the study were turnip greens (_Brassica rapa_) (n = 60), turnip tops (_Brassica rapa_) (n = 85), _Eruca vesciaria_ (n = 18), and _Sinapis alba_ (n = 12). The higher number of harvested _Brassica npa_ samples is due to turnip greens and turnip tops having good commercial prospects, and their consumption, both fresh and processed, has considerably increased in the last years.