Label,Trait,Unit,Scoring method,Materials,Plant part
,leaf nitrogen content,mg/kg,"[Note this is for measuring leaf NITRATE content, not total NITROGEN] 

Three whole leaves taken at rosette stage and freeze dried for 48-60 hours. Leaves were then homogenised in liquid N2 using a pestle and mortar and stored at -80°C prior to analyses. Leaf NO3- concentration was measured by ion chromatography (IC). For each dried, homogenised sample, 20 mg was weighed and transferred to a 1.5 mL Eppendorf tube (Eppendorf AG, Hamburg, Germany), to which 1.5 mL of Milli-Q water (18.2 MΩ cm; Fisher Scientific UK Ltd, Loughborough, UK) containing 20 mg of insoluble polyvinylpolypyrrolidone was added. This was incubated at 4°C for 60 minutes with frequent mixing, then at 90°C for 15 minutes in a water bath, prior to centrifugation at 5,000 RPM for 15 minutes at 4°C in an Eppendorf 5180 centrifuge (Eppendorf). The resulting clear supernatant was transferred into a 0.5 mL anion sample tube (PolyVials; Thermo Fisher Scientific). This was then analysed using a Dionex™ ICS-1100 Ion Chromatography System. Eluents used were Na2CO3 (Fisher) and NaHCO3 (Fisher) at 2.7 mM and 1.8 mM respectively prepared in 2 L deionised water. Standards used were sodium fluoride, sodium chloride, potassium nitrate, potassium di-hydrogen orthophosphate, potassium sulphate, and di-sodium DL-malate prepared to 1000 ppm then diluted between 10 and 150 ppm across six standard samples. Flow rate was 1.4 mL / minute and temperature was 30°C.","",leaf