Seed carbon, nitrogen, and sulfur concentrations
Seeds of each individual plant (n=4) were pooled and dried for 48h at 50°C. The dried seeds were ground manually and the resulting powder (around 3 mg) was placed into tin capsules for analysis. The percentage of total carbon (C), nitrogen (N), and sulfur (S) per mg DM of the dried seeds were determined with a C/N/S analyzer (EA3000, Euro Vector, Milan, Italy) linked to a continuous flow isotope mass spectrometer (IRMS, Isoprime, GV Instrument, Manchester, UK).