Plant growth and treatments application
Brassica oleracea L. var. italica cv. Parthenon (broccoli) seeds were germinated and cultivated as reported in Muries et al., (2011) with some modifications. Firstly, a pre-hydration with deionized water was performed for 24 h. Then, seeds were germinated in dark with vermiculite at 28°C for two days and after, the sprouts were transferred to hydroponic conditions in a controlled-environment chamber with a 16-h light and 8-h dark cycle, with air temperatures of 25 and 20 °C, day/night. The relative humidity (RH) was 60–80% and the photosynthetically active radiation (PAR) was 400 μmol m-2 s-1, provided by a Pacific LED, WT 470C, LED8OS/840 PSD WB L1600, Philips. After 15 days of growth, treatments were applied consisting in: control conditions (Hoagland, 6 mM KNO3, 4 mM Ca(NO3)2, 2 mM NH4H2PO4, 1 mM MgSO4, 25 µM H3BO3, 4 µM MnSO4, 4 µM ZnSO4, 1 µM CuSO4, 0.13 µM (NH4)6Mo7O24, and 40 µM Fe3+-EDDHA), salinity (80 mM NaCl), B starvation (no B was added), B excess (250 µM of B), and the combination of both salinity and B starvation and salinity and B excess. Growth medium was renewed after 1 week and plants were harvested 15 days after treatments applications. Finally, when harvested plant growth was measured by determining dry and fresh weight, and leaf area for calculating the leaf per mass area (LMA).