*4.5. Nitrate Concentrations*

Nitrate concentrations were determined following the salicyl sulfuric acid method [58]. First, 1 g of fresh sample was homogenized in 3 mL of distilled water and then centrifuged (4000 rpm, 15 min), collecting the supernatant. Then, 20 µL of extract was added to 80 µL of 5% salicylic acid in sulfuric acid and to 3 mL of NaOH 1.5 N. The samples were cooled, and the spectrophotometer readings were read at 410 nm. A calibration curve was generated using a KNO<sup>3</sup> standard (0, 1, 2.5, 5, 7.5, and 10 mM KNO3) (*R* <sup>2</sup> = 0.9918).
