Updated project metadata. Ammonium nutrition was studied at short times (24 hours) in roots from one month-old seedlings of maritime pine. Control seedlings were irrigated with 80 mL of water (C) and the experimental seedlings with 80 mL of 3 mM NH4Cl. Root samples were collected at 24 hours post-irrigation and immediately frozen in liquid N. This experiment was carried out three independent times.