The study looked at how different forms of nitrogen affect the growth and metabolism of maritime pine seedlings. Seedlings were given either nitrate or ammonium solutions, and their nitrogen levels were analyzed. Seedlings fed with ammonium grew bigger, with more nitrogen and amino acids in their needles. Nitrate mainly accumulated in the stem, while ammonium was found in the roots. Ammonium-fed seedlings had more sugars and L-arginine in their roots, while nitrate-fed seedlings had more L-asparagine. These differences help the seedlings manage their metabolism and prevent issues with carbon and nitrogen assimilation. This research helps us understand how nitrogen affects plant growth and could improve how we provide nutrients to conifers.