diff --git a/backend/geonature/core/gn_monitoring/models.py b/backend/geonature/core/gn_monitoring/models.py
index 80c14b9ac9..3536985003 100644
--- a/backend/geonature/core/gn_monitoring/models.py
+++ b/backend/geonature/core/gn_monitoring/models.py
@@ -246,7 +246,7 @@ class TObservations(DB.Model):
     digitiser = DB.relationship(
         User, primaryjoin=(User.id_role == id_digitiser), foreign_keys=[id_digitiser]
     )
-    cd_nom = DB.Column(DB.Integer)
+    cd_nom = DB.Column(DB.Integer, DB.ForeignKey("taxonomie.taxref.cd_nom"))
     comments = DB.Column(DB.String)
     uuid_observation = DB.Column(UUID(as_uuid=True), default=select(func.uuid_generate_v4()))
 
diff --git a/backend/geonature/migrations/versions/5b61bcaa18da_monitoring_add_cd_nom_foreign_key.py b/backend/geonature/migrations/versions/5b61bcaa18da_monitoring_add_cd_nom_foreign_key.py
new file mode 100644
index 0000000000..35164b8d34
--- /dev/null
+++ b/backend/geonature/migrations/versions/5b61bcaa18da_monitoring_add_cd_nom_foreign_key.py
@@ -0,0 +1,40 @@
+"""[monitoring] Add cd_nom foreign key
+
+Revision ID: 5b61bcaa18da
+Revises: 2894b3c03c66
+Create Date: 2025-01-07 14:28:20.475116
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = "5b61bcaa18da"
+down_revision = "2894b3c03c66"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # Création clé étrangère sur la table t_observations
+    op.create_foreign_key(
+        "fk_t_observations_cd_nom_fkey",
+        source_schema="gn_monitoring",
+        source_table="t_observations",
+        local_cols=["cd_nom"],
+        referent_schema="taxonomie",
+        referent_table="taxref",
+        remote_cols=["cd_nom"],
+        onupdate=None,
+        ondelete=None,
+    )
+
+
+def downgrade():
+    op.drop_constraint(
+        "fk_t_observations_cd_nom_fkey",
+        table_name="t_observations",
+        schema="gn_monitoring",
+    )