diff --git a/backend/geonature/core/gn_monitoring/models.py b/backend/geonature/core/gn_monitoring/models.py
index 3536985003..a5f0573fc8 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, DB.ForeignKey("taxonomie.taxref.cd_nom"))
+    cd_nom = DB.Column(DB.Integer, DB.ForeignKey("taxonomie.taxref.cd_nom"), nullable=False)
     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/2894b3c03c66_monitoring_add_id_individual_col_t_observations.py b/backend/geonature/migrations/versions/2894b3c03c66_monitoring_add_id_individual_col_t_observations.py
index fc582235c8..088615fc7b 100644
--- a/backend/geonature/migrations/versions/2894b3c03c66_monitoring_add_id_individual_col_t_observations.py
+++ b/backend/geonature/migrations/versions/2894b3c03c66_monitoring_add_id_individual_col_t_observations.py
@@ -24,9 +24,6 @@
 foreign_table = "t_individuals"
 foreign_key = column_name
 
-constraint_name = f"check_{table}_cd_nom_or_id_individual_not_null"
-cd_nom_column_name = "cd_nom"
-
 
 def upgrade():
     op.add_column(
@@ -42,15 +39,6 @@ def upgrade():
         ),
         schema=monitorings_schema,
     )
-    op.alter_column(
-        table_name=table, column_name=cd_nom_column_name, nullable=True, schema=monitorings_schema
-    )
-    op.create_check_constraint(
-        table_name=table,
-        constraint_name=constraint_name,
-        condition=sa.or_(column(cd_nom_column_name).isnot(None), column(column_name).isnot(None)),
-        schema=monitorings_schema,
-    )
 
 
 def downgrade():
@@ -62,7 +50,3 @@ def downgrade():
     """
     )
     op.drop_column(table_name=table, column_name=column_name, schema=monitorings_schema)
-    op.alter_column(
-        table_name=table, column_name=cd_nom_column_name, nullable=False, schema=monitorings_schema
-    )
-    # constraint automatically dropped with drop_column above
diff --git a/backend/geonature/migrations/versions/bc28b69025b3_monitoring_add_trigger_get_individual_.py b/backend/geonature/migrations/versions/bc28b69025b3_monitoring_add_trigger_get_individual_.py
new file mode 100644
index 0000000000..809d67b8e1
--- /dev/null
+++ b/backend/geonature/migrations/versions/bc28b69025b3_monitoring_add_trigger_get_individual_.py
@@ -0,0 +1,96 @@
+"""[monitoring] Add trigger get individual cd_nom
+
+Revision ID: bc28b69025b3
+Revises: 5b61bcaa18da
+Create Date: 2025-01-07 14:50:55.877316
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = "bc28b69025b3"
+down_revision = "5b61bcaa18da"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # Création trigger mise à jour du cd_nom de la table des observations
+    #   lors d'une modification d'un cd_nom d'un individu
+    op.execute(
+        """
+    CREATE OR REPLACE FUNCTION gn_monitoring.fct_trg_t_individuals_t_observations_cd_nom()
+    RETURNS trigger
+    LANGUAGE plpgsql
+    AS $function$
+    BEGIN
+
+        -- Mise à jour du cd_nom de la table observation
+        IF
+            NEW.id_individual = OLD.id_individual
+        THEN
+            UPDATE gn_monitoring.t_observations SET cd_nom = NEW.cd_nom WHERE id_individual = NEW.id_individual;
+        END IF;
+
+    RETURN NEW;
+    END;
+    $function$
+    ;
+
+    CREATE TRIGGER trg_update_t_observations_cd_nom
+        AFTER   UPDATE
+        ON gn_monitoring.t_individuals 
+        FOR EACH ROW
+        EXECUTE PROCEDURE gn_monitoring.fct_trg_t_individuals_t_observations_cd_nom();
+    """
+    )
+
+    # Création d'un trigger qui peuple le champ cd_nom de la table t_observation à partir
+    #   des données de l'individus selectionné
+    op.execute(
+        """
+
+    CREATE OR REPLACE FUNCTION gn_monitoring.fct_trg_t_observations_cd_nom()
+    RETURNS trigger
+    LANGUAGE plpgsql
+    AS $function$
+    BEGIN
+
+        -- Récupération du cd_nom depuis la table des individus
+        IF
+            NOT NEW.id_individual IS NULL
+        THEN
+        NEW.cd_nom := (SELECT cd_nom FROM gn_monitoring.t_individuals ti WHERE id_individual = NEW.id_individual);
+        END IF;
+
+    RETURN NEW;
+    END;
+    $function$
+    ;
+
+
+    CREATE TRIGGER trg_update_cd_nom
+        BEFORE INSERT OR UPDATE
+        ON gn_monitoring.t_observations
+        FOR EACH ROW
+        EXECUTE PROCEDURE gn_monitoring.fct_trg_t_observations_cd_nom();
+"""
+    )
+
+
+def downgrade():
+    op.execute(
+        """
+        DROP TRIGGER trg_update_t_observations_cd_nom ON gn_monitoring.t_individuals;
+        DROP FUNCTION gn_monitoring.fct_trg_t_individuals_t_observations_cd_nom();
+    """
+    )
+    op.execute(
+        """
+        DROP TRIGGER trg_update_cd_nom ON gn_monitoring.t_observations;
+        DROP FUNCTION gn_monitoring.fct_trg_t_observations_cd_nom();
+    """
+    )