diff --git a/Models/PMF/Organs/ReproductiveOrgan.cs b/Models/PMF/Organs/ReproductiveOrgan.cs
index 9bed9209b4..de87ad16f5 100644
--- a/Models/PMF/Organs/ReproductiveOrgan.cs
+++ b/Models/PMF/Organs/ReproductiveOrgan.cs
@@ -369,7 +369,25 @@ public double MinNconc
         {
             get
             {
-                return MinimumNConc.Value();
+                // Biomass allocation today
+                double dmAllocation = potentialDMAllocation.Storage +
+                    potentialDMAllocation.Structural +
+                    potentialDMAllocation.Metabolic;
+                // Required the minimum nitrogen content according to biomass at the end of day 
+                //     and minimum nitrogen concentration
+                double requiredMinNContent = (Live.Wt + dmAllocation) * MinimumNConc.Value();
+                // "requiredMinNContent - Live.N" is the deficit of nitrogen in grain.
+                // Negative: enough nitrogen for grain 
+                // Positive: no enough nitrogen for grain
+                // (requiredMinNContent - Live.N) / dmAllocation: Convert to nitrogen concentration
+                // 0.00001: A small value for minimum nitrogen concentration which cannot 
+                //          be zero in the arbitration model
+                double minNConc = 0.00001;
+                if (dmAllocation > 0)
+                {
+                    minNConc = Math.Max(0.00001, (requiredMinNContent - Live.N) / dmAllocation);
+                }
+                return minNConc;
             }
         }