<asp:TemplateField HeaderText="Produzione">
                        <EditItemTemplate>
                            <asp:DropDownList ID="ddl2" AppendDataBoundItems="true" 
                            runat="server" OnDataBound=popolaDDl2 Text='<%# Bind("PRODUZIONE") %>' selectedValue='<%# Bind("PRODUZIONE") %>'>
                            <asp:ListItem>SI</asp:ListItem>
                            <asp:ListItem>NO</asp:ListItem>
                            </asp:DropDownList>
                        </EditItemTemplate>
                        <ItemTemplate>
                            <asp:Label ID="Label2" runat="server" Text='<%# Bind("PRODUZIONE") %>'></asp:Label>
                        </ItemTemplate>
                    </asp:TemplateField>

Protected Sub popolaDdl2(ByVal sender As Object, ByVal e As EventArgs)
        Dim ddl As DropDownList = DirectCast(sender, DropDownList)
        If ddl.SelectedValue.ToString.Equals("SI") Then
            Dim txtCom1 As TextBox = CType(Me.Datagrid2.FindControl("TextBox5"), TextBox)
            Dim txtCom2 As TextBox = CType(Me.Datagrid2.FindControl("TextBox6"), TextBox)
            txtCom1.ReadOnly = True
            txtCom2.ReadOnly = True
        End If
    End Sub