<asp:TemplateField HeaderText="Вес" SortExpression="WeightValue"   >
            <EditItemTemplate>
                <asp:TextBox ID="Textbox1" runat="server"   Visible="false" Text='<%#  Bind("WeightValue") %>'></asp:TextBox>
                
            </EditItemTemplate>
            <ItemTemplate>
                <asp:Label ID="Label1" runat="server" Text='<%# Eval("WeightValue","{0:F}%") %>'></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>

<asp:BoundField DataField="Scale" SortExpression="Scale" HeaderText="Шкала" HeaderStyle-Width="60px"
            DataFormatString="{0:P}" ReadOnly="True" ItemStyle-HorizontalAlign="Center">
            <HeaderStyle Width="60px"></HeaderStyle>
            <ItemStyle HorizontalAlign="Center"></ItemStyle>
        </asp:BoundField>

TextBox t = ((TextBox)row.FindControl("Textbox1"));

 row.Cells[2].Controls[1]