Here is one example with simple gridview, on button click, one column values are loaded into dropdownlist, hope this helps
<%@ Page Language="C#" AutoEventWireup="true" EnableEventValidation="false" CodeBehind="gridvJq.aspx.cs" Inherits="WebApplication1.gridvJq" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<script src="Scripts/jquery-1.7.min.js"></script>
<script src="Scripts/jquery-1.7.js"></script>
<script type="text/javascript">
$(document).ready(function () {
$("#Button1").click(function () {
$("#<%=GridView1.ClientID %> tr").each(function () {
if (!this.rowIndex) return;
var cellval = $(this).find("td:nth-last-child(2)").html();
$('#DropDownList1').append($("<option></option>").val(cellval).html(cellval));
});
return false;
});
});
</script>
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:GridView ID="GridView1" runat="server"></asp:GridView>
<br />
<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
<br />
<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true"></asp:DropDownList>
</div>
</form>
</body>
</html>