read data from a column of table to a combobox

i want to set data source of one combo box to one column of table and this combo box is one of gridview column my code is :
 

DataTable p = new System.Data.DataTable();
            p = selectcolor();
            (dataGridView1.Columns[4] as DataGridViewComboBoxColumn).DataSource = p;
 
 
 
private DataTable selectcolor()
       {
 
           DataTable k = new System.Data.DataTable();
           try
           {
 
               string str = "Data Source=C:\\Documents and Settings\\almas\\Desktop\\BazarKhodro\\khodro.sdf";
               Qconnection.ConnectionString = str;
               Qcommand.Connection = Qconnection;
 
 
               string commandText = "select color from foroosh";
 
               Qcommand.CommandText = commandText;
               Qcommand.CommandType = CommandType.Text;
               SqlCeDataAdapter a = new SqlCeDataAdapter();
               a.SelectCommand = Qcommand;
               a.Fill(k);
               Qconnection.Open();
               Qconnection.Close();
               return k;
 
           }
           catch (Exception ex)
           {
 
               throw new Exception(ex.Message);
               return k;
           }
       }
 

after runing i see the content of p but content of combobox is:
System.Data.DataRowView

pls help me