In OpenERP 7, We have provision to rotate the label in X-axis by altering the graph.js,
options_line: function (data) {
xaxis : {
labelsAngle: 45,
ticks: this.orientation ? false : data.ticks
}
But in ODOO V9, web_diagram ---> js -----> graph.js, There is no provision to get the line graph and rotate the axis