can multiple requisitions be made into single purchase order?..thanks

Yes. Requisitions are simply a pool of demands. They are created by the users and employees when they need something. Or they could be generated by the inventory system as well when the inventories levels go down. On the other hand the purchase orders are created by buyers. "Buyers" are officially designated people to make purchases with the vendors. Multiple requisitions could be bundled into one purchase order. E.g. if 10 employees need laptops, the buyer can place one order.