The increase in vigour index of fresh seeds of UMI 285, UMI 61 and COH(M) 5 primed with 1% KH2PO4 for 6 hrs were 35, 36 and 36%, respectively over unprimed seeds; whereas the increase in vigour index of aged seeds of UMI 285, UMI 61 and COH(M) 5 primed with 1% KH2PO4 for 6 hrs were 54, 56 and 53%, respectively over unprimed seeds (B of Figure-2).