The rupee weakened by 51 paise to 62 rupees 30 paise against the dollar in early trade today after the International Monetary Fund lowered its projection of India's growth rate. Besides, strengthening of the US dollar against euro and other currencies in the global market and a lower opening in the domestic equity market mainly put pressure on the rupee, dealers said. The rupee ended unchanged at 61 rupees 79 paise against the dollar in the previous session on alternate bouts of demand and supply amid surprise steps by the RBI to increase liquidity.