GRAINCORP believes it can fend off any takeover bid for the grain company by running its business as best as it can.

The agribusiness' managing director and chief executive Alison Watkins said speculation about a takeover of the company had been around for a long time but she was not concerned.

"The best thing for us is to run our business as well as we possibly can," Ms Watkins said.

"That's the best defence for a takeover because an acquirer can't look at you and say I can do that better." 

Speaking after an American Chamber of Commerce luncheon today, Ms Watkins also said there were no plans for acquisitions which would build the company into a bigger global business.

"I always think it is not about being the biggest," she said.

"We would be very cautious about acquisitions.

"We don't have a cheque book as big as those guys (Glencore, Cargill, etc).

"Nor would it be responsible for our current investors."