The National Farmers Union is hoping to persuade Agriculture Minister Gerry Ritz to change the Agricultural Growth Act before it is to take effect next fall.
It would bring Canadian rules on seeds in line with an international convention that outlines, among other things, property rights for plant breeders.
Ritz says the changes would encourage more plant-breeding investment in Canada and urge foreign breeders to sell their varieties to Canadian farmers.
But the National Farmers Union says the act would strengthen the intellectual property rights of multinational corporations.
Union vice-president Ann Slater says the bill would limit the rights of producers to retain seeds from crops for future use, and would expand the amount of time seed companies can collect royalties.
"As farmers lose control of seeds, that means that we as citizens of Canada — both as eaters and farmers — we lose some control over what seeds are grown, which becomes the food we eat," Slater said from St. Thomas, Ont.
"It looks like this bill ... is handing more control over our seeds, and thus our food, to a handful of multinational seed companies."
Ritz said the NFU is interpreting the legislation wrong.
He said the intent is to allow farmers to save seed and help producers meet consumer demand.
He said the old Canadian Wheat Board single desk did not allow new seed varieties to come into Canada.
"Now we are starting to see consumers around the world, customers around the world, demanding a different product to make different products," Ritz said.
"The problem is the NFU don't understand."