WASHINGTON—The Supreme Court on Tuesday didn't appear swayed that an Indiana soybean farmer can replant herbicide-resistant seeds covered by Monsanto Co. technologies without violating its patents rights.

Monsanto requires growers to use the Roundup Ready seeds only for a single crop, and they can't use the later generation seeds generated from previous harvests. Monsanto imposes the conditions because its technology, which renders crops resistant to weed killer, reproduces itself in each generation of seeds.

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