Effect of glyphosate on auxin transport in corn and cotton tissues.

Basipetal auxin transport in 6-day-old dark-grown corn coleoptiles was severely inhibited by increasing levels of glyphosate applied during the transport period.The velocity of basipetal transport of [(14)C]indoleacetic acid in hypocotyls from 7-day-old cotton seedlings was significantly reduced when sublethal doses of glyphosate [N-(phosphonomethyl)glycine] were applied to the cotyledonary leaves 24 hours before transport measurement. Simultaneous application of glyphosate and indoleacetic acid during transport measurement had no effect on basipetal transport in cotton hypocotyl sections.Slowing of transport was inversely proportional to the dosage applied to both species.