Abstract
Greenhouse and field studies were conducted to evaluate Oryza sativa response to the simulated carryover of fluometuron, imazethapyr, metolachlor, and norflurazon in dry- and water-seeded culture. In the greenhouse, fluometuron and norflurazon did not affect O. sativa emergence, but reduced O. sativa shoot and root dry weight at all the residue levels. Greater reduction in O. sativa emergence and shoot dry weight was observed with imazethapyr and metolachlor in dry- compared with water-seeded O. sativa. In the field, imazethapyr at 0.04 kg ai ha−1 injured dry-seeded O. sativa both years, but O. sativa yield was reduced only in the second year. Greater O. sativa injury and yield reduction were observed in dry- compared with water-seeded O. sativa with metolachlor at most residue levels. Norflurazon at 0.42 and 0.21 kg ai ha−1 caused greater O. sativa yield reduction in water-seeded O. sativa than in dry-seeded O. sativa in the first and second year, respectively. The results indicate that water-seeded O. sativa has less risk of being damaged by imazethapyr and metolachlor but is more susceptible to residues of norflurazon compared with dry-seeded O. sativa. Thus, choosing the right seeding method following a specific rotational crop herbicide could help to minimize the risk of O. sativa injury from herbicide carryover.