| To detect wild oat resistant to clodinafop-propargyl (Topik) in Khuzestan wheat fields, a seed bioassay study was conducted in Weed Science Laboratory of Ferdowsi University of Mashhad, College of Agriculture, in 2006. Forty five wild oat biotypes were collected from 7 cities of Khuzestan province including Ahvaz, Andimeshk, Shush, Shushtar, Ramhurmuz, Susangerd (Dashte-Azadegan), along with a susceptible biotype, from regions with no chemical control record. The study was carried out in three steps including determination of discriminating dose for susceptible biotype, screening wild oat biotype with discriminating dose, and dose-response experiment for suspected biotypes. In all experiments shoot length (% of control) in petri dish, 7 days after herbicide application was used as a plant growth index. According to the seed bioassay test, the discriminating dose for sensitive biotype was detected as 0.02 mg a.i. L-1. In the screening test with discriminating dose, 17 biotypes were determined as a suspected resistant. Our results showed that herbicide resistance is evolved in some wild oat biotypes in Khuzestan wheat fields. |
