HPPD 저해 제초제들에 대한 통일형벼 품종의 약해 반응

This study was conducted to investigate the levels of phytotoxicity of Japonica×Indica-typerice varieties to HPPD(4-hydroxy phenylpyruvate dioxygenase)-inhibiting herbicides known for theirefficiency to control the sulfonylurea-resistant weeds. The plant injury and rice yield of threeIndica×Japonica rice (long grain, cv. Hanareumbyeo, Hanareum2, Dasanbyeo) were evaluated byapplication rate of HPPD-inhibiting herbicdes, benzobicyclon and mesotrione+pretilachlor (MP), andbutachlor as control in transplanting rice in 2012 -2013 in Miryang. The herbicide rates of 350g, 140ga.i. ha-1 for recommended rate(1x) and 750g, 280g a.i. ha-1 for 2x with benzobicyclon andmesotri-one+pretilachlor (MP), respectively, were applied as pre-emergence treatments while only the 1x concen-tration of 1,500g a.i. ha−1 was used for butachlor. All three Indica×Japonica rice cultivars wereextremely sensitive to both benzobicyclon and MP herbicides even at the 1x rate as reflected by highvisual injury of leaf chlorosis and the injury was more severe at 2x rate than 1x concentration. The per-centage of foliar chlorosis of Indica×Japonica rices at the 1x rate was only 34~64% for benzobicyclonat 14 days after treatment(DAT) and 63~75% for MP at 7 DAT but the injury was more severe at the 2xrate with 76~83% for benzobicyclon and 83~89%. However, the leaf chlorosis injury of the three ricevarieties recovered at 1x rate of benzobicyclon and MP about 30 DAT but rice plant death of 6.5~11.5%for benzobicyclon and 2.1~3.3% for the MP was observed at the 2x rate, respectively. The heading dateof the injured rice plant was delayed by 1 to 2 days and panicle number per square meter, ripened grainratio and 1000-brown rice weight were decreased due to the injury of rice plant by the herbicide treat-ments as compared with the control treatment of butachlor. Yield of the Indica×Japonica rice varietiestreated with benzobicyclon and MP was significantly reduced by 5~9% even at 1x rate and 14~28% at2x rate, respectively. The result indicates that MP and benzobicyclon should not be used for weed controlin Indica×Japonica varieties and rice plant should be transplanted again to some extent at 2x rate of thebenzobicyclon and MP herbicides.