Abstract: Taking Japonica ( Zheng Rice 18 ) and Indica rice ( Mianyou 838 ) as the test material and combining hydroponics,potted plants and field trials,this study investigated the sensitivity and physiological responses of rice to Fenoxaprop-P-ethyl at different growth stages.In rice germination, the half maximal inhibitory concentration (IC₅₀)of Fenoxaprop-P-ethyl against radicle growth of Japonica and Indica were 0.168 7,0.163 7 μg/mL respec-tively,indicating that both were more sensitive to Fenoxaprop-P-ethyl in the bud stage. For spraying fenoxaprop-P-ethyl in the 2-3 leaf stage,the half maximal inhibitory concentration (IC₅₀) of Fenoxaprop-P-ethyl against Indica rice were 279. 56,173. 49 μg/mL for 15 days and 30 days after treatment respectively. In contrast,under test doses (12.5-400 μg/mL),the Japonica rice growth inhibition rate was less than 30%,indicating that the Japonica rice possesses higher resistance to Fenoxaprop-P-ethyl.In the field, both the injury effect and herbicidal activity of Fenoxaprop-P-ethyl on Japonica rice in 4-5 leaf stage at various concentrations were evaluated. The result revealed that Fenoxaprop-P-ethyl shows good preventive and controlling ability on grass weed at 18.45 a.i g/ha with no in-hibitory activity on rice growth.However,the dosage must be strictly controlled for the narrow range of application doses.The Fenoxaprop-P-ethyl has different effects on the protective enzyme system in these two types of rice such as GSH-Px,SOD,CAT,POD,indicating the differences for these two types of rice in both detoxification and mecha-nisms of response to the stress upon treatment with Fenoxaprop-P-ethyl.

Key words: Fenoxaprop-P-ethyl, Japonica rice, Indica rice, Phytotoxicity, Protective enzyme system

CLC Number: 

• S435.11