Response of Selected Rice (Oryza sativa)Lines to Molinate

Abstract

Seventy-three rice (Oryza sativaL.) cultivars and uniform advanced-generation dwarf lines were evaluated for their response to molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate) at concentrations of 0, 1, 2, and 4 ppmw in a 7-day laboratory screening test. These rice entries varied significantly in their response to each molinate concentration when shoot height of each entry was compared to that at the 0 ppmw level. Entries were ranked according to their molinate response at the 2 ppmw concentration and categorized as being either tolerant, intermediate or susceptible. Entries categorized as susceptible at 2 ppmw were further subdivided into highly susceptible and moderately susceptible categories based on their response to the 1 ppmw concentration. Those categorized as tolerant at the 2 ppmw concentration were likewise divided into highly tolerant and moderately tolerant categories on the basis of their response to the 4 ppmw concentration. The results of this bioassay indicates the possible existence of a genetically inherited response to molinate which might be manipulated by plant breeders to develop cultivars which have a high tolerance to molinate.