| Cotton damage from cotton jassid (Amrasca biguttula Ishida) becomes very serious problem because of 50-100% reduction of cotton yield. In order to reduce more systemic insecticide used for jassid control, jassid tolerant hairy leaf cotton varietal improvement was conducted at Nakhon Sawan Field Crops Research Center in 1997. The hairy leaf variety, IRMA1243, exhibiting jassid tolerance, was crossed with smooth leaf and leaf roll resistant Tak Fa 2, which has high yield and good fiber quality. Thereafter, plants were selected using bulk method in F2-F4 generations, followed by plant-to-row or pure line selection in F5-F6 generations based on hairy leaf with jassid tolerance, leaf roll disease resistance and high yield under non systemic-insecticide... |
