New Mutant Cotton Lines of Good Yields and Resistance to Some Insects by γ-Irradiation

Abstract

M₂ through M₆ of the γ-Irradiated mutant lines, AP₁ an dAP₂ were tested for insect resistance and good yields comparing to the control varieties, SR₂ and R₁, in field and laboratory conditions. Field tests at Suwan Farm revealed seed weight , lint weight and % lint of AP₁ to be the greatest while the highest weight of 10 fresh bolls was found in AP₂. Fiber quality of all varieties/lines were found to be similar and were within the rather high standard levels. Visual rating of damage caused by H. armigera (square and damage) and A. biguttata (hopper burn) to the controls and mutants were similarly rated as moderately resistant and susceptible respectively. According to antibiotic test and chemical analysis of H. armigera, the small increased larval weight and the morphologically abnormal adult fed from leaves of AP₁ and AP₂ were believed to be partially caused by other chemical substances beside gossypol and flavonoids whose contents did not exceed the giver toxic level inhibiting growth.