| Abstrakt: |
Two morphological characters (glabrousness and nectarilessness) and three allelochemics (gossypol, raimondal, and condensed tannins) have been implicated in host plant resistance of cotton, Gossypium hirsutum L., to the bollworm, Helicoverpa zea (Boddie), and the tobacco budworm, Heliothis virescens (F.). Thirty-seven germplasm lines of upland cotton having elevated levels of condensed tannins (CT) were developed by and released by the Texas Agricultural Experiment Station. These lines contain up to 100% more CT than ‘Stoneville 213’ or ‘Stoneville 112’. Several of these lines were documented to have an intermediate level of resistance to the twospotted spider mite, Tetranychus urticae Koch. Thirteen of these lines were evaluated for yield and fiber properties during 1988 at College Station, TX; for yield and fiber properties with and without artificial infestations of tobacco budworm during 1988 and 1989 at Starkville, MS; and for naturally infested bollworm/budworm damage at Pine Bluff, AR, in 1988 and 1989. The 13 lines were evaluated in several feeding trials with neonate tobacco bud worm larvae at Dallas or College Station, TX, from 1987 through 1989. The elevated levels of CT were substantiated during these evaluations, but either the levels were not high enough or CT does not act as a feeding deterrent nor reduce performance of neonate larvae of the bollworm/budworm complex. |
