Chemically induced pollen supression and subsequent natural outcrossing in selected wheat cultivars (Tritcum aestivum L. en Thell)

Graduation date:1989Effective chemical control of pollination would\ud provide an alternative to the cytoplasmic male-sterile\ud system in hybrid wheat (Triticum aestivum L.) production.\ud The objective of this study was to determine\ud concentration, formulation, growth stage of application\ud and genotypic effects on levels of induced pollen\ud suppression and subsequent natural out-crossing from\ud foliar applications of promising Chemical Hybridization\ud Agents (CHA's). Effective concentration ranges for each\ud CHA were determined in preliminary trials. Growth stages\ud of application were made at 1.5cm to 2.5cm mean primordia\ud (spike) length of most advanced tillers.\ud Effective treatments were observed from both high and\ud low concentrations and both growth stages of application\ud with different CHA's. With specific concentrations and\ud stages of application, ten of thirteen CHA's resulted in\ud both high mean sterility (94-99.8 percent) relative to\ud bagged control spikes and high plot grain yields (44.0 to\ud 73.4 percent) relative to control mean plot yield. In\ud some cases, highest CHA concentrations resulted in higher\ud phytotoxicity and subsequent reduced grain yield\ud suggesting some reduced female fertility and/or\ud receptivity. Chemical Hybridization agents were subject\ud to only small modifications with different formulations.\ud Formulations which resulted in higher mean sterility also\ud resulted in higher plant phytotoxicity, lower grain yield,\ud and were generally effective at lower concentrations.\ud Large differences in genotype response were observed\ud with a single concentration application of four CHA\ud candidates. Concentrations high enough to induce high\ud sterility (>95%) for all genotypes resulted higher\ud phytotoxicity and subsequent lower yields of some\ud treatments.\ud Screening genotypes with inherent capacities to\ud receive wind-blown pollen, in addition to identifying\ud superior pollinators, is needed. Assuming treatment\ud genotypes can be efficiently screened for optimum\ud concentrations and stages of application, the future of\ud CHA technology as both a breeding tool and as a vehicle\ud for development of hybrid wheat seems promising