Progress in Polyhaploid Production Techniques of Hexaploid Wheat through Wide Crosses

(Triticum aestivum L.) through wide crosses were evaluated in terms of pollen sources, 2,4-D application, embryo rescue and chromosome retention. Pollen sources included Hordeum bulbosum L., Zea mays L., Pennisetum glaucum (L.) R. Br., Sorghum bicolor (L.) Moench, and Tripsacum dactyloides (L.) L. Maize-mediated polyhaploid production was more stable than the other methods because of a lesser genotypic influence on embryo formation. Application of 2,4-D onto wheat after pollination was critical to promote seed setting and embryo formation in all cross combinations. Embryo rescue was necessary at an appropriate embryo developmental stage to obtain plant regeneration. Paternal chromosomes were eliminated by the stage of active growth of the polyhaploid seedlings. Polyhaploid production frequencies ranged between 10 and 20% of pollinated wheat florets, suggesting germ plasm genotypic effects