Wide hybridization of Hordeum vulgare × Zea mays

Two barley (Hordeum vulgare L.) varieties ('Klages' and 'Harrington') were crossed with an array of maize (Zea mays L.) stocks carrying active transposons. From 1204 florets pollinated and cultured, 98 embryos were rescued. Forty-one of these embryos germinated to give green plants, 38 of which were haploid (2n = 7) and 3 of which were diploid (2n = 14). The overall efficiency of barley haploid production was 4.7% with 'Klages' and 1.5% with 'Harrington'. No maize DNA introgression was detected cytologically or in DNA hybridizations using maize transposable elements and highly repeated sequences as probes.