Haploid production of Australian wheat (Triticum aestivum L.) cultivars through wheat£maize (Zea mays L.) crosses

In order to reduce the labour for wheat haploid production through wheat maize crosses, several emasculation methods were investigated in combination with the ‘spike culture method’. Although the standard method whereby wheat spikes were hand-emasculated and pollinated on the day of anthesis gave a higher efficiency, the ‘non-emasculation method’ gave a comparable response. The use of the non-emasculation method and spike culture could eliminate much of the labour required for emasculation and treatment with 2,4-D, which is normally applied by injection into wheat internodes or by dropping onto florets after pollination with maize. Most of the selfed seeds were easily identified by the presence of endosperm, and the probability of contamination by the embryos originating from selfing among the presumptive haploid embryos in the non-emasculation method was very low. Twenty-seven Australian wheat cultivars were investigated for haploid production through wheat × maize crosses using the non-emasculation and spike culture methods. All of the 27 cultivars produced embryos after crossing with maize, with a mean efficiency of 33·1% (embryos/florets). Except for one cultivar, Tincurrin, plants were recovered from all of the cultivars (average of 61·5% including Tinccurin). This innovation of haploid production through wheat maize crosses is discussed.