Factors Affecting Fertilization Frequency in Crosses of Triticum aestivum cv. ‘Highbury’×Zea mays cv. ‘Seneca 60’;

Crosses of ‘Highbury’בSeneca 60’ were studied to determine the effect of four crossing procedures on the frequency of fertilization. The procedures were: 1) glumes of emasculated florets left intact, 2) glumes cut to expose the stigmas, 3) intact glumes given a 75 mg 1-1 GA spray 2 h after pollination, and 4) cut glumes given a 75 mg 1-1 GA spray 2 h after pollination. Within each treatment florets with developmental ages ranging from 3 days before an-thesis to 3 days after anthesis were pollinated. Fertilized florets were found in all four treatments. Overall, 20.2 % had only an embryo, 2.5 % had only an endosperm and 7.9 % had an embryo and an endosperm. Significant variation in the frequency of embryo formation, and hence in the frequency of potential plants, was found both between treatments and between developmental stages within treatments. The highest frequency (55.8 % of pollinated florets) was found in florets with intact glumes which had not received a GA spray and which had been pollinated on the day of anthesis. Cutting the glumes to expose the stigmas, pollinating earlier or later than the day of anthesis or application of a GA spray all tended to reduce the number of embryos. This was also the case when the total fertilization frequencies (embryos plus endosperms) were analyzed. The potential of wheat × maize crosses for wheat haploid production is discussed.