The Effects of Temperature and Light Intensity on Embryo Numbers in Wheat Doubled Haploid Production through Wheat×Maize Crosses

Triticum aestivum × Zea mays crosses are now widely used in the production of wheat doubled haploids to produce homozygous lines. Seasonal effects are known to influence the number of haploid embryos produced through wheat×maize crosses, but the effects of temperature and light have not been quantified. This study investigated the effect of temperature and light intensity on haploid embryo production. New Zealand wheat cultivars were grown in a glasshouse until booting when they were transferred to growth cabinets at three temperatures (day/night; 17/12, 22/17 or 27/22 °C at an irradiance of 250 μmol m −2 s −1 PAR). In another experiment, wheat lines were transferred to a growth cabinet at one of three light intensities (300, 500 or 1000 μmol m −2 s −1 PAR at 22/17 °C day/night, with a photoperiod of 16 h). The temperature and light intensity at which pollinations were made and subsequent fertilisation and embryo development occurred, significantly ( P <0.01) influenced the frequency of haploid embryo production. The optimal temperature for embryo recovery was 22/17 °C. The greatest number of embryos was produced at a light intensity of 1000 μmol m −2 s −1 . These findings will result in improvements in the overall efficiency of the wheat×maize system for wheat doubled haploid production.