Dicamba and growth condition effects on doubled haploid production in durum wheat crossed with maize

Doubled haploid plants are useful in genetic studies and plant breeding, but a consistent and satisfactory frequency of production has been difficult to achieve in durum wheat, Triticum turgidum L., using the maize pollen method. The objective of this study was to develop an effective method of producing doubled haploids in durum wheat. Plant growing and handling conditions, aspects of hormone treatments, wheat genotype and pollen source were considered. The number of caryopses, embryos, haploids, doubled plants and doubled plants that set seed were measured. Although growth conditions, pollen source, method of handling plants and wheat genotype are important considerations, the type of hormone was found to be most significant in the production of doubled haploid plants. When 50 mg/l dicamba was substituted for 100 mg/l 2,4-D the number of doubled haploids per spike increased from 0.2 for the best 2,4-D treatment to 1.3 for the dicamba treatment. This increased frequency was largely attributed to an increase in the number of caryopses generated for each spike emasculated and from an increased frequency of germination of embryos to haploid plantlets. The best production of caryopses was 0.75 per floret with dicamba compared with 0.41 caryopses per floret with 2,4-D. The best production of haploids per 100 florets was 12 with dicamba and 1.6 with 2,4-D. The frequency of one doubled haploid per emasculated spike through the use of dicamba is a practical level for generating populations for genetic studies.