Spring wheat breeding programs typically perform one generation of crossing and five generations of self-pollination before seed increase and yield testing. With off-season nurseries, this process takes a minimum of three years, limiting rates of genetic gain for yield. Doubled haploids can shorten the time required to begin yield testing, however, doubled haploid technology is costly, requires specialized facilities, only works for selected germplasm, and precludes early-generation selection for high-heritability traits.
A new method for rapid generation advance, called ‘speed breeding’, has considerable advantages for spring wheat because it provides increased recombination during line development and enables selection in early generations for some traits.
The system has been refined over the past 8 years at The University of Queensland, utilizing controlled temperature regimes and 24-hour light to accelerate plant growth and development. The low-cost management system enables up to 6 plant generations of wheat annually – just like Arabidopsis. Phenotypic screens for some target traits have been adapted for use in the speed breeding system (e.g. grain dormancy, rust resistance, root traits), which enables selection in segregating populations during development of inbred lines. The Hickey lab exploits this technology to facilitate crossing and development of improved F4-derived lines within just 12 months.