For field crops limited to 1 to 2 generations annually, introducing disease-resistance and productivity traits to create new crop breeds has typically taken between 10 and 20 years. Analysts say that improvement rate is inadequate to address food security concerns raised by a growing global population living in a changing environment. But a new study details Australian scientists’ speed breeding method that has reduced the seed-to-seed timespan, and has potential to drastically reduce the time it takes to create a new variety of food crop.
Within fully enclosed, controlled-environment growth chambers, high-pressure sodium lamps extended the photoperiod to a 22-hour day and accelerated the developmental rate of plants and the harvesting of the immature seed, therefore reducing generation time. In a year, up to six generations of spring wheat, durum wheat, barley, chickpea and pea were achieved. Four generations of canola were grown in a year compared with a typical 2 to 3 generations.
The Australian team collaborated with Dow AgroSciences to create a new high-protein milling wheat variety, DS Faraday — bred from a cross of EGA Gregory and a novel pre-harvest sprouting donor parent line — which is set to debut later in 2018. The variety contains genes for grain dormancy, increasing its tolerance of wet weather at harvest time.
While desirable traits such as grain dormancy and stripe rust resistance have been successfully implemented in early segregating generations of wheat, the study’s authors caution that phenotypes studied in controlled conditions do not always correlate with field observations, particularly yield and abiotic stress tolerance.
The Australian team believes speed breeding will reduce the generation time for other species, especially sunflower, pepper and radish. The technique has shown success already with amaranth, peanut and pea. The study speculates that while direct application of speed breeding protocols is unlikely to be successful in short-day species such as maize or rice, there is room for optimization of those crops in conjunction with other growth parameters, such as temperature, plant density and watering regimen.
The prolonged photoperiods technique has largely been used to research purposes thus far. The University of Queensland team says it was motivated to write the study, published Jan. 1 in Nature Plants following 10 years of trials, because of overwhelming requests for the protocols from scientists and plant breeders from 23 countries. The team envisions the extended daylight method, in conjunction with genomic tools and resources inspiring plant scientists to perform research on crop plants directly to further accelerate crop improvement.