Since 1990, anthropogenic climate change – or human-caused global warming – has caused an 28% decrease in growing season rainfall across southern Australia.
“The growing season is between April and November,” explains PhD candidate, David Cann. “But over the past thirty years we have seen a steady decline in rainfall, particularly in autumn, which is the optimal time to plant spring wheat varieties in Australia.”
Cann says that this trend has been a game-changer for wheat growers.
“Farmers in low-rainfall zones have responded by sowing wheat earlier than normal,” he says. “There is a yield benefit to this approach but, unfortunately, there are no commercial varieties in Australia that are well suited to early-autumn planting. Our best wheat varieties still prefer an early May sowing time.”
In a new paper published in Frontiers in Plant Science, Cann and an international team have examined how Australian wheat growers could adapt to climate change. They did this by examining the farming practices in the Pacific Northwest of the United States, the driest wheat-producing region in the world. They believe some of the techniques used in this region, including sowing winter wheat varieties early, may provide some solutions for farmers in southern Australia.
“In Australia, winter wheat varieties are traditionally grown in regions with high rainfall, so they haven’t been a serious contender for low-rainfall climates, until now,” Cann explains. “Our research identifies the genetic characteristics and crop management capabilities of winter wheat, and the target traits that will help wheat breeders to develop new varieties more suited to the changing Australian climate.”
“Early sowing, slower developing varieties are key,” explains Cann, “because they flower at the right time. If wheat flowers too early, it gets hit by frost. If it flowers too late, it gets hit by drought and heat. We need to target the ‘Goldilocks period’ that is not too hot and dry, and not too cold.”
Increasing plant cropping efficiency and developing varieties that can be sown deep into the moisture that is stored in the soil are other important traits.
“Developing resilient, high-yielding lines of winter wheat that thrive in low-rainfall environments is the goal,” Cann adds. “The varieties and methods adopted by growers in the Pacific Northwest offer Australian breeders, agronomists and farmers some interesting alternatives.”
“We hope that our identification of key management tools and genotypes will influence breeding programs to accelerate the release of winter wheat varieties and help Australian agriculture adapt to climate change.”