Heatwaves are becoming so extreme, they're 'breaking the biology' of plants

Heatwaves during spring can have a detrimental impact on flowering wheat, causing significant losses. (ABC Midwest: Joanna Prendergast) Heatwaves are becoming more extreme and frequent, making it harder to grow food crops. Extreme temperatures are happening not just in summer, but also during critical spring flowering periods for crops such as wheat. Research is underway to discover and develop more heat-resistant crops, but scientists say more is urgently needed. Link copiedShareShare articleWhen record-breaking heatwaves hit parts of Australia over summer, it wasn't just people and wildlife that suffered. For those trying to grow and supply the nation with fresh food, the extreme heat wiped out entire crops and highlighted a growing struggle for farmers. And it is likely to become an even bigger challenge — not just in summer. Researchers warn increasingly extreme heatwaves throughout the year are putting food security at risk, and more studies are urgently needed to help growers adapt. Anthony De leso manages Thorndon Park Produce — a family business north of Adelaide growing a wide variety of leafy vegetables and herbs. During summer, his farm was hit by three extreme heatwaves that decimated delicate crops. Anthony De leso grows spring onions, continental parsley, coriander and dill all year round north of Adelaide. (Supplied: Anthony De leso) "The last heatwave we had was probably the worst in memory, because we had about three days of 45 degrees, and the days before and after were in the mid to high-30s, so there was no relief for us, the staff, and no relief for the crops," Mr De leso said. "That was kind of like the last nail in the coffin for a lot of our crops. "In the second heatwave, our coriander just decided 'That's it, I'm done'. "It was easier for us just to rotary hoe in our existing crop and start afresh." Mr De leso said lost income from ruined crops, combined with rising input costs, was taking a significant toll on his budget. "In the past, I would have said, 'This is just what's going to happen and we have to take these hits every now and then,'" he said. Coriander is one crop that is highly fragile and prone to heat stress. (Supplied: Anthony De Leso ) "Since 2022 onwards, our input costs, everything's gone through the roof, so now to take these hits is a lot harder to do, to take a loss and just go on. "There definitely has been discussions on what else we do differently — whether we focus on other crops, or put in some protected cropping in certain areas … because now when we have weather events, we definitely feel the losses harder than we used to." Australian National University professor of plant science Owen Atkin said extreme temperatures like those seen in January 2026 "breaks the biology" of plants, causing them to fail. Summer saw areas of South Australia and New South Wales break all-time temperature records, with parts of SA pushing close to 50 degrees in the shade. Temperatures in January 2026 soared over multiple days across much of southern Australia. (ABC News) "Some of my colleagues … were out in the field during that and they were recording temperatures (of) 65 degrees Celsius at the soil surface, and then 55 degrees Celsius about 10 centimetres from above the surface," Mr Atkin said. "It means anything growing near the surface is going to be getting extremely hot." Owen Atkin is director of the ANU's Agrifood Innovation Institute. (Supplied: Owen Atkin.) Mr Atkin said there were certain regions and crops more susceptible to heat damage, such as wheat, grapes and almonds. "That area around Renmark is one which is a real issue — the Riverland, Mallee, Sunraysia area is one at risk," he said. "In SA, we've got crops such as grapes, whether it be dried fruits, table grapes or viticulture for wine — they're all quite susceptible to heat. "You're getting boiling, literally, of the berries on the vines, and that can cause problems to quality and quantity of yield … and affect the quality of wine that's produced as well." While summer heatwaves are making headlines, Mr Atkin said they can and do occur at other times of the year when temperatures push above the normal during the day and night. That includes during spring — a critical time for wheat flowering. Crops like wheat (pictured), grapes and almonds are more susceptible to heat damage. (ABC South East SA: Elsie Adamo) "Pollen is very susceptible to heat," he said. "You can get death of pollen and that ultimately leads to sterile flowers, so you don't get seeds being produced, yield being reduced in wheat, and that'll be something that occurs in other plants as well. "And that could be just one day of heat. "If you get an unusual heatwave in September, you can get … a 10 to 20 per cent reduction potentially in yield from a day's heatwave during that time of the year." Heatwaves significantly impact crops like avocados. (ABC Riverland: Amelia Walters) Professor Atkin said there was

Heatwaves are becoming so extreme, they're 'breaking the biology' of plants

Key takeaways

More in international