Cherry growers in New Zealand and Australia are facing increasingly unpredictable weather patterns, driving research to help growers maintain fruit quality.
Rain events can cause cherries to split, making them unsaleable. To mitigate this, some summer fruit growers have adopted rain covers. While these structures shield fruit from rain, they also change the orchard’s microclimate, trapping heat and increasing humidity.
“Based off preliminary research in Australia, as well as anecdotal feedback from growers, we know that while rain covers protect crops and improve fruit size, they also reduce fruit firmness.
“So currently, both uncovered and covered orchards come with trade-offs,” says Claire Scofield, a scientist with the Bioeconomy Science Institute’s fruit crop physiology team.
The team focuses on understanding how fruit develops and applying that knowledge to help growers improve quality. Claire is currently two years into a PhD, gathering detailed data on orchards in New Zealand and Australia to better understand how microclimate differences impact fruit quality. The goal is to help industry develop science-based management strategies.
“We know that rain covers increase humidity – but we don’t fully understand the effects of this. For example, do we get a direct correlation between relative humidity in the orchard and fruit firmness?”
“This is important because fruit firmness is a key factor in export quality,” Claire notes. “Consumers prefer firm cherries, and if they are too soft, they also don’t survive the journey to high value overseas markets.”
The project is being conducted on both sides of the Tasman – with a small scale trial taking place in Central Otago in New Zealand and larger trials on orchards in Tasmania in Australia.
As part of Claire Scofield’s PhD nearly 4,000 cherries have so far been analysed.
“As part of this work, we’ve created a range of temperature and humidity conditions in trial blocks under plastic tunnels and installed sensors to record data every 10 minutes from September to February. This helps us see how these conditions contribute to softer fruit.”
Claire’s trials also explore the role of the nutrient calcium in keeping cherries firm. Calcium is applied by growers at certain points of the season due to its ability to support cell-walls in fruit, similarly to how it supports strong bones in humans. Claire is also investigating the use of naturally occurring plant hormones as another potential tool to support fruit quality.
“Humid conditions can potentially reduce how much calcium the plant takes up, so part of this work involves looking into whether adding more calcium could offset the impact of humidity or if the relationship is more complicated.”
Alongside the sensor data from research blocks, nearly 4,000 cherries have so far been analysed to measure firmness and understand how microclimate shifts, calcium application and other treatments affect fruit texture.
Claire hopes her research can provide valuable insights for growers experiencing changing climatic conditions.
“Unusual weather events are being experienced more often, and the impact can be costly. I’m hopeful out of this research, we’ll be able to give growers some solid information that will help them to develop new management options so they can get the best out of each season’s crop,” says Claire.
Claire’s research is supported by the Bioeconomy Science Institute and a Tasmanian Graduate Research Scholarship from the University of Tasmania. Her project is part of the ‘Sustainably growing horticulture value in cool climate Australia’ program, funded through Hort Innovation Frontiers with co-investment from the Tasmanian Institute of Agriculture and contributions from the Australian Government.
Source: Bioeconomy Science Institute
