The warming trend varies depending on factors such as location, time and season and may result in fewer berries being produced, a researcher says.
MAINE, USA — A new University of Maine A study found that some blueberry fields heat up faster than others depending on factors such as location, season and time of day, and a researcher in that study said this could result in the production of less of berries.
The study found that blueberry fields in Piscataquis and Washington counties warm faster and have longer growing seasons than other Maine counties analyzed by the researchers, but their average temperatures are not as high.
In terms of location, Zhang told NEWS CENTER Maine that northern blueberry barrens are warming faster than southern barrens, with coastal fields warming faster than interior fields.
The study applies as much to wild blueberries as to those grown by farmers, according to the researcher.
His big message to blueberry growers? “We have to be ready,” he said. Depending on the location and season of a blueberry field, farmers may need to use specific new techniques to mitigate the effects of climate change.
Wild blueberry plants are more drought tolerant. They can recover from a severe drought by growing back, according to Zhang.
“These are amazing plants. They are really strong and resilient,” Zhang said.
But crop yield or berry production is sensitive to climate change or drought. And Zhang said the yield depends on the water conditions of the year. Wild blueberries grow naturally in heathlands during times of drought. They are suitable for these environments.
“They may survive, but they may no longer produce berries in warm and dry conditions,” the researcher said. “If plants can’t get good water conditions, they can’t produce more berries.”
Maine blueberry growers in faster warming regions need to be prepared. The study showed that one of the most damaging effects of global warming is increased water stress. Farmers might need to mitigate this with irrigation, according to Zhang.
“We also noticed that some small producers do not have irrigation systems. Sometimes irrigation can be very expensive,” he said.
Increased warming has both positive and negative effects. Growers may need to use more water and nutrients, Zhang said. Warming is creating longer growing seasons, but there are risks. If a blueberry plant grows earlier in the spring due to warmer temperatures, but is then hit by a frost, it can damage the plants, especially the flowers. They are sensitive to frost.
But an extended growing season can also mean plants have more time to grow and produce sugar, the researcher said. Plants may produce more berries over an extended season if they have enough water and fertilizer.
A warmer environment also means drier soil and plants, which could inhibit the disease. Pathogens generally need moist environments to spread, according to Zhang.
“Overall, I think the warming and [an] an extended growing season has both positive and negative impacts,” he said. “We should use the positive impacts to mitigate these negative effects.
The study also found that nighttime minimum temperatures have increased over the past 40 years in fields in all counties faster than those of daytime maximums. This change could cause blueberries to produce more carbon dioxide than they absorb.
Zhang said night warms faster than day, and plants can only photosynthesize or absorb carbon dioxide during the day when light is present. During the night, they consume sugars. This means that for blueberry plants, they may produce fewer berries because they have to consume the sugars produced during the day.
So what happens next? Zhang said researchers hope to study how blueberries will respond to warming, climate change and increased drought. They will learn new details and mechanisms of how plants will react. And once they have this information, researchers can investigate new techniques to help mitigate the negative effects on plants.
Elana Beal, with Josh’s Pond Farm in Whiting, told the NEWS CENTER Maine in recent years that the start of their blueberry season has slipped earlier and earlier.
“For the past two years, we have started our harvest in July…for the first time in decades!” said Beal. “Our typical start is mid-August.”
Although the growing season started earlier, it also ends earlier, according to Beal.
“We don’t have a longer growing season when it comes to blueberries,” she said. “Our blueberries are only ripe for a certain period of time, and the hot and dry conditions of recent years have actually shortened their peak ripening period with the lack of moisture in the soil.
Beal said the farm isn’t changing how it operates when it comes to warming blueberry fields faster.
She added, “We still monitor the fields the same way we always have and start harvesting when the blueberries are ready.
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