Rising temperatures, irregular spring rains, and prolonged drought are some of the effects of climate change that Chile is currently facing and that may directly impact blueberry production and quality.
Given this scenario, Patricio González, academic and researcher at the Center for Research and Transfer in Irrigation and Agroclimatology (CITRA) at the University of Talca, explained to Blueberries News how this crop responds to new climatic conditions and what aspects producers should consider.
“Blueberries grow in a wide range of climates, which is positive, as they have lower chill hour requirements. The minimum growth temperature is around 7°C, and they can withstand maximums of up to 33°C, making them relatively adaptable to climate change,” said González.
The optimum growing temperature is between 16 and 25 °C, with degree day requirements during the spring to summer period also falling within a wide range. However, the specialist emphasizes that the main focus should be on the winter period. “It is essential to accumulate at least 400 chill hours, ideally close to 1,000 hours, as this provides greater production security. Regions such as Maule and Biobío usually accumulate between 1,000 and 1,200 chill hours, which positions them favorably. In terms of rainfall, the crop requires between 500 and 600 millimeters per year,” he explained.
Temperaturas extremas y riego: Los principales riesgos
According to the academic, there are two major climate risks. “The first is that temperatures exceed 33°C, which can damage crops. The second is that the required number of chill hours during winter are not reached, a phenomenon we are already observing due to increasingly warmer winters in the central region.”
Added to this is the need for proper water management. “It is essential to pay attention to irrigation, especially in spring, which has been warmer in recent years. We have recorded temperatures of 32 and 33 °C, so it is ideal to implement drip or sprinkler irrigation,” he explained.
From a phenological point of view, blueberries have moderate resistance to frost and can withstand temperatures down to –3 °C. However, the greatest risk occurs during budding and flowering.
“The problem is that frosts can occur in September or October, when the crop is at its most sensitive stage. In recent years, we have recorded temperatures as low as –3°C in spring,” warned González.
The impact will depend on both the temperature reached and the duration of exposure. “In Maule and Ñuble, frosts usually reach –1 or –2 °C and last for around two hours. In La Araucanía, they can be more intense, but in general they have been decreasing as a result of global warming, which is positive for this crop,” he said.
The greatest threats are concentrated in summer heat waves. “When temperatures exceed 36 or 37 °C in spring and summer, damage such as fruit shriveling and burns can occur. In cities like Los Angeles, temperatures as high as 39 °C have been recorded,” he said.
Although blueberries can tolerate temperatures of up to 33°C, recent summers have seen peaks of 38°C, which increases evapotranspiration. “Under these conditions, between 70 and 90 m³ of water per hectare can be lost, increasing the risk of water stress, one of the main problems in fruit growing between O’Higgins and La Araucanía,” added the expert.
Areas with better production conditions
When asked about the regions with the highest and lowest climate risk, González was clear: “Today, Maule, Biobío, and La Araucanía have the best conditions for blueberry production: good chill hours, moderate winters, and rainfall close to 400–500 mm.”
The academic explained that further north, in regions such as Valparaíso, O’Higgins, and the Metropolitan Region, expansion has been more limited due to lower water availability. “These three regions are currently the heart of blueberry exports in Chile,” he emphasized.
Adaptation and management measures
To mitigate the effects of climate change, the specialist recommended a preventive approach. “It is essential to stay informed each year about the crop’s phenological cycle, which begins in winter. Ideally, each orchard should have an automatic weather station that allows for the calculation of chill hours, degree days, and evapotranspiration.”
He also highlighted the importance of technified irrigation and having sufficient water available to cope with warmer seasons than expected. “With high temperatures, fruit trees suffer water loss, sunburn, and fruit shriveling. That is why it is essential to monitor each orchard, as each one has its own characteristics depending on its geographical location.”
Regarding climate projections, González warned that several of the risks are already occurring. “Since 2010, we have been facing a mega-drought that will continue over time. The lack of water and snow will continue to be a critical factor. In central Chile, we have deficits of 30% to 40%, and snow has reached deficits of close to 60%, reducing river flows.”
The second major scenario is high temperatures, with warm events beginning as early as November at 32–33 °C and reaching 38 °C in summer. “We are also observing a gradual decrease in chill hours between Maule and Biobío, currently ranging from 700 to 800 hours,” he noted.
Although these levels are still adequate for blueberries—which require between 400 and 1,300 chill hours, depending on the variety—the academic stressed the importance of choosing varieties that are better adapted to the new climatic conditions. “That is the climate we are heading towards, and we must prepare for it starting today,” González concluded.
