Articles
Orchard management changes solar radiation profiles, influencing apple sunburn
Article number
1433_19
Pages
155 – 160
Language
English
Abstract
Fruit sunburn is a physiological disorder, caused by high solar energy rates, exceeding fruit absorbing capacity.
With increasing air temperature, summer heat waves are expected to threaten fruit production in temperate areas of the globe.
Apple growers are beginning to see the effects of both high radiation and air temperature, in northern Italy, where, in the summer of 2022 and 2023, prolonged periods of drought and heat waves occurred.
Mitigation solutions via anti-hail and shading nets are already present, however, the classic 20% shading anti-hail systems may not be enough to prevent sunburn damage on apple.
On behalf of the SHEET project (sunburn and heat prediction in canopies for evolving a warning tech solution), two training systems, in ‘Gala’ orchards, were compared, in summers 2022 and 2023. Their radiation interception, at different heights of the canopy, was evaluated and how it affected the susceptibility to fruit sunburn.
The training systems were a classic spindle (with and without hail protection) versus a planar cordon (with hail protection). Solar radiation interception, was measured on a clear sunny day, in the second half of July at three different heights of the canopy.
Higher interceptions of ultraviolet radiation were found in the unprotected spindle orchard, in both 2022 and 2023. An effect of the training system was evident in 2023, when the planar cordon intercepted lower amounts of ultraviolet radiation.
The higher was the canopy interception of ultraviolet radiation, the higher percentage of damaged fruit was observed: in 2022, the uncovered spindle tested trees reached nearly 40% of damaged fruit, and nearly 20% in 2023. The protected tested trees had damaged fruit only in 2023: nearly 3% in the spindle, while 1.3% in the planar cordon.
These slight differences among protected training systems are however attributable to the irradiation interception profiles.
Wall shaped trees with thin canopies (i.e., the planar cordon) are able to minimize ultraviolet radiation interception, demonstrating a further mitigation effect, along with netting protection.
The training system is therefore an important aspect to be considered in orchard planning, to make future apple production more resilient to climate change.
With increasing air temperature, summer heat waves are expected to threaten fruit production in temperate areas of the globe.
Apple growers are beginning to see the effects of both high radiation and air temperature, in northern Italy, where, in the summer of 2022 and 2023, prolonged periods of drought and heat waves occurred.
Mitigation solutions via anti-hail and shading nets are already present, however, the classic 20% shading anti-hail systems may not be enough to prevent sunburn damage on apple.
On behalf of the SHEET project (sunburn and heat prediction in canopies for evolving a warning tech solution), two training systems, in ‘Gala’ orchards, were compared, in summers 2022 and 2023. Their radiation interception, at different heights of the canopy, was evaluated and how it affected the susceptibility to fruit sunburn.
The training systems were a classic spindle (with and without hail protection) versus a planar cordon (with hail protection). Solar radiation interception, was measured on a clear sunny day, in the second half of July at three different heights of the canopy.
Higher interceptions of ultraviolet radiation were found in the unprotected spindle orchard, in both 2022 and 2023. An effect of the training system was evident in 2023, when the planar cordon intercepted lower amounts of ultraviolet radiation.
The higher was the canopy interception of ultraviolet radiation, the higher percentage of damaged fruit was observed: in 2022, the uncovered spindle tested trees reached nearly 40% of damaged fruit, and nearly 20% in 2023. The protected tested trees had damaged fruit only in 2023: nearly 3% in the spindle, while 1.3% in the planar cordon.
These slight differences among protected training systems are however attributable to the irradiation interception profiles.
Wall shaped trees with thin canopies (i.e., the planar cordon) are able to minimize ultraviolet radiation interception, demonstrating a further mitigation effect, along with netting protection.
The training system is therefore an important aspect to be considered in orchard planning, to make future apple production more resilient to climate change.
Authors
A. Boini, G. Bortolotti, B. Morandi
Keywords
sun radiation, fruit surface, heat waves, light spectrum, tree canopy
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