Introduction
Rain covers (PE tarpaulin) are widely used in cherry orchards to prevent cracking, reduce rain-induced diseases, and protect fruit from environmental stress.
However, research shows that these covers may also alter the orchard microclimate—especially light quality and temperature—which can influence cherry fruit quality.
Understanding both the benefits and drawbacks of rain covers helps growers make better management decisions and choose more advanced materials.
Does Rain Cover Affect Cherry Fruit Quality?
Yes. Rain covers can negatively affect cherry fruit hardness, sugar content, color formation, and nutritional composition.
These changes are strongly linked to how covers modify sunlight—especially UV-B radiation—and temperature.
Below are the main quality attributes affected.
Fruit Hardness
Studies show that cherries grown under PE tarpaulin typically exhibit around 11% lower fruit hardness.
Fruit grown under reduced UV-B and slightly warmer, more humid microclimates tends to soften earlier.
Lower fruit firmness may lead to:
- Reduced resistance during transport
- Shorter shelf life
- Greater susceptibility to bruising
- Lower market value
Soluble Solids Content (SSC) – Sweetness
SSC is a primary indicator of sweetness and consumer preference.
Cherries grown under rain covers tend to have lower soluble solids content (SSC), an indicator of sugar levels that directly affects fruit sweetness.
Findings show:
- SSC is lower under rain covers
- ‘Bing’ shows a statistically significant reduction
- Other cultivars show slight but noticeable decreases
This suggests that reduced light and filtered UV-B may slow sugar accumulation in fruit.
Although the difference is statistically significant only in the ‘Bing’ variety, the lower SSC suggests that cherries under rain covers may have less sweetness, potentially affecting consumer preference.
Fruit Color Development
This effect is most striking in bi-colored cherries like ‘Rainier’.
For bi-color varieties like ‘Rainier’, rain covers significantly reduce red color coverage. This occurs because the covers filter UV-B radiation, which is essential for the production of anthocyanins, the pigments responsible for the red color in cherries.
As a result, ‘Rainier’ cherries grown under covers may have a lighter, less attractive appearance. However, no significant effect on color intensity was observed in red-fleshed varieties like ‘Bing’ and ‘Sweetheart’.
Why color is reduced under covers?
UV-B stimulates anthocyanin synthesis → anthocyanins give cherries their red pigmentation.
Rain covers block UV-B → pigment development is suppressed.
Effects include:
- Poor red blush
- Paler, less attractive fruit appearance
- Lower premium grade proportion
Red-skin varieties (‘Bing’, ‘Sweetheart’) show less impact, but anthocyanin intensity may still decline.
Total Phenolic Content and Antioxidant Capacity
Rain covers also reduce the total phenolic content and antioxidant capacity of cherries.
There was a noticeable decline in phenolics in all three studied varieties, with a statistically significant reduction in antioxidant capacity observed only in ‘Rainier’.
Phenolics & antioxidants influence:
- Nutrition
- Fruit health benefits
- Postharvest quality
- Color intensity
‘Rainier’ shows strongest reduction in antioxidant capacity due to its heavy dependence on UV-driven pigment pathways.
Since phenolic compounds and antioxidants are beneficial for human health, these reductions suggest that cherries grown under rain covers may have slightly lower nutritional value.
Why Do These Negative Effects Occur?
The negative impacts on cherry quality are largely due to changes in sunlight, temperature, and humidity caused by the rain covers.
Rain covers alter the orchard microclimate in three key ways:
Reduced Solar Radiation & UV-B Light
The covers filter out some solar radiation, including UV-B rays, which affect the metabolism related to fruit color, hardness, and nutrient accumulation.
UV-B is essential for:
- Anthocyanin synthesis
- Phenolic metabolism
- Fruit coloration
- Firmness-related biochemical pathways
Blocking UV-B → weaker pigmentation, lower phenolics, softer fruit.
Higher Temperature Under the Canopy
PE covers trap heat, warming the air layer around fruit.
High temperatures accelerate ripening → lower firmness and reduced sugar development.
More Stable Humidity
Lower fluctuation sounds beneficial, but too much humidity under covers can:
- Reduce cuticular (skin) thickening
- Promote a softer fruit texture
Solution: Using Anti-dripping Cherry Cover Film
To avoid the negative impacts of traditional tarpaulin rain covers, growers can use Anti-dripping Cherry Cover Film with 90% sunlight transmittance.
Advantages:
- Allows more UV/visible light → better color & phenolics
- Prevents condensation dripping → less cracking & rot
- Maintains fruit firmness
- Improves sugar accumulation
- Keeps nutritional content more consistent
This material combines rain protection with a more natural light environment.
By improving light exposure and reducing the harmful effects of excess moisture, this film helps maintain fruit quality and nutritional value, offering an optimal solution for cherry growers.
Conclusion
Rain covers are essential tools for protecting cherries, but conventional PE tarpaulins can reduce fruit quality—impacting firmness, sweetness, color, and antioxidant content.
Using advanced materials such as Anti-dripping Cherry Cover Film helps minimize these drawbacks, giving growers both protection and premium fruit quality.
Protect Your Cherries and Maintain Quality!
At EyouAgro, we help growers protect their orchards without sacrificing fruit quality.
📌 Improve firmness
📌 Maintain sweetness
📌 Preserve color
📌 Support antioxidant levels
Contact us to explore advanced rain cover solutions tailored to your orchard.
Ready to improve your cherry crops?
Contact us today to learn how our advanced cover solutions can boost both protection and quality.
FAQ – Rain Covers & Cherry Fruit Quality
1. Do rain covers affect cherry color development?
Yes. They reduce UV-B exposure, which slows anthocyanin production, especially in bi-color cherries.
2. Why are ‘Rainier’ cherries more affected by covers?
Their skin color relies heavily on UV-driven anthocyanin production.
3. Do rain covers impact cherry sweetness?
Yes, SSC (sugar content) is often lower under covers due to reduced light intensity.
4. Do rain covers reduce fruit firmness?
Yes. Increased temperature and humidity under covers soften fruit.
5. How can growers reduce these negative effects?
Using high-transmittance anti-drip films significantly improves light quality while still preventing rain damage.
Reference
Simón Pino,Miguel Palma,Álvaro Sepúlveda,ect, Effect of Rain Cover on Tree Physiology and Fruit Condition and Quality of ‘Rainier’, ‘Bing’ and ‘Sweetheart’ Sweet Cherry Trees
