Preventing Light Stress and 10% Production Loss at De Peelkroon Berries
Summary
- Light Stress Caused 10% Productivity Loss: During a high-light trial in April 2025, De Peelkroon opted for a no-shading strategy against Gardin's recommendations. While traditional indicators suggested strong plant performance, Gardin's sensor data revealed chronic light stress, reducing photosynthetic efficiency, impairing night-time recovery, and resulting in a 6% yield reduction over the month.
- Real-Time Plant Feedback Exposed Strategy Risk: Gardin's chlorophyll fluorescence sensor provided early warnings of photosynthetic decline — insights that traditional climate metrics missed. When shading was reintroduced, plant health and night-time recovery improved, confirming that plant-centric feedback is essential for climate control decisions.
- Data-Driven Shading Strategy Protects Yield: Modelling showed that limiting PPFD to 900 µmol/m²/s with shading would have increased total assimilate production, even in high-light conditions. Gardin's autonomous system empowers growers to move beyond short-term visual cues and make smarter, long-term decisions to maximise yield and protect crop quality.
"We pay closer attention to the shading strategy now we work with Gardin, and take better steps to plan for periods of high light, like we have seen this year. Gardin has helped us to think more about the long-term effects of our crop strategy on plant health rather than choosing short term gains."
Rob Van Enckevort, Owner and Grower at De Peelkroon
Results & Discussion
A Challenging Season with High Light Stress
April 2025 saw a sustained period of unusually high light combined with a dry and relatively cool climate. This created a challenge for growers by straining Vapor Pressure Deficit (VPD) conditions. Under these conditions it is common to apply shading to reduce incoming light levels and raise greenhouse humidity.
De Peelkroon are a leading strawberry grower based in the Netherlands with over 4 hectares of strawberry crops owned and operated by Rob Van Enckevort. Given the high light available early in the season, instead of applying shading as usual, Rob allowed light levels to rise freely, testing the impact on greenhouse climate and plant performance.
On April 3rd, the shades were left open and PAR levels allowed to reach above 1,000 µmol/m²/s and peak near 1,200 µmol/m²/s. Inside greenhouse temperature peaked at 24°C and leaf temperature at 32°C. April 4th had a very similar outside climate but on this day the shades were closed, the inside greenhouse temperature reached 26°C and the leaf temperature fell to 28°C.
Whilst 32 degrees would normally be regarded as a very high leaf temperature that would cause stomata to close, transpiration and water usage was actually higher on the day without shading. Most growers would typically observe this as the plants coping well with the high light and having a positive impact on rates of photosynthesis and water movement through the plant.
Gardin’s Insights Enable Real Time Response
Gardin fills a critical gap by measuring real-time plant light response and photosynthetic efficiency. It guides growers with two lighting strategies: an energy-efficient mode to light conversion using LEDs in Winter, and an aggressive mode to maximise lighting without stressing plants in the summer.
On April 3rd at De Peelkroon, lack of shading led to light levels that stressed the plant, pushing efficiency below the safe threshold and lowering night-time recovery. After shading was applied on April 4th, stress was avoided, and night-time efficiency improved as the plants had time to recover.
Despite these early warnings from Gardin's plant feedback, improvements in transpiration convinced Rob to test a no-shading strategy. Over the next month, plant health declined significantly in two greenhouse zones monitored by Gardin. Poor plant health reduces readiness for growth and photosynthetic efficiency, leading to smaller leaf area, lower fruit quality, and, in some cases, fruit abortion.
Result: 10% Preventable Productivity Loss
This study used Gardin sensor data to estimate potential production had the plants maintained their high health scores from early April, before light stress, by modelling the plant light response (R2 score = 70%). The results showed that with no-shading, photosynthetic efficiency dropped well below expected levels, indicating less of the available light was converted into assimilates.
Final Photosynthesis Results
| Greenhouse | Actual (mol/m2) | Expected (mol/m2) | Difference (mol/m2) | % Diff Abs |
|---|---|---|---|---|
| Section A | 95.7 | 104.9 | -9.2 | 9.6 |
| Section B | 94.1 | 101.0 | -6.9 | 7.3 |
Plant productivity is calculated by combining the expected light use efficiency and incident light (PPFD), to give the electron transport for photosynthesis. The lack of shading and resulting plant stress resulted in a cumulative assimilate deficit over time. In April, this deficit reached 10% in both monitored greenhouse sections. Based on Gardin's historical yield models, this loss would correspond to an estimated 6% reduction in strawberry yield.
The model also indicates that if shading had been used to cap the canopy-level PPFD at 900 µmol/m²/s, total productivity would still have been higher by the end of the month. This provides compelling evidence that an informed shading strategy does not reduce growth; due to the long-term benefits of mitigating light stress on photosynthetic efficiency.
The actual assimilate loss and benefits of shading likely exceed 10%, as early growth would have boosted leaf area and light interception, amplifying productivity over time. This analysis only considered linear productivity per leaf area, not the compounding effect of expanding canopy coverage over the greenhouse area, which will be explored in future research.
Conclusions
These results highlight the critical need to evaluate greenhouse climate strategies through the lens of plant photosynthesis. Not doing so risks drawing incorrect conclusions which can result in significant losses in monthly production of 10%. In this study, high transpiration levels gave the impression of plants coping well under bright conditions, but this led to an incorrect shading strategy and caused long term damage to the plant photosystem.
Rob reflected on these insights from Gardin - "We pay much closer attention to the shading strategy now we work with Gardin, and take better steps to plan for periods of high light, like we have seen this year. Gardin has helped us to think more about the long term effects of our crop strategy on plant health rather than just choosing short term gains".
Gardin offers an easy to use, fully autonomous system for monitoring crop photosynthesis. Its insights help growers target the optimal climate strategy, including lighting and shading to maximise yield at the lowest cost.
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