Testing Solray385FR on Dwarf Cherry Tomatoes: A Light Spectrum Experiment in Vertical Farming
As indoor farming continues to evolve, so does our understanding of how light quality shapes plant growth. In vertical farming, where conditions are tightly controlled and space is limited, light spectra play a key role in unlocking crop potential. Dwarf cherry tomatoes, compact, flavourful, and visually appealing, are increasingly explored as a viable crop for vertical systems. But growing them successfully, especially with consistent quality and yield, is no easy task.
This trial set out to evaluate how our new Solray385FR spectrum performs in promoting yield, fruit quality, and ripening in dwarf cherry tomatoes. We compared it against our trusted AP67 spectrum, which has been used to enhance fruiting in many crops, and a competitor spectrum dominated by red light (80% R)—a common recommendation for tomato cultivation.
The tomatoes were grown in chamber conditions and weekly measurements were taken to evaluate growth, flowering, fruiting, and quality. Here’s what we found.
Results: How the Spectra Stacked Up
Phenology scores (a measure of plant development) remained mostly even across treatments. Toward the end, AP67 showed a trend toward more advanced fruit ripening, though this was just shy of statistical significance when compared to Solray385FR (P = 0.078).
Plant height, on the other hand, did show a clear spectral response. Solray385FR produced the tallest plants, significantly taller than the competitor (P = 0.013), while AP67 was similar in height to Solray385FR. The presence of far-red light in both Valoya treatments likely contributed to the elongation, whereas the competitor spectrum—lacking far-red—resulted in shorter, more compact growth.
When it came to flower production, all treatments performed similarly. The number of flowers did not differ statistically, although the competitor treatment had the lowest average flower count.
However, when looking at fruit yield, spectrum mattered. AP67 outperformed both Solray385FR and the competitor in total fruit number. Solray385FR produced significantly more fruits than the competitor (P < 0.001), but fewer than AP67 (P = 0.05). A similar trend was seen in ripe fruit count: AP67 produced the highest number of ripe berries during the study period, significantly more than both Solray385FR (P = 0.004) and the competitor (P = 0.001). Solray385FR and the competitor tied in ripe fruit count, suggesting that while Solray385FR improved total fruiting, it did not accelerate ripening as effectively as AP67.
One of the most notable quality markers was BRIX, or sugar content. Here, spectrum had a clear impact (P = 0.001). AP67-treated fruits had the highest BRIX values, significantly higher than both Solray385FR (P = 0.001) and the competitor (P = 0.023). These results align with AP67’s balanced spectrum—high red (57%) and moderate blue (12%)—which supports photosynthesis, sugar transport, and accumulation. By contrast, the competitor’s red-dominant spectrum lacked the spectral nuance to optimize flavour, while Solray385FR’s high blue component may have slightly suppressed sugar accumulation.
Dualex SPAD measurements provided further insight into plant physiology. Chlorophyll content did not vary significantly between treatments, though Solray385FR had the highest levels overall (P = 0.07 vs. competitor). More striking were the results for flavonoid content: the competitor treatment surprisingly had the highest levels, significantly higher than both Solray385FR (P = 0.007) and AP67 (P < 0.001). This may be a response to stress—potentially from the unbalanced spectrum or excess red light—leading to increased antioxidant production as a defence mechanism.
Key Takeaways: Where Solray385FR Stands
This trial highlights that light spectrum plays a significant role in tomato performance, even in chamber conditions under extended photoperiods. AP67 remains the top performer, especially in terms of total and ripe fruit yield, as well as BRIX levels. However, Solray385FR showed clear advantages over the red-dominant competitor spectrum, especially in fruit yield and plant height, indicating its value as a modern spectrum for compact crops like dwarf cherry tomatoes.
While Solray385FR did not reach the sweetness levels of AP67, it produced significantly more fruits than the competitor and resulted in healthier, taller plants. With its higher blue and modest far-red content, it offers a well-balanced option for vertical farming setups, especially in crops where compact growth and good fruit structure are desired.
The results are promising: Solray385FR is a strong contender for growers looking to move beyond outdated red-dominant light recipes, offering better yield, better structure, and solid fruit quality in compact tomato varieties.
