Promoting Earliness in Grapes with Sulis®: A Better Alternative to Ethylene-Based Maturation Tools

Achieving optimal color and sugar content in grapes—while preserving firmness and storability—is a challenge for viticulturists worldwide, particularly under warm climatic conditions. Traditional tools like ethephon (an ethylene generator) have been commonly used to accelerate ripening and improve fruit coloration. However, these treatments often come at a cost: reduced firmness, compromised shelf life, and inconsistent internal quality.

Sulis, a novel biostimulant developed by Levity Crop Science, offers a breakthrough approach—enhancing color development and brix accumulation without triggering the softening effects typical of ethylene-based products. Backed by robust field data from trials in Egypt, the United States, and China, Sulis® enables earlier, higher-quality harvests and superior fruit marketability.

The Ethylene Trade-off: Colour vs. Firmness

Ethylene is a powerful plant hormone known to trigger a cascade of ripening signals, particularly useful in climacteric fruits. In grapes, products like ethephon are used to elevate ethylene levels artificially, prompting faster coloration through stimulation of anthocyanin biosynthesis.

However, the downside is significant:

• Ethylene activates cell wall-degrading enzymes (e.g., polygalacturonase, cellulase), which weaken fruit texture.
• The result is softer berries, more prone to bruising, splitting, and decay.
• This leads to shorter shelf life and higher post-harvest loss.

For table grapes and high-end wine varieties, firmness is as essential as appearance, making the ethylene trade-off increasingly unattractive.

Sulis®: A Different Pathway to Earliness

Unlike ethylene-based products, Sulis® stimulates the plant’s own ripening mechanisms, particularly through abscisic acid (ABA)—the key hormone responsible for grape coloration and sugar accumulation.

Key Technical Components:

• Molybdenum (Mo): A critical cofactor in ABA biosynthesis, often deficient in soil.
• Boron (B): Facilitates sugar transport from leaves to berries.
• Blush™ Technology: Proprietary system from Levity that ensures efficient metabolism and use of the nutrients.

Together, these elements support natural color formation and brix development, without increasing ethylene levels. As a result, fruit remains firm and robust, while ripening occurs earlier.

Results from Egypt: Overcoming Heat Stress

In a published two-season study on ‘Redglobe’ grapes in Minia, Egypt, Sulis® was evaluated under conditions where ambient temperatures exceed 37°C—normally suppressing anthocyanin accumulation.

Key results from the study [1]:

• CIRG (Color Index for Red Grapes) improved from 3.42 (control) to 3.81–3.82 with Sulis®.
• Anthocyanin levels more than doubled in treated fruit.
• Sulis® advanced first pick harvests by up to 20 days.
• Sulis® + ethephon combination further improved colour without sacrificing firmness.
• No negative impact was observed on berry size or weight, and firmness was preserved across treatments.

Results from the USA: Visual Impact, Zero Softening

In Washington State, Sulis® was trialled on wine grapes. The goal was to assess visible colour change and any impact on fruit structure.

• Sulis® was applied at 1 pint/acre.
• Colour change was clearly visible within 10 days.
• No reduction in firmness or skin strength was noted.
• Growers reported more uniform ripening.

These outcomes reinforce Sulis® as an ethylene-free strategy to enhance ripening without compromising skin quality.

Results from China: Early Market Entry and Higher Returns

In Jiaxing, Zhejiang, trials on ‘Summer Black’ grapes demonstrated Sulis®’s value in high-pressure fresh markets:

• Sulis® application (500x dilution) advanced harvest by 7 days.
• Grower earned an additional ¥3 per 500g, thanks to earlier and more attractive fruit.
• Treated grapes showed more vivid coloration, greater gloss, and uniformity.

This confirms Sulis®’s market value in China’s competitive retail systems, where visual appeal and timing drive price premiums.

Conclusion: Delivering Maturity Without the Trade-Off

Growers aiming for early harvests typically face a trade-off: speed versus quality. Sulis® eliminates that compromise.

By supporting natural ABA-driven maturation, Sulis® improves color, sweetness, and market timing, while maintaining firmness and integrity—making it ideal for high-value table and wine grapes across climates.

From Egypt’s heat-challenged vineyards to US wine regions and China’s retail-driven systems, Sulis® helps growers harvest not just earlier—but better.

References

• Mohamed, A. A., & Sayed, H. S. (2021). Early Marketable Yield and Better Berry Skin Color of ‘Redglobe’ Grapevines Cultivar Grown under Warm Climate by Application of Sulis®. International Journal of Agriculture Innovations and Research, Vol. 9, Issue 4, pp. 733–739.
• Levity Crop Science. (2025). Field trial summary: Sulis® wine grape coloration – Washington State [Internal trial presentation].
• Levity Crop Science. (2019). China Sulis Trials Summary – Summer Black (Jiaxing) [Internal field data report].
  Marks, D. (2024). Improving Colour Formation in Apples. Levity Crop Science. https://levitycropscience.com/improving-colour-formation-in-apples/