Below is a **professional technical profile of Glera Tonda**, structured for viticultural, oenological, and regulatory reference, with a clear introduction.

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## Glera Tonda – Technical Profile

### Introduction

**Glera Tonda** is a **historic biotype of the Glera family**, traditionally cultivated in northeastern Italy within the Prosecco production zones of **Veneto**, especially in the **Conegliano–Valdobbiadene** area. The name *Tonda* (“round”) refers to its **rounded berries and more compact clusters**, which distinguish it ampelographically from standard Glera and from Glera Lunga.

While no longer widely planted, Glera Tonda is preserved as a **permitted minor variety** in Prosecco appellations, valued for contributing **body, softness, and ripe fruit expression** to blends.

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## 1. Classification & Synonyms

* **Primary name:** Glera Tonda

* **Synonyms:** Prosecco Tondo, Prosecco Tonda (historic)

* **Species:** *Vitis vinifera*

* **Genetic status:** Biotype of Glera (ampelographically distinct, not a separate species)

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## 2. Regulatory Status

### Appellation Use

* **Permitted complementary variety** in:

* Prosecco DOC

* Conegliano Valdobbiadene Prosecco DOCG

* Asolo Prosecco DOCG

### Legal Limits

* Included within the **≤15% non-Glera fraction**

* Cannot be bottled as a varietal wine under Prosecco regulations

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## 3. Ampelographic Characteristics

### Vine

* **Vigor:** Medium

* **Growth habit:** Semi-erect to spreading

* **Budburst:** Medium

* **Ripening:** **Medium**, slightly earlier than Glera Lunga

### Cluster

* **Shape:** Short, cylindrical-conical

* **Size:** Medium

* **Compactness:** **Moderately compact to compact**

### Berry

* **Shape:** **Round (tonda)**

* **Size:** Medium

* **Skin:** Thin, green-yellow at maturity

* **Pulp:** Juicy, neutral to lightly aromatic

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## 4. Viticulture

### Climate Suitability

* Temperate continental climates

* Performs best in **well-ventilated hill sites**

* Compact clusters increase sensitivity to humidity

### Soils

* Calcareous clay

* Marl and limestone-rich soils

* Excess fertility increases compactness and disease risk

### Training Systems

* **Guyot** (preferred)

* **Modified Sylvoz** (less common today)

### Yield

* **Medium to high**

* Requires careful yield and canopy management

* Less productive than Glera Lunga but more compact-fruited

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## 5. Disease Sensitivity

* **Downy mildew:** Moderate to high (cluster compactness)

* **Powdery mildew:** Moderate

* **Botrytis:** **Elevated risk**

* **Drought tolerance:** Moderate

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## 6. Harvest & Must Composition

* **Harvest period:** Early to mid September

* **Typical must parameters:**

* Sugar: 16.5–18.0 °Brix

* Total acidity: 5.5–6.8 g/L (tartaric)

* pH: 3.20–3.35

Earlier ripening produces slightly lower acidity and fuller mouthfeel.

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## 7. Vinification Characteristics

### Fermentation

* Stainless steel

* Fermentation temperature: **14–17 °C**

* Neutral yeast strains to avoid masking texture

### Role in Blends

* Adds **roundness and body**

* Softens sharp acidity from Glera Lunga or Verdiso

* Enhances mid-palate weight in Brut and Extra-Dry styles

### Suitability

* Base wines for Charmat method

* Limited suitability for very low dosage styles

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## 8. Sensory Contribution

### Aromatic Profile

* Ripe pear

* Golden apple

* White peach

* Subtle floral tones

### Palate Impact

* Softer acidity

* Creamier texture

* Slightly broader finish

* Lower perceived tension than standard Glera

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## 9. Comparison: Glera Biotypes

| Parameter | Glera | Glera Tonda | Glera Lunga |

| ------------------- | ------------- | ------------------- | -------------- |

| Berry shape | Oval | **Round** | Elliptical |

| Ripening | Mid | **Early–mid** | Late |

| Acidity | Medium-high | **Medium** | High |

| Cluster compactness | Medium | **High** | Low |

| Structural role | Aromatic base | **Body & softness** | Acid & tension |

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## 10. Oenological Significance

Glera Tonda is increasingly recognized as a **balancing element** within traditional Prosecco blends:

* Useful in **Extra-Dry and Dry** styles

* Mitigates angular acidity in cool years

* Contributes texture rather than aromatics

Preservation efforts focus on **old-vine selections** and clonal conservation programs.

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### Summary

**Glera Tonda** is a **rounded-berry Glera biotype** that contributes **mouthfeel, softness, and ripe fruit character** to Prosecco blends. Though limited in surface area, it remains an important technical component for stylistic balance within the appellation system.

If you want, I can also provide:

* Clonal and DNA distinctions among Glera biotypes

* Blending trials: Glera Tonda % impact

* Climate-change adaptability comparison

* Full minor varieties matrix (Verdiso, Perera, Bianchetta, Glera Lunga)

* Export-ready technical table (Excel-compatible)