Lecture 2:

1. Lecture 2: Grape Composition and Ripening: Viticulture from the Plant’s Perspective

2. Reading Assignment: Text, Chapter 2, p. 13-52

3. Characteristics of Plants • Stuck where they are: use chemical strategies to deal with problems • Nutrient limitation • Competition • Excess/shortage of water • Extremes of temperature • Disease/Pest pressure • Lack of light

4. Characteristics of Plants • Prioritize nutrient use for survival • Role of fruit: • Dispersal of seed • Fruit is attractive to mobile agents that will disperse seed (animals; insects; birds) • Seed itself designed to “taste bad” so it will not be consumed

5. Characteristics of Grapevines • Grown in a wide variety of soils/climates • Persist in nutrient deficient soils • Crop set happens in previous season • Dormant buds developmentally programmed in prior season • Extensive root structure: can represent up to 90% of the mass of the vine

6. Factors Impacting Grapevine Performance • Soil • Topography/Location: hillside, valley floor • Disease/Pest pressure: impacts composition of fruit

7. Factors Impacting Grapevine Performance • Climate • Temperature • Sunshine • Humidity • Rainfall • Evaporation • Wind • Water availability

8. Factors Impacting Grapevine Performance • Microclimate • Climate of individual vines: heating of vineyard floor • Climate of individual clusters: • Shading effects • Humidity retention

9. Factors Impacting Grapevine Performance • The Human Element • Irrigation practices • Use of fertilizers • Timing of treatments • Canopy management • Trellising system • Use of rootstocks • Pruning practices • Cluster manipulation: leaf removal, dropping of fruit

10. Berry Structure • Skin: 3 layers • Epidermis • Hypodermis • Outer mesocarp • Fleshy mesocarp • Brush and center septum • Vascular system • Ovular • Ventral • Dorsal • Seeds

11. AJEV (1987) 38(2): 120-7

12. Berry Development: Maturation of Fruit Follows Maturation of Seed • Flowering/Fertilization • Green Berry Stage Cell division occurs Acids accumulate • Veraison Color changes occur • Ripening Berry swells and softens Sugars Water Acids

13. Factors Affecting Berry Development and Maturation • Climate: Warmer: mature faster, less acidity, less color, higher pH, fewer late berry characters • Variety: Mature at different rates • Disease/Pest pressure: alters composition of fruit, alters timing of development • “Balance” of vine: carbohydrate demands of vine versus fruit versus level of photosynthesis

14. Berry Composition at Harvest g/L Sugar 200 Organic Acids 10 Amino Acids 5 Phenolics 2-5 Volatiles trace Water 800

15. SUGARS (hexoses): glucose fructose sucrose Sucrose is the circulating product of photosynthesis cleaved to produce glucose and fructose in berry

16. SUGARS (pentoses): arabinose xylose Not metabolized by yeast

17. Sucrose glucose + fructose Allows for accumulation of sugar in berry

18. ORGANIC ACIDS: malate tartrate

19. MALATE: COOH From the TCA cycle HOCH Cytoplasmic CH2 Used for energy generation COOH

20. TARTRATE: COOH Accumulates in vacuole HOCH From ascorbic acid and 5-ketoglutarate HCOH COOH

21. Amino Acids: glutamate glutamine arginine alanine proline Typically comprise 90% of all amino acids

22. Amino Acids: High -Amino Butryic Acid (GABA) indicates fruit was held at a high temperature post-harvest

23. Phenolics: Large Variety Found as tartaric acid esters Caftaric Acid Most Prevalent HO HO CH=CH-CO-Tartate

24. Volatile Compounds: terpenes esters

25. Sulfur-Containing Compounds glutathione (glu-cys-gly) cysteine methionine

26. AJEV (1987) 38(2):120-7

27. Location of Compounds in Berry Sucrose Glucose

28. Location of Compounds in Berry Malate Tartrate

29. Location of Compounds in Berry Phenols Phenolic compounds

30. Location of Compounds in Berry Potassium

31. Location of Compounds in Berry Inorganic anions