Chemistry of the Vine Flashcards
What are the most important needs of the vine for photosynthesis?
Sunlight
Water
Carbon Dioxide
What is the photosynthetic process?
The production of energy in a plant through the conversion of Sunlight, Water, and Carbon Dioxide into Carbohydrates, specifically Glucose which is stored as Sucrose in the vine. Oxygen is a byproduct.
Why is Sucrose important to the vine?
It holds Glucose in storage for the vine to use as energy or to create larger carbohydrates such as Cellulose.
Sucrose is not as soluble as Glucose but can be broken down by enzymes as the vine requires.
What is Cellulose?
A complex carbohydrate made from a Glucose chain that helps build the vine’s roots, trunk, shoots, leaves, and fruit.
Why is Glucose important to the vine?
1) Provides energy
2) Used for carbohydrate construction
3) Building block for tannins, acids, and flavor molecules
How does the vine obtain nutrients?
Roots pull nutrients from the soil that are found naturally or applied by the grower.
At what temperature is the vine dormant?
-10°C
What is the effect of heat on a vine’s metabolism?
Direct correlation: as heat increases, metabolism increases.
The vine needs more sugars to regulate itself, thus requiring more sunlight, water, and carbon dioxide.
What is the optimal temperature zone for the grape vine?
22°C-25°C
What happens in the grape vine above temperatures of 25°C?
Metabolic needs increase faster than the vine’s ability to photosynthesize sugars, thereby slowing the vine’s vegetative growth.
Describe the temperature range for biochemical reactions inside the vine.
Dormant at -10°C
Little grapevine growth below 10°C
Biochemical reactions begin at 10°C and double for every 10°C
The maximum limit of enzyme-catalysed reactions in the vine is 30°C - 35°C
What is the average temperature required for flowering?
20°C
What temperature range is ideal for the creation of anthocyanins in the grape?
20°C - 25°C daytime temperatures
10°C - 15°C nighttime temperatures
At what amount of sunlight do leaves become photosynthetically saturated?
33%
At what temperature range is anthocyanin synthesis inhibited?
35°C+
What is the vine’s preferred pH level in a soil?
~7 (Neutral pH)
Optimal nutrient uptake occurs between 5.5 and 8 pH.
How does soil pH affect the availability of nutrients?
Acidity and alkalinity affects the solubility of nutrients
What function does Nitrogen (N) have in the vine?
The most important nutrient, directly controlling rate of growth. Second only to water in importance of vine growth.
Primary constituent of proteins, nucleic acids, and chlorophyll
Too much nitrogen will increase vegetative growth at the expense of fruitfulness
What effect does Nitrogen (N) deficiency have on the vine?
Reduced vigor characterized by smaller leaves and shoots
Yellowing of the leaves, sometimes reddening (especially of the petiole) as a result of reduced photosynthesis
Reduces berry weight and, if left unchecked, crop yield
What function does Potassium (K) have in the vine?
Regulates flow of water and sugar in the plant, internal acidity, and production of acidity in the grapes
Activates enzymes
Encourages grape ripening
What effect does Potassium (K) deficiency have on the vine?
First visible in older leaves where the margins become yellow (white cultivars) or red (black cultivars)
Shoot and fruit growth is limited
Grape bunches are smaller than usual with uneven ripening, reduced yield and quality
Susceptible to drought stress, powdery mildew, and cold injury in winter
What function does Phosphorus (P) have in the vine?
A consituent of cell membranes and genetic material
Involved in photosynthesis and energy fixation
Essential for root branching and fruit ripening
What effect does Phosphorus (P) deficiency have on the vine?
Gradual reduction in shoot and root growth
Fruit set initiation may be compromised
Creates low bunch numbers (low yield)
Inter-veinal area of the leaves may turn yellow, reducing photosynthesis efficiency
Red spots may appear on leaves
What function does Calcium (Ca) have in the vine?
Important structural component of the vine
Forms part of the cell walls and maintains integrity of cell membranes, prolonging the cell’s life
Regulates cell acidity
Encourages positive enzyme activity during photosynthesis
What effect does Calcium (Ca) deficiency have on the vine?
Calcium deficiency is rare as it is readily found in vineyards.
Negatively affects fertilization and fruit set
Causes breakdown of cell walls and the cell membrane to leak, which is fatal.
What function does Magnesium (Mg) have in the vine?
It is an essential component of chlorophyll and is involved with enzyme activation
Regulates internal acidity and sugar metabolism
Encourages ripening
What effect does Magnesium (Mg) deficiency have on the vine?
Inter-veinal (between the veins) yellowing of older leaves of white cultivars
Inter-veinal (between the veins) reddening of older leaves of black cultivars
Yield can be affected, as can fruit ripening, if deficiency begins early in the growing season
Common on light sandy soils
What function does Sulfur (S) have in the vine?
A constituent of chlorophyll and proteins
Component of enzyme co-factors, responsible for enzyme function and energy generation
What effect does Sulfur (S) deficiency have on the vine?
Similar to Nitrogen (N) deficiency with yellowed leaves and shortened shoot growth
Deficiency is rare due to Sulfur (S) applications in the vineyard to control powdery mildew
What function doe Iron (Fe) have in the vine?
Essential component of chlorophyll and its production
Involved in energy trapping and transfer, as well as photosynthesis and respiration
What effect does Iron (Fe) deficiency have on the vine?
Inter-veinal (between the veins) yellowing of young leaves due to a lack of chlorophyll (Chlorosis), causing a notable decrease in photosynthesis and, thus, sugar production
Fruit set and yield are restricted
What function does Manganese (Mn) have in the vine?
A component of catalysts involved in the synthesis of chlorophyll and nitrogen metabolism
What effect does Manganese (Mn) deficiency have on the vine?
Inter-veinal (between the veins) yellowing of the leaves in broad bands
Vine growth and berry ripening are delayed
Most commonly found on calcareous and sandy soils
Easily corrected by spraying with manganese sulfate
What function does Molybdenum (Mb) have in the vine?
Involved in nitrogen metabolism
What effect does Molybdenum (Mb) deficiency have on the vine?
Symptoms mimic Nitrogen (N) deficiency with reduced and stunted growth and yield
Relatively rare and easily corrected with molybdenum sprays
What function does Copper (Cu) have in the vine?
Involved in chlorophyll production, cell wall metabolism, photosynthesis, and respiration
A component of the enzymes of oxidation
What effect does Copper (Cu) deficiency have on the vine?
Stunted roots and shoots
Small leaves
Decreased fruit set
Deficiency is rare due to the presence of copper in sprays (Bordeaux mixture)
What function does Zinc (Zn) have in the vine?
A component of a catalyst involved in cell metabolic reactions
Involved in protein and hormone production, as well as fruit set
What effect does Zinc (Zn) deficiency have on the vine?
Creates ‘Little Leaf’, causing small, mottled leaves
Stunts growth
Reduced fruit set and millerandage
What function does Boron (B) have in the vine?
Involved in internal regulation of growth by plant hormones
Has a role in fruit set
What effect does Boron (B) deficiency have on the vine?
Inter-veinal (between the veins) yellowing of recently matured leaves
Stunted growth and death of the shoot tip
Poor fruit set, small berries, and millerandage
What is the formula for photosynthesis?
6 CO2 + 6H2O + Light > C6H12O6 + 6O2
Carbon Dioxide + Water + Light Energy
CONVERTS TO
Carbohydrates (Glucose) + Oxygen
What level of Potassium (K) is present in the grapevine?
Comprises up to 3% of the dry weight of a vine and the most abundant mineral in grape berries
What is the appropriate level of Iron (Fe) and Manganese (Mn) in the grapevine?
Between 50 and 150 mg/L
What is the appropriate level of Molybdenum (Mb), Copper (Cu), Zinc (Zn), and Boron (B) in the grapevine?
Between 0.5 and 40 mg/L
What effect does excessive Nitrogen (N) have on the vine?
Vigorous vegetative growth that can cause excessive shading
Can reduce fruit set fruitfulness the following season due to excessive shading of the buds
What effect does excessive Potassium (K) have on the vine?
Lower total acidity in the berry’s juice, causing microbial stability issues in the wine (a higher risk in warmer climates)
What effect does excessive Copper (Cu) have on the vine?
Compromised function of soil micro-organisms.
Too much copper in the soil is implicated in reduced uptake of phosphorus and iron.
