Chemistry of the Vine

Question 1

What are the most important needs of the vine for photosynthesis?

Answer 1

Sunlight

Water

Carbon Dioxide

Question 2

What is the photosynthetic process?

Answer 2

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.

Question 3

Why is Sucrose important to the vine?

Answer 3

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.

Question 4

What is Cellulose?

Answer 4

A complex carbohydrate made from a Glucose chain that helps build the vine’s roots, trunk, shoots, leaves, and fruit.

Question 5

Why is Glucose important to the vine?

Answer 5

1) Provides energy
2) Used for carbohydrate construction
3) Building block for tannins, acids, and flavor molecules

Question 6

How does the vine obtain nutrients?

Answer 6

Roots pull nutrients from the soil that are found naturally or applied by the grower.

Question 7

At what temperature is the vine dormant?

Answer 7

-10°C

Question 8

What is the effect of heat on a vine’s metabolism?

Answer 8

Direct correlation: as heat increases, metabolism increases.

The vine needs more sugars to regulate itself, thus requiring more sunlight, water, and carbon dioxide.

Question 9

What is the optimal temperature zone for the grape vine?

Answer 9

22°C-25°C

Question 10

What happens in the grape vine above temperatures of 25°C?

Answer 10

Metabolic needs increase faster than the vine’s ability to photosynthesize sugars, thereby slowing the vine’s vegetative growth.

Question 11

Describe the temperature range for biochemical reactions inside the vine.

Answer 11

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

Question 12

What is the average temperature required for flowering?

Answer 12

20°C

Question 13

What temperature range is ideal for the creation of anthocyanins in the grape?

Answer 13

20°C - 25°C daytime temperatures

10°C - 15°C nighttime temperatures

Question 14

At what amount of sunlight do leaves become photosynthetically saturated?

Answer 14

33%

Question 15

At what temperature range is anthocyanin synthesis inhibited?

Answer 15

35°C+

Question 16

What is the vine’s preferred pH level in a soil?

Answer 16

~7 (Neutral pH)

Optimal nutrient uptake occurs between 5.5 and 8 pH.

Question 17

How does soil pH affect the availability of nutrients?

Answer 17

Acidity and alkalinity affects the solubility of nutrients

Question 18

What function does Nitrogen (N) have in the vine?

Answer 18

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

Question 19

What effect does Nitrogen (N) deficiency have on the vine?

Answer 19

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

Question 20

What function does Potassium (K) have in the vine?

Answer 20

Regulates flow of water and sugar in the plant, internal acidity, and production of acidity in the grapes

Activates enzymes

Encourages grape ripening

Question 21

What effect does Potassium (K) deficiency have on the vine?

Answer 21

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

Question 22

What function does Phosphorus (P) have in the vine?

Answer 22

A consituent of cell membranes and genetic material

Involved in photosynthesis and energy fixation

Essential for root branching and fruit ripening

Question 23

What effect does Phosphorus (P) deficiency have on the vine?

Answer 23

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

Question 24

What function does Calcium (Ca) have in the vine?

Answer 24

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

Question 25

What effect does Calcium (Ca) deficiency have on the vine?

Answer 25

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.

Question 26

What function does Magnesium (Mg) have in the vine?

Answer 26

It is an essential component of chlorophyll and is involved with enzyme activation

Regulates internal acidity and sugar metabolism

Encourages ripening

Question 27

What effect does Magnesium (Mg) deficiency have on the vine?

Answer 27

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

Question 28

What function does Sulfur (S) have in the vine?

Answer 28

A constituent of chlorophyll and proteins

Component of enzyme co-factors, responsible for enzyme function and energy generation

Question 29

What effect does Sulfur (S) deficiency have on the vine?

Answer 29

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

Question 30

What function doe Iron (Fe) have in the vine?

Answer 30

Essential component of chlorophyll and its production

Involved in energy trapping and transfer, as well as photosynthesis and respiration

Question 31

What effect does Iron (Fe) deficiency have on the vine?

Answer 31

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

Question 32

What function does Manganese (Mn) have in the vine?

Answer 32

A component of catalysts involved in the synthesis of chlorophyll and nitrogen metabolism

Question 33

What effect does Manganese (Mn) deficiency have on the vine?

Answer 33

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

Question 34

What function does Molybdenum (Mb) have in the vine?

Answer 34

Involved in nitrogen metabolism

Question 35

What effect does Molybdenum (Mb) deficiency have on the vine?

Answer 35

Symptoms mimic Nitrogen (N) deficiency with reduced and stunted growth and yield

Relatively rare and easily corrected with molybdenum sprays

Question 36

What function does Copper (Cu) have in the vine?

Answer 36

Involved in chlorophyll production, cell wall metabolism, photosynthesis, and respiration

A component of the enzymes of oxidation

Question 37

What effect does Copper (Cu) deficiency have on the vine?

Answer 37

Stunted roots and shoots

Small leaves

Decreased fruit set

Deficiency is rare due to the presence of copper in sprays (Bordeaux mixture)

Question 38

What function does Zinc (Zn) have in the vine?

Answer 38

A component of a catalyst involved in cell metabolic reactions

Involved in protein and hormone production, as well as fruit set

Question 39

What effect does Zinc (Zn) deficiency have on the vine?

Answer 39

Creates ‘Little Leaf’, causing small, mottled leaves

Stunts growth

Reduced fruit set and millerandage

Question 40

What function does Boron (B) have in the vine?

Answer 40

Involved in internal regulation of growth by plant hormones

Has a role in fruit set

Question 41

What effect does Boron (B) deficiency have on the vine?

Answer 41

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

Question 42

What is the formula for photosynthesis?

Answer 42

6 CO2 + 6H2O + Light > C6H12O6 + 6O2

Carbon Dioxide + Water + Light Energy

CONVERTS TO

Carbohydrates (Glucose) + Oxygen

Question 43

What level of Potassium (K) is present in the grapevine?

Answer 43

Comprises up to 3% of the dry weight of a vine and the most abundant mineral in grape berries

Question 44

What is the appropriate level of Iron (Fe) and Manganese (Mn) in the grapevine?

Answer 44

Between 50 and 150 mg/L

Question 45

What is the appropriate level of Molybdenum (Mb), Copper (Cu), Zinc (Zn), and Boron (B) in the grapevine?

Answer 45

Between 0.5 and 40 mg/L

Question 46

What effect does excessive Nitrogen (N) have on the vine?

Answer 46

Vigorous vegetative growth that can cause excessive shading

Can reduce fruit set fruitfulness the following season due to excessive shading of the buds

Question 47

What effect does excessive Potassium (K) have on the vine?

Answer 47

Lower total acidity in the berry’s juice, causing microbial stability issues in the wine (a higher risk in warmer climates)

Question 48

What effect does excessive Copper (Cu) have on the vine?

Answer 48

Compromised function of soil micro-organisms.

Too much copper in the soil is implicated in reduced uptake of phosphorus and iron.