Developmental physiology and Climate

Question 1

The majority of the fluctuations in fruit composition are caused by

Answer 1

Climate variability

Question 2

In terms of cultural practices, how can we use them and and is it possible that they can change the wine composition given harvest consistency?

Answer 2

Cultural practices can be used to fine-tune what nature imposes. We can see different anthocyanin amounts and different volatile compounds given harvesting with a consistent level of brix

Question 3

Difference between direct solar radiation and diffused solar radiation on clear vs. cloudy days

Answer 3

On a clear day we have a much bigger spike in direct solar radiation and very little diffused light. On cloudy days their values are identical

Question 4

What is albedo?

Answer 4

the proportion of the incident light or radiation that is reflected by a surface (plants, snow, water…)

Question 5

Grapes are physiologically mature when…

Answer 5

the seeds attain their ability to germinate (i.e. immediately after veraison)

Question 6

________ is the most important climatic factor affecting grape composition.

Answer 6

Sunlight

Question 7

What happens when shaded leaves die? What can happen because of this?

Answer 7

their nutrients are recycled back to important sinks.

The berries might receive a dose of nitrogen, potassium and other nutrients, which might eventually lead to an increase in juice pH.

Question 8

__________ production might decrease in the shade as the synthesis of its precursor ascorbate is light sensitive.

Conversely, _______ is higher in shaded clusters likely due to a temperature driven effect.

Answer 8

1. Tartaric acid
2. malate

Question 9

Anthocyanins and hydroxycinnamic acids are stimulated primarily by….
w hereas flavonols react predominantly to ______.

Answer 9

1. Visible Light
2. UVB

Question 10

What is the graphed relationship between glucose and light exposure?

Answer 10

Positive linear

Question 11

Color formation is primarily dependent on…

Answer 11

Temperature

Question 12

Overcast conditions slow down

Answer 12

anthocyanin accumulation

Question 13

________ anthocyanins often dominate the color profile because their production seems to be less responsive to low solar radiation than that of other anthocyanins.

Answer 13

Malvadin based

Question 14

However too much radiation of UVB can inhibit ________ and induce degradation or previously formed anthocyanins.

Answer 14

anthocyanin production

Question 15

Therefore grape berries are more vulnerable to sunburn if…

Answer 15

Bright, hot days suddenly follow a period of low light conditions or if shaded berries are suddenly exposed to the sun.

Question 16

Are pre-veraison berries more susceptible to sunburn or post veraison?

Answer 16

There is no difference. The self defense mechanism happens pre-veraison (synthesis of “sunscreen compounds”)

Question 17

Anthocyanins have a photosynthetic protection, so….

Answer 17

White grapes are more susceptible due to their lack of anthocyanins.

Question 18

Sussceptibility to shade is ______

Answer 18

Genetic

We saw that shade has a very little effect on syrah, however it has a very large impact on sangiovese.

Question 19

What can we learn from the graph showing a relationship between brix and methoxypyrazines?

Answer 19

We can see that there is a large difference between the amount of methoxypyrazines at the same Brix levels. In the case of shaded grapes there were higher levels of methoxypyrazines than in exposed grapes

Question 20

What is water use efficiency and does it increase or decrease at low PAR? We know that photosynthesis more sensitive to light than ______ is.

Answer 20

Water use efficiency is the ratio between CO2 and H2O (photosynthesis and respiration)

At low PAR it decreases

gs which is stomatal conductance