DORMANCY
Have you ever wondered as
winter approaches why some plant leaves appear to change colour and then
start to fall from the deciduous trees & plants?
At the present in our
vineyard this phenomenon is occurring and it is leaving the vineyard looking
a little shabby. It is the onset of dormancy a kind of sleep for the plant,
a time of no green growth. Grape vines are also deciduous plants.
Dormancy occurs in all
deciduous plants and is a natural response to the falling temperatures of
winter. The main purpose of dormancy is for the plant to be able to
survive for long periods of harsh cold weather and somehow have a
nutrient supply at hand for when the weather conditions become more
favourable.
What is going on?
I mentioned that the leaves
appear to change colour and this is true. The brilliant reds and
yellows you see are always present in the leaves but they are masked by the
far greater presence of chlorophylls. Chlorophylls are the green chemicals
in plants and are responsible for many processes. The most important of
which is photosynthesis. Photo means light and to synthesis is to
produce something. Therefore photosynthesis is the process by which plants
use light to manufacture something and this something is food.
In fact, accept for a
small group of fungus, plants produce all the food of the world and this is
in turn eaten by animals or by animals that eat animals that ate the plants
and so on. Sugars are the primary food source produced and they are stored
in various structures such as grape berries or converted to starch and
proteins and protected by fibre as in the potato.
Back to dormancy:
As the temperatures start
to fall the plant converts the chlorophylls to soluble nitrates (plant
nutrients) and transports them to the woody parts of the plant (stems, trunk
and roots) for storage. These parts are thick and provide protection against
the cold. Once the leaf has had all the chlorophyll removed the leaf will
die and fall from the plant. When all the leaves have fallen the plant is
said to be dormant.
When the temperatures
become warmer and more favourable for life the plant remobilises the
nitrates and ships them back to where growth tissues exist, usually in some
sort of bud, and shoots with small leaves start to appear. This is commonly
called budburst.
In our vineyard at Carool
the Chardonnay has budburst towards the start of September and the red
varieties will burst about one month later. I think that this is the
prettiest time for the vines as the new growth is a wash with brilliant
pinks on the Chardonnay shoots and the bronze and copper colours of the
Cabernet Sauvignon accompanied by the shinny, fresh green new leaves. Much
like the birth of your child all fresh and perfect and full of promise of
what the future may bring.
Summary:
Dormancy
is the shut down of the plant to be able to survive cold winters while
retaining a nutrient supply on hand when conditions are more favourable for
life to proceed.
Dormancy also signals the
time for the worst job in the vineyard, Pruning. I will share some
thoughts on this with you in a future newsletter. Pruning affects the vines
shape, quantity and the quality of the fruit.
Taste
award winning local wines today at ILNAM Estate
ILNAM Estate is
a unique tourist attraction as we are the only winery on
the Tweed. ILNAM Estate Winery is located just 20 minutes from the Gold Coast
Airport, 40 minutes from Surfers Paradise and only 1 hour 20 minutes from
Brisbane.
ILNAM ESTATE WINERY- 750 Carool Road,
Carool NSW- Ph (07) 5590 7703
