A vine goes through different phases each year of its life, which follow one another in a constant order and which together form the vegetative cycle of the vine.
In the northern or boreal hemisphere, the shoots begin to grow at the beginning of spring (March or April), ending the vegetative cycle in autumn (October or November), while in the southern or southern hemisphere the seasons are reversed, with a lag of six months, sprouting the vine (September or October) and ending the vegetative cycle in spring (April or May).
Below we summarize the different stages of this vegetative cycle:
1. I CRY
It is the first activity of the plant after the winter rest. When the temperature of the roots and the soil exceeds 10ºC, the weeping that flows from the wounds and pruning cuts appears. This moment shows the beginning of the activity of the plant, cellular respiration begins, the recovery of the absorption of water and mineral elements. The water and dissolved mineral matter flows upwards through the woody parts of the plant, peeking out like tears from the wounds and cuts from previous pruning.
2. SPROUTING
The activity of the root, which is the one that begins first, manifests itself successively throughout the plant: it mobilizes the elaborated sap accumulated in it, first in the buds, and then reaches the entire node and internodes. The yolk swells up to the separation of the scales that cover them, appearing clear, and then the green organs, forming the “butterfly”.
3. FLOWERING
From the bud, the vine develops the vegetative organs and creates other new organs: roots, buds, grandchildren and clusters, etc. Growth occurs in length and girth. The temperature and insolation have a major influence on the speed of this phenomenon.
Highlight the existence of latent buds, because the buds have the potential to develop, but they remain at rest due to an inhibitory hormone. So much so that the clusters of flowers (inflorescences) in the dormant buds have their initiation and development in the cycle preceding their sprouting. The formation of the inflorescences or the foliar initiation is carried out in the dormant buds of the previous year around the months of June to July.
4. RIPENING
The development and maturation of the grapes, that is, the formation and growth of the berries, originates from and is a consequence of the action and triple hormonal stimulus of pollination, fertilization and seed formation, as well as the contribution of substances nutritious for the plant.
In certain privileged climates, where there are usually no weather incidents, the bunch can remain on the vines to reach a higher degree of sugar. It is the so-called over-ripening, which is more physical than physiological, because its components are concentrated and the berry loses weight, due to the evaporated water.
5. AUTUMN GROWTH
The stoppage of growth in summer, which normally happens at the time of veraison, is not always definitive, since the rains at the end of summer can activate growth again. Well advanced in the summer and at its end, the branches appear, small leaves at the tips of the grandchildren, a growth caused by a small activity in the cell multiplication of the plant. After the cessation of growth, the anatomical structure of the shoot changes, acquiring a caramel yellow color.
6. LEAF FALL
When the temperature begins to decrease notably to the vicinity of zero, below which we know that the activity of the plant ceases, its leaves fall; but before, the food materials descend through the woody parts and constitute reserves mainly in the arms, trunk and roots of the vine. The leaves turn yellow or red, dry up and finally fall. The vine has entered its winter rest phase. Early winters with frosts can determine an anticipated, partial or total leaf drop, damaging the accumulation of reserves for subsequent blooms.
7. WINTER REST
After the leaves fall, the vine does not present apparent vegetative activity, calling this phase dormancy or vegetative or winter rest. The dormancy of the buds carried by a shoot sprouted the previous year also occurs.
CURIOUS PHENOMENA: MULTI-VENDEMIES
In tropical climates, when temperatures do not drop below 12ºC, there is no interruption of the vegetative cycle, and the growth of the vine, as well as its fruiting, is continuous, even up to three harvests per year with a cycle vegetative from 110 to 130 days, achieving uneven grape quality among them.
The climatic conditions of these areas, with temperatures between 21º and 36ºC, together with a high rainfall of 1,000 to 2,000 mm, allow this curious phenomenon, which can be attenuated by the altitude of the vineyards.
