In the taxonomic system, the grapevine is assigned to the subclass Rosidae (rose plants), the order Vitales (grapevine species), the family Vitaceae (grapevine plants) as well as the genus Vitis (see Weinrebegrapevine systematics). It is a creeping plant that originally climbed up trees. A grapevine can reach enormous dimensions and in extreme cases can reach an age of over 300 years. The morphology is divided into three main organs: roots, shoot axis (stem with shoots) and leaves. The entire root system lies underground, the largest part of it at a depth of 20 to 50 centimetres, which of course depends strongly on the type of soil. This anchors the vine in the soil and provides it with all the necessary nutrients and water.
In many countries of the New World, artificial irrigation is common practice; in the EU this is subject to permission. In the form of grafted vines, which is common by grafting, the root functions are fulfilled by the rootstock. The ideal soil has a balanced relationship between water storage capacity and water withdrawal, so that the roots are forced to spread far and deep in the soil. In loose soil, the roots can penetrate to a depth of up to 15 metres. The lateral roots spread mainly in the upper layers and absorb water and nutrients via the thin fibre roots (root hairs). The tau roots (day roots or aerial roots) spread just below the surface of the earth.
Above the earth's surface lies first the so-called "old" wood, i.e. the trunk formed from the grafting of graft rice during grafting and the cordons (legs) branching off from it. Water shoots (undesirable secondary shoots) can form on the trunk (also underground) from adventitious buds. The biennial rods and cones stand on the thighs, and the eyes (axillary buds) are formed on the nodes in the leaf axils. From the winter eyes of the "previous year's" wood, new green summer shoots are formed the following spring, on which the leaves, indispensable for photosynthesis, grow. From the summer buds in the leaf axils, stingers with stinging grapes can develop laterally. The winter buds, which also grow in the leaf axes from May to July, mature and lignify by the end of October. As frost-hardy "winter eyes", they remain dormant through the winter until budding in the spring of the following year.
Basal winter eyes on the stem often develop only green fruitless shoots with up to 40 leaves, while from the second to fifth eye fruit bearing shoots with inflorescences (apparitions) develop, from which the grapes ripen after flowering. Only from the buds of the "biennial" wood, fruit-bearing shoots emerge, so that the winter pruning and the number of eyes left on the shoots determine the next year's yield. Decisive for the formation of the inflorescences in the next year is the course of growth during the vegetation cycle in connection with the climate and weather in the previous year. This means that the yield (quantity of grapes) was influenced by the number and size of the clusters and the number of individual flowers (from which the berries are formed) in part already in the previous year. Opposite to the leaves, the tendrils (fastening organs) form at the node.
Depending on the variety, it takes three to six years before the first yield, the virgin harvest, is possible after a new planting. Today, the vine is generally used for viticulture for 30 to 40 years and then cleared. However, it can get much older, some vines that are more than 200 years old have mostly been preserved as house vines on historic buildings. The oldest vine still under yield is in the garden of the Tudor Palace "Hampton Court Palace" near London, it was planted in 1769. The quality of the wine increases with age. However, vines can also age, so that after a few decades a rejuvenating pruning should be done. Since the yields slowly decrease with age, old vines are now only used for special crescences by wineries that are geared towards top quality.
The criteria for the suitability of a region for viticulture, which usually have to be positively fulfilled, are called winegrowing suitability. The vine is very adaptable and can adapt to extreme environmental conditions such as heat, drought or frost. It is viable down to minus 18 °C, and specially frost-hardy cultivated grape varieties even have a resistance down to minus 30 °C. The ideal daytime temperature is between 23 and 25 °C, with a good supply of nutrients and water, as well as optimum exposure (on slopes at best). Sunny days alternating with cooler nights are an advantage. Even the fungal infestation with Botrytis cinerea (grey mould) is used to produce special wines from noble rotten berries.
In about 100 of the total of about 200 countries in the world today, vines are planted for viticulture or at least table grape cultivation. Whether a vine thrives in a certain climate depends, among other things, on the grape variety. The best climatic conditions are found in the vine belts (40th to 50th north and 30th to 40th south latitude) at an altitude of 100 to 400 metres above sea level. Very exposed are vineyards in the tropics near the equator, as well as the northernmost vineyards around 60th to 62nd latitude and the southernmost vineyards in the world on New Zealand's South Island at 45th latitude. The highest vineyards in the world are in Salta (Argentina) at an incredible 3,111 metres above sea level. From the 1980s onwards, the global changes caused by climate change have been noticeable on a large scale.
The determination of grape varieties is described in detail under DNA (deoxyribonucleinacidand) and molecular genetics, the annual growth with the developmental stages under vegetation cycle, the different vineyard soils with effect on yield and quality under soil type, the numerous pests and diseases under vine enemies, the pedigree with the grape species under vine systematics, as well as the ancestors of the cultivated grape varieties under wild vines. Complete lists of all relevant keywords on the subject are included under the keywords vine and vineyard area.
Grape: Common free, Link
Vine old: by CecileOSaveurs from Pixabay
Vine drawings: taken from Bauer/Regner/Schildberger
Viticulture, ISBN: 978-3-70402284-4, Cadmos Publishing House
Grapes: All a Shutter / Shutterstock.com
Map: Der Winzer 1 - viticulture, Ulmer Verlag 2019, 4th edition