Leaves are the energy plants of green plants and, along with the roots, the most important nutritional organs. At the Rebstock they form like that eyes (Summer and winter eyes), tendrils and inflorescences (Notes or later grapes) as a lateral outgrowth on the Nodien (Knot) young growing shoots, As the shoot tip grows in length, new leaves continuously branch off, which develop according to a species and variety-specific blueprint. With the help of leaf pigments like chlorophylls. carotenoids and flavonoids the light energy of the sun is absorbed by the leaves and during the photosynthesis under the use of carbon dioxide and water in high energy glucose (Dextrose) and oxygen converted. The necessary carbon dioxide is from the air through the stomata (Stomata) mostly recorded on the underside of the leaf. The oxygen produced during the day escapes through these small stomata.
Due to the lack of water vapor saturation in the air, every plant cell constantly loses water, which evaporates to the outside into the air. This complex process is called evapotranspiration designated. The constant loss is compensated for by the supply of water through the roots from the soil, so that there is a constant flow of water through the plant. This perspiration suction allows that mineral nutrient in the soil solution can be transported from the root to the plant at all. At 100% relative humidity and water vapor saturation of the air, water is no longer physically evaporated. In such cases, a slow water flow can be maintained through active energy-consuming pumping movements in the roots (root pressure) and a drop by drop of water through special pores. This osmotic pressure is called guttation (Excretion of excess water).
The leaf axillary is the angle between the shoot axis and the leaf that branches off from it. The starting point of the petiole at the node is called the leaf base. The leaf blade (lamina = leaf surface) sits on the petiole. Depending on the grape variety, the leaf margin can be undivided, notched or bulged. Stronger binding results in three-, five- or seven-lobed leaves. The leaf blade is traversed by five main nerves (ribs), which branch into side nerves and branching veins connected to them. The latter supplies each cell of the leaf tissue with nutrients and water and the sugar produced is transported to the grapes. The leaves are next to the grapes an excellent indicator of the health status of the vine. Diseases, lack of nutrients and pest attacks show up as, among other things, as Gallen and necrosis, as well as discoloration or yellowing (see also under leaf diseases ).
On all nodes (nodes) one Triebes there is one sheet each. The leaves are alternate, that is, alternately arranged left and right. A summer eye and a winter eye form in each leaf axil. The summer eye emerges during the summer and forms a miser. The winter eye does not sprout until the following spring and then forms the new summer instinct. There are two consecutive sheets on the side opposite the sheet (and the two eyes) tendril, as a rule, the third leaf is tendril-free. There are no tendrils on the bottom nodes of the shoot. In the upper part of the shoot some tendrils are replaced by inflorescences. The tendrils and the notes are very similar in structure, so that there can also be mixed forms of the two.
The variety-specific morphology of the leaf is an important criterion for the identification of varieties, Leaf size (hand to plate circumference), leaf shape, number of flaps, depth of the bay, opening width of the stem and leaf side bays, type and density of the perforation, density of hair and bristles are important determining features in the context of ampelography, The use of ampelometric criteria such as the opening width of the leaf angle between the main nerves and other measurable features was developed by the ampelograph Hermann Goethe (1837-1911) first suggested in 1876. Before DNA analysis The visual determination of grape varieties based on morphological varietal characteristics was the only, however sufficient and still the fastest and cheapest method. With the leaf fall the annual ends in late autumn growth cycle of the vine. With different Deciduous care measures the leaf production is regulated. See also a list below grapevine,
Graphics: taken from Bauer / Regner / Schildberger, viticulture, ISBN: 978-3-70402284-4, Cadmos Verlag GmbH