Canopy (vine)
Encyclopedia
In viticulture
, the canopy of a grapevine
includes the parts of the vine visible aboveground - the trunk
, cordon, stem
s, leaves
, flowers, and fruit
. The canopy plays a key role in light energy capture via photosynthesis
, water use as regulated by transpiration
, and microclimate of ripening grapes. Canopy management is an important aspect of viticulture due to its effect on grape yield
s, quality, vigor
, and the prevention of grape diseases. Various viticulture problems, such as uneven grape ripening, sunburn, and frost damage, can be addressed by skillful canopy management. In addition to pruning
and leaf trim, the canopy is often trained on trellis systems to guide its growth and assist in access for ongoing management and harvest.
in the ground up to the cordons, or arms, of the vine. When the grape is young the trunk is very pliable and must be supported by stakes as part of a vine training system. The height of the trunk varies depending on grape variety and the type of trellis system being used and can range from 4 inches (10 cm) to 30 feet (10 m). During winter dormancy
, the trunk can be vulnerable to extreme freezing conditions and will be sometimes buried and insulated with soil to protect it.
The trunk is composed of sleeves of conductive tissue
-most notably the phloem
and xylem
. The outside bark
of the vine contains the phloem tissues which transports sap
, enriched by sugar
s and other molecules, from the leaves to the rest of the vine. During the annual growth cycle of the grapevine, the vine will start to store carbohydrate
energy in the wood part of the trunk and roots. The downward passage of phloem sap to the roots and this storing process can be interrupted by the viticultural practice of "girdling" or cincturing the vine. This process can improve fruit set by forcing the vine to direct most of its energy towards developing the grape clusters. The xylem is the woody tissue on the inside of the trunk that moves sap, enriched with water
, mineral
s and other compounds, up from the roots to the leaves.
s are sometimes used interchangeably but viticulturalists generally make some differentiation. The stem of the grapevine item, extending from cordon, is considered the shoot and this part is most often pruned in the process of "shoot thinning" to control grape yields. The stalk extending out to hold the grape cluster is known as the bunchstem while the stem of the individual grape berry is the pedicel
.
The shoot of the vine develops from new bud
s located on the cordon and grow to include the leaves, tendril
s and eventually grape clusters. Shoots first begin to the appear in spring, following bud break, accelerating growth till the flowering stage and usually slowly by the time that the vine begins veraison
. During the stage of veraison (typically mid to late summer), the shoot starts to harden and change color from green to brown. The shoot is ripening at this point and becomes known as a "cane". In wintertime, the canes of the grapevine are usually completely cut off with the amount and weight of the cane being used to gauge the amount of pruning and canopy management that will be needed for the upcoming year. The "tip" of the shoot is the small (0.4 in/1 cm) part of the shoot furthermost from the vine. Viticulturalist use the growth of this tip as an indication of vine vigor due to the fact that the tip competes with the grape clusters for resources from the vine. Ideally, shoot growth should come to a stop around the time of veraison but a vine that continues growing the shoots will stand the chance of less fully develop grape clusters.
A grapevine's leaves are the most visible part of the canopy and also one of the most important. It is through the leaves that the vital physiological process of photosynthesis
takes places which creates the carbohydrates that the vine needs to grow and process grape clusters. The size of the leaves vary due to grape varieties with varieties like Merlot
having very large leaves and Gewürztraminer
noted for having small leaves. The typical size is normally comparable to that of a human hand. In addition to size, there are many of other unique characteristics to the leaves that ampelographers use for plant identification. The size and shape of the leaf's sinus
(the opening space where the blade of the leaf connects to the petiole
, the shape of the "teeth" along the outer edge, the arrangement of the five lobes
or projecting parts and the angle and length of the veins can all assist in identifying the grapevine.
The color of the leaf can be an indication of the health and nutrition of the vine. Chlorophyll
in the leaf gives it a natural greenish color. Prior to the winter dormancy, the vine will stop being photosynthetically active which will contribute to a natural break down of chlorophyll and changing of color. However, deficiency in nitrogen
or sulfur
could cause the vine to turn prematurely (such as before harvest
) yellow. The appearance of reddish spots of brown "dead zones" could be the sign of a viral infection (such as the leafroll virus) or contamination through the use of herbicide
s.
Viticulturalist will use a leaf to fruit ratio as a guideline in determining a vine's ability to fully ripen grapes. Quite different from the consideration of yields, the balance of leaf cover (needed for photosynthesis) and proportion of fruit (judged by weight rather than number of clusters) could have the most substantiate effect on the quality of the grape for winemaking
. Pioneered by viticulturalist Richard Smart
, the idea of maintaining a "balanced vine" is to have just enough leaf cover for the plant to produce the energy needed to ripen the grape without having too much photosynthetic activity to where the vines has a surplus of energy and continues growing more shoots. Additionally, leaves provide shade to the grape clusters which be beneficial in protecting the clusters from the harshness of heat stress ("sunburn") but excessive shade can also decrease the development of sugar
s, anthocyanin
s, phenolic
s and other important compounds in the grape. Many vineyards employ the practice of leaf removal throughout the growing season to try to maintain optimal leaf coverage.
Viticulture
Viticulture is the science, production and study of grapes which deals with the series of events that occur in the vineyard. When the grapes are used for winemaking, it is also known as viniculture...
, the canopy of a grapevine
Vitis
Vitis is a genus of about 60 species of vining plants in the flowering plant family Vitaceae. The genus is made up of species predominantly from the Northern hemisphere. It is economically important as the source of grapes, both for direct consumption of the fruit and for fermentation to produce...
includes the parts of the vine visible aboveground - the trunk
Trunk (botany)
In botany, trunk refers to the main wooden axis of a tree that supports the branches and is supported by and directly attached to the roots. The trunk is covered by the bark, which is an important diagnostic feature in tree identification, and which often differs markedly from the bottom of the...
, cordon, stem
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
s, leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, flowers, and fruit
Grape
A grape is a non-climacteric fruit, specifically a berry, that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or they can be used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, molasses and grape seed oil. Grapes are also...
. The canopy plays a key role in light energy capture via photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
, water use as regulated by transpiration
Transpiration
Transpiration is a process similar to evaporation. It is a part of the water cycle, and it is the loss of water vapor from parts of plants , especially in leaves but also in stems, flowers and roots. Leaf surfaces are dotted with openings which are collectively called stomata, and in most plants...
, and microclimate of ripening grapes. Canopy management is an important aspect of viticulture due to its effect on grape yield
Yield (wine)
In viticulture, the yield is a measure of the amount of grapes or wine that is produced per unit surface of vineyard, and is therefore a type of crop yield...
s, quality, vigor
Vigor (disambiguation)
Vigor may refer to:Biology*The ability of an organism to survive and grow*Heterosis, the vigor of a hybrid breedPeople*Vigor Bovolenta, Italian volleyball player*Saint Vigor , French saintPlaces*Saint-Vigor...
, and the prevention of grape diseases. Various viticulture problems, such as uneven grape ripening, sunburn, and frost damage, can be addressed by skillful canopy management. In addition to pruning
Pruning
Pruning is a horticultural practice involving the selective removal of parts of a plant, such as branches, buds, or roots. Reasons to prune plants include deadwood removal, shaping , improving or maintaining health, reducing risk from falling branches, preparing nursery specimens for...
and leaf trim, the canopy is often trained on trellis systems to guide its growth and assist in access for ongoing management and harvest.
Vine
The vine is the main part of the grapevine, extending from the root systemRoot system
In mathematics, a root system is a configuration of vectors in a Euclidean space satisfying certain geometrical properties. The concept is fundamental in the theory of Lie groups and Lie algebras...
in the ground up to the cordons, or arms, of the vine. When the grape is young the trunk is very pliable and must be supported by stakes as part of a vine training system. The height of the trunk varies depending on grape variety and the type of trellis system being used and can range from 4 inches (10 cm) to 30 feet (10 m). During winter dormancy
Dormancy
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
, the trunk can be vulnerable to extreme freezing conditions and will be sometimes buried and insulated with soil to protect it.
The trunk is composed of sleeves of conductive tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
-most notably the phloem
Phloem
In vascular plants, phloem is the living tissue that carries organic nutrients , in particular, glucose, a sugar, to all parts of the plant where needed. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Greek word "bark"...
and xylem
Xylem
Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...
. The outside bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
of the vine contains the phloem tissues which transports sap
Sap
Sap may refer to:* Plant sap, the fluid transported in xylem cells or phloem sieve tube elements of a plant* Sap , a village in the Dunajská Streda District of Slovakia...
, enriched by sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s and other molecules, from the leaves to the rest of the vine. During the annual growth cycle of the grapevine, the vine will start to store carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
energy in the wood part of the trunk and roots. The downward passage of phloem sap to the roots and this storing process can be interrupted by the viticultural practice of "girdling" or cincturing the vine. This process can improve fruit set by forcing the vine to direct most of its energy towards developing the grape clusters. The xylem is the woody tissue on the inside of the trunk that moves sap, enriched with water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
, mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
s and other compounds, up from the roots to the leaves.
Cordon
The cordon, or "arms", of the grapevine extend from the trunk and are the part where additional arms and eventually leaves and grape clusters extend. The cordons are usually trained along wires as part of a trellis system. This training usually fixes the cordon into a permanent position, such as horizontal extending from the trunk in opposite directions.Stem
The terms stem, stalks and shootShoot
Shoots are new plant growth, they can include stems, flowering stems with flower buds, and leaves. The new growth from seed germination that grows upward is a shoot where leaves will develop...
s are sometimes used interchangeably but viticulturalists generally make some differentiation. The stem of the grapevine item, extending from cordon, is considered the shoot and this part is most often pruned in the process of "shoot thinning" to control grape yields. The stalk extending out to hold the grape cluster is known as the bunchstem while the stem of the individual grape berry is the pedicel
Pedicel (botany)
A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....
.
The shoot of the vine develops from new bud
Bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of the stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots, or may have...
s located on the cordon and grow to include the leaves, tendril
Tendril
In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape that is used by climbing plants for support, attachment and cellular invasion by parasitic plants, generally by twining around suitable hosts. They do not have a lamina or blade, but they can photosynthesize...
s and eventually grape clusters. Shoots first begin to the appear in spring, following bud break, accelerating growth till the flowering stage and usually slowly by the time that the vine begins veraison
Veraison
Véraison is a viticulture term meaning "the onset of ripening". It is originally French, but has been adopted into English use...
. During the stage of veraison (typically mid to late summer), the shoot starts to harden and change color from green to brown. The shoot is ripening at this point and becomes known as a "cane". In wintertime, the canes of the grapevine are usually completely cut off with the amount and weight of the cane being used to gauge the amount of pruning and canopy management that will be needed for the upcoming year. The "tip" of the shoot is the small (0.4 in/1 cm) part of the shoot furthermost from the vine. Viticulturalist use the growth of this tip as an indication of vine vigor due to the fact that the tip competes with the grape clusters for resources from the vine. Ideally, shoot growth should come to a stop around the time of veraison but a vine that continues growing the shoots will stand the chance of less fully develop grape clusters.
Leaves
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
takes places which creates the carbohydrates that the vine needs to grow and process grape clusters. The size of the leaves vary due to grape varieties with varieties like Merlot
Merlot
Merlot is a darkly blue-coloured wine grape, that is used as both a blending grape and for varietal wines. The name Merlot is thought to derive from the Old French word for young blackbird, merlot, a diminutive of merle, the blackbird , probably from the color of the grape. Merlot-based wines...
having very large leaves and Gewürztraminer
Gewürztraminer
Gewürztraminer is an aromatic wine grape variety that performs best in cooler climates. It is sometimes referred to colloquially as Gewürz, and in French it is written '...
noted for having small leaves. The typical size is normally comparable to that of a human hand. In addition to size, there are many of other unique characteristics to the leaves that ampelographers use for plant identification. The size and shape of the leaf's sinus
Sinus (botany)
In botany, a sinus is a space or indentation, usually on a leaf, between two lobes or teeth that does not break the continuity of the structure....
(the opening space where the blade of the leaf connects to the petiole
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
, the shape of the "teeth" along the outer edge, the arrangement of the five lobes
Lobe (anatomy)
In anatomy, a lobe is a clear anatomical division or extension that can be determined without the use of a microscope This is in contrast to a lobule, which is a clear division only visible histologically....
or projecting parts and the angle and length of the veins can all assist in identifying the grapevine.
The color of the leaf can be an indication of the health and nutrition of the vine. Chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
in the leaf gives it a natural greenish color. Prior to the winter dormancy, the vine will stop being photosynthetically active which will contribute to a natural break down of chlorophyll and changing of color. However, deficiency in nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
or sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
could cause the vine to turn prematurely (such as before harvest
Harvest (wine)
The harvesting of wine grapes is one of the most crucial steps in the process of winemaking. The time of harvest is determined primarily by the ripeness of the grape as measured by sugar, acid and tannin levels with winemakers basing their decision to pick based on the style of wine they wish to...
) yellow. The appearance of reddish spots of brown "dead zones" could be the sign of a viral infection (such as the leafroll virus) or contamination through the use of herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
s.
Viticulturalist will use a leaf to fruit ratio as a guideline in determining a vine's ability to fully ripen grapes. Quite different from the consideration of yields, the balance of leaf cover (needed for photosynthesis) and proportion of fruit (judged by weight rather than number of clusters) could have the most substantiate effect on the quality of the grape for winemaking
Winemaking
Winemaking, or vinification, is the production of wine, starting with selection of the grapes or other produce and ending with bottling the finished wine. Although most wine is made from grapes, it may also be made from other fruit or non-toxic plant material...
. Pioneered by viticulturalist Richard Smart
Richard Smart
Dr. Richard Smart is an Australian viticulturalist and leading global consultant on viticulture methods, who is often referred to as “the flying vine-doctor”. He is considered responsible for revolutionising grape growing due to his work on canopy management techniques.-Biography:Dr...
, the idea of maintaining a "balanced vine" is to have just enough leaf cover for the plant to produce the energy needed to ripen the grape without having too much photosynthetic activity to where the vines has a surplus of energy and continues growing more shoots. Additionally, leaves provide shade to the grape clusters which be beneficial in protecting the clusters from the harshness of heat stress ("sunburn") but excessive shade can also decrease the development of sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s, anthocyanin
Anthocyanin
Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue according to pH...
s, phenolic
Natural phenol
Natural phenols, bioavailable phenols, plant phenolics, low molecular weight phenols or phenoloids are a class of natural products. They are small molecules containing one or more phenolic group. These molecules are smaller in size than polyphenols, containing less than 12 phenolic groups...
s and other important compounds in the grape. Many vineyards employ the practice of leaf removal throughout the growing season to try to maintain optimal leaf coverage.