In
botany
Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
, chlorosis is a condition in which leaves produce insufficient
chlorophyll
Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to ...
. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to manufacture
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may o ...
s through
photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...
and may die unless the cause of its chlorophyll insufficiency is treated and this may lead to a plant diseases called rusts, although some chlorotic plants, such as the albino ''
Arabidopsis thaliana
''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. ''A. thaliana'' is considered a weed; it is found along the shoulders of roads and in disturbed land.
A winter ...
'' mutant ''ppi2'', are viable if supplied with
exogenous
In a variety of contexts, exogeny or exogeneity () is the fact of an action or object originating externally. It contrasts with endogeneity or endogeny, the fact of being influenced within a system.
Economics
In an economic model, an exogen ...
sucrose
Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula .
For human consumption, sucrose is extracted and refine ...
.
The word ''chlorosis'' is derived from the Greek ''khloros'' meaning "greenish-yellow", "pale green", "pale", "pallid", or "fresh".
In
viticulture
Viticulture (from the Latin word for '' vine'') or winegrowing (wine growing) is the cultivation and harvesting of grapes. It is a branch of the science of horticulture. While the native territory of '' Vitis vinifera'', the common grape vine, r ...
, the most common symptom of poor nutrition in grapevines is the yellowing of grape leaves caused by chlorosis and the subsequent loss of chlorophyll. This is often seen in
vineyard soil
The soil composition of vineyards is one of the most important viticultural considerations when planting grape vines. The soil supports the root structure of the vine and influences the drainage levels and amount of minerals and nutrients that the ...
s that are high in limestone such as the
Italian wine
Italian wine is produced in every region of Italy. Italy is the world's largest producer of wine, with an area of under vineyard cultivation, and contributing a 2013–2017 annual average of 48.3 million hl of wine. In 2018 Italy accounted fo ...
region of
Barolo in the
Piedmont
it, Piemontese
, population_note =
, population_blank1_title =
, population_blank1 =
, demographics_type1 =
, demographics1_footnotes =
, demographics1_title1 =
, demographics1_info1 =
, demographics1_title2 ...
, the
Spanish wine
Spanish wine () includes red, white, and sparkling wines produced throughout the country. Located on the Iberian Peninsula, Spain has over 1.2 million hectares (2.9 million acres) planted in wine grapes, making it the most widely ...
region of
Rioja and the
French wine
French wine is produced all throughout France, in quantities between 50 and 60 million hectolitres per year, or 7–8 billion bottles. France is one of the largest wine producers in the world, along with Italian, Spanish, and Ameri ...
regions of
Champagne
Champagne (, ) is a sparkling wine originated and produced in the Champagne wine region of France under the rules of the appellation, that demand specific vineyard practices, sourcing of grapes exclusively from designated places within it, ...
and
Burgundy
Burgundy (; french: link=no, Bourgogne ) is a historical territory and former administrative region and province of east-central France. The province was once home to the Dukes of Burgundy from the early 11th until the late 15th century. The ...
. In these soils the grapevine often struggles to pull sufficient levels of
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
which is a needed component in the production of chlorophyll.
[Wine & Spirits Education Trust ''"Wine and Spirits: Understanding Wine Quality"'' pg 16, Second Revised Edition (2012), London, ]
Causes
Chlorosis is typically caused when leaves do not have enough nutrients to synthesise all the chlorophyll they need. It can be brought about by a combination of factors including:
* a specific mineral deficiency in the soil, such as iron, magnesium or zinc
[Botany for Gardeners, p. 178, 3rd edition, Brian Capon, Timber Press 2010]
* deficient nitrogen and/or proteins
* a
soil pH
Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the ne ...
at which minerals become unavailable for absorption by the roots
* poor drainage (waterlogged roots)
* damaged and/or compacted roots
*
pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and ...
s and particularly
herbicide
Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...
s may cause chlorosis, both to target
weeds and occasionally to the
crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydropon ...
being treated.
* exposure to sulphur dioxide
* ozone injury to sensitive plant
* presence of any number of bacterial pathogens, for instance ''Pseudomonas syringae pv. tagetis'' that causes complete chlorosis on
Asteraceae
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae ...
* fungal infection, e.g.
Bakanae
or bakanae disease (, , ), from the Japanese for "foolish seedling", is a disease that infects the rice plant. It is caused by the fungus ''Gibberella fujikuroi'', the metabolism of which produces a surplus of gibberellic acid. In the plant, this ...
.
However, the exact conditions vary from plant type to plant type. For example,
Azalea
Azaleas are flowering shrubs in the genus '' Rhododendron'', particularly the former sections '' Tsutsusi'' (evergreen) and '' Pentanthera'' (deciduous). Azaleas bloom in the spring (April and May in the temperate Northern Hemisphere, and Oct ...
s grow best in acidic soil and
rice
Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...
is unharmed by waterlogged soil.
In grape vines
Like many other plants,
grape vine
''Vitis'' (grapevine) is a genus of 79 accepted 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, ...
s are susceptible to chlorosis, and symptoms of iron deficiency tend to be common on soils rich in
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...
. In the wake of
The Great French Wine Blight
The Great French Wine Blight was a severe blight of the mid-19th century that destroyed many of the vineyards in France and laid waste to the wine industry. It was caused by an aphid that originated in North America and was carried across the Atl ...
, when European ''
Vitis vinifera
''Vitis vinifera'', the common grape vine, is a species of flowering plant, native to the Mediterranean region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran. There are cur ...
'' were affected by ''
Phylloxera
Grape phylloxera is an insect pest of commercial grapevines worldwide, originally native to eastern North America. Grape phylloxera (''Daktulosphaira vitifoliae'' (Fitch 1855) belong to the family Phylloxeridae, within the order Hemiptera, bu ...
'', chlorosis became a greater problem in
viticulture
Viticulture (from the Latin word for '' vine'') or winegrowing (wine growing) is the cultivation and harvesting of grapes. It is a branch of the science of horticulture. While the native territory of '' Vitis vinifera'', the common grape vine, r ...
. To deal with the Phylloxera blight, ''V. vinifera'' was grafted onto
rootstock
A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to a ...
based on American species of the genus ''
Vitis
''Vitis'' (grapevine) is a genus of 79 accepted 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, ...
'', such as ''
Vitis riparia'', ''
Vitis rupestris
''Vitis rupestris'' is a species of grape native to the United States that is known by many common names including July, Coon, sand, sugar, beach, bush, currant, ingar, rock, and mountain grape. It is used for breeding several French-American ...
'', and ''
Vitis berlandieri''. However, many of these were less adapted to the lime-rich soils that were common in France's vineyards, in particular many of those that produced wines of top quality. Many grafted vines in lime-rich vineyards therefore showed signs of iron deficiency, and in France this specific form of chlorosis was termed ''chlorose calcaire.'' The problem was largely overcome by the selection of lime-resistant American vines as basis for hybrid vines used for rootstock material. However, since such rootstocks may be less than optimal in other respects, it is necessary for the viticulturalist to balance the need for chlorosis resistance against other viticultural needs. This is illustrated by one of the most common lime-resistant rootstocks, 41 B, which is a hybrid between ''V. vinifera'' cultivar
Chasselas
Chasselas or Chasselas blanc is a wine grape variety grown mainly in Switzerland, France, Germany, Portugal, Hungary, Romania, New Zealand, Croatia and Chile. Chasselas is mostly vinified to be a full, dry and fruity white wine. It ...
and ''V. berlandieri'', which generally has a sufficient, but not extremely high, Phylloxera resistance.
Treatments
Specific
nutrient
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excre ...
deficiencies (often aggravated by high
soil pH
Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the ne ...
) may be corrected by supplemental feedings of
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
, in the form of a
chelate or
sulphate,
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...
or
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
compounds in various combinations.
See also
*
Forest pathology
*
Phytopathology
Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomy ...
*
Virescence
References
{{Authority control
Physiological plant disorders