Chlorosis

Chlorosis
A corn plant with severe chlorosis (left) beside a normal plant (right).

In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green colour of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to manufacture carbohydrates through photosynthesis and may die unless the cause of its chlorophyll insufficiency is treated, although some chlorotic plants, such as the albino Arabidopsis thaliana mutant ppi2 are viable if supplied with exogenous sucrose[1].


Chlorosis is derived from the word Chloris or from the Greek Khloros meaning "greenish-yellow," "pale green," "pale," "pallid" or "fresh".

Contents

Causes

A Liquidambar leaf with interveinal chlorosis
Citron shrub with chlorosis

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[2] or magnesium [3]
  • deficient nitrogen and/or proteins[3]
  • a soil pH at which minerals become unavailable for absorption by the roots [4]
  • poor drainage (waterlogged roots) [4]
  • damaged and/or compacted roots [4]
  • pesticides and particularly herbicides may cause chlorosis, both to target weeds and occasionally to the crop being treated.[5]
  • exposure to sulphur dioxide[6]

Of course, the exact conditions would be different for different plants. For example, Azaleas prefer unusually acidic soil and rice isn't troubled by waterlogged soil.

  • ozone injury to sensitive plants [2]

Chlorosis in viticulture

Like many other plants, grape vines are susceptible to chlorosis, and symptoms of iron deficiency tend to be common on soils rich in limestone. In the wake of The Great French Wine Blight, when European Vitis vinifera were affected by Phylloxera, chlorosis became a greater problem in viticulture. To deal with the Phylloxera blight, V. vinifera was grafted onto rootstock based on American species of the Vitis genus, such as Vitis riparia, Vitis rupestris, 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 and V. berlandieri, which generally has a sufficient, but not extremely high, Phylloxera resistance.[7][8]

Treatments

Specific nutrient deficiencies (often aggravated by high soil pH) may be corrected by supplemental feedings of iron, in the form of a chelate or sulphate, magnesium or nitrogen compounds in various combinations.

References

  1. ^ Kubis S, Patel R, Combe J, et al. (August 2004). "Functional specialization amongst the Arabidopsis Toc159 family of chloroplast protein import receptors". Plant Cell 16 (8): 2059–77. doi:10.1105/tpc.104.023309. PMC 519198. PMID 15273297. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=519198. 
  2. ^ Koenig, Rich and Kuhns, Mike: Control of Iron Chlorosis in Ornamental and Crop Plants. (Utah State University, Salt Lake City, August 1996) p.3
  3. ^ a b Botany for Gardeners, p. 178, 3rd edition, Brian Capon, Timber Press 2010
  4. ^ a b c Schuster, James. "Focus on Plant Problems - Chlorosis". University of Illinois. http://www.urbanext.uiuc.edu/focus/chlorosis.html. Retrieved 2008-12-22. 
  5. ^ Pests of Landscaped Trees and Shrubs: An Integrated Pest Management Guide By Steve H. Dreistadt, Jack Kelly Clark, p. 284, Regents of the University of California Division of Agriculture and Natural Resources, 2004
  6. ^ [1] Trees for Problem Landscape Sites -- Air Pollution, Virignia Tech May 2009
  7. ^ Jancis Robinson, ed (2006). "Chlorosis". Oxford Companion to Wine (3rd ed.). Oxford: Oxford University Press. pp. 170. ISBN 0-19-860990-6. 
  8. ^ Jancis Robinson, ed (2006). "Rootstock". Oxford Companion to Wine (3rd ed.). Oxford: Oxford University Press. pp. 591–3. ISBN 0-19-860990-6. 

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Look at other dictionaries:

  • Chlorosis — Chlo*ro sis, n. [NL., fr. Gr. chlwro s light green: cf. F. chlorose.] 1. (Med.) The green sickness; an an[ae]mic disease of young women, characterized by a greenish or grayish yellow hue of the skin, weakness, palpitation, etc. [1913 Webster] 2.… …   The Collaborative International Dictionary of English

  • chlorosis — chlorosis. См. хлороз. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Chlorosis — Chlorōsis (Chlorōse), s. Bleichsucht …   Kleines Konversations-Lexikon

  • chlorosis — [klə rō′sis] n. [ModL: see CHLOR(O) & OSIS] 1. an abnormal condition of plants in which the green parts lose their color or turn yellow as a result of a lack of chlorophyll production due to disease, lack of light, etc. 2. a form of iron… …   English World dictionary

  • Chlorosis (medicine) — For iron deficiency in plants, see Chlorosis (plant disorder). In medicine, chlorosis (also known as green sickness ) is a form of anemia named for the greenish tinge of the skin of a patient. Its symptoms include lack of energy, shortness of… …   Wikipedia

  • chlorosis — noun Date: 1678 1. an iron deficiency anemia especially of adolescent girls that may impart a greenish tint to the skin called also greensickness 2. a diseased condition in green plants marked by yellowing or blanching • chlorotic adjective …   New Collegiate Dictionary

  • chlorosis — Yellowing or bleaching of plant tissues due to the loss of chlorophyll or failure of chlorophyll synthesis. Symptomatic of many plant diseases, also of deficiencies of light or certain nutrients …   Dictionary of molecular biology

  • chlorosis — chlorotic /klaw rot ik, kloh /, adj. chlorotically, adv. /klaw roh sis, kloh /, n. 1. an abnormally yellow color of plant tissues, resulting from partial failure to develop chlorophyll, caused by a nutrient deficiency or the activities of a… …   Universalium

  • chlorosis — noun a) An anaemia, due to deficiency of iron, characterized by a yellow green colouration of the skin; greensickness. b) A yellowing of plant tissue due to loss or absence of chlorophyll. See Also …   Wiktionary

  • chlorosis — Rarely used term for a form of chronic hypochromic microcytic (iron deficiency) anemia, characterized by a great reduction in hemoglobin out of proportion to the decreased number of red blood cells; observed chiefly in females from …   Medical dictionary

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