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In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. 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 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. Chlorosis is derived from the word Chloris or from the Greek ''khloros'' meaning 'greenish-yellow', 'pale green', 'pale', 'pallid', or 'fresh'. In viticulture, 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 soils that are high in limestone such as the Italian wine region of Barolo in the Piedmont, the Spanish wine region of Rioja and the French wine regions of Champagne and Burgundy. In these soils the grapevine often struggles to pull sufficient levels of iron 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, ISBN 9781905819157〕 ==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,〔Koenig, Rich and Kuhns, Mike: ''Control of Iron Chlorosis in Ornamental and Crop Plants''. (Utah State University, Salt Lake City, August 1996) (p.3 )〕 magnesium or zinc 〔Botany for Gardeners, p. 178, 3rd edition, Brian Capon, Timber Press 2010〕 * deficient nitrogen and/or proteins〔 * a soil pH at which minerals become unavailable for absorption by the roots * poor drainage (waterlogged roots) 〔 * damaged and/or compacted roots 〔 * pesticides and particularly herbicides may cause chlorosis, both to target weeds and occasionally to the crop being treated.〔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〕 * exposure to sulphur dioxide〔() Trees for Problem Landscape Sites -- Air Pollution, Virginia Tech May 2009〕 * ozone injury to sensitive plants () * presence of any number of bacterial pathogens, for instance ''Pseudomonas syringae pv. tagetis'' that causes complete chlorosis on Asteraceae. 〔https://www.unifr.ch/webnews/content/20/File/artikel_weedresearch(1).pdf〕 However, the exact conditions vary from plant type to plant type. For example, Azaleas grow best in acidic soil and rice is unharmed by waterlogged soil. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Chlorosis」の詳細全文を読む スポンサード リンク
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