View source for Guar

{{Short description|Species of flowering plant in the bean family Fabaceae}}
{{Distinguish|Gaur|Gwar}}
{{Speciesbox
|image = Cluster bean-guar-Cyamopsis psoralioides-Cyamopsis tetragonolobus-TAMIL NADU73.jpg
|image_caption = Guar bean cluster
|taxon = Cyamopsis tetragonoloba
|authority = ([[Carl Linnaeus|L.]]) [[Paul Hermann Wilhelm Taubert|Taub.]]
|synonyms =
* ''Cyamopsis psoralioides'' <small>auct., orth. var.</small>
* ''Cyamopsis psoraloides'' <small>DC.</small>
* ''Cyamopsis psoraloides'' <small>(Lam.) DC.</small>
}}
The '''guar''' (from {{langx|hi|ग्वार}} : gvār) or ''' cluster bean''', with the botanical name '''''Cyamopsis tetragonoloba''''', is an [[annual plant|annual]] [[legume]] and the source of [[guar gum]]. It is also known as gavar, gawar, or guvar bean.
The genus name ''Cyamopsis'' means ''bean-like'' (from {{langx|el|κύαμος}} : kýamos "bean" + {{langx|el|ὄψις}} : ópsis "view'). The specific name is from {{langx|la|tetragōnoloba}} meaning ''four-lobed''.
The origin of ''Cyamopsis tetragonoloba'' is unknown, since it has never been found in the wild.<ref name=Whistler>Whistler R. L. and Hymowitz T. 1979. Guar: agronomy, production, industrial use and nutrition. Purdue University Press, West Lafayette</ref> It is assumed to have developed from the African species ''[[Cyamopsis senegalensis]]''. It was further domesticated in [[South Asia]], where it has been cultivated for centuries.<ref name=Mudgil>{{Cite journal | last1 = Mudgil | first1 = D. | last2 = Barak | first2 = S. | last3 = Khatkar | first3 = B. S. | doi = 10.1007/s13197-011-0522-x | title = Guar gum: Processing, properties and food applications—A Review | journal = Journal of Food Science and Technology | year = 2011 | pmid =  24587515| pmc = 3931889 | volume=51 | issue = 3 | pages=409–18}}</ref>
Guar grows well in semiarid areas, but frequent rainfall is necessary.
This legume is a valuable plant in a crop rotation cycle, as it lives in symbiosis with nitrogen-fixing bacteria.<ref name="Undersander">Undersander D. J., Putnam D. H., Kaminski A. R., Doll J. D., Oblinger E. S. and Gunsolus J. L. 1991. Guar. University of Wisconsin-Madison, University of Minnesota [http://www.hort.purdue.edu/newcrop/afcm/guar.html] Accessed November 8, 2012.</ref>
Agriculturists in semi-arid regions of Rajasthan follow [[crop rotation|crop-rotation]] and use guar to replenish the soil with essential fertilizers and [[nitrogen fixation]], before the next crop. Guar has many functions for human and animal nutrition, but the gelling agent in its seeds (guar gum) is the most important use.<ref name=Mudgil/> Demand is rising due to the use of guar gum in hydraulic fracturing ([[oil shale gas]]).<ref name=Mudgil/> It is also a major ingredient of the toy [[Slime (toy)|Slime]]. About 80% of world production occurs in [[India]], but due to strong demand, the plant is being introduced elsewhere.
==Biology==
''Cyamopsis tetragonoloba'' grows upright, reaching a maximum height of up to {{convert|2–3|m|ft|0}}.
It has a main single stem with either basal branching or fine branching along the stem.
Guar taproots can access soil moisture in low soil depths.<ref name=Undersander/> This [[legume]] develops root nodules with nitrogen-fixing soil bacteria [[rhizobia]] in the surface part of its rooting system.
Its leaves and stems are mostly hairy, depending on the cultivar. Its fine leaves have an elongated oval shape ({{convert|5 to 10|cm|in|0}}) and of alternate position. Clusters of flowers grow in the plant axil and are white to blueish in color. The developing pods are rather flat and slim containing 5 to 12 small oval seeds of {{convert|5|mm|in|frac=4}} length (TGW = {{convert|25-40|g|oz|frac=2}}). Usually mature seeds are white or gray, but with excess moisture they can turn black and lose germination capacity. The chromosome number of guar seeds is 2n=14.<ref name=Uni>[http://bibd.uni-giessen.de/gdoc/2000/uni/p000003/guarbohn.htm "Guarbohne (Cyamopsis tetragonolobus &#91;L.&#93; Taub. &#91;=C. psoralioides DC.&#93;)"] Accessed November 8, 2012.</ref>
The seeds of guar beans have a remarkable characteristic. Its kernel consists of a protein-rich germ (43–46%) and a relatively large endosperm (34–40%), containing large amounts of the galactomannan.<ref name=Mudgil/> This is a polysaccharide containing polymers of [[mannose]] and [[galactose]] in a ratio of 2:1 with many branches.<ref name=Garti>Garti N. and Leser M. E 2001. Emulsification properties of hydrocolloids. Polymers for Advanced Technologies 12: 123–135.</ref> Thus, it exhibits a great hydrogen bonding activity <ref name=Whistler/> having a viscosifying effect in liquids.
==Cultivation==
===Climate requirements===
Guar is drought-tolerant and sun-loving, but it is susceptible to frost.<ref name=Whistler/> Although it can cope with little but regular rainfall, it requires sufficient soil moisture before planting and during maturation of seeds.<ref>Anderson E. 1949. Endosperm mucilages of legumes: occurrences and composition. Industrial and Engineering Chemistry Research 41:2887-2890.</ref> Frequent drought periods can lead to delayed maturation.<ref name=Undersander/> On the contrary, excessive moisture during the early growth phase and after maturation lead to lower seed quality.<ref name=Whistler/> Guar is produced near to coastal areas in the Gandhidham region of Kutch, Gujarat, India.
===Soil requirements===
''Cyamopsis tetragonoloba'' (L.) can grow on a wide range of soil types. Preferably in fertile, medium-textured and sandy [[loam]] soils that are well-drained, since waterlogging decreases plant performance. Guar grows best in moderate alkaline conditions (pH 7–8) and is tolerant of salinity. Its taproots are inoculated with rhizobia nodules and thus it produces nitrogen-rich biomass and improves [[soil quality]].<ref name=Undersander/>
===Cultural practices===
<ref name=Undersander/><ref name=Uni/>
{| class="wikitable"
|-
| Seeding ||
* Seedbed: firm, weed-free
* Date: soil temperature > 21&nbsp;°C (optimum: 30&nbsp;°C); monsoon-regions: after first rain event in June or early July
* Rate: seed use: 10–30&nbsp;kg/ha, biomass use: 50–100&nbsp;kg/ha
* Row spacing: seed use: 45–60&nbsp;cm, biomass use: 30–45&nbsp;cm
|-
| Fertilizer ||
* Nitrogen: not necessary
* Phosphorus: often limiting, US: Superphosphate 200–250&nbsp;kg/ha
|-
| Plant Protection ||
* Weeding: young guar plant development is susceptible to weeds. Early, well prepared seedbeds help reduce weed harm
* Diseases: choose disease-resistant cultivars, 2 major diseases: ''Alternaria cucumerina var. cyamopsidis'' and ''Xanthomonoas cyamopsidis''
* Predators: ''Contarinia texana'' guar midge: rainfall or sprinkler irrigation reduce midge populations
|-
| Harvest||  seed pods: dry, brown, 60–90 days after sowing; biomass: first lower pods turn brown
|-
| Yield|| seeds: 5–8 dt/ha; biomass: 40–50 t/ha
|-
|}
===Cultivation areas===
Guar is grown principally in north-western India with smaller crops grown in the semiarid areas of the high plains of Texas in the [[United States|US]],<ref>[http://juniper.tamu.edu/Agronomy/guar_production.htm "Guar Production"] Vernon Agricultural Research & Extension Center, Texas A&M Univ. 2006.</ref> Australia and Africa. The most important growing area centres on Jodhpur in Rajasthan, India, where demand for guar for fractionation produced an agricultural boom as in 2012.<ref name=NYT71612>{{cite news|title=In Tiny Bean, India's Dirt-Poor Farmers Strike Gas-Drilling Gold|url=https://www.nytimes.com/2012/07/17/world/asia/fracking-in-us-lifts-guar-farmers-in-india.html|access-date=July 17, 2012|newspaper=The New York Times|date=July 16, 2012|author=Gardiner Harris}}</ref> Currently [When? As of 2023?], India is the main producer of cluster bean, accounting for 80% production of the world's total, while the [[Rajasthan]], [[Gujarat]] and [[Kutch district|Kutch]] regions occupy the largest areas (82.1% of total) dedicated to guar cultivation. In addition to its cultivation in India, the crop is also grown as a cash crop in other parts of the world.<ref>{{Cite journal | last1 = Pathak | first1 = R. | last2 = Singh | first2 = S. K. | last3 = Singh | first3 = M. | last4 = Henry | first4 = A. | title = Molecular assessment of genetic diversity in cluster bean (Cyamopsis tetragonoloba) genotypes | doi = 10.1007/s12041-010-0033-y | journal = Journal of Genetics | volume = 89 | issue = 2 | pages = 243–246 | year = 2010 | pmid =  20861578| s2cid = 7056607 }}</ref> Several commercial growers<ref>[http://westtexasguar.com "large scale guar growers"]</ref> have converted their crops to guar production to support the increasing demand for guar and other organic crops<ref>{{Cite web |url=http://guar-tex.com/ |title="organic fertilizer crops" |access-date=2022-03-20 |archive-date=2013-06-05 |archive-url=https://web.archive.org/web/20130605060808/http://guar-tex.com/ |url-status=dead }}</ref> in the United States.
===Varieties===
Pusa Naubahar and Pusa Sadabahar. Seeds at the rate of 30 kilograms/hectare (9–11&nbsp;lb/acre) are planted at a spacing of 45–60 × 20–30&nbsp;cm (18–24 × 8–12 in) in February–March and June–July. During the rainy season, seeds are sown 2–3&nbsp;cm (~1 in) deep on ridges and in furrows during summer months. FYM is applied at the rate of 25 tonnes/ha (11.1 tons/acre). N, P<sub>2</sub>O<sub>5</sub> and K<sub>2</sub>O recommendation for the crop is 20:60:80&nbsp;kg/ha (18:53:71&nbsp;lb/acre). Average yield is 5 to 6 tonnes/ha (2.2–2.6 tons/acre). Meager information is available for genetic variability in cluster bean addressing the qualitative traits (Pathak et al. 2011).<ref>{{cite journal | last1 = Pathak | first1 = R. | last2 = Singh | first2 = M. | last3 = Henry | first3 = A. | year = 2011 | title = Genetic diversity and interrelationship among clusterbean (Cyamopsis tetragonoloba) for qualitative traits | journal = Indian Journal of Agricultural Sciences | volume = 81 | issue = 5| pages = 402–406 }}</ref>
==Uses==
===Guar plant===
Agriculture
* [[Forage]]: Guar plants can be used as cattle feed, but due to hydrocyanic acid in its beans, only mature beans can be used.<ref name=Whistler/>
* [[Green manure]]: Guar plantings increase the yield of subsequent crops as this legume conserves soil nutrient content.<ref name=Whistler/>
Domestic use
* [[Vegetable]]: Guar leaves can be used like spinach, and the pods are prepared like salad or vegetables.<ref name=Uni/> Its beans are nutritious, but guar protein is not usable by humans unless toasted to destroy the [[trypsin inhibitor]].
===Guar gum===
{{Main|Guar gum}}
The seeds of the guar bean contain a large endosperm. This endosperm consists of a large polysaccharide of galactose and mannose. This polymer is water-soluble and exhibits a viscosifying effect in water. Guar gum has a multitude of different applications in food products, industrial products, and [[extractivism|extractive industry]].
====Food====
In several food and beverages guar gum is used as additive to change its viscosity or as fiber source.
{| class="wikitable"
|-
! Food !! Function
|-
| Baked goods || Dough improver <ref>{{cite journal | last1 = Kohajdova | first1 = Z. | last2 = Karovicova | first2 = J. | year = 2008 | title = Influence hof hydrocooloids on quaality of baked goods | journal = ACTA Scientiarum Polonorum Technologia Alimentaria | volume = 7 | pages = 42–49 }}</ref>
|-
| Cheese || Texture improver <ref>{{cite journal | last1 = Klis | first1 = J.B | year = 1966 | title = Woody's Chunk O'Gold cold-pack chees food weeps no more | journal = Food Processing Marketing | volume = 27 | pages = 58–59 }}</ref>
|-
| Ice Cream || Smaller ice crystals <ref>{{cite journal | last1 = Sutton | first1 = R.L. | last2 = Wilcox | first2 = J. | year = 1998 | title = Recrystallization in ice cream as affected by stabilizers | journal = Journal of Food Science | volume = 63 | pages = 104–107 | doi=10.1111/j.1365-2621.1998.tb15686.x}}</ref>
|-
| Fried Products|| Oil uptake reduction <ref>{{cite journal | last1 = Sakhale | first1 = B.K. Badgujar J.B. | last2 = Pawar | first2 = V.D. | last3 = Sananse | first3 = S.L. | year = 2011 | title = Effect of hydrocolloids incorporation in casing of Samosa on reduction of oil uptake | journal = Journal of Food Science | volume =  51| issue = 3 | pages =  409–18| doi = 10.1007/s13197-011-0522-x | pmid=24587515 | pmc=3931889}}</ref>
|}
'''Partially hydrolyzed guar gum''' (PHGG) is produced by the partial enzymatic [[hydrolysis]] of guaran, the [[galactomannan]] of the endosperm of guar seeds ([[guar gum]]). It is a neutral [[polysaccharide]] consisting of a [[mannose]] backbone chain with single [[galactose]] side units occurring on almost two out of every three mannose units. The average [[molecular weight]] is about 25,000 [[Dalton (unit)|daltons]]. This gives a PHGG that still assays and functions as a soluble dietary fiber.
PHGG as sold commercially is completely soluble, acid and heat stable, unaffected by ions, and will not gel at high concentrations. Commercial PHGG is approximately 75% dietary fiber and has minimal effect on taste and texture in food and beverage items. PHGG is fully fermentable in the large bowel, with a high rate of volatile fatty acid formation. The pH of the feces is lowered along with an increase in fecal bulk that mainly consists of bacterial cell mass and water. Clinical studies have demonstrated a [[prebiotic (nutrition)|prebiotic]] effect of PHGG. Studies have shown that PHGG can be used to maintain regularity. PHGG is used in foods for particulate suspension, emulsification, anti[[staling]], ice crystal control, and reduced fat baked goods.
[[File:Gawar Phali With Aaloo (Guar Bean With Potatoes).JPG|thumb|250px|Gawar phali with aaloo (guar bean with potatoes) (India)]]
[[File:Guar Chibhad ji bhaaji.jpg|alt=Guar Chibhad ji bhaaji is a popular Thari dish|thumb|333x333px|'''''Guar chibhad ji [[Curry|bhaaji]]''''' is a popular [[Tharparkar|Thari]] dish]]
====Industry====
Derivatives of guar gum that have been further reacted are used in industrial applications, such as the paper and textile industries, ore flotation, the manufacture of explosives and [[hydraulic fracturing]] (fracking) of oil and gas formations.<ref name=NYT71612/><ref name=NYTimes>{{cite web |title=In Tiny Bean, India's Dirt-Poor Farmers Strike Gas-Drilling Gold (Published 2012) |website=[[The New York Times]] |archive-url=https://web.archive.org/web/20190107072503/https://www.nytimes.com/2012/07/17/world/asia/fracking-in-us-lifts-guar-farmers-in-india.html?smid=go-share |archive-date=2019-01-07 |url-status=live |url=https://www.nytimes.com/2012/07/17/world/asia/fracking-in-us-lifts-guar-farmers-in-india.html?smid=go-share}}</ref> Guar gum is often crosslinked with boron or chromium ions to make it more stable and heat-resistant. The crosslinking of guar with metal ions results in a gel that does not block the formation and helps efficiently in formation cleaning process. Guar and its derivatives make gel complexes with ions of aluminium, zirconium, titanium, chromium and boron.<ref name="Guar derivatives in Fracturing Fluids">{{cite web |url=http://www.chemtotal.com/guar-gum-derivatives-as-fracturing-fluids.html |title=Guar gum derivatives |publisher=Chemtotal |access-date=3 March 2013 |archive-url=https://web.archive.org/web/20130225174108/http://www.chemtotal.com/guar-gum-derivatives-as-fracturing-fluids.html |archive-date=25 February 2013 |url-status=dead }}</ref>  The borate&ndash;guar reaction is reversible, and depends on the pH (hydrogen ion concentration) of the solution. This reaction is used to give the toy [[Slime (toy)|"slime"]] its consistency. Crosslinking of guar with borate occurs at high pH (approximately 9&ndash;10) of the solution. Guar gum has proven as useful substitute for [[locust bean gum]] (made from [[carob]] seeds).
====Feeds====
Guar meal korma and guar meal churi are widely used as raw material for producing various kinds of cattle feeds, aqua feeds, fish feeds, poultry feeds, dairy feeds, swine feeds, etc.
====Fracking agent====
The use of guar gum in the [[hydraulic fracturing]] (fracking) extraction of oil and shale gas has increased demand substantially. Only 10% of Indian production is used domestically. The remaining 90% is exported for shale gas and oil industries. Consequently, many former cotton or wheat fields are converted into guar fields as production costs are lower. The increase of guar gum prices also has other reasons.<ref>{{cite web |url=http://www.downtoearth.org.in/content/guar-mine |title=Guar mine |website=www.downtoearth.org.in |access-date=November 8, 2012}}</ref>  <!--But since prices are lower the farmers stop harvesting the Guar and returned to cotton & cumin and sesame crops sowing.  <<  ??  -->
==Further reading==
* Pathak, Rakesh: ''Clusterbean: Physiology, Genetics, and Cultivation.'' Springer, Singapore 2015, {{ISBN|978-981-287-905-9}}
* Link for latest Market Price Movement and other latest information on Guar.
https://www.guargumcultivation.com
{{commons}}
==References==
{{Reflist}}
{{Taxonbar|from=Q264770}}
{{Authority control}}
[[Category:Indigofereae]]
[[Category:Edible legumes]]
[[Category:Crops originating from Africa]]
[[Category:Crops originating from Asia]]