ORIGIN OF WHEAT AND ITS INTRODUCTION IN NEPAL

INTRODUCTION

Scientific Classification

Kingdom: Plantae

(unranked): Angiosperms

(unranked): Monocots

(unranked):Commelinids

Order: Poales

Family: Poaceae

Subfamily: Pooideae

Tribe: Triticeae

Genus: Triticum

Botanical Name: Triticum sp.

Common Name: Wheat, gehun

Wheat is etymologically the ‘white’ grain. The word comes from prehistoric Germanic khvaitjaz (German weizen, Dutch weit, Swedish hvete, and Danish hvede), which was derived from a variant of the base khwīt, source of English white. It alludes to the ‘white’ flour produced by grinding the grain. Wheat   (Triticum spp.) is a grass, originally from the Fertile Crescent region of the Near East, but now cultivated worldwide (Belderok et al., 2000). There are many kinds of wheat in the world today. The two most common are common wheat, Triticum aestivum, also known as bread wheat and accounting for some 95% of all the consumed wheat in the world today; and durum wheat T. turgidum ssp. durum, which is that used in pasta and semolina products. Different species of wheat are T. aestivum, T. aethiopicum, T. araraticum , T. boeoticum, T. carthlicum, T. compactum, T. dicoccoides,  T. dicoccum, T. durum, T. ispahanicum, T. karamyschevii, T. macha, T. militinae, T. monococcum,  T. polonicum,  T. spelta, T. sphaerococcum, T. timopheevii, T. turanicum, T. turgidum, T. urartu, T. vavilovii and T. zhukovskyi

Importance of wheat

Wheat is the most important food plant for more than one third of the world’s population. It is one of the first cereals known to have been domesticated and is also probably the oldest crop known to human civilization. Millions of people throughout the world depend on wheat.  Long before the beginning of agriculture, people gathered wild wheat for food. It is a miracle cereal because of its nutritious value, storage capacity and processing importance. Wheat was a key factor enabling the emergence of city-based societies at the start of civilization because it was one of the first crops that could be easily cultivated on a large scale, and had the additional advantage of yielding a harvest that provides long-term storage of food. Wheat is a factor in contributing to city-states in the Fertile Crescent including the Babylonian and Assyrian empires. Its grain is a staple food used to make flour for leavened, flat and steamed breads, biscuits, cookies, cakes, breakfast cereal, pasta, noodles, couscous (Cauvain et al., 2003) and for fermentation to make beer (Palmer, 2001), other alcoholic beverages (Neill, 2002) or biofuel. It is planted to a limited extent as a forage crop for livestock, and its straw can be used as a construction material for roofing thatch. (Smith, 1995 and Bridgwater et al., 1966) The whole grain can be milled to leave just the endosperm for white flour. The products of this are bran and germ. The whole grain is a concentrated source of vitamins, minerals, and protein, while the refined grain is mostly starch. Wheat is grown on more land area worldwide than any other crop and is a close third to rice and corn in total world production. It is well adapted to harsh environments and is mostly grown on windswept areas that are too dry and too cold for the more tropically inclined rice and corn, which do best at intermediate temperature levels.

History and Origin

 It is believed that agriculture originated in the Middle East when wheat was first cultivated in ancient times. Wheat is believed to have originated in south­western Asia. Some of the earliest remains of the crop have been found in Syria, Jordan, and Turkey. Primitive relatives of present day wheat have been discovered in some of the oldest excavations of the world in eastern Iraq, which date back 9,000 years. Other archeological findings show that bread wheat was grown in the Nile Valley about 5,000 B.C. as well as in India, China, and even England at about the same time (Gibson and Banson, 2002). There are several archaeological evidences to show the presence of carbonized wheat grains at the Neolithic sites in Jarmo in Northern Iraq, and in Central and North Eastern Europe dating back to the period 6,750 B.C. to 7,500 B.C. The archaeological record suggests that this first occurred in the regions known as the Fertile Crescent, and the Nile Delta. These include south eastern parts of Turkey, Lebanon, Syria, the Levant, Israel, and Egypt. Recent findings narrow the first domestication of wheat to a small region of south eastern Turkey and Einkorn wheat at Nevali   Çori 40 miles (64 km) northwest of Gobekli Tepe in Turkey has been dated to 9,000 B.C (Lev-yadun et al., 2000). The oldest known wheat is the diploid wheat. The carbonized remains of wild einkorn and imprints of grains in baked clay have been discovered at the Neolithic site of Jarmo in Northern Iraq, dating as far back as 6,750 B.C. Wild einkorn has also been reported from several other archeological sites such as at Ali Kosh in South Western Iran, dated between 6,750 and 7,500 B.C. at Hailar, West Central Anatolia, dated at about 7,000 B.C., and Tell Mureybit (North Syria) from about 8,000 B.C. (Van Zeist and Casparie, 1968). Similar findings have also been made in deposits of the Neolithic lake dwellers and in many other sites in Central and North Eastern Europe. Apparently, there has been no appreciable change in these types of wheat over the centuries. There are, however, no records of its prehistoric occurrence in India, China and Africa. Archaeological evidence for domesticated wheat has been found at several sites in the Fertile Crescent, sites such as Abu Hureyra (Syria), Jericho (West Bank), and Cayönü (Turkey). The oldest evidence for both einkorn and emmer wheats found to date was at Abu Hureyra, in occupation layers dated to 9600 years ago; some scholars (Colledge and Conolly 2010) have argued that the evidence does not show cultivation at this time (Splund et al.,2010 and Doebley et al.,2006).

  

However evidence for the exploitation of wild barley has been dated to 23,000 B.C. and some say this is also true of pre-domesticated wheat (Piperno et al., 2004). These and other observations suggest that wheat spread rapidly and widely throughout Asia and Europe after its domestication in the Middle East (Rao and Pandey, 2006). The origins of modern wheat, according to genetics, are found in the Karacadag mountain region of southeastern Turkey. There, some 10,000 years ago or so, two types of wheat were domesticated: einkorn or Triticum monococcum and emmer (reported both as T. araraticum and T. turgidum ssp. dicoccoides). Spelt, T. spelta, and T. timopheevii were ancient forms of wheat developed by the late Neolithic, neither of which have much of a market today. Wheat was first grown in the United States in 1602 on an island off the Massachusetts coast. A global wheat failure would be a disaster that few nations could survive for even one year (Gibson and Banson, 2002).  Cultivation of wheat began to spread beyond the Fertile Crescent after about 8000 BCE. Jared Diamond traces the spread of cultivated emmer wheat starting in the Fertile Crescent about 8500 BCE, reaching Greece, Cyprus and India by 6500 BCE, Egypt shortly after 6000 BCE, and Germany and Spain by 5000 BC (Diamond, 1997). "The early Egyptians were developers of bread and the use of the oven and developed baking into one of the first large-scale food production industries." ^[18] By 3000 BC, wheat had reached England, and Scandinavia. A millennium later it reached China. Wheat spread throughout Europe and in England; thatch was used for roofing in the Bronze Age, and was in common use until the late 19th century.

Vavilov classified different types of wheats into 14 species. Other wheat taxonomists recognize either more or fewer species. All the types of wheats are classified under the genus Triticum. Triticum is the member of family Poaceae (earlier Gramineae), sub family Poideae and the tribe Triticeae. The different species of wheat can be grouped into three categories on the basis of their chromosome number which have been given in the table:

 

Species	Botanical Name	Common Name	Chromosome
			No	Genomes
Diploid	T. aegilopoides	Wild Einkorn	7	A
	T. monococcum	Einkorn	7	A
Tetraploid	T. dicoccoides	Wild Emmer	14	AB
	T. dicoccum	Emmer	14	AB
	T. durum	Macaroni wheat	14	AB
	T. persicum	Persian wheat	14	AB
	T. turgidum	Rivet wheat	14	AB
	T. polonicum	Polish wheat	14	AB
Hexaploid	T. aestivum	Bread wheat	21	ABD
	T.sphaerococcum	Short wheat	21	ABD
	T. compactum	Club wheat	21	ABD
	T. spelta	Spelt wheat	21	ABD
	T. macha	Macha wheat	21	ABD

              Table 1. Different Species of wheat

                                     Source: Mangelsdorf (1953)

There are diploid wheats having 2n=14 chromosomes, tetraploid wheat with 2n=28 chromosomes and hexaploid wheat with 2n=42 chromosomes. Detailed cytological analysis of these wheats also revealed that there are three different genomes. The diploid wheat has been recognized, having the AA genome. The tetraploids and hexaploids are not autoploids (i.e. possessing similar genome to the diploid). They are alloploids with dissimilar genomes. The tetraploids wheat has the AABB genome while the hexaploid wheat has the AABBDD genome.

According to Heun et al., (1997), the emergence of agriculture in the near east also involved the domestication of einkorn wheat. Phylogenetic analysis that was based on the allelic frequency at 288 amplified fragments length polymorphism molecular markers loci indicates that a wild sp. of Triticum monococcum var. boeoticum lines from the Karacadag Mountain (Southern Turkey) is the likely progenitor of einkorn varieties. Evidence from archaeological excavations of early agricultural settlements nearby supports the conclusion that domestication of einkorn wheat began near the Karacadag Mountain. Although the so called bread wheats are common to most of us, there are many uncertainly related species that make up the genus Triticum. This likely was due to a number of natural crossings with wild species during its early evolvement. Some of the species closely related to our common wheats would be einkorn, emmer, durum, and spelt.

The tetraploid wheat grows naturally in the Middle East, and appears to have originated as a result of natural crossing between Triticum monococcum (AA) and Triticum speltoides (Syn. Aegilops speltoides) (BB). Closely related to wild emmer is the true cultivated emmer that has arisen from T. dicoccoides by mutation, domestication and selection. Both of the emmers have covered or hulled grains. Emmer was once the most widely grown of all the types of wheats. Wild emmer and cultivated emmer have been found in the Neolithic sites of the Mureybit and Ali Kosh respectively. Ancient caves in Europe and mummies in Egypt have also yielded their grains.

The hexaploid wheats are the most recently evolved one and the most useful to men today. All the hexaploid wheats are cultivated, none having been reported to grow wild. All of them are products of hybridization of tetraploid wheat (AABB) with a wild (14-chromosomes) relative (DD), almost certainly a grass Triticum tauschii, earlier known as Aegilops squarrosa, followed by doubling of the chromosomes to give rise to a plant with six set of seven chromosomes (AABBDD). T. tauschii is a weed growing in wheat fields, from the Balkans to Afghanistan.

History of emmer wheat

Archaeological analysis of wild emmer indicates that it was first cultivated in the southern Levant with finds at Iraq ed-Dubb in northern Jordan dating back as far as 9600 BC. (Feldman et al., 2007). Genetic analysis of wild einkorn wheat suggests that it was first grown in the Karacadag Mountains in southeastern Turkey. Dated archeological remains of einkorn wheat in settlement sites near this region, including those at Abu Hureyra in Syria, suggests the domestication of einkorn near the Karacadag mountain range. With the anomalous exception of two grains from Iraq ed-Dubb, the earliest carbon-14 date for einkorn wheat remains at Abu Hureyra is 7800 to 7500 years BC (Huen et al., 1997). Remains of harvested emmer from several sites near the Karacadag Range have been dated to between 8600 (at Cayonu) and 8400 BC (Abu Hureyra), that is, in the Neolithic period. With the exception of Iraq ed-Dubb, the earliest carbon-14 dated remains of domesticated emmer wheat were found in the earliest levels of Tell Aswad, in the Damascus basin, near Mount Hermon in Syria. These remains were dated by Willem van Zeist and his assistant Johanna Bakker-Heeres to 8800 BC. They also concluded that the settlers of Tell Aswad did not develop this form of emmer themselves, but brought the domesticated grains with them from an as yet unidentified location elsewhere (Ozkan et al., 2002).

Characteristics of wild wheat

Cultivation and repeated harvesting and sowing of the grains of wild grasses led to the creation of domestic strains, as mutant forms ('sports') of wheat were preferentially chosen by farmers. In domesticated wheat, grains are larger, and the seeds (spikelets) remain attached to the ear by a toughened rachis during harvesting. In wild strains, a more fragile rachis allows the ear to easily shatter and disperse the spikelets (Tanno et al., 2006).  Selection for these traits by farmers might not have been deliberately intended, but simply have occurred because these traits made gathering the seeds easier; nevertheless such 'incidental' selection was an important part of crop domestication. As the traits that improve wheat as a food source also involve the loss of the plant's natural seed dispersal mechanisms, highly domesticated strains of wheat cannot survive in the wild.

The main differences between the wild forms of wheat and domesticated wheat are that domesticated forms have larger seeds and a non-shattering rachis. When wild wheat is ripe, the rachis-the stem that keeps the wheat shafts together-shatters so that the seeds can disperse themselves. But that naturally useful brittleness doesn't suit humans, who prefer to wait until the wheat is ripe to harvest it, and so, the theory goes anyway, selected wheats with rachis that didn't become brittle at harvest time.

Wheat Genetics

Wheat genetics is more complicated than that of most other domesticated species. Some wheat species are diploid, with two sets of chromosomes, but many are stable polyploids, with four sets of chromosomes (tetraploid) or six (hexaploid) (Hancock, 2004)

• Einkorn wheat (T. monococcum) is diploid (AA, two complements of seven chromosomes, 2n=14) (Belderok et al., 2000)
• Most tetraploid wheats (e.g. emmer and durum wheat) are derived from wild emmer, T. dicoccoides. Wild emmer is itself the result of hybridization between two diploid wild grasses, T. urartu and a wild goatgrass such as Aegilops searsii or Ae. speltoides. The unknown grass has never been identified among now surviving wild grasses, but the closest living relative is Aegilops speltoides. The hybridization that formed wild emmer (AABB) occurred in the wild, long before domestication (Hancock, 2004) and was driven by natural selection.

• Hexaploid wheats evolved in farmers' fields. Either domesticated emmer or durum wheat hybridized with yet another wild diploid grass (Aegilops cylindrica) to make the hexaploid wheats, spelt wheat and bread wheat (Hancock, 2004). These have three sets of paired chromosomes, three times as many as in diploid wheat.

Wild grasses in the genus Triticum and related genera, and grasses such as rye have been a source of many disease-resistance traits for cultivated wheat breeding since the 1930s  (Hoisington et al.,1999). Synthetic hexaploids made by crossing the wild goatgrass wheat ancestor Aegilops tauschii and various durum wheats are now being deployed, and these increase the genetic diversity of cultivated wheats.^[23]

Plant Breeding

F1 hybrid wheat cultivars should not be confused with wheat cultivars deriving from standard plant breeding. Heterosis or hybrid vigor (as in the familiar F1 hybrids of maize) occurs in common (hexaploid) wheat, but it is difficult to produce seed of hybrid cultivars on a commercial scale as is done with maize because wheat flowers are complete and normally self-pollinate (Bajaj, 1990). Hybrid wheat has been a limited commercial success in Europe (particularly France), the United States and South Africa (Basra, 1999).  

Hulled versus freed threshing wheat

The four wild species of wheat, along with the domesticated varieties einkorn (Potts, 1996), emmer (Nevo, 2002) and spelt (Vaughan and Judd, 2003) have hulls. This more primitive morphology (in evolutionary terms) consists of toughened glumes that tightly enclose the grains, and (in domesticated wheats) a semi-brittle rachis that breaks easily on threshing. The result is that when threshed, the wheat ear breaks up into spikelets.  

Naming

There are many botanical classification systems used for wheat species. The name of a wheat species from one information source may not be the name of a wheat species in another.

Within a species, wheat cultivars are further classified by wheat breeders and farmers in terms of:

• growing season, such as winter wheat vs. spring wheat (Bridgwater and Beatrice, 1966) by gluten content, such as hard wheat (high protein content) vs. soft wheat (high starch content), or by grain color (red, white or amber).
• Protein content. Bread wheat protein content ranges from 10% in some soft wheats with high starch contents, to 15% in hard wheats.
• The quality of the wheat protein gluten. This protein can determine the suitability of a wheat to a particular dish. Strong and elastic gluten present in bread wheats enables dough to trap carbon dioxide during leavening, but elastic gluten interferes with the rolling of pasta into thin sheets. The gluten protein in durum wheats used for pasta is strong but not elastic.
• Grain color (red, white or amber). Many wheat varieties are reddish-brown due to phenolic compounds present in the bran layer which are transformed to pigments by browning enzymes. White wheats have a lower content of phenolics and browning enzymes, and are generally less astringent in taste than red wheats. The yellowish color of durum wheat and semolina flour made from it is due to a carotenoid pigment called lutein, which can be oxidized to a colorless form by enzymes present in the grain.

Major cultivated species of wheat

• Common wheat or Bread wheat (T. aestivum) – A hexaploid species that is the most widely cultivated in the world.
• Durum (T. durum) – The only tetraploid form of wheat widely used today, and the second most widely cultivated wheat.
• Einkorn (T. monococcum) – A diploid species with wild and cultivated variants. Domesticated at the same time as emmer wheat, but never reached the same importance.
• Emmer (T. dicoccum) – A tetraploid species, cultivated in ancient times but no longer in widespread use.
• Spelt (T. spelta) – Another hexaploid species cultivated in limited quantities.

Classes used in the United States are

• Durum – Very hard, translucent, light-colored grain used to make semolina flour for pasta and bulghur.
• Hard Red Spring – Hard, brownish, high-protein wheat used for bread and hard baked goods. Bread Flour and high-gluten flours are commonly made from hard red spring wheat. It is primarily traded at the Minneapolis Grain Exchange.
• Hard Red Winter – Hard, brownish, mellow high-protein wheat used for bread, hard baked goods and as an adjunct in other flours to increase protein in pastry flour for pie crusts. Some brands of unbleached all-purpose flours are commonly made from hard red winter wheat alone. It is primarily traded by the Kansas City Board of Trade. One variety is known as "turkey red wheat", and was brought to Kansas by Mennonite immigrants from Russia (Moon, 2009)
• Soft Red Winter – Soft, low-protein wheat used for cakes, pie crusts, biscuits, and muffins. Cake flour, pastry flour, and some self-rising flours with baking powder and salt added, for example, are made from soft red winter wheat. It is primarily traded by the Chicago Board of Trade.
• Hard White – Hard, light-colored, opaque, chalky, medium-protein wheat planted in dry, temperate areas. Used for bread and brewing.
• Soft White – Soft, light-colored, very low protein wheat grown in temperate moist areas. Used for pie crusts and pastry. Pastry flour, for example, is sometimes made from soft white winter wheat.

Red wheats may need bleaching; therefore, white wheats usually command higher prices than red wheats on the commodities market.

 Geographical variation

There are substantial differences in wheat farming, trading, policy, sector growth, and wheat uses in different regions of the world. In the EU and Canada for instance, there is significant addition of wheat to animal feeds, but less so in the USA.

The two biggest wheat producers are China and the EU, followed currently by India, then USA. Developed countries USA, Canada, Australia, the EU and increasingly Argentina are the major exporters with developing countries being the main importers, although both India and China are close to being self-sufficient in wheat. In the rapidly developing countries of Asia, Westernization of diets associated with increasing prosperity is leading to growth in per capita demand for wheat at the expense of the other food staples.

In the past, there has been significant governmental intervention in wheat markets, such as price supports in the USA and farm payments in the EU. In the EU these subsidies have encouraged heavy use of fertilizers inputs with resulting high crop yields. In Australia and Argentina direct government subsidies are much lower (Neill, 2002).

Wheat introduction in Nepal

Three hundred and fifty-five DArT markers were used to evaluate genetic diversity among 705 wheat landrace accessions in the Australian Winter Cereals Collection (AWCC), chosen to represent 5 world regions. Diversity Arrays Technology (DArT ) analysis was capable of distinguishing accessions from different geographic regions, and suggested that accessions originating from Nepal represent a unique gene pool within the collection.(Stodart et. al., 2007).

Mexico, India and Nepal are countries of origin for 26 cultivars. In Nepal four cultivars had been originated and the maximum number of cultivars was originated from Mexico. Four cultivars were released in 1997, which is the year of releasing highest number of cultivars. These cultivars were Achyut, Kanti, Pasang Lhamu and Rohini. Lerma 52, first improved cereal variety to be released in the history of cereal breeding in Nepal (Bland 2001) was released in 1960. (Joshi et al., 2004).

Transmission routes of wheat from its origin to East Asia

Transmission of wheat to east asia through three routes was traced out by the analysis of asian wheat landraces with isozymes and RAPD and it was suggested that asian wheat could be divided into at least three lineages. The first lineage of wheat consisted of population from Turkey to Sichuan (China), suggesting the spread of wheat to south west china through the ancient Myanmar route. Wheat populations introduced to China through route were mostly of red grain type and it was considered that wheat adapted to humid and rather hot condition in southern slope of Himalaya had been selected and introduced to China.Moreover, along this route transmission, T. sphareococcum seems to be arisen as a spontaneous mutant at around 2500 BC, in northeastern part in Indian subcontinent.

REFERENCES

Piperno, Dolores; et al. (2004-06-04). "Processing of wild cereal grains in the Upper Palaeolithic revealed by starch grain analysis". Nature 430 (7000): 670–673. doi:10.1038/nature02734. PMID 15295598. http://www.nature.com/nature/journal/v430/n7000/abs/nature02734.html.

10"Which came first, monumental building projects or farming?". Archaeo News. 2008-12-14. http://www.stonepages.com/news/archives/003061.html. 

18 Direct quotation: Grundas ST : Chapter: Wheat: The Crop, in Encyclopedia of Food Sciences and Nutrition p6130, 2003; Elsevier Science Ltd

23 Synthetic hexaploids

B. J. Stodart , M. C. Mackay  and H. Raman(2007) Assessment of molecular diversity in landraces of bread wheat (Triticum aestivum L.) held in an ex situ collection with Diversity Arrays Technology (DArT™). Australian Journal of Agricultural Research 58(12) 1174–1182        http://dx.doi.org/10.1071/AR07010

Bajaj, Y. P. S. (1990) Wheat. Springer. pp. 161-63. ISBN 3-540-51809-6.

Bal K Joshi1, Ashok Mudwari1, Madan R Bhatta and Guillermo O Ferrara.(2004) Genetic Diversity in Nepalese Wheat Cultivars Based on Agro-Morphological Traits and Coefficients of Parentage. Nepal Agric. Res. J. Vol. 5, 2004.

Basra, Amarjit S. (1999) Heterosis and Hybrid Seed Production in Agronomic Crops. Haworth Press. pp. 81-82. ISBN 1-56022-876-8.

Belderok, Bob & Hans Mesdag & Dingena A. Donner. (2000) Bread-Making Quality of Wheat. Springer. p.3. ISBN 0-7923-6383-3.

Bonjean, AP, Agnus WJ. 2001 The World Wheat Book, A history of Wheat Breeding.

Bridgwater, W. & Beatrice Aldrich. (1966) The Columbia-Viking Desk Encyclopedia. Columbia University. p. 1959.

Cauvain, Stanley P. & Cauvain P. Cauvain. (2003) Bread Making. CRC Press. p. 540. ISBN 1-85573-553-9.

Diamond J (1997) Guns, Germs and Steel, A short history of everybody for the last 13,000 years. Viking UK Random House ISBN 0-09-930278-0

Evans LT, Peacock WJ (eds.) Wheat Science– Today and Tomorrow, Cambridge

 Feldman, Moshe and Kislev, Mordechai E., Israel Journal of Plant Sciences, Volume 55, Number 3 - 4 / 2007, pp. 207 - 221, Domestication of emmer wheat and evolution of free-threshing tetraploid wheat in "A Century of Wheat Research-From Wild Emmer Discovery to Genome Analysis", Published Online: 03 November 2008  

Hancock, James F. (2004) Plant Evolution and the Origin of Crop Species. CABI Publishing. ISBN 0-85199-685-X.

Harlan J. R. (1976). Plant and animal distribution in relation to domestication. J. R. Phil. Trans. R. Soc. London. B. 275:13-25

Harlan JR, (1981) The early history of wheat: earliest traces to the sack of Rome. In:

Heun M., Pregal-Schafer R., Klawan D., Castagan R., Accesbi M., Borghi B., Salomini F. (1997). Site of einkorn wheat domestication identified by DNA fingerprinting. Science. 278: 1312-1314

Heun MR et al (1997) Site of Einkorn Wheat Domestication Identified by DNA Fingerprinting Science 278:1312-4 DOI: 10.1126/science.278.5341.1312

Hoisington, D; Khairallah, M; Reeves, T; Ribaut, JM; Skovmand, B; Taba, S; Warburton, M (1999). "Plant genetic resources: What can they contribute toward increased crop productivity?". Proc Natl Acad Sci USA 96 (11): 5937–43. doi:10.1073/pnas.96.11.5937. PMC 34209. PMID 10339521. http://www.pnas.org/cgi/content/abstract/96/11/5937.

 I. Usha Rao & B. K. Pandey(2006).  Economy Botany :Origin and introduction of crop plants, cereals and pulses. Department of Botany, University of Delhi(Retrived 7 August 2011).

Lavoisier Publishing, Paris, France.

Lev-Yadun, S; Gopher, A; Abbo, S (2000). "The cradle of agriculture". Science 288 (5471): 1602–3. doi:10.1126/science.288.5471.1602. PMID 10858140. 

Mangelsdorf P. C. (1953) Wheat. Sci. Ameri. 189: 50-59

Michael L. Morris^, H. J. Dubin and Thaneswar Pokhrel(1994).The economics of wheat research in developing countries. Agricultural Economics Volume 10, Issue 3, May 1994, Pages 269-282

Moon, David (2008). "In the Russian Steppes: the Introduction of Russian Wheat on the Great Plains of the UNited States". Journal of Global History 3: 203–225.

Neill, Richard. (2002) Booze: The Drinks Bible for the 21st Century. Octopus Publishing Group - Cassell Illustrated. p. 112. ISBN 1-84188-196-1.

Neill, Richard. (2002) Booze: The Drinks Bible for the 21st Century. Octopus Publishing Group - Cassell Illustrated. p. 112. ISBN 1-84188-196-1.

Nevo, Eviatar & A. B. Korol & A. Beiles & T. Fahima. (2002) Evolution of Wild Emmer and Wheat Improvement: Population Genetics, Genetic Resources, and Genome.... Springer. p. 8. ISBN 3-540-41750-8.

Ozkan, H; Brandolini, A; Schäfer-Pregl, R; Salamini, F (October 2002). "AFLP analysis of a collection of tetraploid wheats indicates the origin of emmer and hard wheat domestication in southeast Turkey". Molecular biology and evolution 19 (10): 1797–801. PMID 12270906. http://mbe.oxfordjournals.org/cgi/content/full/19/10/1797.

Palmer, John J. (2001) How to Brew. Defenestrative Pub Co. p. 233. ISBN 0-9710579-0-7.

Potts, D. T. (1996) Mesopotamia Civilization: The Material Foundations Cornell University Press. p. 62. ISBN 0-8014-3339-8.

Smith, Albert E. (1995) Handbook of Weed Management Systems. Marcel Dekker. p. 411. ISBN 0-8247-9547-4.

Tanno, K Willcox; Willcox, G (2006). "How fast was wild wheat domesticated?". Science 311 (5769): 1886. doi:10.1126/science.1124635. PMID 16574859.

University Press, Cambridge, pp 1-19.

Van Zeist W., and Casparie W.A. (1968). Wild Einkorn wheat and barley from tell Mureybit in Northern Syria. Acta. Bot. Neerl. 17(1): 44-53

Vaughan, J. G. & P. A. Judd. (2003) The Oxford Book of Health Foods. Oxford University Press. p. 35. ISBN 0-19-850459-4.

splund L, Hagenblad J, and Leino MW. 2010. Re-evaluating the history of the wheat domestication gene NAM-B1 using historical plant material. Journal of Archaeological Science 37(9):2303-2307.

Doebley, John F., Brandon S. Gaut, and Bruce D. Smith. 2006. The molecular genetics of crop domestication. Cell 127: 1309-1321.

Stodart, B.J. , M. C. Mackay  and H. Raman(2007). Assessment of molecular diversity in landraces of bread wheat (Triticum aestivum L.) held in an ex situ collection with Diversity Arrays Technology (DArT™). Australian Journal of Agricultural Research 58(12) 1174–1182 Available on:  http://dx.doi.org/10.1071/AR07010

Bland, B. (2001). Nepalese wheat pool. In: The world wheat book: A history of wheat breeding (AP Bonjean and WJ Angus, eds). Intercept, TEC and DOC, LAVOISIER, New York. Pp. 817-830.

Joshi B.K., Ashok Mudwari, Madan R Bhatta and Guillermo O Ferrara(2004) Genetic Diversity in Nepalese Wheat Cultivars Based on Agro-Morphological

Traits and Coefficients of Parentage. Nepal Agric. Res. J. Vol. 5, 7-17

Gibson, L. and G. Benson(2002). Origin, History, and Uses of Oat (Avena sativa) and Wheat (Triticum aestivum). Iowa State University, Department of Agronomy. Revised January 2002.