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Common wheat

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Common wheat, scientifically known as *Triticum aestivum*, is a vital cultivated species. It is frequently called bread wheat due to its widespread use. This plant is the most widely planted crop by land area. As of 2009, it held that title among all crops. It is also the cereal with the highest monetary yield. This means it generates more economic value than other grains.

A field of wheat
A field of wheat

The biology of bread wheat is quite complex. It is an allohexaploid organism. This term means it contains six sets of chromosomes. These chromosomes come from different parent species. Four sets of these chromosomes originated from emmer wheat, or *Triticum turgidum*. The remaining two sets came from a wild diploid goatgrass called *Aegilops tauschii*.

This genetic history provides specific advantages for the plant. Emmer wheat itself was formed through an earlier event. This was a tetraploidy between two different diploids. Those parents were wild einkorn and *Aegilops speltoides*. The contribution from the wild goatgrass is especially important. It gives bread wheat greater cold hardiness. Because of this, it can grow in temperate regions worldwide.

Triticum aestivum subsp. vavilovii MHNT.BOT.2015.34.15
Triticum aestivum subsp. vavilovii MHNT.BOT.2015.34.15

Humans have shaped the history of this wheat for millennia. It was first domesticated in West Asia during the early Holocene. It eventually spread to North Africa, Europe, and East Asia. Archaeologists have found naked wheats in Roman burial sites. These sites date from 100 BCE to 300 CE. In the 16th century, Spanish missions brought wheat to North America. By the 1870s, the colonization of the prairies made North America a major exporter.

A field of wheat
A field of wheat

Global events have also shifted wheat production. During World War I, grain exports from Russia stopped. This caused grain production in Kansas to double. Today, bread wheat is well adapted to modern industrial baking. It has displaced many other species once used for bread. These include various types of barley and rye. This shift is particularly noticeable in Europe.

Modern plant breeding has significantly changed the plant's structure. In the 1960s, Norman Borlaug introduced specific dwarfing genes. He sourced these from Norin 10 cultivars grown in Japan. These are known as *RHt* genes. They work by reducing a plant's sensitivity to gibberellic acid. This is a hormone that normally lengthens plant cells. The resulting short stems are very important for farmers.

Short stems prevent a problem called lodging. Lodging occurs when stems collapse under their own weight. This happens if high levels of chemical fertilizers are used. Without these genes, the stems would grow too tall and fall. Short stems also ensure that plant heights are even. This uniformity is necessary for modern harvesting techniques.

usdacompactum
usdacompactum

There are also closely related compact wheats. These include club wheat, or *Triticum compactum*, and a type found in India. These varieties have a much more compact ear. This is caused by shorter rachis segments. These segments cause the spikelets to pack closer together. Many scientists classify these compact wheats as subspecies. For example, they may be called *Triticum aestivum* subsp. *compactum*.

usdacompactum
usdacompactum
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File:Triticum aestivum subsp. aestivum MHNT.BOT.2015.2.31.jpg
Triticum aestivum subsp. aestivum...
File:Triticum aestivum subsp. vavilovii MHNT.BOT.2015.34.15.jpg
Triticum aestivum subsp. vavilovii...
File:A field of wheat.JPG
A field of wheat.JPG
File:usdacompactum.jpg
usdacompactum.jpg
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