Wheats of the World

A selection of species of wheat that are, or were, cultivated in different parts of the world are occasionally grown in the cereal cage. Four of the species are tetraploid wheats, the other six are hexaploid. Most are "free-threshing" but three, notably Vavilovi and Macha Wheats and Spelt retain the hard shell or 'hull' of the early wheat species and make the extraction of the grain a more difficult task.
Tetraploid Wheats (28 chromosomes)
Hexaploid Wheats (42 chromosomes)
2. Persian Wheat
Triticum carthlicum
4. Oriental Wheat
Tricum turanicum
6. Vavilovi Wheat
Triticum vavilovi
8. Macha Wheat
Triticum macha
10. Spelt or Dinkel
Triticum spelta
1. Polish Wheat
Triticum polonicum
3. Rivet or Cone Wheat
Triticum turgidum
5. Indian Shot Wheat
Triticum sphaerococcum
7. Club Wheat
Triticum compactum
9. Bread Wheat
Triticum aestivum

Bread Wheat is now the most widely cultivated wheat in the world, grown in most temperate regions. Over many years, newer varieties have been developed that have a greater yield than many of the older traditionally grown wheat species. This has led to a replacement of the traditional species by bread wheat in some parts of the world, with a subsequent loss of the older types from cultivation. The loss of species diversity may mean that some useful characteristics, such as fungal resistance or lodging resistance, could become unavailable to scientists creating new varieties. Seed banks, such as those held by the John Innes Centre, custodian of the UK's cereal genetic resources, are therefore important for maintaining reserves of these species for possible use in future wheat breeding programs.

In addition to the Triticum species in the above table, another tetraploid wheat, Durum Wheat (Triticum durum) is widely cultivated in areas with mild winters and hot summers. The ears are free-threshing with large, hard-textured grains that produce a coarse textured flour, known as semolina, when milled. After mixing with water to form a stiff dough, it can be extruded into various shapes before being dried to create a wide range of pasta products, including macaroni, spaghetti and lasagne. When cooked, the starch in these products absorbs water and softens but the high gluten content ensures that they retain their original shape without dissolving.

Work by NIAB (National Institute of Agricultural Botany) to increase the genetic diversity of Bread Wheat has used Durum Wheat as the tetraploid source. Replicating the hybridisation that occurred about 8,500 years ago in the Evolution of Bread Wheat, a selection of wild diploid Goat Grasses have been used to create new SHW's (Synthetic Hexaploid Wheats). These have been examined for any improved commercial advantages, such as improved fungal resistance or increased yields, and if they would be suitable for creating new commercial wheat varieties.

The remaining species were more commonly cultivated in the past, although often restricted to limited areas, such as the Vavilovi Wheat of Armenia. A selection of these species that have been grown at the Mill in previous years are included in photographs showing the seed spikes in early July and the ripened plants in August.

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