Khorasan wheat

Khorasan wheat or Oriental wheat (Triticum turgidum ssp. turanicum also called Triticum turanicum) is a tetraploid wheat species. The grain is twice the size of modern-day wheat, and has a rich, nutty flavor.

Taxonomy
Original botanical identifications were uncertain. The variety is a form of Triticum turgidum subsp. turanicum (also known as Triticum turanicum), usually called Khorasan wheat. Identifications sometimes seen as T. polonicum are incorrect as the variety, although long-grained, lacks the long glumes of this species. Recent genetic evidence from DNA fingerprinting suggests that the variety is perhaps derived from a natural hybrid between T. durum and T. polonicum, which would explain past difficulties in arriving at a certain classification.

Life form
As an annual, self-fertilized grass that is cultivated for its grains, Khorasan wheat looks very similar to common wheat. However, its grains are twice the size of modern wheat kernel, with a thousand-kernel weight of up to 60 g. They contain more proteins, lipids, amino acids, vitamins and minerals than modern wheat. The grain has an amber colour and a high vitreousness.

Yield
The actual average yield of Khorasan wheat is 1.1–1.3 t/ha. In drier years, Khorasan wheat can sometimes yield even more than durum wheat. However, in normal or wet years, it yields approximately 1/3 less than the durum wheat.

Distribution
With only 16000 acre cultivated worldwide, Khorasan wheat does not play an important role in the world food system. By capturing this niche market, Khorasan wheat counterbalances its weak agronomic traits.

Product use
Khorasan wheat is used similarly as modern wheat. Its grains can be consumed whole, or milled into flour. It can be found in breads, bread mixes, breakfast cereals, cookies, waffles, pancakes, bulgur, baked goods, pastas, drinks, beer, and snacks.

Apart from its nutritional qualities, Khorasan wheat is recognized for its smooth texture and nutty, buttery flavor.

Nutrients
In a 100 g reference serving, Khorasan wheat provides 337 kcal of food energy and is a rich source (more than 19% of the Daily Value, DV) of numerous essential nutrients, including protein (29% DV), dietary fiber (46% DV), several B vitamins and dietary minerals, especially manganese (136% DV) (table). Khorasan wheat is 11% water, 70% carbohydrates, 2% fat and 15% protein (table).

Composition
Khorasan wheat has high protein content which improves its vitreousness which indicates a high milling yield.

Gluten
As khorasan wheat contains gluten, it is unsuitable for people with gluten-related disorders, such as celiac disease, non-celiac gluten sensitivity and wheat allergy sufferers, among others.

Requirements for climate and soil
A temperate continental climate with cold nights in the early spring (see vernalisation), low to moderate precipitation rates (500–1,000 mm per year), and a sunny warm summer for optimal ripening are therefore the typical preferred climatic conditions of Khorasan wheat. These conditions are very similar to those of durum wheat, which originates in the same region. But, because breeding efforts for Khorasan wheat have been very sparse (see chapter below), its adaptation to other climatic conditions is still limited.

Khorasan wheat is especially known for its drought tolerance, which is even better than that of durum wheat. Too much precipitation, especially in the end of the season, usually leads to dramatic disease problems (see section below).

Soils typically used for Khorasan wheat are the same as for durum wheat: deep friable black clays with a certain water storing capacity, also known as vertisols.

Cultivation
The cultivation practices are quite similar to other wheat species, especially durum. As most of the Khorasan wheat is organically produced, the nutrient supply (especially nitrogen) should be granted by using an appropriate crop rotation, such as previous pasture legumes. The nutritional content of Khorasan wheat is the most important characteristic of this crop and the reason why it is cultivated. Therefore, the nutrition supply is one of the critical aspects of this production.

Harvest in general follows the same procedure as in the other wheat species. As soon as the grains are mature, a combine harvester threshes the Khorasan wheat. But contrary to common wheat, the seeds of Khorasan wheat are very brittle and crack in half very easily, which leads to a necessarily more gentle harvest and post-harvest treatment.

Diseases
The range of diseases in Khorasan wheat is more or less the same as in all other wheat species. Main diseases are typically caused by fungi, such as the Fusarium head blight or the "black tip". Khorasan wheat has been found very susceptible to Fusarium head blight.

Because of the high susceptibility to fungi, crop rotation is quite important, especially under organic production conditions. The rotation requirements resemble more or less those of durum wheat. Depending on the specific production setting, Khorasan production after maize or other cereals should be avoided. Typical robust rotations would contain some of the following crops: canola, sunflower, pulses, sorghum and pasture legumes.

Aspects of breeding
The traditional aim of plant breeding is to improve the agronomic or nutritional qualities of a crop. Typical goals are improved yield, reduced susceptibility to diseases and pests, homogeneous maturation (to optimize harvest) and increased tolerance to environmental stresses, i.e., drought, acid soil, high or cold temperature, etc. Most of the known wheat species today are polyploid. Whereas common bread wheat is hexaploid, Khorasan wheat is tetraploid. To do further breeding with this tetraploid Khorasan wheat, the genetic pool to use is a little bit limited to the tetraploid subspecies of triticum turgidum such as durum (subsp. durum), Polish (subsp. polonicum), Persian (subsp. carthlicum), Emmer (subsp. dicoccum) and Poulard (subsp. turgidum) wheat. Especially to develop resistances against common fungi (e.g., Fusarium head blight), this genomic pool is interesting. Problematic in this case, is the economic unimportance of most of the tetraploid subspecies of wheat (except durum), which limits the investment to do intensive breeding, especially compared to the highly important common bread wheat.