Triticale
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Triticale (x Triticosecale) is an artificial hybrid of wheat (Triticum) and rye (Secale) first bred in laboratories during the late 19th century. The grain was originally bred in Scotland and Sweden. Commercially available triticale is almost always a 2nd generation hybrid, i.e. a cross between two kinds of triticale (primary triticales). As a rule, triticale combines the high yield potential and good grain quality of wheat with the disease and environmental tolerance (including soil conditions) of rye. Only recently has it been developed into a commercially viable crop. Depending on the cultivar, triticale can more or less resemble either of its parents. It is grown mostly for forage or animal feed although some triticale-based foods can be purchased at health food stores or are to be found in some breakfast cereals.
The word ‘triticale’ is a fusion of the latin words triticum (or wheat) and secale (rye). When crossing wheat and rye, wheat is used as the female parent and rye as the male parent (pollen donor). The resulting hybrid is sterile and thus has to be treated with the alkaloid chemical colchicine to make it fertile and thus able to reproduce itself.
The primary producers of triticale are Germany, France, Poland, Australia, China and Belarus. In 2005, according to the Food and Agriculture Organization (FAO), 13.5 million tons were harvested in 28 countries across the world.
The triticale hybrids are all amphidiploid, which means the plant is diploid for two genomes derived from different species, in other words triticale is an allotetraploid. In earlier years most work was done on octoploid triticale. Different ploidy levels have been created and evaluated over time. The tetraploids showed little promise, but hexaploid triticale was successful enough to find commercial application. (Oetler 2005)
The CIMMYT triticale improvement program wanted to improve food production and nutrition in developing countries. According to Villegas (1973) triticale has potential in the production of bread and other food products such as pasta and breakfast cereals. The protein content is higher than that of wheat although the glutenin fraction is less. Assuming increased acceptance, the milling industry will have to adapt to triticale, as milling techniques used for wheat don’t suit triticale. Sell et al. (1962) delivered reports of triticale suitability as a grain feed and it is a better ruminant feed than other cereals due to its high starch digestibility. (Bird et al. 1999) As a feed grain triticale is already well established and of high economic importance. Triticale has received attention as a potential energy crop and research is currently being conducted on the use of the crops biomass in bioethanol production.
Earlier work with wheat-rye crosses was difficult due to low survival of the resulting hybrid embryo and spontaneous chromosome doubling. (Oetler, 2005). These two factors were difficult to predict and control. To improve the viability of the embryo and thus avoid its abortion, in vitro culture techniques were developed. (Laibach, 925) Colchicine was used as a chemical agent to double the chromosomes. (Blakeslee & Avery 1937) After these developments a new era of triticale breeding was introduced. Earlier triticale hybrids had four reproductive disorders namely, meiotic instability, high aneuploid frequency, low fertility and shriveled seed. (Muntzing 1939; Krolow 1966). Cytogenetical studies were encouraged and well funded to overcome these problems.
It is especially difficult to see the expression of rye genes in the background of wheat cytoplasm and the predominant wheat nuclear genome. This makes it difficult to realise the potential of rye in disease resistance and ecological adaptation. One of the ways to relieve this problem was to produce secalotricum in which rye cytoplasm was used instead of that from wheat.
Triticale is essentially a self-fertilizing (naturally inbred) crop. This mode of reproduction results in a more homozygous genome. The crop is however adapted to this form of reproduction from an evolutionary point of view. Cross-fertilization is also possible, but it is not the primary form of reproduction.