Although it is not immediately obvious, upon close examination we see that rye (Secale cereale), like the other temperate cereal crops (wheat, barley and oat), is a grass that has been highly modified by the domestication process. All four crops are native to southeast Europe/southwest Asia, where their wild relatives still grow. Domestication of rye probably occurred in northern Europe over 5,000 years ago when, as a weed of the other cereals, it came to predominate in fields, was harvested, used, and hence became a crop in its own right. It is likely that during the Middle Ages in Europe rye was more important than wheat as a human food. In eastern Europe and Russia rye has traditionally been an important component of local breads, and these areas are now the major producers of rye. Compared to the other temperate cereals, rye is now a relatively minor crop in the rest of the world. Early settlers, particularly those from eastern Europe and Russia, introduced rye into Canada.
The rye plant resembles other grasses in its pattern of growth. Starting from a seed, leaves are produced above ground and then, depending on the environment, a number of tillers (stems) are produced from the base of the plant. Within each of these tillers a single ear is produced, which in the case of fall-seeded rye will usually emerge in May (later in the case of spring-seeded rye). Each ear will contain up to sixty flowers that produce a single grain after pollination. Unlike other cereal crops, rye is cross-pollinated, requiring pollen from another rye plant for fertilization. Because of this, rye is very susceptible to a fungal disease called ergot. If infected, individual grains are replaced by hard black ergot bodies, which contain a number of undesirable and even toxic components. Ergot poisoning was relatively common in Europe in areas of high rye consumption because rye heavily contaminated with ergot bodies was milled and used to make bread. Hallucinogenic compounds are present in the ergot body, and early cases of ergot poisoning were referred to as “St. Anthony’s Fire.”
As a crop, particularly as a prairie crop, rye has a number of positive attributes. Foremost among these, it is the most cold-hardy of the temperate cereals. Unlike fall-seeded wheat (the next cereal in terms of cold-hardiness), rye does not require the same care in terms of management practices in order to survive throughout the winter and regrow in the spring. A fall-seeded crop provides cover for the ground from late fall to early spring (reducing erosion), and allows the crop to take full advantage of spring moisture and escape disease. In addition, rye tends to be resistant to diseases other than ergot and to be drought-tolerant. As such, rye would appear to be the ideal grain crop for the prairies.
Rye grain is used for animal feed, milled to make bread, or used to make rye whiskey. Compared to wheat bread, rye bread is dark in colour and does not rise as much because of its lower level of gluten proteins. However, rye has high levels of soluble fibre, which is now recognized as a valuable component of the human diet; the same high levels of soluble fibre limit the value of rye as an animal feed: if used in an animal ration, the level of rye is usually limited to approximately 25% in order to avoid feeding problems. The inclusion in the ration of enzymes that break down the soluble fibre has been shown to help alleviate this problem. Recent research has also shown that the level of soluble fibre is under genetic control, and could be either increased or decreased through plant breeding.
A significant increase in the demand for rye (through increased use as an animal feed, increased human consumption, or use as a fuel stock for ethanol production) could possibly be stimulated by either appropriate breeding work or through the promotion of the beneficial effects of rye in the human diet. Until this occurs, rye is likely to remain a minor crop on the prairies. Despite its desirable attributes, with little incentive to carry out research because of the low demand, rye appears likely to remain a “Cinderella” crop of Canada and the prairies for the foreseeable future, compared to wheat, barley and oat.