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Triticale is a product of a century of dreams and forty years of
active pursuit of the all-but- impossible.
B. S. DODGE
It Started in Eden
TRITICALE'S BEGINNINGS
In fields where wheat and rye grow in proximity, cross-pollination sometimes-although rarely-occurs. The two plants were first deliberately crossed by Alexander Stephen Wilson. In 1876, in his greenhouse in Scotland, this amateur botanist took pollen from rye plants and used it to fertilize wheat flowers. The hybrid plants he grew from the resulting seeds were exciting to biologists, but were uninteresting to farmers because they could not reproduce themselves. It is now known that wheat and rye imparted their chromosomes to those seeds, but that these incompatible chromosomes could not pair up. Thus, although the hybrid produced egg and pollen cells, it remained sterile.
The first indication that this line of investigation might not be a dead end came in 1891 when a German botanist, Wilhelm Rimpau, succeeded in finding a natural wheat/rye hybrid that was partially fertile. Several decades later, in the 1920s and 1930s, Soviet and Swedish researchers attempted to develop this and similar specimens into crops. 1918. To prevent cross-pollination, the wheat plots had been separated from each other by rows of rye plants. In one plot, as much as 20 percent of the grains on the wheat plants were hybrids. This work, by G. K. Meister, was suddenly stopped in the 1930s when he "disappeared," charged with not fulfilling his overly optimistic projections for the new hybrids. Elsewhere, however, the fact that rye pollen could fertilize wheat flowers remained an academic curiosity.
The next fundamental advance came in 1937 when botanists learned that colchicine (a natural chemical extracted from the autumn crocus plant) can "double" the chromosomes in newly forming cells. Pernice, but its implications lay unappreciated for almost SO years. Information from O.J. Eigsti. This opened new vistas: in the cells of the man-made, sterile, hybrid seedlings, chromosomes of both wheat and rye could be artificially doubled into pairs so that the meiotic cells could proceed with normal reduction division. From then on, making triticale fertile no longer depended on Rimpau's seeds or natural chance.
By 1938, Swedish plant geneticist Arne Muntzing applied the colchicine treatment to his own wheat/rye hybrids and found that it transformed them into plants that produced viable seeds.
Neither a wheat nor a rye, this was a new plant. Its common name had been coined from Triticum and Secale, the scientific names for the respective genera of wheat and rye. Seysenegg, one of the rediscoverers of Mendel's laws of genetics and the person who "created" naked-seed pumpkin. It varies in appearance depending on the varieties of wheat and rye used to make it. Generally, however, it looks like wheat; from a distance, triticale fields resemble wheat fields. Only close inspection shows that most of the plants have a covering of soft velvety hairs just below the seed head ("hairy neck"); long, droopy spikes; and long beards (awns)-a characteristic of rye but of few wheats.
The first triticales were made using bread wheats. Pissarev. The results are called "octoploids" because they have eight sets of chromosomes: bread wheat's six combined with rye's two (chapter 5). A different type of triticale was created in 1948 when Joseph G. O'Mara crossed a durum wheat with rye.(5) This produced "hexaploid" triticales that have six sets of chromosomes: durum wheat's four combined with rye's two. At present, these triticales appear to hold more promise than the octoploids, and they are the main subject of this report.
MIDDLE PERIOD
The current interest in triticale had its origins in Canada. In 1954, L. H. Shebeski and B. C. Jenkins of the University of Manitoba gathered triticale specimens from researchers around the world. Their goal was to use triticale as a bridge for transferring rye's natural resistance to leaf diseases into Canada's durum-wheat crop.
During this period of the 1950s and 1960s, a few European researchers were also exploring triticales. In Spain, Enrique Sanchez-Monge developed a variety (Cachirulo) that was released for production in 1969. In Hungary, Arpad Kiss developed triticales so successfully that in 1969 Hungarian farmers planted 40,000 hectares of them, mainly for animal feed.
In the mid 1960s, researchers were starting to feel good about the crop and its potential, and the University of Manitoba and CIMMYT established a joint program to develop triticales for use in developing countries. Rockefeller Foundation. CIMMYT was formed out of this organization in 1966. In Mexico, CIMMYT researchers began testing the Canadian lines. In the research plots where the famous Green Revolution wheats had been developed, the results were disappointing, At Ciudad Obregon and Toluca, the triticales-some of which in Canada occasionally equaled the best wheat yields-failed to produce more than half as much grain as the best Mexican wheats. Magnificent-looking plants-some surpassed wheat in total green matter-their grain yields were depressed by late maturity, diseases, lodging (the tendency to fall over), seed shriveling, and the failure of many flowers to produce seed because the hybrid sterility had not been fully overcome.
In an effort to overcome these limitations, many of those early triticales were crossbred with each other as well as with bread wheats. This produced promising new types that began to attract favorable attention in several parts of the world. Indeed, the crop's performance appeared so promising that it soon stimulated much press attention and enthusiastic promotion.
Those early triticales were exceptionally nutritious: their grains contained far more protein and lysine (an essential amino acid vital to human health) than wheat. The time was one in which famine and a "global protein gap" were major world concerns, and the new crop seemed to offer a miraculous solution. One researcher predicted that by about 1990, "triticale will have begun to compete seriously with the bread wheats as one of the world's most important food crops." This might well have happened, but the first commercial triticales were primitive and in practice proved to have many agronomic deficiencies, including:
Low grain yields. They averaged only about half the yield of the wheats grown beside them for comparison.
Poor seed set. Many florets failed to produce seeds, so that fields that looked extremely productive often yielded little grain.
Shriveled grain. Instead of the smooth, plump grains typical of wheat, they had wrinkled, lusterless seeds with deep creases.
Poor adaptation. The same seeds planted in various locations under different climatic conditions proved notably different in agronomic performance.
Excessive height. The plants were tall and weak; storms easily knocked them down.
Premature sprouting. In humid climates many grains often sprouted while still on the mother plant.
Low germination. The shrunken, malformed seed germinated poorly when planted.
Lack of tillering. The plants seldom produced more than one seedbearing shoot.
Disease susceptibility. The resistance to stripe rust-a disease widespread in many cool, moist, wheat-growing regions-was low.
Late maturity. Because they had been developed in Canada where summer days are long, they performed badly when grown at tropical latitudes where days are short. When planted in the fall, they took so long to flower that the stress of early summer heat caused their grains to fill out poorly. Planted in the spring or summer, they sometimes could not mature their grain before fall frosts killed the plants- especially at high elevation sites. Moreover, daylength sensitivity made it difficult to grow more than one crop in a year.
Low baking quality. Weak gluten, often made worse by premature sprouting of the grain, prevented dough from rising into the light, fluffy breads that most consumers prefer.
To most observers, this massive combination of difficulties seemed a barrier that could never be breached. The field performance was unacceptable to farmers; the grain's appearance was unacceptable to grain merchants, the low flour yield was unacceptable to millers,(8) and the poor baking properties were unacceptable to bakers. It is understandable, therefore, that almost everyone concluded that triticale was a "flash-in-the-pan," unworthy of any further consideration. In the mid-1970s, a backlash arose as rapidly as the enthusiasm of a few years earlier. Disenchanted farmers and agricultural companies quickly discarded the new cereal. Most universities and other research institutions dropped all triticale work from their roster of research. The crop that had once had so much promise now seemed dead.
MODERN HISTORY
Despite disappointment in the plant's performance, a few researchers refused to despair. For example, in Mexico a handful of CIMMYT wheat scientists maintained the viable triticale research program. Their goal was to eliminate the plant's undesirable traits and to make it into a food crop for poor people in poor countries.
A breakthrough' which had previously occurred in one of CIMMYT's nurseries, proved to be crucial. In 1967, a woebegone triticale plant was accidentally fertilized by pollen blown in from nearby plots of dwarf bread wheats. After a few generations of selection it resulted in a new breeding line called Armadillo. This new triticale had better fertility (seed set); also, its yield was high, it was insensitive to daylength, it was short and stiff-strawed, it matured early, and its grain was only slightly shriveled. Thus, in one fell swoop, Armadillo helped resolve many of triticale's agronomic problems.
Later, it was discovered that these traits were stable and heritable, and that Armadillo could be backcrossed readily with both wheats and ryes. As a result, this accident of nature rejuvenated prospects for the crop. By 1970 practically every triticale at CIMMYT included Armadillo in its pedigree, and around the world the few remaining triticale breeders incorporated Armadillo materials into their own strains with renewed hope.
Encouraged by this breakthrough, two Canadian organisations funded a 5-year program at CIMMYT and the University of Manitoba to develop triticales for use in Third World regions. The International Development Research Centre and the Canadian International Development Agency. As a result, CIMMYT and Canadian researchers set out to produce high-yielding lines with semidwarf habit and straw stiff enough to withstand windstorms and to accept high levels of fertilization without lodging.
To ensure that future lines would have built-in adaptability, the international collaborators transferred genes for daylength insensitivity from Mexican bread wheats into their triticales. Moreover, they shuttled the seeds of successive generations from a winter crop at Ciudad Obregon (near sea level, fertile environment, latitude 27°N) to a summer crop at Toluca (high elevation, less fertile, latitude 19°N) and even to Manitoba, Canada (latitude 50°N). Only those lines able to thrive at every site were retained. All were based on the ''miraculous" Armadillo, but this back-and-forth shuttling created breeding pressures that enhanced the subsequent lines' genetic variability, particularly their adaptability to differing soil types, soil fertilities, temperature regimes, photoperiods, rainfalls, and diseases.
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THE BREAKTHROUGH I must tell you that the largest and most important step toward making the breakthrough in triticale improvement was executed by capricious mother nature herself, one early March morning in 1967 in Ciudad Obregon, Sonora, while scientific man was still in bed. One promiscuous, venturesome stray wheat pollen grain with a potent and valuable "genetic load" from thee nearby wheat breeding plots floated across the road under cover of darkness and fertilized a sad but permissive tall, sterile, degenerate triticale plant. A year later(two generations), scientific men identified several unusually promising plants in a segregating population. The genetic makeup of those plants clearly indicated the value of the illicit stray wheat pollen grain. Its triticale progeny indicated that in the act of fertilization it had created dwarfs, introduced partial photoperiodic insensitivity, and completely overcome the sterility barrier, which had inhibited progress in triticale improvement for decades. NORMAN BORLAUG, 1969 |
Along with this selection for field performance, CIMMYT's food quality laboratory selected lines that also performed well in foodstuffs, such as raised breads.
In less than a decade, the resultant gene pool contained many triticales that would grow well under a wide array of different environments. There were also lines with good handling qualities, hard and soft seeds, and improved gluten and breadmaking qualities.
Enthusiasm began to rise once again. The plant had been transformed, and by the end of the 1970s triticales were being tested in 400 locations in 83 countries. The once maligned crop was coming back for a second chance.
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