by G. Varughese, W.H. Pfeiffer, and R. J. Peña

Humans have existed on earth for more than two million years-over 99 percent of this period as huntergatherers. It was only during the last 10,000 years that they learned to domesticate plants and animals. During this period, they played an enormous role in shaping the evolution of cultivated plants. Today's agricultural crops are their creation. Humans cannot survive without them-nor can the crops they have selected and bred survive without their presence.

The past century was a remarkable period in history because of the human ability to manipulate the earth's natural resources to our advantage. Our knowledge of the basic principles governing the evolution of crop species, their relationship to their kins, and inheritance of traits have culminated in an array of improved cultivated crops including the creation of triticale (X Triticosecale Wittmack).

To date, progress made by triticale has been remarkable. The time span from its creation to its commercialization has been less than 100 years, as compared with thousands of years for a species to evolve in nature. In 1979, Arne Müntzing said in his book on triticale: "It can be expected that the new, manmade cereal, triticale, will definitely join the old cereals as food for the rapidly growing human populations and their domestic animals." The first commercial triticale cultivars were released in 1969 and as of today, 25 years later, triticale is grown on more than 2.4 million hectares worldwide. This crop contributes more than 6 million metric tons per year to global cereal production.

Main triticale producers (Area harvested in thousand hectares)

COUNTRY	1986	1991/92
Australia	160	100
Brazil	5	90
Bulgaria	10	100
France	300	162
Germany	30	207
Poland	100	659
Portugal	7	90
South Africa	15	95
(former) USSR	250	500
Spain	30	80
USA	60	180
World	1,076	2,468

Today's successful triticales are the secondary amphiploids of durum wheat and rye. Durum wheat, the donor of the A and B genomes, is known for its high yield potential and adaptation to relatively dry environments. On the other hand, rye, the R genome donor, has lower yield potential but is well adapted to extreme cold, drought, and acidic soils and is grown in almost all geographic ranges. Triticale cultivation around the world during the last 25 years indicates that it possesses the yield potential of wheat and the hardiness of rye. Consequently, triticale is successfully grown in almost all environments where its parental species are grown.

The yield potential of triticale under optimum crop production environments has reached the level of wheat while outperforming wheat in marginal environments. A recent comparison between triticale and wheat indicates that triticale accumulates more nitrogen during heading and physiologic maturity than does wheat. The difference in nitrogen accumulation is maximum under lower levels of N application, indicating that triticales are better crops for soils with low nitrogen fertility. Most studies, to date, would indicate that the initial biologic problems, such as partial sterility, shriveled seed, excessive height, and lateness in establishing triticale as a productive crop, have been resolved. Acceptance of triticale by producers and consumers in different parts of the world would also indicate that triticale is here to stay as a classical example of ingenuity in modifying crops to our needs.

History

The first deliberate hybrid between wheat and rye was reported by A. S. Wilson in Scotland in 1875. However, the first doubled-and hence fertile hybrid between wheat and rye-was produced by W. Rimpau in 1888. It was during the crop season of 1918 at the Saratov Experimental Station in Russia that thousands of natural hybrids between wheat and rye appeared in many wheat fields. For the next 16 years, Meister and his colleagues exploited these hybrids. The name '"triticale" first appeared in the scientific literature in 1935 and is attributed to Tschermak, one of the rediscoverers of Mendelian Law. It was also during this same year that Arne Müntzing at Svalov, Sweden, initiated his lifelong dedication to triticale.

Today, CIMMYT/Mexico and Poland have the two most successful triticale programs in the world; they were initiated in 1964 and 1968, respectively. Several people have contributed to the success of triticale and the details of their efforts are summarized in several historic reviews.

In 1965, when CIMMYT's Triticale Program was initiated, plants were tall, highly sterile, and late maturing. They also had shriveled grains-commercially unusable. Progress in overcoming triticale's technical limitations has been made in incremental steps. Improvement was driven by the genetic variability scientists were able to generate. The techniques to systematically produce primary triticales and create genetic variability opened the door for directed genetic improvement.

Production statistics in Europe indicate increased adoption of winter triticales due to their lowinput features under conditions of lowcost production and/or better adaptation compared to other small grains, for growing on both barren rye soils and high productive wheat soils. Triticale appears to be an ideal lowinput crop for nonextractive, sustainable agriculture and organic farming. Differences in N uptake and efficiency favor spring and winter triticales when compared with other small grains. Genetic variabilities for these traits among triticales could be exploited in future breeding efforts.

Yield potential

There has been considerable progress made in improving genetic yield potential in winter and spring triticales. In CIMMYT spring triticales, maximum grain yields measured at Ciudad Obregon under irrigated, near optimal conditions increased from 2.5 t/ha in 1968 to 9.7 t/ha in 1991 (Fig. 1). Comparison of complete triticales developed in the 1980s and 1990s over three years in maximum yield trials at Obregon reveals overall yield progress to be 17 percent. Major contributions resulted from increases in harvest index (16%) and spikes per square meter (12%) with an associated increase in grains per square meter (17%). Average plant height decreased from 140 to 125 cm (11%) and test weight increased 12 percent from 68 to 76 kg/ha. Modest reductions in days to maturity and grainfill duration by four and three days, respectively, were accompanied by a 10% reduction in vegetative growth rate and straw yields but a 21 percent increase in the grain biomass production rate.

Agronomic traits

For most of the earlier problems (e.g. excessive plant height, low head fertility, low test weight, poor winterhardiness, and late maturity), significant improvements have been achieved (Fig. 2) Existing genetic variabilities for valueadded traits, trait heritabilities, and correlations among these traits suggest high projected genetic gains for agronomic components associated with grain yield, test weight, most of the traits associated with plant morphology and phenology, and agronomic traits such as threshing ability. Traits, like grainfill duration, where projected progress may occur in small incremental steps, warrant special attention in future breeding efforts.

Abiotic stresses

Breeding for marginal lands (acidic, sandy, or alkaline soils), trace element deficiencies (copper, manganese, and zinc), or trace element toxicities (high boron), and the different types of moisture stress environments constitutes a major effort in spring and winter triticale improvement. Breeding for acid soils, moisture stress, and enhanced tolerance to high and low temperatures is generally addressed by exploiting key locations during germplasm selection, screening, and yield testing, as well as by shuttle breeding and laboratory screening methods.

Human consumption

As a food grain, triticale uses-although in many cases proven to be suitable-have not been extended to the commercial level. Given its generally inferior breadmaking quality, triticale is not yet envisioned to be a suitable flour for breadmaking, particularly if wheat flour is available. In limited cases and due to wheat shortages, triticale has been used, particularly by smallscale landholders, alone or blended with wheat, for the manufacture of local homemade breads. Rolled triticale ("flakes") and whole meal flour, whole meal specialty breads, and other health foods have been marketed in small amounts in different countries.

Food Uses of Triticale in Some Major Producer Countries

Country	Product	Proportion of Triticale Flour
Australia	Breads, cookies & biscuits	100%, blend
Brazil	Variety breads	35%
Germany	Leavened bread	40%
Poland	Rye-type bread	100%
Russia	Rye-type bread	100%, blend
U.S.A.	Layer cake	50%

Animal feeding

Most triticale production is utilized as a feed grain forage, or both in animal feeding, including poultry, monogastrics, and ruminants. Triticale serves as a substitute for other cereal grains or as a partial substitute for protein sources such as soybean meal.

One important problem faced by the feed grain industry in Australia is that the large variation in grain protein content exhibited by triticale in a given cropping year does not permit incorporating a steady amount of triticale in the feed formula.

Miscellaneous uses

Triticale has been used as a cover crop to prevent runoff and erosion in vineyard soils of South Africa and to control wind erosion in Texas cotton production areas. Triticale has proven suitable in the reclamation of highly compacted and polluted mine spoils in Czechoslovakia. However, further studies are needed to determine triticale's potential in metal uptake (cadmium, lead) for specific pollution situations and to compare it with other crops. Triticale also has been considered as a raw material in bioethanol production and as insulation material in building construction. Although bioethanol production equivalent to 1,000 L of fuel per hectare can be achieved, feasibility will depend on energy input per hectare and government policies.

Outlook

The transformation of triticale from a scientific curiosity to a viable crop in the course of a few decades has been a remarkable achievement in plant breeding. However, several grain and nongrain factors have caused triticale to fail as a commercial food grain. Overenthusiastic promotion of triticale as a "great nutritious new grain" in the early 1970s disappointed those who attempted to exploit it commercially, greatly damaging the "image" of a cereal that was still far from having more stable and acceptable attributes. Global wheat surpluses, lack of yeartoyear consistency in the composition of triticale grain, absence of official triticale grading systems, and lack of proper promotion are additional factors that have not permitted the formation of the farmerindustry-consumer chain necessary for triticale to become established as a commercial food grain. This resulted in disappointment for both farmers and researchers in developed and developing countries.

Despite this, efforts to resolve the basic problems of triticale continued. As a consequence, the areas under triticale production worldwide during the 1986-1992 period increased from 1 million to nearly 2.5 million hectares. At present, most triticale cultivation is in Europe (78%), followed by North America (7%), Africa (6%), Latin America (5%), and Australia and New Zealand (4%). Except for a few planted areas in China, the crop is not commercially grown in Asia. Active research in enhancing the productivity and endproduct quality and promotion of triticale is underway in more than thirty countries.

Farmers in every part of the world have adopted new techniques and accepted new crops that are considered profitable and consistent with their circumstances. The first factors, which favored farmers' adoption of triticale, were its superior performance under unfavorable production conditions including acidic soils, severe disease or insect pressures, or drought. Second, it had the ability to produce higher biomass and high regrowth capacity after grazing and ability to grow better under relatively cool temperatures, making it an excellent forage crop. Third, and equally important, was the usefulness of triticale as a feed grain mainly for monogastric animals.

Considerable effort is underway to improve the milling and baking qualities of triticale. Millers and markets find it difficult to accept a new crop because of the additional investments involved in modifying the milling procedure or adding new holding facilities. However, when the world is faced with the problem of slowing productivity of established crops like wheat, maize, and rice and the population keeps growing at its high rate, options like triticale to enhance sustainable production will continue to be important in feeding the world population.

(Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT)