8 Research Needs

In the last five decades, and mostly in the last two, research has transformed triticale from a taxonomic anomaly into a commercial crop. In a historical sense, the progress has been phenomenal: triticale can, under certain circumstances, match the performance of wheat, which has been under development for at least 10,000 years. Despite this progress, however, triticale is no miracle. Uncertainties and problems persist and, to varying degrees, need to be illuminated and overcome by research. Some of these are highlighted in this chapter.

FIELD TRIALS

Triticale is so new that in many of the environments where it is most promising, it is little known. A range of different cultivars needs to be tested and the most appropriate ones selected for local adaptation. These environments include the grain-growing areas with acid and alkaline soils, recurrent droughts, changeable weather, and high disease pressures.

Specific Third World regions where triticale trials should be conducted include:

· The highlands of eastern Africa;

· Much of North Africa (Algeria, Morocco, and Libya, for example);

· The Himalayan zone (particularly in the northern rim of Pakistan and India), Cambodia, and Thailand, where soils are acid;

· Tibet, other inland areas of China, and Sumatra (particularly sites where there are both acid soils and extended dry seasons);

·The Cerrados (acid soil) region of Brazil;

· The highlands of Central and South America; and

· Droughty zones in the Middle East (such as Syria).

GENETICS AND BREEDING

Broadening the Gene Pool

For practical reasons, ClMMYT's triticale breeders had to rely entirely on the genetic endowment of Armadillo. It was this variety that produced the fertile lines with plump seeds (see chapter 2). However, this huge benefit also had a drawback-it was a genetic bottleneck that left CIMMYT triticales with a narrow gene base.

Now is the time to broaden the base of the CIMMYT triticale germplasm. A huge potential exists for this: some 200,000 wheats exist in the world's collections; fewer than I percent have ever been used in making primary triticales. (Indeed, all of today's advanced triticales come from only a handful of wheats.) There is also a massive gene pool on the rye side. It is particularly vital to explore this because rye is the parent that endows triticale with the resilience and adaptation to difficult environmental conditions.

Disease Resistance

Although diseases have not been devastating as yet, it is reasonable to expect that they will increase in severity. Good opportunities exist to counter this. On the one hand, triticale benefits indirectly from the ongoing production of disease-resistant wheats. This is because most triticale diseases also occur in wheat, and resistance located in wheat can usually be transferred (leaf-rust resistance is a good example). On the other hand, triticale can also benefit from its rye parent. Resistance to many diseases is inherent in the rye plant and can be transferred to triticale. However, this usually takes considerable effort. Triticale's resistance to bunts and smuts provides an advantage for the crop, but at higher elevations the possibility of ergot problems introduces a new uncertainty that will have to be evaluated on a case-by-case basis.

A particular immediate need is to select triticales with solid stems. These would confer resistance to sawfly and stem borer. A good start has already been made, and both CIMMYT and Bulgarian researchers have developed experimental solid-stem triticale lines.

Agronomic Improvements

Perhaps the most important agronomic requirement is to select for early maturity. This trait helps the crop escape end-of-season diseases and climatic stresses. Currently, the long period between flowering and seed maturity is hindering triticale's acceptance. However, early types are becoming available (see figure 3.4).

The crop's yields could rise dramatically if it were repartitioned to emphasize grain over foliage. Because the plant produces more total dry matter than wheat, it would seem, theoretically, to have a higher yield potential. Repartitioning to emphasise grain over leaves and stems may push its yields well above those that are achievable today.

Although triticale lines with relatively high test weights exist, these tend to be among the lowest yielding. More development is needed to ensure that the types with the most desirable grain structure are also the highest producing.

To eliminate the lodging problem completely, there is a need to improve straw strength and to overcome crown weakness.

Sprouting

Preharvest sprouting is a limitation still to be solved if CIMMYT triticales are to be grown successfully in humid or rainy sites. Where conditions are dry at harvest time, few of these lines ever sprout, but where conditions at harvest are damp, many sprout unacceptably.

Australian farmers have found that where rains occur late in the growing season, the seeds absorb water. Even brief showers can lead to soft grains and shriveling. Research has shown that the feed value is unaffected, but the wrinkled and bleached appearance and loose seed coat destroy the grain's market acceptability.

This bleaching has also been noted in Canada, western Oregon, North Dakota, and elsewhere where brief rains occur after the grain has ripened. The problem is being slowly overcome as hard-seeded types become available, but more concentrated research is needed to eliminate it entirely.

Octoploid Triticales

Octoploids deserve more attention, particularly because their bread wheat parent is likely to lead to new triticales with excellent baking qualities.

Hybrid Triticales

A development that may project triticale to the forefront of cereals is the possibility of intraspecific hybrids. Many first-generation (F1) crosses between two different triticale lines produce plump seeds;given intense study, it should be possible to produce them for commercial use. Creating such intraspecific hybrids involves the same problems as making hybrid wheat (something long sought, so far without commercial success), but triticale produces pollen prolifically, and might be more successful.

This is a long shot, but research to explore the mechanisms of producing hybrids is warranted. Among the relatives of wheat are several in whose cytoplasms wheat becomes male sterile, and it would not be surprising if one or more of these would sterilize triticale as well. Then it would only be necessary to find fertility-restoring genes, perhaps transferred from the contributor of the cytoplasm, that override the effect of the alien cytoplasm on fertility.

NUTRITION AND FOOD USES

The plant's wide genetic variability offers many opportunities for improving the grain's nutritional qualities. Chemical and nutritional screening techniques should be developed that can easily identify nutritionally superior types at early stages of selection, and on a mass- screening basis. The techniques should be sensitive enough that individual seeds can be sampled without being destroyed. The desirable ones can then be planted.

Antinutritional Factors

Although chemical and biological data are still incomplete, and in fact are sometimes conflicting, it appears that the most recent triticale varieties can form up to at least 50 percent of the cereal base in the diets of pigs and poultry without causing nutritional problems (see chapter 6).

Nonetheless, research is needed to identify and establish the substances responsible for the conflicting biological performance in animal feeding trials. This knowledge may allow researchers to select lines that are low in antinutritional factors. Also, it will allow researchers to study the fate of antinutritional factors in various processing methods.

Feeding Trials

Controlled animal studies are needed using well-characterized triticales to quantify protein digestibility, absorption, and other practical nutritional details on varieties that are being released for production. Further, there is a need to check to ensure that normal processing procedures do not overly damage the nutritional quality.

End-Use Research

Insufficient attention has been paid to end uses. At this time, triticale can act as a substitute for wheat, but no unique market has yet been developed. As a result, most triticale now sells in the least profitable grain markets-animal feed, for example.

Research funds should be spent on improving triticale's quality for leavened bread and other premium uses. The goal should be to keep all the genes for hardiness, disease resistance, and tolerance to adverse soils while upgrading the grain's performance, especially in raised breads in large-scale bakeries.

One basic limitation, as previously noted, is the "sticky dough" problem. Among the gliadin proteins, which cause bread to rise, is one whose production is controlled by a gene on chromosome 1R. This particular gliadin is believed to cause the dough to stick to the high- speed mixing equipment used in industrial bakeries. If the 1R gene is really at fault, its modification or even its elimination (perhaps by genetic engineering) could solve the problem.

It seems likely that chromosomal constitutions may be found that could enhance the breadmaking characteristics of hexaploid triticales even more. For example, it might be possible to select ones with the AADDRR or BBDDRR constitutions or various combinations of A and B chromosomes with DDRR.(4)

Actually, it should only be necessary to introduce chromosome 1D to improve breadmaking quality. Substituting 1D for 1R may not be desirable, however, because of 1R's possible favorable effect on yield as well as disease resistance, but substituting 1D for 1B or 1A might be successful.(5) Of course, chromosome insertion is no guarantee of success; gene expression after insertion is the ultimate test.

(4) Muntzing, 1979. (5) Information from E. Sears.

TRITICALE AS A GENETIC BRIDGE

As noted previously, triticale can be used to improve both wheat and rye because it can be back crossed to either of its parental species. In this regard, it offers a conduit for gene transfer between the two. In fact, the situation is already getting to the point where wheat and rye are one continuous gene pool.

Spontaneous crosses of wheat and rye have occurred many times in the past and some chromosome segments from rye have been naturally translocated to wheat chromosomes.

Such wheat/rye translocations are used in wheats throughout the world as well as in the

Veery wheats developed by CIMMYT. While it is theoretically possible that nature can introduce wheat chromosome segments into rye, this has not been demonstrated so far.

However, by passing through triticale as an intermediary, both processes may be made a routine part of both wheat breeding and rye breeding.

OTHER WIDE CROSSES

Triticale's progress from a curiosity to the threshold of global commercial cultivation encourages the hope that other such "wide crosses" will soon follow. The possibility of blending the genes of disparate genera has, at least in speculation, long appealed to plant scientists as a powerful tool.

The implications of this are far reaching. The development of fertile triticale suggests that the unbreakable laws of nature that keep different genera apart can at least be bent. And through this process breeders might be able to custom-tailor many more cereals to specific human needs and to special agricultural niches. Some possibilities within the cereals are briefly mentioned here (see also table 8.1).

IMPROVEMENT OF WHEAT In the past, many wheat breeders have viewed triticale as a competitor and potential usurper. However, triticale is an excellent source of genes for adding to wheat. The two crops share so many genes that in future they may be seen as a single extended gene pool. For wheat breeders triticale could become a helper to be employed when appropriate, not viewed as a rival to be shunned. For example, rye genes have been transferred from rye to wheat via triticale, thereby producing wheats that grow better in copper-deficient soils.* Also, a "triticale bridge" has been used to transfer disease resistance from rye to wheat. One example is the transference of resistance to cereal cyst nematode (a major problem of wheat growers in Mediterranean climates).** In future, triticale may provide the solution to the fungal disease called "take-all"-the single worst wheat disease in Australia and several other leading wheat-growing nations. Wheat is highly susceptible to this disease and contains no known sources of resistance. Rye, on the other hand, is highly resistant. Triticale might be the link that allows the genes to be brought into wheat.

Wheat x Wheatgrass

It is known that wheat can be crossed with wheatgrasses (Agropyron species). Grains of the resulting hybrid, which has been called "agrotricum," have high lysine contents. A few have been grown as forage crops. They have been widely used by wheat breeders around the world as sources of resistance to diseases and environmental stress. At CIMMYT and in Sweden, these crosses are being used in attempts to improve kernel quality in triticale. Agrotricum strains with high kernel quality have already been obtained, but so far their undesirable properties have kept them from being released to farmers.(7)

(7) Transferring their fine kernel quality to triticale would be of immense value. Gustafson, 1974.

In an attempt to create perennial wheat in the 1930s, an agrotricum (called "W-21") was developed by the United States Department of Agriculture. It resulted from crossing bread wheat with tall wheatgrass (Agropyron elongatum). The researchers were about three years from releasing the variety for food use when the project was dropped. However, the germplasm was saved, and today this hybrid is grown as a winter cover and food for game birds. The plant should be reinvestigated. It is weakly perennial, surviving 2-3 years where winters are mild. Yields of up to 2,200 kg per hectare have been obtained in plots in

Pennsylvania.(8,9)

(8) Information from Rodale Research Center, R.D. 1, Box 323, Kutztown, Pennsylvania 19530. Seed is available from Kester's Wild Game Food Nursery, P.O. Box V, Omro, Wisconsin 54963, USA.

(9) Similar attempts to develop perennial wheats were made in the USSR, but as yet no perennial cereals are commercially available. Tritsin, 1960.

The perennial trait is valuable because the land does not have to be plowed and exposed to potential erosion each year.

Wheat x Self-Fertile Rye

In the 1970s, it was recommended that self-fertile common ryes or wild ryes (Secale vavilovii and S. silvestre) be tried as parents of triticales.(10)

(10) Qualset et al., 1976; Muntzing, 1979.

The rationale is that self-sterile ryes are highly heterozygous and commonly carry deleterious genes (in heterozygous condition), some of which become homozygous in triticale and presumably result in reduced vigor and/or fertility. The self-fertile species should have less heterozygosity and consequently should retain fewer of the deleterious recessives. So far, triticales made by crossing wheat and S. vavilovii have proven to have very low fertility.

TABLE 8.1 Some Promising Cereal Hybrids for the Future.

	Parents of Hybrid
Common Name	Maternal	Paternal	Attributes
Tritordeum	Hordeum chilense	Triticum turgidum	high protein
Tritordeum	Hordeum chilense	Triticum polonicum	high protein
Tritordeum	Hordeum californicum	Triticum aestivum	soil acidity tolerance
Tritordeum	Triticum timopheevi	Hordeum bogdanii	undetermined
Agrotricum	Triticum turgidum	Agropyron distichum	virus resistancesalt
			tolerance
Agrotricum	Triticum aestivum	Agropyron distichum	virus resistance
			salt tolerance
			leaf-rust resistance
			stem-rust resistance
Agrotricum	Triticum aestivam	Agropyron elongatum	salt tolerance
			protein content
			large seed
			early heading
			enhanced tillering
Agrotricum	Triticun aestivum	Agropyron intermedium	stem-rust resistance
			leaf-rust resistance
			stripe-rust
			resistance
			streak-mosaic
			resistance
			virus resistance
			leaf pubescence
			cold hardiness
Agrotricum	Triticum turgidum	Agropyron elongatum
Agrotricum	Triticum timopheevi	Agropyron elongatum
Agrotricum	Triticum turgidum	Agropyron intermedium
Agrotricum	Triticum aestivum	Agropyron junceum	salt tolerance
Agrotricum	Triticum aestivum	Agropyron rechingeri

SOURCE. G. Fedak (see Research Contacts).

When self-fertile selections of common rye have been inbred, with selection for vigor and fertility, and then combined with wheat, the results have been sufficiently encouraging that further work in this direction seems to be justified. Wheat x Elymus

Wheat can also be crossed with grasses of the genus Elymus.(12) (12) Cicin, 1972.

The resulting plants are especially interesting because they produce exceptionally large spikes, containing up to about 200 spikelets. They are also somewhat fertile.

Incomplete amphiploids with 42 chromosomes- comprising the wheat genomes A and B and one of the two genomes. of Elymus-have been found. If the number of seeds set per spike can be raised, this line of research may lead to new, extremely high yielding grain crops.

Barley x Other Grasses

Many intergeneric hybrids between barley (both cultivated and wild and other grasses have been made in Australia, Canada, the Unite' States, and elsewhere. These have included crosses between various barleys and wheat, rye, triticale, wheatgrass, ryegrass, and Psathyrostachys species. Canada K1A 0C6.

The first barley x wheat cross of consequence was made in Australia, where six of the seven possible wheat, barley addition lines (each with one pair of barley chromosomes added to wheat) were produced. These hybrids are potentially interesting because there are surely characteristics of barley-at least disease resistance-that would be useful if transferred to wheat. They provide a means to transfer barley characteristics to wheat.

Wheat x Aegilops Species

Tschermak, the person who named triticale in 1935 (see chapter 2) made hybrids between many different cereals. For instance, he succeeded in producing an amphidiploid between tetraploid wheat and Aegilops ovata, which he named Aegilotricum. This opened the way for transfer of variability through interspecific hybridization. The possible future importance of this is that numerous Aegilops species are crossable with wheat and they have a great variety of characteristics. Many are resistant to all or nearly all the diseases of wheat. Some have the D-genome, from which genes can easily be transferred; others, less closely related to wheat, will require complex but already established cytogenetic methods for transfer of genes to wheat. Alternatively, molecular biological methods, not yet in place for wheat, give promise for transference of some kinds of genes.