|Triticale: Promising Addition to the World's Cereal Grains (BOSTID, 1989, 95 p.)|
The greatest service which can be rendered any country is to add
a useful plant to its culture; especially, a bread grain....
THOMAS JEFFERSON, 1821
In solving triticale's basic agronomic problems, CIMMYT has contributed greatly to the creation of this promising new crop. Overcoming the shriveled seed was particularly important as far as the crop's end uses are concerned. For example, it improved the milling yield and gluten content. Unfortunately, however, it produced grains that result in a dough so sticky that it won't roll out of high-speed mixers. For industrial bakeries turning out perhaps 50,000 loaves a, hour, that is clearly unacceptable.
What will finally make triticale a major resource is the improvement of the end-use products-particularly leavened breads made in largescale bakeries. A plant combining triticale's field qualities with all of bread wheat's baking qualities would sweep rapidly into massive use around the world.
As noted previously, triticale can already be used in many products without sacrificing quality. For making chapatis or tortillas and other flat breads, it is already commercially viable. For small-scale bakeries, the sticky dough is also of little consequence, and triticale is even now appropriate for widespread use in making raised breads on all but the largest scale.
However, the fact that leavened breads cannot be made in industrial quantities casts a shadow over the whole crop. For one thing, triticale grain faces difficulties as an export to industrialized nations that plan to use it as a bread grain. For another, the biggest single grain buyers- even in poor countries-are often large city bakeries. For their highspeed equipment they need grain without the sticky-dough problem. If nations are to avoid two-tier marketing and if triticale is to shed the stigma of inferiority, the crop should be suitable for even the most challenging bread baking processes.
Although recent triticale varieties in Mexico have demonstrated greatly improved milling and baking qualities, triticale grain, by and large, has a slightly lower flour yield (milling rate) than wheat. This is especially true if it was produced under conditions that promote shriveled kernels.
In producing spring triticales, the variety Armadillo was a breakthrough. It brought fertility, high yields, and plump seeds at a time when these seemed impossible to achieve. But it was also a bane. Although, the high fertility found in Armadillo led to many of today's successes in spring triticales, it also created a genetic vulnerability. In passing through Armadillo, CIMMYT had to sacrifice the breadth of environmental tolerance that would have come if several "Armadillos" had been found. Also, in its earliest stages, the small ClMMYT research program had to make its triticales from wheats developed for irrigated agriculture.
These had less than average tolerance for adversity. The result of these genetic bottlenecks is that today's triticales have a fairly narrow germplasm base. The crop already has shown remarkable adaptability, but when additional genetic diversity is available, its resilience could become even more remarkable.
Agronomically, triticale is similar to wheat. The two crops are subject to the same stresses and limitations, and their cultivation and management are usually handled in the same way. Triticale, therefore, has the major advantage in that it requires no new technology or methods.
However, triticale is not wheat, and-depending on the varieties used and the local climatic and soil conditions-slight modifications are needed. Thus, one cannot assume that the new crop's requirements are identical to those of wheat. Triticale agronomy has to be "finetuned" in each area where it is to be grown.
Also, in certain locations various triticale lines may show unexpected agronomic problems. Highlighted below are some specific concerns over the currently available lines. For each concern, modern breeding has obtained fairly good lines; the problem remains to combine them into several varieties. (It should be recognized, of course, that even in wheat no faultless variety exists.)
"Top-heaviness" or weak straw can still be a problem in wellwatered, highly productive areas where the plants grow overly tall and lush. However, triticale is most likely to be employed in marginal environments where lodging is seldom a problem. Short, highly promising lines are now under evaluation so that soon, even under good environmental conditions, lodging should not be a problem.
The long grain-filling period of the current cultivars makes the crop more susceptible to stresses. In environments where there is drought or excessive heat during and after flowering, the grain can fill out poorly and end up shriveled. This is also true for wheat, but triticale is more susceptible because present lines take longer to mature their grains. This problem, too, is likely to soon pass. Early-maturing types are already in advanced stages of development (see figure 3.4).
Triticale harvests easily and threshes well, and seed shattering is not a problem. However, a few types-notably, some European winter varieties and some of the completes (all rye chromosomes present, see chapter 5)-are hard to thresh. Some of these recalcitrant types have glumes that clasp the grain too tightly; others have soft grains that can break during threshing. (Harder types are now becoming available, however.)
Dormancy and Sprouting
There are large differences in dormancy between triticale varieties: winter triticales have dormancy; spring triticales from CIMMYT currently have little or none. The types with dormancy require a "rest period" before they will germinate. The types without dormancy germinate readily, sometimes so readily that if the weather is damp at harvest time, they may begin sprouting even before being harvested from the parent plant. Although new lines are greatly improved, preharvest sprouting is still a problem with most CIMMYT triticales. It does not occur everywhere, nor with every line, but in those sites where moist conditions prevail during harvest (for example, in parts of Mexico, Brazil, Canada, and northern Europe), sprouting can limit the quality of current CIMMYT varieties.
Like other crops, triticale is susceptible to some diseases, and local adaptation is needed to overcome this. As noted, most triticale diseases are not devastating. However, it is too soon to tell what the effects will be if the crop is grown on large areas and resistances break down. This has already happened in Australia where previously resistant varieties suddenly and unexpectedly succumbed to stem rust.
In general, the most serious threats are leaf rust, stem rust, stripe rust, scab, eye-spot, spot blotch, and bacterial diseases. Leaf rust reduces yield but does not kill the plant. The others, however, are potentially devastating. In the long run, most diseases can probably be overcome by incorporating genes from resistant strains of wheat or rye. Resistance to rust diseases can almost certainly be incorporated this way, but even in wheat, resistance to scab and spot blotch is limited, and finding ways to overcome them will be more complicated. It is not impossible, however, because triticale's rye genome brings all the cultivated and wild ryes within reach for transferring resistance to triticale. Also, cytogenetic methods have been developed-and molecular biological techniques are in the making-that permit transfer of resistance genes from even more genetically distant wild relatives.
Ergot, a worrisome disease of rye, also affects triticale. This fungal infection spreads from wild grasses and can be a problem in temperate regions. However, ergot infects empty florets, and in triticale the improvement in floral fertility has dramatically reduced its incidence. In most areas (outside high latitudes-such as Canada), ergot in triticale has now decreased to levels comparable to the low levels of wheat.
Genetic Reproductive Stability
Because it is so new and because it is a combination of divergent species, today's triticales are prone to genetic instability. Occasional missing chromosomes produce plants with poor seed, poorly filled spikes, and sometimes even sterility. If the seeds of any triticale crop are repeatedly resown over several generations, an accumulation of chromosomal instability may lead to an increase of sterility, a decline in grain yield, and a rise in highly unstable types.
The kernels of most triticales are softer than those of hard wheats, and are therefore slightly more subject to insect damage. This, in general, makes them slightly more difficult to store. However, plant breeders are increasing the kernel hardness, and the problem should soon disappear.
LACK OF RECOGNITION
In the marketplace, triticale faces a general lack of appreciation. The plant's agricultural and dietary niches are not established in many places thus far, and few countries have established pricing structures or grain standards for triticale. This can be a considerable handicap for a newcomer confronting well-established, centuries-old systems of marketing and processing, all based on the characteristics and uses of other grains.
Anywhere that triticale is to be produced on a commercial scale it needs a clear set of procedures for marketing, transporting, handling, and grading the grain. Farmers can then adjust their planting and marketing plans accordingly.
If triticale brings a lower price than competing crops-as seems likely, given its newness-it will have to present yield or other advantages to compensate. There is ample evidence that it can do this, particularly in marginal areas where it is likely to outperform wheat by a profitable margin. If it is for use in animal feeds, it must also outperform barley, sorghum, oats, or other competing grains.