Cereal: Variety Selection
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811: Agronomy Guide > Cereal
> Variety Selection
The principles of selecting a winning variety do not vary greatly from crop to crop. Quality factors for specific end-use products and the impact on price and yield are confounding factors with wheat variety selection. Ontario grows more types of wheat than any other region in Northeastern North America. Milling and horse oat markets also have specific quality parameters, as does barley for food or malting purposes.
Seed dormancy, or sprouting resistance, varies greatly between varieties. Several genes are responsible for the dormancy factor in wheat. One of the strongest of these genes is linked to the genetic coding for red wheat or the red colouration of the bran. In general, red wheat varieties will not sprout as readily as white wheat varieties, and often hard red wheat varieties will sprout less readily than soft red varieties. As white wheat varieties lack sprout tolerance, growers are advised not to grow more white wheat than they combine in two or three days. Harvest white wheat varieties first, as soon as possible, and dry if necessary. This will ensure crop quality and maximize profitability.
Sprouting tolerance should not be confused with germination of the crop once planted. Seed dormancy is dependent on time, light and temperature. By the time the seed is planted in the fall, enough time has passed, and the dark, cool conditions of the soil will overcome any dormancy. The speed of emergence after planting is entirely related to the seed vigour of the variety and seed lot, and not at all to colour or market class.
Winter wheat can tolerate extremely cold temperatures (-23°C) in its most hardy state. Winter barley cannot withstand as severe conditions (-10°C). While the threat of cold temperature injury often exists, Ontario conditions rarely cause plant death, except where icing occurs. Snow offers excellent insulation from cold temperatures, while ice conducts cold directly to the plant. More detailed information on cold tolerance and winter hardiness is available in the University of Saskatchewan Winter Wheat Production Manual (Chapter 12, Winter Survival).
In livestock regions, the need and value of straw can be significant. Straw quality is also a factor. Moisture absorbency is a factor for most livestock bedding. Dry loose straw has an approximate density of 40 kg/m3 (2.5 lb/ft3), while baled straw has an approximate density of 80 kg/m3 (5 lb/ft3) and water absorption of 293-335 L/m3 (1.8-2.1 Imp. gal/ft3). The horse industry is only interested in "dust-free" straw. Straw has been one of the driving forces for growers to continue growing barley rather than spring wheat, even though the economics of grain production would favour spring wheat.
In general, two-row barley varieties produce more straw than six-row varieties. Oat straw quantity and quality are good. Wheat straw is less absorbent than oat or barley straw, and there is less straw produced by most spring wheat varieties than by spring barley varieties Table 4-5, Straw Quantity vs. Straw Quality.
Johnson, 2003/2004 and Falk, 2004/2005.
The value of straw is often a hotly debated question. Straw has value from both the nutrients removed and the organic matter addition it will return to the soil. Table 4-6, Straw Nutrients, shows the range of nutrients that straw may contain. Straw nutrient concentration can vary greatly, Straw from hard wheat varieties will generally contain less (approximately 2.75 lb/tonne or 1.25 kg/tonne) nitrogen than soft wheat straw (Falk, 2005). Potash concentration varies tremendously in straw, as potash is readily leached from straw by rainfall after maturity. The only accurate way to determine nutrient value is through an analysis.
There is added debate about whether the nitrogen component should be included in the value of straw. The carbon:nitrogen ratio of straw is quite high (80:1), which would require additional nitrogen for breakdown by soil organisms. Thus, many growers do not add nitrogen into the value calculation. Using average nutrient concentrations, straw value can be calculated using the formulas shown in Table 4-6.
The value of the organic matter that straw returns to the soil is much more difficult to calculate. There is no doubt that the organic matter value is extremely significant. Estimates range from at least equal value to the nutrient removal, to estimates that removal of four high-yield straw crops could reduce soil organic matter by 0.1%. This 0.1% organic matter could be capable of holding up to 4.4 cm (1.75 in.) of available water for crop growth. In dry seasons, this amount of water might result in an additional 0.24 t/ha (3.5 bu/acre) of soybeans, or 0.88 t/ha (14 bu/acre) of corn yield. While these are simply mathematical estimates of the organic matter impact, they drive home the point of just how valuable that component can be.
Within wheat, the number of market classes continues to increase Table 4-7, Characteristics of Various Cereal Market Classes, this page). Since the mid-1980s, when only spring feed wheat and soft white winter wheat were grown in Ontario, the number of market classes has expanded dramatically. This increase in wheat classes is likely to continue, with varieties for other specific market uses in development. Many of these market classes have yield and price premium implications that must be considered when selecting varieties. For example, high protein, non-pastry wheat varieties generally have a yield penalty (approximately 10%) associated with achieving higher protein. However, these varieties have a price premium. It is much easier to achieve high protein and earn premiums on farms with more inherent soil nitrogen (i.e., livestock farms with manure and/or forages). On cash crop farms, it often takes significantly more nitrogen to achieve optimum protein levels in these non-pastry wheat varieties Red Winter Wheats. All these factors must be considered when selecting varieties.
All barley has the genetic potential to develop six rows of grain in the head (six-rowed barley). Two-rowed barley only develops two of these rows. In general, two-rowed varieties are larger seeded, shorter and more resistant to lodging, leaf rust and mildew. Two-rowed varieties often mature later and have lower yields than six-rowed types. Six-rowed varieties usually have better resistance to scald and are more tolerant of heat and moisture stress, making them more tolerant of late planting. The more open canopy of six-rowed types makes them less competitive for underseedings, while the lodging resistance of two-rowed types must be taken into account when underseeding.
Both spring and winter types of barley are grown in Ontario. Winter barley requires a period of cold temperatures to "vernalize" the plant and initiate flowering and grain development. Winter barley planted in the spring will not produce grain. Spring barley does not require this vernalization process.
Winter barley is much higher yielding than spring barley but is considerably less winter hardy than winter wheat. It survives only in areas with milder winter conditions or excellent snow cover. Winter barley must be planted earlier than winter wheat, making it more prone to barley yellow dwarf virus (BYDV) and snow mould. Winter barley matures earlier than winter wheat, and some years may be suitable for double cropping. In areas that are adapted to winter barley production, yields of up to 8.1 t/ha (150 bu/acre) have been achieved.
Covered or hulled barley consists of approximately 10% hull and 90% kernel. With hulless types, much of the hull is removed at harvest. Hulless barley has a higher test weight and lower fibre content than covered barley. The seeds must be handled carefully, as the embryo (germ) is susceptible to damage. The amount of hull removed from the grain is somewhat dependent on weather conditions at harvest. Hulless barley will yield less than regular varieties, because the weight of the hulls is left in the field, but the concentration of energy and protein will be greater.
Oat is a traditional feed crop in Ontario, particularly for horses. Oat has better balanced protein and higher fibre content than barley. Grow leaf rust-resistant varieties. Buckthorn acts as the alternate host for leaf rust in oat. Remove buckthorn from field margins whenever possible.
Milling oat is used for human consumption and therefore must meet special quality requirements, including plump kernels, high test weight and groats (grain) that are free of discolouration and foreign material (insects, weeds or other crop seeds). Requirements for milling oat can be found at Canadian Grain Commission, Grain Quality," to find the Official Grain Grading Guide.
Hulless oat may be of interest to pig and poultry producers because the grain (groat) is approximately the same metabolizable energy content as corn. They have good quality protein and high protein content (14%-20%). Diets can be formulated with hulless oat as a major energy source and only small amounts of soybean meal, canola meal or the amino acid lysine need be added to obtain performance comparable to a standard corn-soybean meal diet.
Hulless oat becomes groats when they are threshed. The thin hulls are left in the field as chaff, resulting in a kernel weight loss of 25%-30% compared to regular varieties where the hull is retained. Current varieties have a coating of fine hair on the groat that prevents the oat from flowing freely. These hairs cause itching, making the oat unpleasant to handle. Recent variety introductions have greatly improved on these issues.
Pay special attention to planting, harvesting, handling and storage of hulless oat. Since the hull does not protect the seed, germination is easily reduced. Take care during the planting process. Embryo damage can occur during harvest and handling. The high oil content at the surface of the seed makes the seed more attractive to storage insects. Moistures should be below 10% to ensure the grain does not go "off quality" in storage.
Mixed grains occupy a significant acreage in the province. Most mixed grains are a combination of oat and barley, but mixtures may include spring wheat or field peas. Mixed grains are only grown for feed.
No specific recommendations regarding the best mixtures can be made. Generally, the highest yielding varieties of oat and barley in pure stands also perform best in mixtures, but maturity ratings of the components of a mixture must be matched. The addition of wheat or peas to the mix will increase the energy or protein of the grain, but yields will be reduced.
Leaf and head diseases are usually much less severe with mixed grains than where oat or barley is grown alone. Mixtures of oat and barley are more tolerant of variable drainage conditions, with the barley component becoming predominant in drier areas of the field and the oat component producing more in poorly drained areas.
Winter wheat is grown on the largest acreage of any of the cereal crops and is grown across most of the province. Like winter barley and winter rye, winter wheat requires vernalization, a period of cold temperature (0°C-5°C), that induces the crop to shift from a vegetative to a reproductive state. While wheat vernalizes most effectively at the five-leaf stage, the vernalization process can be completed once germination begins. Therefore winter wheat can be planted at any time in the fall, right until freeze-up, and still head out normally the following year. Winter wheat planted in the spring will not enter the reproductive stage, as it has not been vernalized. In some cases, winter wheat has been spring planted to give the appearance of a lawn that almost never needs cutting.
Feed wheat is a more concentrated source of protein and energy for livestock than barley or oat. In non-ruminant diets, take care to limit the amount of feed wheat in the ration to avoid digestive problems. The general guideline is to include no more than 25% of the total ration as wheat. Be sure to consult a nutritionist for further information.
Some feed wheat varieties can produce yields that are competitive with oat and barley as feed grain. At times, these varieties may achieve quality that allows them to be included in the milling wheat market. Check with your seed supplier or the Ontario Wheat Producers Marketing Board to determine if a variety is generally of milling or feed quality. When feed wheat varieties do make milling quality, consider it a bonus and not something to depend on.
To ensure market acceptance, take care to grow a quality product. This includes factors such as selecting the proper variety, early planting and good weed control. Spring wheat varieties generally have a very open canopy, making weed control more critical. This open canopy makes them ideal as a nurse crop for underseeded alfalfa or hay crops.
Both spring and winter types of rye are available and grown in Ontario. Typically, winter rye is grown on the light sandy soils of tobacco and vegetable farms to control wind erosion and build up organic matter. Spring rye is occasionally grown as an annual forage crop. Unlike the other cereal crops, rye is quite susceptible to ergot, which is detrimental to its use as either feed or food.
Winter rye is the most winter hardy of all the winter cereals. It is extremely early maturing - well ahead of either winter wheat or winter barley. Rye is hard to thresh, and despite the early maturity is not harvested until well after wheat and barley crops. This allows the straw to degrade and facilitates the threshing of the grain from the head.
Some producers looking for extra forage have started to plant winter rye after the corn is harvested. This rye will begin to head about mid-May the following spring, when it is cut for baleage or haylage. Soybeans or dry edible beans are then planted with almost no yield loss due to delayed planting. Concerns from this practice include potential allelopathic effects (the toxic effects of rye residue breakdown during new crop growth) from the rye residue and the possibility of volunteer rye in wheat crops in succeeding years.
Triticale and Spelt
Both triticale and spelt are grown in Ontario on a limited basis. Triticale, a cross between wheat and rye, is only grown as emergency forage when hay crops winterkill, mostly in combination with peas Warm-Season Annual Grasses. Spelt, an earlier version of modern day wheat, is mostly grown organically for that market. There is almost no genetic difference between spelt and wheat, just the genetic coding for the "chaff" to either adhere to the grain or be easily removed. In wheat, the chaff comes away easily, while in spelt it does not.
Most crop plants are diploids, meaning that they have one pair of each chromosome. Both barley and oat are diploids. Durum wheat is a tetraploid: having two pairs of chromosomes. All other wheats grown in Ontario are hexaploid, with three pairs of chromosomes. This makes gene transfer in wheat somewhat more difficult. The profit margin in cereals for seed production and breeding is much less than in many other crops. Additionally, the acceptance of genetically modified wheat plants by consumers has been very low, resulting in less investment in biotechnology in wheat. Thus, cereal crops have been at a standstill in the development of varieties having special traits using gene transfer technology.
This situation appears ready to change. How the industry and consumer will respond to these changes has yet to evolve. Growers should be aware of these developments and the criteria for identity preservation and separation that may go along with any new developments.
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