Buckwheat seeds are the fruits (matured ovaries) of the plant. The indehiscent fruit (seed) is an achene because the three sided pericarp (hull) encloses only one true seed (Robinson 1980). The seed is similar in size and weight to barley.
Until recently, only two cultivated and seven wild species of buckwheat were believed to exist (Onishi 1995). However, seed collection and classification by Onishi (1995) has resulted in a total of 14 species of buckwheat, with new discoveries occuring every year. The genetic origins of buckwheat are believed to occur in the Yunnan and Sichuan provinces of China (Onishi 1995). The recent discoveries of new wild species have provided valuable genetic material for advancing cultivar development. The most notable of these discoveries is Fagopyrum homotropicum. This species is self pollinated and has many characteristics similar to F. esculentum, thus allowing plant breeders to improve and develop new varieties with desirable production and consumption characteristics (Campbell 1995). Table 1 lists the various species of buckwheat described by Onishi (1995).
Buckwheat is self incompatible, so cross pollination is essential for production. The plants flower profusely, but only 10% to 20% of the flowers set seed (Obendorf et al. 1991). A given population is divided equally between pin (long pistils, short stamens) and thrum (short pistils, long stamens) flowers. Legitimate cross pollination occurs only between pin and thrum flowers. Buckwheat displays considerable plant to plant variability, which can cause considerable yield variability. Some plants set well over 200 seeds, while some plants set only 10 to 20 seeds.
The development rate of buckwheat is heat unit driven and closely related to air temperature. Gorski (1986) found that buckwheat development was highly correlated with average daily temperature from planting to initiation of flowering (r2 = 0.84), but correlation between average temperature and maturity was much weaker (r2 = 0.53). This was due to the fact that buckwheat can have ripe seeds, developing seeds, and flowers on the plant all at the same time. Edwardson (1995d) correlated buckwheat development with growing degree days to assist in estimating optimum windrowing time (i.e. when 75% of the seeds are ripe as per Gubbels and Campbell 1984). Buckwheat ripening is highly correlated with growing degree days (r2 = 0.93), and growing degree days offer a fairly precise method for estimating optimum windrowing time (Edwardson 1995d). Fig. 1 shows the relationship between accumulated growing degree days (AGDD) and the percentage of ripe seeds (Edwardson 1995d). Unpublished data from Edwardson indicates that a "typical" buckwheat plant is 100 cm tall, has 15 leaves on the main stem, has 3 to 5 axillary branches, and matures at an accumulated level of 1200 growing degree days (with base temperature at 5°C). In general, buckwheat follows a fairly disciplined pattern of development that is more reflective of a determinate crop, as opposed to the indeterminate classification of buckwheat reported in most production guides (Edwardson 1995; Obendorf et al. 1991). Reducing the variability of seed set and yield is a major issue for cultivar improvement.
Buckwheat will store safely at 14% to 16% moisture content. In order for the crop to be marketed, it is important for the groat to maintain a green color. Over time, oxidation will cause the groat to turn red, which reduces milling quality. Research targeted at maintaining the green color of the groat is currently in progress. Results from this research will be very beneficial in maintaining crop quality during storage.
Typical buckwheat yields in North America range from 1,000 to 3,000 kg/ha. Unfortunately, the variability can be quite extreme, with yields as low as 200 kg/ha, to over 3,000 kg/ha. Table 3 presents buckwheat yields at various agricultural experiment stations in North Dakota. Yields in other states are typical of yields presented in Table 3.
The few buckwheat cultivars available in North America are of two basic types: small seeded and large seeded. 'Tokyo', 'Tempest', and 'Common' are small seeded, whereas 'Manor', 'Mancan', 'Manisoba', and 'Giant American' are large seeded. Processors prefer the large seeded cultivars, with 'Mancan' and 'Manor' being the most widely utilized, and breeding research is currently focused on these cultivars (Campbell 1995).
Buckwheat is produced extensively in North Dakota. Approximately 13,355 ha are produced in the state each year (North Dakota State Consolidated Farm Service Agency records, 1991 to 1994). Buckwheat production is widespread, with concentrated production regions in the south central and southwest regions of the state. It is estimated that total U.S. buckwheat output is 17,000 to 22,000 t annually (Peterson et al. 1992). Buckwheat is also produced in South Dakota, Minnesota, Montana, Washington, Pennsylvania, and New York. Production estimates were not available for these states, since USDA production records for buckwheat ceased in 1964 (Robinson 1980).
Buckwheat production has been decreasing in North Dakota in recent years (Table 4) because more farmers are shifting their acreage to canola, which has a more thoroughly developed market, and wet conditions often interfere with planting. Nonetheless, buckwheat is a viable crop for numerous producers. Crop area will become more stable when cultivar development and crop management result in improved yield uniformity. At present, buckwheat requires more management expertise than other crops.
Buckwheat production and consumption is relatively widespread in Europe (Matano and Ujihara 1995; Borghi 1995). Although no formal statistics on area and quantity of production are currently available (Matano and Ujihara 1995), buckwheat is produced in Poland, Germany, Italy, Slovenia, and the Ukraine. Each of these countries have established buckwheat research programs (Matano and Ujihara 1995). Most of the production in these countries is consumed internally, and consequently exports from each country are relatively limited (Matano and Ujihara 1995). Quantification of crop area, production, and consumption patterns in each of these countries will assist in determining potential barriers to increasing North American buckwheat exports in Europe.
About 95% of the buckwheat produced in North Dakota and surrounding states is exported to Japan (Harris Peterson, Minn-Dak Growers Ltd., pers. commun.). The Japanese mill buckwheat into flour for use in soba noodles, which are a staple part of their diet (Udesky 1992). Japan consumes over 100,000 t of buckwheat every year, but only produces 20% to 30% of their needs domestically (Ujihara 1995). Although North American buckwheat exporters enjoy solid relationships with the Japanese market, it is desireable to develop additional markets, especially with respect to value-added buckwheat.
Buckwheat flour has numerous uses. It is used in pancake mixes as well as in various breads. It is often blended with wheat flour for use in bread, pasta products, and some breakfast cereals (Robinson 1980). The Japanese mill buckwheat groats into flour for use in the production of soba noodles, which are a main part of the Japanese diet (Udesky 1992). In Eastern Europe, buckwheat flour is used in cooking similar to wheat flour. Bread, cakes, and dumplings are made with the addition of wheat flour. Buckwheat flour is used alone in some dishes, such as polenta and zganci.
Buckwheat fields in bloom can serve as a valuable source of nectar for bees. Honey produced from buckwheat is typically dark and has a stronger flavor than honey produced from clover, and is preferred by some consumers.
Studies have shown that up to 60% buckwheat flour mixed with wheat flour produced an acceptable bread (Pomeranz 1983). In general, buckwheat flour in bread mixes comprises only 30% to 40% of the total. Buckwheat flour may also be used in deserts, ice cream cones, dietetic foods, pancake mixes, canned meat products, canned vegetable products, and dried breakfast cereals.
Pasta produced from a mixture of wheat and buckwheat flour, with the addition of egg yolk, vital gluten, and skimmed powdered milk has been characterized to possess shorter cooking time. This provides buckwheat with numerous potential applications in nutritious foods that could be packaged for rapid preparation.
Buckwheat can be used to produce extruded cereal and snack products. Extruded buckwheat products are of very high nutritional quality when compared with products extruded from maize, wheat, or barley alone. The specific character of the proteins allows buckwheat to potentially be used in extruded products targeted to special nutrition needs.
Buckwheat is one of the best sources of high quality, easily digestible protein in the plant kingdom. It has over 90% of the value of non-fat milk solids and over 80% of whole egg solids (Udesky 1992). The balanced amino acid profile and a high level of essential amino acids allow buckwheat to be used in human diets, especially where shortages of lysine and sulfur containing amino acids appear.
Buckwheat is quite complementary to cereal flours, and can be used to improve their nutritional quality, since it is high in essential amino acids as evidenced in Table 6. The main protein solubility fraction in buckwheat is globulin. In addition, the content of prolamines is low. It is relatively high in potassium and phosphorus, and contains 150% more vitamin B than wheat. Buckwheat has no more calories than wheat products or most other grains. It is gluten free, thus making it a valuable nutrient in the diets of people who are sensitive to gluten.
Starch is the major carbohydrate in buckwheat, comprising 51% to 67% of the seed (Pomeranz 1983). Robinson (1980) reports that buckwheat flour is very high in starch (Table 7). Buckwheat starch has a water binding capacity of 103.7%, blue value of 0.35 and amylose content of 25% (Pomeranz 1983). Amylograph data showed that the starch had an initial pastin temperature of 64°C. This starch forms satisfactory fillings, but not acceptable quality cakes.
Total lipids in whole buckwheat grain are 1.5% to 3.7%. Buckwheat oil contains 16% to 20% saturated fatty acids, 30% to 45% oleic acid, and 31% to 41% linoleic acid. Palmitic (19.3% to 22.9%), oleic (29.1% to 31.6%), linoleic (19.1% to 34.8%) and linolenic acids (4.7% to 6.8%) account for about 95% of buckwheat fatty acids. Phospholipids comprise ~3.6% of the buckwheat flour and are ~67% of the conjugated lipids (Pomeranz 1983).
The mineral composition of buckwheat is also quite complementary to cereal crops (Table 8). The inclusion of buckwheat in food products that contain other cereals would assist in improving nutritional quality.
The nutritional characteristics of buckwheat place this crop in an excellent position to be included in a variety of food products. New developments in medical research are providing new avenues for consideration in advancing the utilization of buckwheat.
A recently introduced term in the food ingredients industry is nutraceutical. A nutraceutical is defined as any substance that is a food or part of a food and provides medical or health benefits, including the prevention and treatment of disease (DeFelice 1994). Since nutraceuticals will no doubt transcend a broad range of food products, their value will need to be supported by good clinical research data.
Numerous research articles are published on buckwheat as a food ingredient. Both Food Science and Technology Abstracts (FSAT) and the MEDLINE medical database contain a relatively large amount of research based information on the food ingredient applications and medicinal benefits of buckwheat. Buckwheat enjoys the following nutritional and health benefits (Udesky 1992):
The addition of buckwheat to human diets could also help cut calories and keep blood sugars at optimal levels. Buckwheat grain is digested more slowly than other carbohydrates (Buckwheat diet 1989). Consequently, the inclusion of buckwheat in a meal leaves people feeling full longer, thus reducing the urge to snack. The slow uptake of buckwheat also has potential to prevent adult-onset diabetes, as well as improve glucose tolerance in those who have developed the disease (Buckwheat diet 1989).
Incorporating present knowledge of medicinal and health benefits with targeted market research will provide the framework necessary to advance the utilization of buckwheat.
Every three years, the International Buckwheat Research Association (IBRA) assists in organizing an international buckwheat research symposium. Symposiums have been held in Slovenia (1980), Miyazki, Japan (1983), Pulawy, Poland (1986), Russia (1989), Taiyuan, China (1992), Ina City, Japan (1995), and is slated for Winnipeg, Manitoba, Canada in 1998. Proceedings have been published from each international buckwheat symposium. The 1995 symposium had a large portion of the proceedings devoted to food science and human health (Matano and Ujihara 1995).
Previous information suggests that buckwheat has nutritional characteristics which place this crop in an excellent position for expanding utilization. Increasing the utilization of buckwheat as a food ingredient will require targeted market research. Since the cost of introducing new food products into the market is substantial, buckwheat processors will need to focus on the health benefits of buckwheat, then target those products in which buckwheat would be complementary. Present market expansion research indicates that buckwheat is well positioned to be included in specialty breads, pasta, snack foods, and ready to eat cereals (Edwardson 1991b, 1992b, 1993b, 1994, 1995a).
At present, there are very few buckwheat researchers in North America. Research efforts have typically focused on buckwheat production practices within a given state, while research on processing and utilization has been somewhat fragmented. In July 1994, buckwheat researchers and processors from North America gathered in Carrington, North Dakota to discuss current research efforts in buckwheat, and to develop a plan for advancing the utilization of this crop. Japanese buckwheat millers and traders also participated in this conference. This conference resulted in the formation of the North American Buckwheat Consortium (NABC). The industry representatives of this group agreed to jointly fund specific research efforts on buckwheat with the public sector. Proceedings from this conference outlined needed research efforts at the production, processing, and marketing levels (Edwardson 1995c).
Until 1995, Agriculture Canada had the only active buckwheat breeding program in North America. This program was led by Dr. Clayton Campbell at the Agri-Food Diversification Research Center at Morden, Manitoba. Reductions in research funding caused Agriculture Canada to eliminate the buckwheat breeding program. Fortunately, private sector traders and processors decided to privatize this breeding program so that cultivar development would continue. Efforts to formalize a new buckwheat breeding company in Canada are in progress.
Buckwheat is produced extensively in many regions of the world. Production practices for buckwheat are well documented, and the crop is relatively easy to produce across a wide range of environmental conditions. Buckwheat is complementary to crop rotations, and is also nutritionally complementary to cereal grains.
Although current buckwheat use is limited to soba noodles, pancake mixes, and kasha, the potential for including buckwheat in other products (e.g. pasta, ready to eat cereals, extruded snacks, and specialty breads) is tremendous. The nutraceutical characteristics of buckwheat offer substantial dietary benefits to people with high blood pressure and other ailments.
There is a wealth of published information on producution, processing, and utilization of buckwheat. The international buckwheat research symposiums have been very beneficial in presenting current advances in buckwheat research. The formation of the North American Buckwheat Consortium further demonstrates a committment from both the public and private sector to advance the utilization of this crop.
In summary, buckwheat is: (1) relatively easy to produce; (2) readily available; (3) very nutritious; (4) complementary to cereal grains; (5) functional in many food products; and (6) underutilized. Continued integration of research across production, processing, and marketing levels will greatly assist in developing the future for buckwheat.
|F. esculentum Moench||Most widely utilized form of buckwheat|
|F. homotropicum Onishi||Recently discovered, can be crossed with F. esculentum|
|F. cymosum||Perennial wild species|
|F. tartaricum||Also known as "bitter buckwheat"|
|F. statice||Perennial specie with well established root system|
|F. urophyllum||Ochrea is green, not transparent|
|F. ue||Recent discovery, classification in process|
|F. leptopodum||Ovate leaf blades|
|F. lineare||Linear leaf blades|
|F. callianthum||Erect plant, erect growth habit|
|F. uf||Recent discovery, classification in process|
|F. pleioramosum||Has many creeping branches|
|F. gracilipes||Known for its drooping inflorescence|
|F. capillatum||Erect branches, cordate or ovate blade|
|Crop development:||Emerges 5 to 7 days after planting. Begins flowering about 5 weeks after planting. Optimum seed set period is during weeks 5 to 7 after planting. Makes many flowers, but not all will set a seed. Wilts in hot weather, not real drought tolerant. Matures in 75 to 90 days.|
|Rooting depth:||45 to 60 cm.|
|Soils:||Adapts to a wide range of soil types. Prefers medium texture soils. Peforms well on poor soils. Soils that crust easily can cause emergence problems.|
|Planting rate:||50 to 70 kg ha-1; 15 to 17 cm row spacing.|
|Planting date:||May 25 to June 15. Planting up to July 1 has occurred in North Dakota, but yields are reduced. Buckwheat is not frost tolerant at any stage.|
|Planting depth:||2 to 5 cm.|
|Fertility:||Nitrogen: 55 kg N per 1000 kg ha-1 yield goal. Phosphorous use is similar to wheat (use of a drill row starter is a good practice).|
|Weed control:||No chemicals are registered in the United States. Buckwheat is usually quite competitive.|
|Chemical carryover:||Sensitive to carryover of trifluralin, atrazine, and sulfonylurea products (e.g. Glean, Ally).|
|Rotation:||Usually placed between small grains (e.g. wheat and barley).|
|Insects:||Aphids and grasshoppers. Insects are usually not a major problem in buckwheat production.|
|Diseases:||Subject to Rhizoctonia root rot, alternaria, and downy mildew. These diseases are not reported often.|
|Harvest:||Swath when 75% of seeds in upper 1/3 of plant are ripe. Swath when field is damp to reduce shatter loss. Swath immediately after a frost to reduce shatter loss. Stores safe at 14% to 16% moisture content when seed is clean of foreign material.|
|Cultivars:||Mancan, Manor, and Giant American (all are large seeded).|
|Market:||Used in Japan for milling into flour. Flour is used in buckwheat (soba) noodles. Also used in pancake mixes.|
|Typical yields:||1100 to 1700 kg ha-1. Yields over 2200 kg ha-1 have been reported. Yields are very dependent upon environment in a given region.|
|Year||Total areaz (ha)||Yieldy (kg/ha)||Total output (t)||Farm pricey ($/t)||Farm gate value ($)|
|Crop||Year||Yield (kg/ha)||Price ($/t)||Gross revenue ($/ha)||Variable costs ($/ha)||Return over variable costs ($/ha)|
|Content as % of whole grain|
|Buckwheat dark flour||14.1||68.6||3.5||8.3||1.8|
|Buckwheat light flour||11.7||72.0||2.5||1.6||1.8|
|Buckwheat white flour||6.4||79.5||1.2||0.5||0.9|
|Bread wheat flour||11.8||74.7||1.1||0.3||0.4|
|Content (mg/100 g)|
|Corn meal (whole grain)||6||3.45||127||241||287||35||1.82||0.193||0.498|
Fig. 1. Relation between accumulated growing degree days (AGDD) and percent ripe seed in buckwheat.