Fagopyrum esculentum (aesculentum) Moench. commonly called buckwheat, belongs to the family Polygonaceae and was formerly named Fagopyrum sagittatum Gilib. or Polygonum fagopyrum L.. Other common names include beechwheat, French wheat, Saracen corn and green manure crop, and it has also been called Japanese buckwheat, differentiating it from Fagopyrum tataricum Gaertn., the Tartary buckwheat.
Buckwheat has been used as a food, as a source of rutin which is used medicinally, and as a green manure. The plant is a small branching annual, reaching 80 cm, possessing smooth succulent stems with lateral branches given off alternately from opposite sides. The leaves are cordate or sagitate and from July to September a pinkish white or white inflorescence is formed as a cyamose panicle or sometimes as broken individual flowers. It is normally a plant of cool, moist, temperate regions and thrives best in well-drained sandy soils, but it will grow even in dry areas with poor soil and drainage.
Distribution and Importance
Buckwheat probably originated in the Himalayan region of Western China or Northern India, and was cultivated in China for at least 1000 years before arriving in Europe via Russia.
The name “buckwheat” is a corruption of the Dutch “boekweit” or beech wheat, the name referring to a close resemblance between its fruit, a three-cornered achene, and the beechnut). The endosperm of this fruit is used to prepare buckwheat flour, used in the preparation of bread and cakes, buckwheat cakes being a popular delicacy in America. The gluten content of the flour, although low, is sufficient to allow, the making of yeast bread, and the seeds generally contain around 2% fat, 11% digestible carbohydrate, and 11% protein, although they may contain as much as 18% protein, with the highest lysine content known in the plant kingdom, and comparable in this respect to animal protein. The biological value of the buckwheat protein is < 90%, but a relatively high tannin content (1.5-1.7%) causes only 80% to be digestible protein. Extruded buckwheat flour has also been used in human milk substitutes and buckwheat flour, therefore, has great potential as a source of protein in the diet, either alone or in admixture with other grains.
Russia has been the largest producer but, as in Europe, crop production has decreased. The crop also declined in Canada until the early 1960s but then increased because of export demand, mainly to Japan.
Conventional Methods of Cultivation
Buckwheat is a fast-growing plant, maturing in 60-100 days. It is frost-sensitive but highly tolerant of soils which are light, acid, or of low fertility. Seeding is generally in late spring to July to be free of early frosts, and harvesting is completed before the first frosts of the winter. The fruit does not all ripen at the same time and at harvest the plant will have a mixture of mature grain, green grain, and flowering buds. The rapid growth rate enables two crops to be grown in a season in suitable climates, or buckwheat may be a second crop after early vegetables or early wheat. Sowing rate is around 40-50 lb/acre (45-56 kg/ha) in shallow drills in rows 12-15 in apart when grown for grain. In northern Moldavia, optimum seeding rates for dense and wide-row seeding were 100 and 50 kg/ha respectively and optimum fertilizer rates were 60 kg/ha each for N, P, and K. N had the highest effect on crop yield. Yields of grain are typically around 1100 lb/acre (1290 kg/ha) although up to 2 t/ha can be obtained. Addition of 7-8 kg/ha of N, however, increases the yield by only 54 kg/ha and because buckwheat thrives on poor soils, fertilizers are often not used. The plant can utilize undissolved mineral phosphates and in the absence of a fertilizing program buckwheat can remove excessive amounts of nutrients, making poor soils even poorer and depressing the yields of following crops. Buckwheat may, however, be grown as a green manure, the plants being ploughed into the ground before they have flowered, and two or even three green manure crops can be grown in a season, commencing with an April sowing, most of the N rapidly becoming available under good mineralization. Rutin content varies according to seeding time and growth phase, the highest level being in the leaves at pollination time. Plants from a May seeding had the highest absolute rutin content. Presowing treatment of buckwheat seed with trace element supplements also increased the rutin content of the crop.