Biology and cultivation features of buckwheat in the Republic of Belarus

In the USA, it occupies 0.2 million hectares, and in Russia, almost 1.8 million hectares. The main regions for buckwheat cultivation in the CIS are Ukraine, Belarus, and the non-chernozem zone of Russia (Bryansk, Moscow, Nizhny Novgorod provinces, Tatarstan, and Bashkortostan). However, due to its early maturity, buckwheat is spreading further north.

The gross harvest of buckwheat in the Republic of Belarus in 2003 was 15 thousand tons, with a yield of about 1.1 t/ha. At present, buckwheat still occupies small areas, which is due to the low and unstable yield of this crop. The production of buckwheat groats is about 0.7—17 kg per year per inhabitant of the republic, or 12—25% of the demand, which does not allow providing the population of Belarus with buckwheat groats even according to minimum medical standards (6 kg per person per year).

At the Scientific and Practical Center of the National Academy of Sciences of Belarus for Agriculture, in the laboratory of cereal crops, 27 buckwheat cultivars have been created, 16 of which are zoned in Belarus and beyond: diploid buckwheat (2n = 16): Chernoplodnaya, Zhnyayarka, Anita Belorusskaya, Zhaleyka, Smuglyanka, Volma, Karmen, Vlada; tetraploid buckwheat (4n = 32): Minchanka, Svityazyanka, Iliya, Lena, Aleksandryna.

In Belarus, from 2003—2005, the sown areas were occupied by such diploid buckwheat cultivars as Anita Belorusskaya — 41.7% of the area, Smuglyanka — 20.5%, and Svityazyanka — 8%. The average yield of diploid buckwheat at the Shchuchin Agricultural Experimental Station was (in centners/ha) 28.3, at the Turov station — 25.5, and at the Bobruisk station — 20.8.

Among the new cultivars of diploid buckwheat, the Vlada cultivar at the Volkovysk station showed a yield (in centners/ha) of 21, and at the Gorki station — 20.5. Among the new high-yielding tetraploid buckwheat cultivars at the Shchuchin station, the following were noted (in centners/ha): Aleksandryna — 30.4, Iliya — 26.9.

Thus, in terms of height and yield stability, buckwheat is inferior not only to winter cereals but also to spring cereals. The main reason for the low yield of buckwheat should be considered the misconception that it is a crop that is undemanding to soil and agricultural practices.

As a cultivated plant, buckwheat was formed in the high-mountain humid regions of the Indian Himalayas about 6 thousand years ago; from there, it was brought to Europe by the Mongols in the 13th century, and it only received widespread distribution in the 15th century. There is no reliable data on the origin of cultivated buckwheat. There is reason to believe that cultivated buckwheat originated from a wild relative — tartary buckwheat (Fagopirum tataricum [L.] Gaertn.), but common buckwheat is not known in the wild state.

Common buckwheat, or buckwheat (Polygonum fagopyrum L., =Fagopyrum sagittatum Gilib., =F. esculentum Moench.), is an annual plant from the Buckwheat family (Polygonaceae) (Fig. 25, a—d). Another species, wild buckwheat or tartary buckwheat (F. tataricum [L.] Gaertn.), is also found as a weed in common buckwheat crops everywhere.

Cultivated buckwheat is divided into two subspecies: common buckwheat (ssp. vulgare Stol.), cultivated as a cereal crop and a honey plant, and multi-leaf buckwheat (ssp. multifolium Stol.) — tall and well-foliated, cultivated in the Far East. Recently, tetraploid (large-seeded) buckwheat, characterized by increased protein content and resistance to lodging and diseases, has been gaining recognition. Hybrids of common and tetraploid buckwheat have also been obtained.

Among grain crops, buckwheat is distinguished by the shortest growing season (60—75 days). This makes it possible to use it for reseeding fields of perished winter crops and early spring crops, as well as for stubble sowing. Buckwheat is cultivated almost everywhere, except for the Far North and the arid south. The main areas are located in regions with sufficient moisture — in the central part of the country.

Although buckwheat is inferior to both winter and spring cereals in terms of height and yield stability, leading farms obtain high yields — 2.5—3.0 t/ha or more. Despite the great economic importance of this crop, its sown areas remain insignificant.

Buckwheat has a specific type of growth and development: all phases, except for emergence, occur simultaneously, overlapping one another, and continue until harvesting. They cannot be strictly limited in time, but only the beginning of a phase and its mass onset can be noted.

The stem is up to 1.5 m high, branched, ribbed, hollow, and colored with anthocyanin. The leaves are spear-shaped and heart-shaped; the upper ones are sessile, and the lower ones are petiolate; the petioles form a sheath. The root system is taproot-based, with long root hairs.

The roots penetrate to a depth of 90 cm, but the bulk of them is located in the top 25—30 cm layer of soil. It effectively absorbs poorly soluble phosphorus compounds that are inaccessible to other plants, which is associated with the release of organic acids by the roots:

• formic
• acetic
• citric
• oxalic

Common buckwheat is an annual herbaceous plant that has a tap root system with long root hairs. The roots penetrate to a depth of up to 1 m, but the main mass of the roots is located in the arable layer. Buckwheat roots age quickly, which is one of the reasons for its low yield. By the time of full flowering, 75% of the roots have already turned brown.

Fig. 25. Common buckwheat (a, b, c, d) and Tartary buckwheat (e); morphological features of common buckwheat and Tartary buckwheat (a, e); flowering of common buckwheat (b); fruit formation of common buckwheat (c); nutlets of common buckwheat (d)

Biological features of buckwheat and its place in crop rotation

Buckwheat is a light- and heat-loving crop with a short day requirement, extremely demanding for moisture during flowering and grain filling. The inflorescence is a raceme, corymb, or umbel, and the fruit is a three-edged nutlet of grey, brown, or black color with a pericarp not fused to the seed. Buckwheat's five-part bisexual flowers possess pronounced dimorphism: some plants have long stamens and short styles, while others have the opposite. This flower structure stimulates cross-pollination; therefore, it is highly recommended to bring beehives to the fields during the flowering period.

The best predecessors for buckwheat are fertilized winter crops, grain legumes, row crops, and perennial grasses. Buckwheat should not be placed after oats: its decomposing crop residues hinder the development of the root system. Buckwheat itself is considered an excellent predecessor for the majority of field crops. Due to late sowing dates and rapid initial growth, it shades the soil well and suppresses weeds, leaving the fields clean. Furthermore, it improves the physical and mechanical properties of the soil and reduces the susceptibility of subsequent cereal crops to root rots.

Due to a weakly developed root system, buckwheat should be grown on light loamy and sandy loam soils, avoiding heavy clay areas. The best soils for it are fertile, loose, deeply permeable, and well-warmed sod-carbonate, sod-podzolic, light and medium loamy, as well as sandy loam soils with a pH of 5.5. At the same time, buckwheat is generally not very demanding regarding soil fertility and can produce a normal harvest on poor lands; it also tolerates acidic soils and drained peatlands.

Cultivation technology and crop management

Soil preparation for buckwheat is similar to the tillage for other spring crops. All practices should be aimed at loosening the soil, conserving moisture, and destroying weeds. The main condition is to perform autumn ploughing on time, no later than September 10–15, or ideally in August. Delaying ploughing increases weed infestation in buckwheat fields by 2–3 times, and performing spring ploughing for this crop is unacceptable.

Fast-growing buckwheat requires nutrients, especially in the first half of the growing season. On sod-podzolic soils with low humus content, 15–20 t/ha of organic fertilizers are applied in autumn under winter ploughing, along with mineral fertilizers: 25 kg/ha of phosphates and 15 kg/ha of potassium chloride. During pre-sowing cultivation, 10 kg/ha of ammonium nitrate, 25 kg/ha of superphosphate, and about 58 g/ha of micronutrients — boron and molybdenum — are applied. Nitrogen fertilizers must be strictly dosed: buckwheat uses nitrogen better on light soils, but its excess leads to rapid vegetative mass growth to the detriment of grain yield.

Before sowing, it is necessary to thoroughly prepare the seed material. Large and heavy seeds ensure uniform emergence and high yield. Preparation includes the following sequential stages:

1. Sorting: submerge seeds in water and select only those that have settled to the bottom for sowing.
2. Drying and warming: dry the seeds while simultaneously performing air-thermal treatment.
3. Seed treatment: treat the seeds with the preparation TMTD (80%, 2 kg/t) in advance or before sowing for protection against fusarium, downy mildew, cercospora leaf spot, grey mold, and molding.
4. Growth stimulation: to increase resistance to frost and drought, treat the seeds with growth regulators (Hydrogumat, Maltamin, or Phenomenal at a dose of 2–4 kg/t of seeds).
5. Micronutrient enrichment: perform pre-sowing seed treatment with micronutrient salts if their content in the soil is below the critical level.

Parameters for seed treatment with micronutrients are presented in the table:

Adherence to timing, temperature conditions, and sowing depth directly affects the field emergence of buckwheat:

• Sowing date — the third ten days of May
• Soil temperature for sowing — 10–12 °С
• Seeding rate — 80–100 kg/ha
• Sowing depth on light soils — 4–6 cm
• Sowing depth on heavy soils — 3–5 cm
• Date of autumn ploughing — no later than September 10–15

Buckwheat suffers significantly from weeds during the early stages of the growing season. To control them, pre-emergence harrowing (3–5 days after sowing) is performed, and, if necessary, post-emergence harrowing — before the seedlings develop leaves. In wide-row crops, at least two inter-row cultivations are mandatory: the first — at the first true leaf phase (to a depth of 5–6 cm), the second — at the budding phase. In a wet year, the depth of the second cultivation is increased to 10–12 cm, and in a dry year, it is reduced to 5–7 cm.

In case of heavy infestation during the "sowing — emergence" period, it is advisable to apply the soil herbicide Gesagard (1 l/ha) on the 2nd–3rd day. Against couch grass and annual cereal weeds, growing crops are sprayed with Fusilade or Targo-Super preparations (1–2 l/ha). Chemical weeding of growing buckwheat is permissible exclusively during the period from the true leaf phase to the beginning of budding.

Conditions during the flowering and fruit set period are critically important for the harvest. Heat, drought, rain, fog, strong winds, and sudden cold spells disrupt pollination and seed filling. To prevent harvest losses, it is recommended to arrange for the transport of beehives to buckwheat fields during the flowering period.

In its development pattern, buckwheat differs sharply from cereal grains: bud formation begins as early as 8—10 days after emergence, and flowering lasts for 25—40 days; simultaneously with flowering, seed filling occurs (on withered flowers) and the growth of above-ground biomass continues. Consequently, the ripening period in buckwheat is prolonged. Buckwheat is harvested when ~ 2/3 of the fruits on the plants have ripened.