Economic importance and biological features of rapeseed in Belarus

Nutritional value, winter hardiness, and choice of rapeseed cultivars

Rapeseed (Brassica napus L., ssp. oleifera Metzg.) is represented by winter (biennis) and spring (annua, or colza) forms. In terms of quality, rapeseed oil is comparable to sunflower and soybean oil, approaching olive oil, and is also used as a raw material for chemical synthesis, lubricants, and biofuels. Oilseed cake and meal are valuable concentrated feed containing up to 45% protein, which in composition and nutritional value is close to soy protein.

Given favorable overwintering, winter rapeseed leads in productivity among all oil crops in Belarus. In southern regions, it is profitable to grow as an intermediate crop for green forage and green manure in post-mowing and post-harvest sowings. The plant forms a tap, weakly branched root and an erect, branching stem with a glaucous waxy bloom. The lower leaves are lyrate and petiolate, the middle ones are elongated-lanceolate, and the upper ones are lanceolate. The yellow flowers are gathered in loose racemes; the fruit is a pod containing 4–5 spherical dark brown seeds.

The official lists of permitted cultivars include 13 winter rapeseed and 15 spring rapeseed cultivars. Domestically bred cultivars occupied 95% of the winter rapeseed area in 2007. The most common winter cultivars are Lider (45% of the area), Kozerog (more than 30%), and Progress (12%); Dobrodey and Zorny are sown less frequently. The line of spring rapeseed is represented by Belarusian cultivars Antey, Vodoley, Hermes, Granit, Magnat, Neman, Smak, Strelets, Yavar, Yantar, as well as foreign cultivars and hybrids (Ability, Liaison, Siesta, Slavutich, Ural, Hanna, etc.).

Rules for placement in crop rotation and sowing dates

When choosing a predecessor for rapeseed, the phytosanitary condition of the field is of key importance. Neglecting the rules of crop rotation leads to the accumulation of common infections in the soil. Rapeseed is affected by the same pathogens as many other popular crops in the crop rotation:

• sclerotinia also develops on peas, clover, and sunflower;
• rhizoctonia is dangerous for peas, fava beans, and sunflower;
• verticillium wilt affects peas, sunflower, alfalfa, clover, potatoes, and sugar beet;
• clubroot and neck rot affect all cruciferous crops.

Winter rapeseed requires early autumn sowing, so predecessors must vacate the field in a timely manner. The best options are annual grasses for green forage and early potatoes. If harvesting is fast, sowing after barley and winter cereals is permitted. Due to the late harvesting dates of spring wheat and oats, sowing winter rapeseed after them is prohibited. Winter rapeseed itself serves as an excellent predecessor for winter and spring cereals.

It is advisable to place spring rapeseed after small grain cereals. Sowing after any cereal predecessors is permitted, but placement after cruciferous crops is strictly excluded. One should also avoid fields after peas and flax.

• Optimal sowing date for winter rapeseed — first ten days of August
• Return period for rapeseed to the same field — not earlier than 4 years
• 1000-seed weight — 3—7 g
• Yield of spring cultivars and hybrids — 22—40 centners/ha

Soil requirements and pre-sowing preparation

Spring rapeseed is resistant to spring cold spells. Its seeds begin to germinate at a temperature of 1–3 °C, seedlings withstand frosts down to −3...−5 °C, and adult plants tolerate temperature drops down to −8 °C. It is best to place the crop on fertile sod-podzolic light and medium loamy soils. Sandy lands are poorly suited for rapeseed due to low water-holding capacity, as are areas with high groundwater levels and peat-bog soils, where there is a high risk of root rot and bacteriosis.

Rapeseed produces high yields of seeds and green mass only on a high agricultural background. To produce one ton of oilseeds, plants consume a significant amount of macronutrients, which must be taken into account when calculating doses of mineral fertilizers.

The soil for rapeseed is prepared as carefully as for winter cereal crops. Small seeds require a perfectly leveled field surface free of clods, furrows, and ridges; therefore, the depth of tillage before sowing is only 4–5 cm. During harvesting of the cereal predecessor, ensure that stems are cut low and straw is completely removed. A large amount of crop residues complicates tillage, reduces sowing quality, binds soil nitrogen, and inhibits the seedling emergence of rapeseed.

Winter rapeseed responds poorly to minimum tillage following a cereal predecessor. When planting after perennial grasses, it is important to prepare a finely crumbled top layer and compact the soil at a depth of 2–3 cm, strictly following the sequence of technological operations.

1. Ploughing one month before sowing for high-quality incorporation of the sod.
2. Cultivation 7–10 days after ploughing to level the field.
3. Sowing with combined units that integrate pre-sowing soil preparation and precision seeding.

Before sowing, it is essential to protect the seed from root rots and fusarium at the initial stage of development. To do this, seed treatment or coating with TMTD or Vitavax 200 is carried out. It is advisable to combine the treatment with the application of micronutrients at a rate of 200 g of boron and 300 g of manganese per ton of seed.

Sowing technology and integrated crop protection

Sowing is carried out using row or wide-row methods with inter-row spacing of 30 and 45 cm. Spring rapeseed is sown as early as possible — as soon as the soil dries out. This allows seedlings to grow stronger before the mass appearance of pests.

• Seed germination temperature — 1–3 °C
• Sowing depth — 2–3 cm
• Application rate — 1.1–1.5 million seeds/ha
• Seedling density in autumn — 80–120 plants/m²
• Seedling density in spring — 60–100 plants/m²
• Yield losses without pest protection — 30–75 %

The main threat to spring rapeseed seedlings is the crucifer flea beetle. Early sowing and pre-sowing seed treatment help protect the crops from them. In autumn, the turnip sawfly can cause serious damage to winter rapeseed crops. Upon its appearance, insecticides such as Decis, Karate, Sumi-alpha, or their analogs are applied.

During the growing season, spring rapeseed is threatened by a complex of pests: the pollen beetle, leaf weevils, large stem weevils, seed weevils, the swede midge, and aphids. Two treatments are performed against them. The first insecticide application with pyrethroids (Decis, Karate, etc.) is done at the beginning of the budding stage when the pest population reaches 3 per plant or when 10 % of the crops are infested. After 10–12 days, at the end of the budding stage, the treatment is repeated with Fastac (10 %).

To control weed vegetation, an integrated system is used. Before sowing, herbicides such as Treflan (and its analogs), Trophy 90, or Teridox are applied to the soil. After sowing and post-emergence, Butisan 400, Butisan Star, or Sultan 50 are applied. For the destruction of dicotyledonous weeds, Lontrel 300 is used, and against grass-type species — graminicides such as Fusilade, Aramo, Pantera, and others.

In recent years, the development of alternaria (black spot), white and grey rot, downy mildew, cylindrosporiosis, phoma, and bacteriosis has increased on winter rapeseed. Protection is based on seed treatment and adherence to crop rotation, while high-yielding fields are additionally treated with fungicides at the end of flowering. For complete soil cleaning from accumulated pathogens, the non-rapeseed period in the crop rotation should be at least 4–5 years.

Harvesting and post-harvest rapeseed processing

Timely harvesting of rapeseed minimizes losses from pod shattering. To accelerate ripening and facilitate the harvesting of unevenly ripening crops, desiccation is performed. Work begins in the early ripening phase, when pods on the central raceme turn brown and seed moisture drops to 30–35%. For treatment, Reglone or glyphosate-based preparations are used — Roundup, Glialka, Glyphos.

Rapeseed crops are harvested by direct or two-phase methods. Direct combining is suitable for weed-free fields in favorable weather. The two-phase method is used on weedy plots, during uneven ripening, or if drying facilities are limited. Swathing is carried out at 30–40% seed moisture, when pods are yellow-green and the seeds inside are brown and black.

Biological characteristics and cultivation of winter cress and mustard

As an alternative to rapeseed, farms cultivate winter cress (winter small-seeded rapeseed), as well as brown and white mustard. These crops are less demanding of soil and climatic conditions and suffer less from pests. Wintering forms of winter cress excel winter rapeseed in winter hardiness and ripen at an earlier time. In the Polesie regions of Belarus, the domestic winter cultivar Veronika is sown, in Ukraine — the Mestnaya Chernyakhovskaya cultivar, while in the Non-Chernozem region of Russia, spring winter cress is mainly grown. The agricultural technology for the crop does not differ from that of rapeseed; sometimes it is cultivated in a mixture with flax or mustard.

Brown mustard is a long-day plant, resistant to drought and cool weather. Its seeds begin to germinate at a temperature of 1–2 °C, and seedlings tolerate spring frosts down to −3...−5 °C. The best soil for the crop are chernozems and chestnut soils, on which it forms high yields and serves as an excellent honey plant. In Belarus, the Krasnolistnaya cultivar is regionalized; in the Russian Federation — Donskaya 5 and VNIIMK 11.

In crop rotation, brown mustard is placed after winter crops, row crops, and grain legumes. It must not be sown after other cruciferous crops, including rapeseed, due to common pests and diseases. Mustard itself is a good predecessor for spring cereals and corn, and is also used as a cover crop for alfalfa.

• Growing season of brown mustard — 90–100 days
• Application rate (row method) — 3–4 million seeds/ha
• Application rate (wide-row method) — 2–3 million seeds/ha
• Sowing depth of seeds — 3–4 cm
• Humidity of seeds during storage — no more than 10 %

1. Thoroughly prepare the soil using the improved autumn ploughing method.
2. In spring, carry out pre-sowing cultivation to a depth of 5–7 cm and level the field with harrows.
3. Perform sowing at early dates to protect seedlings from drought and flea beetles.
4. Roll the field immediately after sowing is completed.
5. Maintain the crops: carry out harrowing over the emergence, till the row spacings in wide-row sections, and carry out pest control.

Harvesting of brown mustard is carried out using the separate method when most of the pods turn yellow and leaves begin to fall. Delaying mowing is unacceptable, as the lower pods crack and lose seeds. The mown mass is dried in swaths, avoiding over-drying. Cleaned seeds are poured into storage at a humidity of no more than 10%.

White mustard is valued as a honey plant, green manure, and a source of high-quality food and technical oil. In livestock farming, it is used for green forage — 100 kg of green mass contains 12 feed units. The crop is represented by the cultivars Aresa, Elena, and Yarynka. Its fruit is a pod covered with stiff hairs containing 5–6 seeds, which does not crack upon ripening, which significantly reduces losses.

White mustard is a moisture-loving and cold-resistant crop, a long-day plant. Due to the high absorbing capacity of its roots, it grows well on podzolic soil.

Early sowings suffer less from flea beetles (a dangerous pest on seedlings) and drought. The application rates for the wide-row method are 2 million, and for the standard row method — 3.0–3.5 million germinating seeds per 1 ha. Depth of sowing seeds 3–6 cm.

Combine harvesting begins when all pods of the main mass of plants have ripened. Seeds are stored at a humidity of no more than 10 %.