Winter cereals of group I

Winter hardiness

Winter hardiness is the resistance of plants to unfavourable conditions during the overwintering period. In terms of winter hardiness, cereal crops can be arranged in decreasing order: rye, triticale, wheat, barley, oats.

The resistance of winter crops to low temperatures developed during evolution. Winter hardiness and frost resistance are complex physiological properties; they are variable and are formed at certain stages of development, especially during the hardening of plants. I. I. Tumanov determined that hardening takes place in autumn in two phases. The first phase occurs under conditions of intense light and temperatures from 8 to 15 °C during the day and about 0 °C at night. In the first phase, plastic substances, especially sugars, accumulate in the plants, primarily in the tillering nodes, since during cool nights their consumption for growth processes and respiration slows down. Before entering winter, winter crops accumulate 20–25% sugars calculated on dry matter. Having passed the first phase of hardening, plants are able to withstand temperatures down to −10…−12 °C.

The second phase of hardening is the main one. In this phase, gradual dehydration of cells occurs, water flows out of the cytoplasm into intercellular spaces, and insoluble organic substances in the cells are transformed into soluble ones. As a result, the concentration of cell sap in the tillering nodes and leaf sheaths increases.

Winter rye passes the second phase of hardening faster, winter wheat more slowly, and winter barley very slowly. After the second phase, the resistance of plants to unfavourable wintering conditions increases. This phase takes place in plants in light and in darkness at temperatures from 0 to −5 °C.

The duration of the hardening phase depends on the plant species, variety, and meteorological conditions. During hardening, soluble carbohydrates (oligosaccharides) and amino acids (proline, asparagine, glutamic acid) accumulate in vegetative organs, especially in tillering nodes. The amount of accumulated carbohydrates and amino acids directly affects the frost and winter hardiness of varieties. Oligosaccharides, gradually turning into soluble sugars, increase frost resistance.

Hardening depends on meteorological conditions in autumn. Clear, sunny weather with warm days and cool nights favours hardening; by contrast, cloudy weather with warm days and nights slows it down. Optimal sowing dates and autumn fertilizing with phosphorus-potassium fertilizers promote good hardening.

For complete hardening under optimal conditions, 20–24 days are required.

Freezing out

In the steppe regions of the North Caucasus, Ukraine, and the Volga region, damage and death of winter crops are often noted from freezing out, associated with weak autumn development, sharp temperature fluctuations with insufficient snow cover, and also with the presence of packed and hanging ice crust.

In the southern part of the forest-steppe, in years with insufficient snow cover, winter crops are at risk of freezing out. In the northern regions of the Chernozem zone and in the south of the Non-Chernozem zone, a frequent cause of death is ice crust. In the central regions of the Non-Chernozem zone, winter crops die from suffocation under snow and waterlogging, sometimes from freezing out.

In the north-east of the Non-Chernozem zone, death of winter crops occurs from suffocation under snow, caused by deep snow cover and the development of snow mould and sclerotinia. In the north-west of the Non-Chernozem zone and in the Baltic region, winter crops suffer from waterlogging associated with excessive moisture.

Freezing out occurs because water crystallizes in intercellular spaces under the influence of low temperatures. The resulting ice crystals draw water out of the cells, which leads to an increase in the concentration of cell sap and dehydration of the protoplasm. The formation of ice in intercellular spaces and in cell sap does not yet lead to death of the plant. With a gradual increase in temperature, vital activity is restored, and the water formed during slow melting of crystals is absorbed back into the cells. However, dehydration of the protoplasm leads to death of the cell. Plants die from freezing of the protoplasm itself, which is noted only during severe frosts and insufficiently deep placement of the tillering node.

In winter-hardy varieties, the tillering node is located deeper than in less winter-hardy ones. To combat freezing out of winter crops, it is necessary to use frost-resistant varieties. Also important are soil tillage, nutrient supply, optimal sowing dates, and seed placement.

Snow retention or snow accumulation is effective, primarily in the south-east of Russia, the North Caucasus, Ukraine, and other regions. Rolling snow on winter crop sowings is used only when snow cover is more than 15 cm; with a smaller thickness, the snow cover between the rolls remains too small or is completely removed, which leads to freezing out of plants.

The effectiveness of snow retention as a method of protecting winter crop sowings from freezing out is confirmed experimentally. For example, in the steppe zone, with snow cover from 2 to 12 cm, freezing out amounted to 50% of wheat plants, whereas with a thickness from 15 to 25 cm it was 27%, and with a thickness of 35–45 cm it was 4%. Stable snow cover of sufficient thickness prevents the formation of ice crust; on the other hand, snow retention carried out on an already formed ice crust leads to preservation of winter crops under the crust. Melting snow makes it looser and spongy, and in such a state it is not dangerous.

In the southern and south-eastern regions, strip (kulis) sowings show high effectiveness as a method of snow retention. For kulis, sunflower or mustard is used; maize and sorghum are not used, since they lodge after the first frosts. According to long-term experiments of the Voronezh Agrarian University (V. A. Fedotov), kulis sowings show high effectiveness in the Central Chernozem zone. Kulis are sown during fallow cultivation no later than mid-July, that is, 45–55 days before sowing winter crops, perpendicular to the prevailing winter winds.

Single-row kulis with a distance of 8 or 12 m are used. For this, seeders with one sowing coulter are used as part of a unit of 2–3 cultivators. The first pass is made along markers, subsequent ones along the marker lines. The seed rate for kulis is: for sunflower 1.5–3 kg/ha; for rapeseed or mustard 0.4–0.5 kg/ha. At the same time, 20–25 sunflower seeds or 60–70 mustard seeds should be sown per 1 metre of kulis row.

Two-row kulis are also used, with the density in each row reduced by half. Soil cultivation between kulis is carried out in the same way as in clean fallow, leaving small protective zones along the rows. Winter crops are sown across the kulis to reduce damage to young plants. Summer kulis are created over the entire area of clean fallow, and if possible also on occupied fallow. Considering that creating summer kulis requires small costs, owing to the increased yield of winter crops this method is generally economically justified.

The resistance of winter crops to unfavourable conditions is influenced by the application of granular superphosphate enriched with manganese in the rows at a rate of 10–12 kg/ha P₂O₅ during sowing. Fertilizing with phosphorus and manganese in the initial period of vegetation promotes the accumulation of plastic substances in the tillering nodes and increases winter hardiness. Abundant nitrogen nutrition during this period enhances plant growth and negatively affects hardening.

After the beginning of spring regrowth, the resistance of the tillering node to negative temperatures decreases. Thus, at a temperature of −8…−10 °C, winter crops that have started growing may die. In addition, after emergence from under the snow, frozen plants remain green, but after thawing they turn yellow.

Suffocation under snow

The main causes of suffocation of sowings:

• entering winter as strongly overgrown and poorly hardened plants, covered in winter by a thick layer of snow that does not melt for a long time in spring;
• shallow freezing of the soil, while owing to heat under the snow cover the plants begin to revive and respire;
• as a result of the formation of a hanging ice crust, under which plants begin to renew vital activity under the influence of heat and light;
• when a large amount of snow falls suddenly on unfrozen soil, while plants, continuing vital activity under the snow, quickly consume nutrient reserves.

Suffocation under snow is noted when winter crops harden poorly, when snow falls on unfrozen soil. For a long time, death of winter crops from suffocation was explained by the lack of air oxygen supply. Later it was established that even under a thick snow cover, in direct proximity to suffocating plants, the air contains a sufficient amount of oxygen. I. I. Tumanov proved that plants suffocate not from a lack of oxygen but from exhaustion. Using accumulated nutrients for respiration, plants under conditions of almost complete absence of light under snow cannot replenish reserves through assimilation.

Further exhaustion of plants occurs as a result of protein breakdown and accumulation of amino acids. Weakened plants are easily affected by snow mould and other diseases. According to data of I. M. Petunin and V. A. Moiseichik, death from suffocation in the Non-Chernozem zone occurs at a temperature at the depth of the tillering node of about 0 °C after 90–100 days. Winter rye is less resistant to suffocation than winter wheat, especially in the central and northern regions of Russia.

To prevent plant death from suffocation, in autumn the sowings are rolled after snow falls on thawed ground. With dense snow, freezing of the soil accelerates, which slows down vital processes in plants, and suffocation is prevented.

Of great importance for preventing suffocation is too early and dense sowing, which increases the probability of death from suffocation, as well as excessive nitrogen nutrition. In the case of overgrowth, primarily of rye, autumn high mowing may be useful.

Waterlogging

Waterlogging is noted in lowered places where meltwater accumulates and is retained. As a result, anaerobic processes intensify in plant tissues, poisoning and death of plants occur. When exposed to flooding, plants turn yellow after 8–10 days, and after 12–15 days they become discoloured and die. Winter rye is less resistant to waterlogging than winter wheat.

To prevent waterlogging, open drainage is arranged; for this, in the moistened zone after sowing, drainage furrows are made that remove excess water and prevent stagnation. In “saucers”, water is released by slitting or drilling wells down to a water-permeable soil layer.

Heaving of plants

Heaving, that is, displacement of tillering nodes to the soil surface, leads to rupture of roots and is caused by the formation of subsurface cellular ice or soil settling. It is more often observed on heavy and structureless soils. Heaving is especially dangerous with alternating freezing and thawing during frosty, snowless, windy autumn or spring, as well as dust storms.

To prevent heaving, varieties with sufficiently deep placement of the tillering node are used. To prevent heaving from soil settling, the last deep soil tillage is carried out at optimal dates without delay, since it is important that the soil has time to settle before sowing.

If for some reason sowing is carried out on unsettled soil, it is preliminarily compacted with ring rollers. In years when tillering nodes are exposed, spring rolling of winter crops is carried out with smooth trailed rollers of the ZKVG-1.4 type. The tillering nodes are pressed to the soil, which promotes moisture supply to them and accelerates the formation of new, secondary roots. Spring harrowing is not carried out when heaving of plants is detected.

Pre-sowing treatment of winter crop seeds with retardants leads to deepening of the tillering node by 10–15 mm and better development of the root system; as a result, winter hardiness and yield increase. Retardants are effective only with early and optimal sowing dates; when delayed, they may give a negative result.

Ice crust

Ice crusts can be packed, that is, directly on the soil surface, and hanging. The most dangerous is a packed transparent film. A crust that does not affect the tillering nodes is less dangerous.

Under a hanging ice crust, plant vital activity may persist, which promotes their suffocation and waterlogging. To combat hanging ice crust, it is destroyed completely or in strips.

Packed ice crust appears during alternating thaws, when snow completely melts, and subsequent cooling, when the resulting water freezes. In this case, the ice crust freezes together with the upper soil layer. It poses a danger to sowings, since ice does not weaken, like snow, but on the contrary enhances the effect of frost owing to 5 times greater thermal conductivity, which leads to freezing out of winter crops.

Freezing of plants completely into ice leads to disruption of gas exchange.

It is impossible to destroy packed ice crust without damaging plants. To mitigate the negative effect of the crust, snow retention is carried out. Also, at the end of winter, the surface is sprinkled with ash, peat crumbs, potassium fertilizers, or other materials to accelerate melting.

Ice crust on the snow surface (crust) is considered not dangerous for sowings.

Snow mould and sclerotinia

Snow mould on winter crops is caused by the parasitic fungus Microdochium nivale (syn. snow fusarium Fusarium nivale Ces.). Plants, more often winter rye, emerging from under the snow, are covered with a whitish or pink coating. Snow mould develops on dead or dying plants as a result of suffocation or other unfavourable phenomena. The mould can also affect living plants weakened during overwintering.

In addition to snow mould, in spring a disease caused by the fungus Sclerotinia borealis (syn. Sclerotinia graminearum Elenev) can develop on overwintered winter crops. In this case, first white, then dark brown dense nodules, sclerotia, appear on the plants. Mass infection by sclerotinia is noted in the regions of Ivanovo, Nizhny Novgorod, and Kirov oblasts.

To prevent damage to sowings by snow mould, varieties resistant to fusarium are introduced. Disinfection of seeds before sowing, for example with fundazol, removal of excess snow, arrangement of drainage furrows, release of excess water with the help of wells, and raking of dead leaves in spring to remove infection foci from the field are also effective.

Seeds

To obtain high and stable yields of high-quality grain, released intensive varieties resistant to lodging are sown. With intensive technology and large sown areas, it is advisable to sow at least two varieties.

The seeds should be large, uniform, of the first class of sowing conditions. The weight of 1000 grains is 40–50 g, growth force is not less than 80%.

The best option, especially for the Non-Chernozem zone, is if the seeds are from last year’s harvest from a carry-over fund. Freshly harvested seeds in the Non-Chernozem zone may be physiologically immature.

Before sowing, seeds are treated with moistening (10 L of water per 1 t of seeds) with granosan, fundazol, baytan, pentathiram, vitavax 75% (2.5–3 kg/t of seeds), or other preparations.

Additional treatment of seeds with retardants, for example, tur (chlormequat chloride) or others, serves as an effective method of increasing the resistance of winter crops to unfavourable overwintering conditions, lodging, and drought, and helps increase yield by 0.2–0.5 t/ha.

Crop rotation

The main requirements for predecessors of winter cereal crops:

• sufficient time between harvesting the predecessor and sowing winter crops in order to prepare the soil with high quality;
• fields must be clean of weeds with sufficient reserves of moisture and nutrients.

Cereal crops, especially winter crops, are very sensitive to continuous sowing. Their yield with repeated sowing, even at a high level of agrotechnology, decreases strongly, with the exception of winter rye. The use of fertilizers somewhat reduces the effect of continuous sowing; crop rotation in this case increases the yield by 30–34% in spring cereals and by 34–53% in winter crops, which makes it possible to use continuous sowing of cereals against a highly fertilized background and after good predecessors.

The best predecessor is clean fallow, which makes it possible to effectively clean fields of weeds and accumulate reserves of moisture and nutrients in the soil. Sowings after clean fallow develop quickly in autumn, overwinter well, and give high yields. However, clean fallow is mainly used in arid climate conditions.

In the zone of sufficient moisture, occupied fallow is a good predecessor. In this zone, the yield of winter crops after occupied fallow approaches the yield after clean fallow, but the shortfall in grain is compensated by the yield of the fallow-occupying crop.

The best fallow-occupying crops include maize for green fodder, early potato, early ripening pea, vetch-oat and vetch-rye mixtures, perennial grasses for green fodder and hay, lupine, and other green manures for green fertilizer.

As non-fallow predecessors of winter crops, sunflower, maize, castor bean, winter barley, winter wheat, winter rye, and sometimes spring barley are used. At the same time, they are grown for grain and harvested later than the fallow-occupying crop, so after them a minimum of time remains for soil preparation. As predecessors, these crops are used in regions with a long warm and moist autumn. Here, predecessors can also be grain legumes and maize for silage.

When sowing winter crops after occupied fallow and non-fallow predecessors, the fields must be freed in the Non-Chernozem zone no less than a month before sowing winter crops, and in other regions 1.5–2 months before.

Under irrigation and in arid conditions, sowing after occupied fallow is possible. On heavily weed-infested soils under conditions of sufficient moisture, clean fallow may temporarily be effective.

Winter cereal crops cultivated using intensive technology are placed after the best predecessors ensuring good moisture accumulation, for example, after a layer of perennial grasses, grain legumes, annual grasses. In the zone of insufficient moisture, after clean fallow.

A high level of intensification and chemicalization of agriculture creates the possibility of expanding winter crop sowings after non-fallow predecessors. In the steppe zone, winter crops are sown after early-harvested winter and spring cereals, maize for grain, and sunflower. In the Non-Chernozem zone, predecessors of winter crops can be perennial grasses of the 2nd year of use, fibre flax, buckwheat, pea, etc. Mandatory conditions for obtaining high yields are sowing the preceding crop after the best predecessors, timely harvesting, and application of fertilizers.

Soil tillage system

Main page: Soil tillage for winter crops

Sowing

Sowing winter crops at optimal dates in moist soil ensures uniform emergence, good development of the root system, tillering, and autumn hardening. Too early sowing, especially with a warm and long autumn, leads to overgrowth of plants and damage by pests and diseases. Delay in sowing does not allow plants to tiller before frosts, form a strong good root system, and undergo hardening. In both cases, winter crops overwinter poorly and are subjected to freezing out and other unfavourable effects.

For good rooting and tillering (before entering winter, 3–4 developed shoots should form) under normal weather, about 50 days are required from emergence to cessation of autumn growth. Growth stops at a temperature below 5 °C. The dates are specified taking into account the crop, variety, weather conditions, moisture, and quality of soil tillage and predecessors.

Winter cereals are sown by the conventional row method with row spacing of 15 cm, narrow-row with row spacing of 7.5 cm, and cross method.

Seeding rates. To determine seeding rates, climatic features, seed quality, variety, soil properties, dates, and methods of sowing are taken into account. When field germination decreases, for example owing to late sowing or dry soil, the seeding rate is increased. In regions of sufficient moisture on fertilized soils, with high agrotechnology, narrow-row sowing, and for strongly tillering varieties, the rate is reduced. In arid conditions, on less fertile soils, the rate is reduced.

Sowing is carried out leaving a technological track of 1800 mm with two unsown strips of 450 mm.

Sowing depth. To obtain uniform emergence, seeds are placed in the moist soil layer and at the same depth. Too deep placement, especially of rye, reduces tillering and leads to thinning. With shallow placement, there is a risk of plants being blown out, exposure of tillering nodes, and freezing out.

Fertilization

Winter cereal crops, primarily wheat, are demanding of soil fertility. To form 1 t of grain and the corresponding amount of straw, 25–40 kg of nitrogen, 9–15 kg of phosphorus, and 16–30 kg of potassium are consumed. Nutrient removal by intensive varieties is 1.5–2 times greater than by extensive ones.

On chernozem soils of the central and southern regions, 15–20 t/ha of manure, 30–60 kg/ha of phosphorus fertilizers, and 30–45 kg/ha of potassium fertilizers are applied as the main fertilizer. Fertilizers are applied under ploughing (in black fallow in autumn, in early fallow in spring) or in the first half of summer during fallow cultivation. In arid regions, organic fertilizers are applied in autumn under the main ploughing. In the Non-Chernozem zone, 30–40 t/ha of manure, 45–60 kg/ha of phosphorus, and 30–50 kg/ha of potassium are applied. The greatest effect is achieved with combined application of organic and mineral fertilizers.

For winter cereals, part of the nitrogen fertilizers is applied before sowing to create optimal conditions for development in the autumn period.

During sowing, phosphorus fertilizers are applied in the rows at a rate of P10–20. On soils poor in nitrogen, primarily after occupied fallow or non-fallow predecessors (except legumes), N_20–30 is applied during pre-sowing cultivation.

In spring, after snow melt, winter crops need top dressing primarily with nitrogen fertilizers, and to a lesser extent with phosphorus and potassium. At the same time, 30–45 kg/ha of nitrogen and 15–20 kg/ha each of phosphorus and potassium are applied.

In occupied fallow, the main fertilizer is applied under the fallow-occupying crop, and also in spring during pre-sowing cultivation N_20–30, and in the rows during sowing of fallow-occupying plants P_10–20.

After harvesting the fallow-occupying crops, under deep ploughing or, with surface tillage, under disking, 35–50 kg/ha of phosphorus, 30–45 kg/ha of potassium, and, if the soil is deficient, 20–30 kg/ha of nitrogen are applied. Row fertilizer and top dressings are the same as for sowings after clean fallow.

On sandy, clayey, and podzolic soils of the Non-Chernozem zone, green fertilizer is effective.

Liming is carried out under deep ploughing at a dose of 4–6 t/ha depending on acidity. The aftereffect of lime is 7–10 years. Small doses are applied under disking and incorporated more shallowly.

All fertilizer application rates must be adjusted taking into account the actual content in the soil and the needs of plants for the planned yield.

Nitrogen fertilizers are applied as top dressing. If, according to soil diagnostics, the reserves of mineral nitrogen in the soil in autumn are insufficient, then before sowing 20% of the total calculated rate of nitrogen fertilizers is applied. The first top dressing is carried out in spring in the tillering phase, the second in the stem elongation phase.

Average increases in grain yield on chernozems from top dressing with nitrogen fertilizers are 0.2–0.6 t/ha, on sod-podzolic and grey forest soils 0.3–0.7 t/ha.

In regions of sufficient moisture, in the first top dressing 30% of the calculated nitrogen rate is applied, in the second 50%, but not more than 80 kg/ha. If nitrogen fertilizers were not applied in autumn, then in the first top dressing 1/3 of the calculated rate is applied, and in the second 2/3.

In arid regions and under conditions of rapid soil drying, the first top dressing is carried out by root application in an amount of 50% of the rate.

To improve grain quality, in the heading phase, top dressing with 40 kg/ha of nitrogen is carried out.

Top dressing can be carried out with RUM-5, 1RMG-4 machines along the technological track. Deviation from the established rate should be no more than ±5%. The width of fertilizer spreading may exceed the working width of the sowing unit by 5%.

Crop care

The main methods of caring for winter cereal crops include: rolling, top dressing, snow retention, spring harrowing, control of lodging, weeds, diseases, and pests, irrigation, and artificial supplementary pollination of winter rye.

Post-sowing rolling is carried out if sowing was done in insufficiently moist or loose unsettled soil, with ring-spur rollers. This method promotes rapid and uniform emergence, good autumn tillering, and overwintering.

Under conditions of excessive moisture in autumn, in lowered relief areas, to prevent water accumulation, furrows or other methods of water removal are arranged.

Snow retention is carried out in arid conditions and regions with little snow in winter. The method increases yield by 0.3–0.6 t/ha. A snow cover height of 30–50 cm is considered sufficient. For snow retention, field-protective forest belts, kulis, brushwood shields are used; when snow cover is more than 10 cm, snow ploughs are used.

In spring, methods are carried out in sowings to retain meltwater or remove it in lowered places.

Early spring harrowing reduces moisture loss, improves the air regime and microbiological activity in the soil, destroys weed seedlings, removes dead plant parts, and prevents the appearance of crust and cracks on the surface.

Well-overwintered sowings are harrowed in two passes, weakened ones in one pass. On sandy and sandy loam soils, severely damaged sowings after winter are not harrowed. Harrowing is replaced by rolling in the case of heaving of tillering nodes.

Plant protection system

Measures to control pests, diseases, and weeds are planned taking into account development forecasts. The dates and advisability of carrying out are adjusted according to survey data and assessment of the phytosanitary state of sowings.

Treatment with chemical plant protection agents is carried out with sprayers, for example, OPSH-15, POM-630, or analogues.

Herbicide treatment is carried out before heading. To control weeds, the following herbicides are used:

• 2,4-D amine salt 40%, application rate 1 kg/ha;
• Lontrel 30%, application rate 0.2 kg/ha;
• Dialen 40%, application rate 1.2 kg/ha.

Treatment is carried out in the tillering phase with aqueous solutions; the working solution application rate is 150–200 L/ha.

To control brown rust, powdery mildew, and root rots, sowings are treated with fungicides:

• Bayleton 25%, application rate 0.25 kg/ha;
• Fundazol 50%, application rate 0.3 kg/ha in the interphase period tillering–flowering.

Against cutworm caterpillars (Agrotis segetum) and cereal flies (Chloropidae), when the harmfulness threshold is exceeded, treatments are carried out with chlorophos, metaphos, or vofatox.

Against the sunn pest (Eurygaster integriceps), cereal aphids, cereal leaf beetle, thrips, and Swedish and Hessian flies, sowings are treated with insecticides:

• metaphos 30%, application rate 0.2–0.4 kg a.i./ha;
• rogor 40%, application rate 0.28–0.6 kg a.i./ha.

To control mouse-like rodents, baits are placed, for example, zinc phosphide (application rate 290–320 g/ha) or bactorodencid (application rate 1–2 kg/ha).

To prevent lodging of sowings, retardants are used on:

• winter wheat — tur 60%, application rate 4 kg a.i./ha;
• winter rye — campozan M, application rate 2 kg a.i./ha.

Treatment is carried out at the end of the tillering phase and the beginning of stem elongation.

Harvesting

Grain harvesting is carried out by the separate (two-phase) method or by direct combining (single-phase). In the separate method, plants are cut at a height of 15–20 cm and laid on stubble in windrows. When the windrows dry, threshing is carried out. The two-phase method makes it possible to reduce grain losses and labour costs. Separate harvesting begins in the wax ripeness phase.

With full ripeness, prolonged rainy weather, thinned and short sowings, and intensive cultivation technology, harvesting is carried out by direct combining. In this case, the crops are cut, picked up, and threshed immediately.

During harvesting, grain is cleaned and dried to a moisture content of 13–14%. During harvesting or after the field, it is freed from straw to prepare the soil for the following crops.

Fuchsine staining method

For rapid determination of the state of plants, P. A. Vlasyuk and M. A. Gurilyova proposed a method based on staining sections of the growth cone with acid fuchsine solution. Under the action of fuchsine, dead parts acquire a red-pink colour, whereas the undamaged growth cone is not stained.

Monolith method

The monolith method is the most widespread, simple, lengthy, labour-consuming, and less reliable. For this, monoliths 30×30×15 cm are cut out in the field, placed in boxes, and covered to protect them from frost. Then they are covered with a moist cloth and gradually thawed at a temperature of +5…+10 °C. After thawing, the boxes are transferred to the light and the temperature is raised to +15…+20 °C; the above-ground part of the plants is cut at a height of 5–6 cm so that the regrowth of new leaves is better visible. The number of living plants is counted after 10 and 20 days. Living plants are those that have formed new leaves and nodal roots.

Method of regrowth on water

Regrowth of plants on water makes it possible to accelerate determination of plant viability. For this, samples are cut out to a depth of 8–10 cm, covered with burlap and film. After thawing, the plants are separated from the soil and washed with water. The roots are cut at a distance of 3–4 cm from the tillering node, and the leaves at a height of 5–6 cm, and placed in germination trays with water, which is changed after a day. Then the plants are inserted into holes in the lids and placed in a light place at a temperature of +15 °C. Viability is assessed after 7 days; during this time, living plants form new leaves and roots.

Accelerated method of regrowth of tillering nodes

An accelerated method for determining plant viability by the intensity of regrowth of the tillering node, proposed by V. M. Orlov and A. I. Vigilyova in the 1970s–80s, is also used (Don Zonal SRIA). The principle of the method is that in plants taken by the previous methods, the stems are cut at a distance of 1–1.5 cm from the tillering node, and the roots are completely cut off. Such plants are placed in glass containers (Petri dishes) on moistened filter paper, cotton wool, or gauze, covered with a lid, and kept for 12–24 h at a temperature of 24–26 °C or 24 h at 10–15 °C. Well-preserved plants give stem growth up to 10 mm, weakened ones 3–5 mm. After this, the stand density of plants per 1 m² is determined by counting living, weakened, and dead plants.

The method was improved. Along the diagonal of the field, 30–50 plants with undamaged tillering nodes are selected. Selection is, if possible, carried out at an air temperature of −3…−5 °C. At an air temperature below −14 °C, the selected samples are protected from cold. The samples are thawed at a temperature of +5–6 °C, then washed from the soil in cold water. After that, leaves and roots are cut 3–4 cm from the tillering node; the segments are placed in glass or plastic jars with a volume of 250–500 mL or in polyethylene bags with moist filter paper (cotton wool) at the bottom. More than 50 segments are placed in the jars and closed to create a moist environment. Regrowth is carried out for at least 3 days at a temperature of +18 °C in a shaded place.

Spring survey of the state of winter crop sowings

On the basis of the spring survey of winter crop sowings between the renewal of vegetation and harrowing, a decision is made for each field. Good sowings are considered to be green sowings, plants actively renewing vegetation; the tillering node is white and dense, and during regrowth white nodal roots appear. Dead plants have a brown underground part, a yellow-brown watery tillering node, and roots are not formed. The distribution of dead plants in sowings may be relatively uniform or patchy, when they occur as bare patches subjected to waterlogging or ice crust in depressions, as well as freezing out on elevated areas. Based on the survey results, a visual assessment of sowings is established:

• 5 points — almost all plants overwintered, no thinning or patches;
• 4 points — overwintering good, thinning not more than 25%;
• 3 points — thinning and death of plants amounts to 26–50% of plants;
• 2 points — more than 50% of plants died;
• 1 point — only single plants survived.

Sowings with scores of 5 and 4 are retained; strongly thinned sowings with scores of 1 and 2 are reseeded.

Fields with a score of 3, if the plants that survived and tillered well in autumn can form 400–500 ears per 1 m², the sowing is left. If patches of dead plants make up 50% of the area, they are sown with barley in compressed timeframes. If thinning is uniform across the field, sowings are left, providing good care, or completely reseeded. Undersowing, which is often practised in production, does not always give a positive result. The effectiveness of reseeding moderately thinned sowings depends on weather conditions in spring. With an early spring, reseeding is not carried out, since owing to good care they will give a good yield. With a late spring and rapid onset of warmth, the tillering period is shortened, and the yield will be low. In such cases, reseeding with early spring crops (barley, wheat) or late spring crops (buckwheat, millet, maize) is more advisable.

V. D. Medinets (Poltava Oblast, Ukraine) proposed an ecological indicator — the time of renewal of spring vegetation (TRSV), characterizing the expected combination of light and thermal conditions of winter crop life in spring. To obtain a high yield of good quality, the winter crop care system is adjusted taking into account the TRSV. This indicator is assessed by awakening plants under certain light and thermal conditions.

In years with an early TRSV, favourable conditions develop for root system development and tillering, phytomass accumulation proceeds intensively, but at the same time the tendency to shading and lodging increases. As a rule, a good yield of low quality is formed with reduced protein and gluten content in the grain.

With a late TRSV, sowings tiller worse, are formed low-growing, quickly pass into the heading phase, do not lodge, accumulate small phytomass, including a reduced yield with high protein and gluten content.

Taking this indicator into account makes it possible to correct the care system in a timely manner, for example, to use growth regulators and nitrogen top dressings. In the forest-steppe and steppe zones of the European part of Russia, in years with a late TRSV, the effectiveness of growth regulators is low even against the background of nitrogen top dressings. However, with an early TRSV, they serve as a means of increasing grain yield. With an early TRSV, top dressings are not carried out at very early dates, and the nitrogen dose is reduced.

When applying complete mineral fertilizer, the doses of phosphorus and potassium are increased. To improve grain quality, later top dressings (in the heading phase) are carried out with an increased nitrogen dose. With a late TRSV, to stimulate vegetative mass growth, the first and second top dressings are carried out as early as possible with increased nitrogen doses; if this is not possible, the entire dose is applied at early dates.

Varieties and seeds

Varieties must be released, of intensive type, responsive to a high agricultural background, and resistant to lodging. Winter wheat varieties must meet the requirements for strong, valuable, and durum wheat.

For sowing, large, uniform seeds of the first class of sowing conditions are used. Before sowing, treatment is carried out with permitted preparations of high effectiveness.

Incrustation of seed material with simultaneous use of fungicides, an adhesive, and an insecticide is promising.

Predecessors

The place of winter crops in crop rotation must ensure full use of natural resources, primarily soil moisture and nutrients. Therefore, winter crops are placed after the best, moisture-provided predecessors, for example, after clean and occupied fallow, grain legumes, a layer of perennial grasses, annual grasses, and other early-harvested crops.

Soil tillage system

Soil tillage system is built taking into account zonal features. It must ensure protection of the soil from erosion, accumulation and preservation of moisture, and maintenance of fields free from weeds. In the zone of insufficient moisture, clean fallow is cultivated with non-mouldboard implements. In regions of sufficient moisture on heavy soils, ploughing is carried out using implements of the PVR type.

When cultivating soil after non-fallow predecessors, flat-cutting cultivators and disk harrows are used.

For pre-sowing treatment, cultivators of the KSHP-8, KPS-4, and KSHU types and combined RVK units are used.

In the North Caucasus and the south of the Central Chernozem zone, combined AKP and AKR units are effective. Harrows or rollers are used in the unit with cultivators.

Before sowing, the field must be levelled; the number of soil clods 1–5 cm in size must be not less than 80% (by mass); clods larger than 10 cm are not allowed. Deviation of tillage depth from the specified one must be no more than ±1 cm.

Fertilization

Organic fertilizers are applied to the fallow field at a rate of 30–40 t/ha. On acidic soils, liming is carried out under the main treatment; the lime application rate must ensure a change in soil solution reaction to close to neutral (pH more than 6.5).

Rates of mineral fertilizers are determined taking into account the content of nutrients in the soil and the needs of plants for the planned yield. Phosphorus fertilizers are applied under the main treatment. During sowing in the rows — P20. The full rate of potassium fertilizers is applied under the main treatment; nitrogen fertilizers are applied in split doses during periods of maximum nitrogen consumption. If nitrogen is deficient in the soil, it is applied before sowing at a rate of 20–30% of the total nitrogen fertilizer dose.

Sowing

Sowing is carried out at optimal dates for specific soil-climatic zones with SZ-3.6A and SZP-3.6A seeders to a depth of 4–5 cm. The seeding rate is determined based on achieving the optimal density of productive stems.

To leave a technological track 1,800 mm wide with two unsown strips of 450 mm on the seeder directly following the tractor, the 6th, 7th, 18th, and 19th sowing units are switched off. When sowing with three-seeder and one-seeder units, the inter-track space is 10.8 m. When using a four-seeder unit, it is 14.4 m. In the future, a machine complex designed for a 22-metre inter-track space is planned.

The technological track when placing sowings on slopes with a steepness of up to 3° is made across the slope. On fields with complex relief, the technological track is not made.

Crop care

When caring for sowings, full nutrition of plants and protection from lodging, weeds, diseases, and pests are ensured.

Top dressing of sowings is carried out with nitrogen fertilizers in 2–3 applications, taking into account the results of soil and plant diagnostics. In regions of sufficient moisture, the first top dressing is carried out in spring in the tillering phase, with 20% of the nitrogen dose applied. The second is carried out during formation of the first stem node, with 30% of the nitrogen dose applied. The third is in the phase of grain formation and filling, 30% of the dose. In regions of insufficient moisture, the first and second top dressings are combined; the application rate should be no more than 80 kg/ha of nitrogen.

To increase resistance to lodging, treatment with retardants is carried out:

• at the end of the tillering phase and beginning of stem elongation of winter wheat, treatment with tur (60%) — 3–6 L/ha;
• in the middle of the stem elongation phase and beginning of stem formation of winter rye, treatment with campozan (50%) — 4 L/ha or a mixture of 1.5–2 L campozan (50%) + 3 L tur (60%) per 1 ha.

To control weeds, herbicides are used:

• 2,4-D amine salt (40%), application rate 1.5–2.5 kg/ha;
• 2,4-D butyl ester (43%), application rate 0.7–1.2 kg/ha;
• 2M-4X 50%, application rate 2.5–3.2 kg/ha;
• Dialen (40%), application rate 1.9–2.5 L/ha;
• Lontrel (30%), application rate 0.2–0.6 L/ha in the tillering phase.

To control powdery mildew, brown rust, and root rots, sowings are treated with fungicides:

• Bayleton (25%), application rate 0.5–1 kg/ha;
• Tilt (25%), application rate 0.5 L/ha;
• Fundazol (50%), application rate 0.5–0.6 kg/ha in the period tillering–flowering.

Against the sunn pest, ground beetle, cereal leaf beetle, cereal aphids and flies, and thrips, treatment is carried out with insecticides:

• metaphos (40%), application rate 0.5–1 L/ha;
• vofatox (18%), application rate 0.1–1.4 kg/ha.

Harvesting

Harvesting is carried out by direct combining or by the separate method, depending on the state of sowings and weather conditions. As a rule, the best results are achieved by combining the two methods.

Cleaning, drying, and sorting of grain are carried out in a stream with harvesting.

Treatment of winter cereal crop seeds

Preparations for disease control during the growing season

Preparations for protection against pests and rodents

Herbicides for weed control in sowings