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According to A.I. Nosatovsky, soil moisture, slightly higher than the moisture content of capillary rupture, is already optimal for seed germination and emergence of seedlings winter wheat... The so-called provocative shoots of winter wheat appear when soil moisture is slightly higher than the wilting coefficient. In this case, in the absence of precipitation wetting the sowing layer, germinating seeds often die. Therefore, sowing winter wheat seeds into soil, the moisture content of which at the depth of planting seeds is close to "provocative", is more dangerous than sowing into dry soil, the moisture content of which is lower than the wilting coefficient.
What is the reason for the decrease in field germination of seeds in soil with insufficient moisture? If there is little moisture in the soil for the growth of the seedling, but enough for the seeds to swell and peck, then for the most part they germinate; with further drying of the soil, the seedling also loses moisture. Sprouted seeds die directly from drying only when soil moisture is below the maximum hygroscopicity. In addition, in the soil moisture content ranging from maximum hygroscopicity to wilting moisture, seeds are affected by microorganisms and pests, the exposure time of which is significantly increased, since the seedling is in relative suspended animation.
The degree of loss of field germination largely depends on the presence of moisture in the soil. The fact is that active germination of seeds of winter wheat begins when the seed absorbs 40-45% of water from its weight, and the threshold for germination of fungal spores is much lower. When sowing in semi-moist soil, the rate of seed germination is inhibited, and therefore their damage by fungi increases. Therefore, the longer non-germinated seeds lie in the soil, the lower their field germination capacity.
Temperature has a great influence on the acceleration of water absorption by a grain. The higher the temperature, the more vigorously the water is absorbed by the grain. At 24 ° C, the grain absorbs twice as much water during the same period than at 4 ° C.
In the future, the more water has been absorbed by the grain, the weaker its further moistening is. When combined high humidity and high soil temperature, the swelling of the grain proceeds very quickly. So, at 24 ° C the grain in a day contained up to 50% moisture of its weight, and at 4 ° C the same grain contained only 16% moisture.
The most optimal temperature for germination of wheat seeds is 12 ... 20 ºС. A decrease in temperature below the optimal one delays the process of water absorption by 4-7 days, although even at 0 ° C it does not stop completely. And in the absence or less moisture, the swelling process is delayed for an indefinitely long time. In Crimea, it is not uncommon for wheat sown in autumn to sprout in February, even in March, during the thaw period. These crops have never been able to match the yield of wheat, which sprouted on time, in October. In addition, the lack of moisture for swelling and the low temperature of the soil is not an obstacle for the active work of microorganisms, mainly molds, which can, to one degree or another, destroy the sown seeds.
When the grain germinates, the sprout must pass through the soil layer, to the depth of which the grain is sown. Therefore, the emergence of seedlings in the field occurs much later than the germination of grain. The sprouting rate depends not only on the temperature and moisture of the soil, but also on the depth of seeding.
In conditions of unstable moisture, one of the main prerequisites high yields winter wheat is to receive timely and friendly seedlings. For this, the seeds must be sown in moist and well-aerated soil.
According to A.I. Zadontsev and V.I.Bondarenko (1958), with normal temperature conditions for the friendly germination of winter wheat seeds, it is necessary that the soil moisture in the sowing layer be at least 18%. However, very often due to high temperatures and dry winds, the top layer of the soil by the time of sowing winter crops is very dry and its moisture content drops below the minimum required for seed germination. At the same time, in the deeper layers of the soil, there is enough moisture to obtain seedlings. Therefore, the regulation of the depth of planting of seeds is so important for obtaining normal and friendly seedlings of winter wheat.
The optimal planting depth for winter wheat seeds in Crimea is 5-6 cm. But, according to E.V. Nikolaev, when sowing, seeds should be planted at a depth of 6 cm when sowing at an optimal and early date. ...
P.V. Petkilev believes that with an increase in the seeding depth of more than 6 cm, field germination decreases. But he claims that there is no linear dependence when the depth of planting of seeds changes from 4 to 10 cm: in some cases, the decrease in field germination is significant, in others it is not.
V.F. Podvysotsky argues that when seeds are planted in a dried layer of soil, the sowing period - seedlings is very stretched, and a significant part of the seeds does not germinate at all. However, in conditions of sufficient moisture, field germination increases with shallower embedding.
In an area with insufficient moisture, when sowing, seeds should be placed in a moist soil layer (so that the seeds swell and germinate). However, this layer is sometimes deep and wheat shoots appear on the surface after a long period of time and weakened. The negative consequences of deep planting of seeds are aggravated when sowing on poorly cut soil, when part of the seeds falls under its large clods. In addition, when sowing at a later date at a great depth (8-10 cm), some of the seedlings do not have time to emerge on the soil surface under conditions of rapidly decreasing t.
At the same time, shallow embedding of seeds in dry soil is dangerous because small precipitation - 5-10 mm can moisten this soil layer and cause germination of seeds, and then their death due to lack of moisture. Therefore, sowing winter wheat in Crimea to a depth of less than 5 cm in dry autumn is very risky.
An important factor increasing the field germination of winter wheat seeds is the sowing period, precisely the one at which the soil temperature at the depth of planting seeds does not go beyond the economically optimal, and soil moisture ensures the rapid swelling of seeds and the growth of seedlings.
If in the optimal calendar sowing time (in Crimea this is the first decade of October), the soil is dry (less than 20 mm of available moisture in the arable layer) and the weather is warm, wheat sowing should be postponed until the soil temperature drops to 15 ° C (usually this is the second decade of October). In this case, the safety of seeds sown even in dry soil will increase, since the activity of soil microorganisms and especially insects, which are especially active at 18-20 ° C, will decrease.
In terms earlier than optimal, it is possible to sow only when absolutely necessary and if there is at least 30 mm of moisture available to plants in the arable soil layer.
As for the effect of the mass of 1000 seeds on field germination, this issue has been studied in part in the scientific literature, and only that concerns the large fraction. For example, N. Ye. Tsabel in his book "Spermatology, or the doctrine of seeds" indicates that for sowing it is necessary to use the largest grain, since it germinates more quickly and gives stronger and more productive plants. SP Kostychev notes that sowing with large seeds is just as effective as fertilizing. But you need to keep in mind that what larger seeds, the higher the seeding rate. In our time, many works have been published showing the advantage of large seeds. However, if we recognize all these data in generalized form as correct and consider only the largest seeds in the seed deviation as complete, then two questions arise: which seeds are considered large and how does it relate to the seeds of the middle fractions? Can they be used for sowing and what happens during this? All these researchers do not give answers to such questions, since there were no medium-sized seeds in their experiments. Many researchers have tested only small seeds and only large ones. Although the middle fractions of the seeds were not tested, their inferiority was always implied, since they are not the largest. Many examples of such studies could be cited. For example, E.M.Shumakova (1949) compared the seeds of winter wheat weighing 1000 grains 42.3 and 17.5 g. Naturally, small seeds germinated worse than large ones. But what are seeds with a 1000-grain weight of 42.3 g? Were they the largest in the crop?
At the same time, one should not discard the experimental data on this issue of well-known scientists - plant breeders I. D. Budrin, A. I. Stebut, V. Ya. Yuriev, P. I. Lisitsyn and others, who did not recognize the advantages of large seeds.
A.I. Stebut believed that in the first place is the high viability of seeds, and not their size - in this he saw the main advantage of seeds. Many researchers attribute the advantage of large seeds to the fact that they have more spare nutrients, the larger the embryo, which determines their biological value. V.Ya. Yuriev, who wrote that if large seeds had a high value, then only large-seeded varieties would remain in production.
A.I. Nosatovsky, when studying the effect of grain size on field germination, found that large grain absorbs moisture more slowly than small grain. So, for example, a small grain in a day contains twice as much water as a large one, so it germinates more likely than a large one. As a result, when sowing seed material that is heterogeneous in size, seedlings do not appear at the same time.
At the same time, the larger the seeds, the higher the seeding weight. For example, optimal rate sowing when sowing wheat at the optimum time on dry land is 6 million viable seeds per hectare. If we sow with seeds weighing 1000 which are 30 grams, then the weight rate of sowing will be 180 kg / ha, and if with seeds weighing more than 45 grams, then it will already be 276 kg / ha. In this case, the cost of seeds sown per hectare will be 1.5 times higher.
All these facts indicate that it is not so much the size of the seeds that is important, but the evenness. seed material by grain size and their usefulness. This does not mean that the size of the seeds does not matter, but, according to I. G. Strona, the usefulness of the seeds is better manifested in medium seeds than in the largest ones. A lot of controversy arises around this issue and scientists cannot come to a consensus.
In addition to the size of the grain, field germination can be influenced by chemical composition grain, namely its protein content. This issue has been studied even less than the size of the seeds.

All plants during the growing season, from seed germination to the maturation of new seeds, go through certain phases that are closely related to each other and successively replace each other. The onset of each phase is established visually according to the external morphological characteristics plants, characterizing the quantitative and qualitative changes occurring in a living organism. Such observations are called phenological. At each stage of growth and development, plants experience different needs for nutrition, moisture and other factors of life. Therefore, knowledge of the growth phases allows you to monitor the state of crops and timely carry out the necessary agrotechnical measures aimed at meeting the needs of plants in a particular factor of life.

In the process of development, the plant of grain loaves successively undergoes the following phases: shoots, tillering, emergence into the tube, heading (or sweeping), flowering and ripening. In Western countries, another phenological Zadoks scale is adopted, which is a decimal code for the development of cereals. The entire cycle of plant development is divided into 10 main phases, which are numbered from 0 to 9. Each phase is divided into 10 microphases (Fig. 9). This classification is more preferable, since it allows you to more accurately determine the stage of plant development and carry out computer processing of the observation results. The beginning of the phase is noted when at least 10% of the plants enter it, and the full onset of the phase - if the corresponding signs are present in 75% of the plants.

The emergence of a crop is preceded by the swelling of seeds and their germination. The swelling rate of the sown grain depends on the moisture, temperature and aeration of the soil. For seed swelling

Figure 3.12. Growth phases of winter wheat and stages of organogenesis according to Zadoks

wheat and rye require water about 55% of the dry grain weight. For barley, this figure is 50, for oats - 65, for corn - 40, millet - 25. Moisture activates the activity of seed enzymes, the embryo comes out of dormancy and goes to active life. The seeds begin to sprout. First, the embryonic roots start to grow. Their number depends on the type of plant. Wheat has 3 - 5 roots, rye - 4, barley 5 - 8, oats 3 - 4, breads of group 2 sprout with one root (Figure 3.13).

Figure 3.13. Germination of cereals: 1-rye; 2 oats; 3-corn; 4-wheat; 5-barley

Following the primary roots, a stem shoot begins to grow. For breads of the 1st group, the first leaf that breaks through the soil layer is covered with a transparent cover - coleoptile, which protects the sprout from damage (Figure 3.14-a). When it reaches the surface of the soil, the coleoptile stops growing, it breaks and the first green leaf comes out into the formed crack (Figure 3.14-b). The size of the coleoptile is limited, and therefore, when seeding too deeply, it often does not reach the soil surface. An unprotected leaf dies, or the non-coleoptile entrances are weakened.

In order to get friendly, uniform shoots, it is necessary that the seeds are planted to the optimal depth, and the soil contains a sufficient amount of moisture and air (Figure 3.14).

Figure 3.14. Germination of the first leaf and exit from the coleoptile

This is ensured by thorough soil preparation. The sowing layer should be loose, grainy, the seedbed should be dense and moist, and the soil surface should be even.

Figure 3.15 .. Seedlings of winter wheat 10-20 stage according to Zadoks

Tillering in cereal bread begins with the appearance of 3-4 leaves. It is fixed when the tips of the first leaves of lateral shoots are shown from the sheaths of the leaves of the main shoot. The growth of new shoots occurs due to the underground branching of the stem, and the node in which this process takes place is called tillering knot, From the tillering node, secondary (nodal roots) begin to form, and a bush consisting of several stems forms on the soil surface (Fig. 12). The number of stems (shoots) forming a plant is called general bushiness... There are also productive bushiness- the number of stems on one plant that gave ripe grain. Stem shoots, on which ears (panicles) were formed, but the grain did not have time to ripen, are called fit, and shoots without inflorescences - squat. Fitting and dropping is undesirable in crops, as they consume moisture with batteries and make harvesting difficult.

Figure 3.16. Winter wheat tillering: a-corn; b-primary roots; v- stem shoot; G-lateral shoots from the embryonic node; d- tillering node; e-nodal roots; f- the main stem; s-lateral shoots

Bushiness degree cereals due primarily to the biological characteristics of the species and variety. In addition, bushiness depends on the area of ​​plant nutrition, soil moisture, time and depth of sowing, fertility and quality of soil cultivation, temperature, lighting. On fertile soils and with high agricultural technology, tillering proceeds more vigorously. With thickened sowing and deep planting of seeds, the plants bush worse (Figure 3.17).

With a lack of moisture, tillering does not occur, the secondary root system is not formed, which leads to a sharp decrease in yield. A factor holding back tillering may be a lack of nitrogen in the soil.

Figure 3.17. The effect of sowing depth on the development of wheat plants

If the tillering node dies, all plants die. The tillering node in winter crops is especially at risk, therefore keeping it from unfavorable conditions wintering is the main task of the autumn and winter periods. If the tillering node is preserved, shoots and roots that have died in winter can be restored from it.

Exit into the tube (booting) is noted when the upper node of the main stem shoot rises 5 cm above the soil surface (Fig. 14). At this height, you can feel it with your fingers.

Trumpetting is a very important stage in the development of grain crops. At this time, the vegetative mass is growing rapidly - straw, leaves, roots. Plants have an increased need for moisture and nutrients. This period is critical, therefore, the creation of favorable conditions for plant growth during the period of entering the tube largely determines the size of the grain yield.

Figure 3.18. Beginning of tubing and booting of wheat

Heading (sweeping) (Figure 3.19) begins with the appearance of 1/3 of a spike (panicle) from the leaf sheath of the upper leaf. In this phase, plants are also very demanding on nutritional and moisture conditions. In a dry hot year, maybe

Figure 3.19. Heading wheat

the formation of flower organs is disrupted, which will lead to a deterioration in the grain content of ears (panicles). Cold, rainy weather during the earing period extends the period of this phase, and, consequently, extends the maturation and harvesting periods.

Flowering (Fig. 3.20) in most grain crops follows heading (in barley, it sometimes happens before heading out). By the nature of flowering, cereals are divided into self-pollinating (barley, wheat, oats, millet, rice) and cross-pollinating (rye, corn, sorghum). In spike crops (wheat, rye, barley), flowering begins from the middle part of the ear, then spreading up and down. It is in the middle part of the ear that the largest grains are formed. Panicled breads (millet, oats, sorghum, rice) bloom from the top

panicles. The duration of the flowering phase is different for

Figure 3.20. Wheat bloom

different cultures. In wheat, for example, the flowering of one spike lasts 3 - 5 days, and the whole field 6 - 8 days. This period can be longer in cold rainy weather and shorter in hot and dry weather. Extreme weather conditions adversely affect the fertilization of cross-pollinated crops. In case of incomplete pollination, through the grain is observed.

After flowering and fertilization, the growth of the stem of leaves and roots practically stops. The plastic substances formed by this time are used for the formation and filling of caryopses. At this time, it is very important to keep the leaves from disease and prolong their functioning. This contributes to the formation of larger, higher quality grains.

Grain formation and ripening. The process of grain formation includes three stages - formation, filling and maturation of grain.

The formation of the caryopsis begins soon after fertilization. The embryo is formed first, followed by the endosperm (Fig. 3.21). In 10 - 12 days, the caryopsis grows to its final length.

Figure 3.21. Formation and filling of weevils

Its contents are located in gelatinous liquid condition, the growth in length is suspended, the filling begins. The thickness and width of the caryopsis increases, the inner content goes into a phase dairy, and then pasty states. By the end of the filling, the moisture content of the grain is reduced to 40%. At this time, the flow of plastic substances to the grain stops, it goes on to ripening.

Maturation is divided into 2 stages: phase wax ripeness and phase full ripeness(Figure 3.22). At the beginning of the waxy ripeness, the grain completely loses its green color, the contents of the grain are not squeezed out, but easily rolls into a ball. In the middle of the waxy ripeness, the moisture content of the grain is reduced to 35 - 25%, the endosperm of the grain can be cut with a fingernail. By the end of the wax ripeness, when pressed with a fingernail, a trace remains on the grain, but it is no longer possible to cut the grain.

Figure 3.22. Wheat ripening stages: dairy, waxy and full ripeness

Mowing loaves into rolls during separate harvesting begins in the middle (rye - at the end) of wax ripeness (Figure 3.23).

In the phase of full ripeness, the moisture content in the grain decreases to 17 - 16%, it is easily threshed from

Figure 3.23. Mowing into rolls

ears, but not yet crumbled. Endosperm is hard, mealy or vitreous at the break. At this time, one-phase harvesting of grain is carried out (Figure 3.24).

With a delay in harvesting (over-growing), grain losses are inevitable due to its shedding.

The grain harvested in full ripeness is not yet physiologically mature and may have a reduced germination capacity. Post-harvest ripening can continue for another 3 weeks to 2 months. This property must be taken into account when using freshly harvested seeds of winter crops for sowing.

During the period of grain filling and ripening, phenomena occur that cause disturbances in the normal process of plant development.

Figure 3.24. Single phase cleaning

Lodging loaves (Figure 3.25) occurs in thickened crops with an excess of nitrogen supply and moisture, as a result of rainstorms, hail of strong winds. Lying plants are less well lit, and fungal diseases can develop on them. At the same time, the outflow of assimilants into the grain decreases, it is formed small, the quality is low.

Fuse plants occurs in extreme heat and dry winds, when the stomata lose their ability to close. In this case, moisture evaporates so quickly that the roots do not have time to supply it to the leaves, and it is sucked out of the inflorescences. A similar phenomenon occurs when capture plants, which is associated with a lack of moisture in the soil (and not only heat). Often, fuse and seizure occur at the same time. As a result, the grain is formed small, shriveled with a small amount of starch.

Figure 3.25. Lying crops of wheat

purpose of work: Study the growth phases of grain crops using the example of winter wheat

Materials and equipment: Canned plant specimens, reference books, posters and drawings.

Diagram of the movement of water, nutrients and plastic substances through the plant

Winter wheat. The growing season of winter wheat is 240–320 days (2200 ° C sum of effective temperatures). From germination to tillering, plants consume 30–40% of nitrogen, phosphorus and potassium from the total consumed amount, in the booting - earing phase - 40–50%, during the period of grain filling - 10–30%. The accumulation of dry matter during this period is only 8-10%. At this time, the root system is still poorly developed and young plants are very sensitive to the presence of easily assimilated nutrients in the soil. Their lack leads to irreversible disruption of biochemical processes, which negatively affects the development and formation of the crop. In this regard, the beginning of tillering is considered a critical period in relation to the elements of mineral nutrition. Their maximum consumption occurs during the tillering – earing period. When the phase of milk ripeness of grain is reached, the supply of nutrients from the soil practically stops.

Winter wheat places high demands on the soil. The reaction of the latter should be neutral, pH 6.0–7.5. This crop gives the most stable yields on fertile, sufficiently moist and weed-free chernozems and dark chestnut soils. In the Nonchernozem zone, the best for it are weakly podzolized, medium loamy and gray forest soils. On light sandy loams and drained peat bogs, it works poorly. Lowered and wetlands are also unfavorable for her.

Spring wheat- unlike winter wheat, it has a shorter growing season (75–115 days depending on the variety, cultivation areas and weather conditions, 1500 ° C the sum of effective temperatures).

The absorption of nutrients in spring wheat is more intensive than in winter wheat. During the germination period, spring wheat consumes 5–7% of the total removal, in the tillering phase - 15–20%, the output of plants into the tube and heading - 50–60%, milk ripeness of grain - 20–30%, wax ripeness - 3– 5%. In the period from the appearance of entrances to tillering, spring wheat is very sensitive to a lack of nutrients, especially phosphorus. Lack of phosphorus in the first period of development is not compensated by subsequent application and causes a decrease in grain yield. Phosphorus uptake continues until the end of maturation.

Spring wheat has a relatively underdeveloped root system, characterized by a reduced assimilating ability, therefore it is demanding on the presence of readily available substances in the soil and cannot stand acidic soils... In order to develop a powerful root system and reduce the risks of a low yield, it is necessary to include seed treatment with growth stimulants, for example, Raikat Start (0.25–1.0 l / t), in the wheat feeding technology.

Along with basic fertilizers, foliar feeding is of great importance for improving root nutrition, which is traditionally carried out in the tillering phase, but is also necessary in the earing phase.

Often, during the period of exposure to stress factors (low temperatures, heat, drought, treatment with plant protection products), the use of foliar feeding is the only way to deliver nutrients to the metabolic system of plants.

In combination, seed treatment and foliar feeding significantly increase the efficiency of spring wheat root nutrition. So, the increase from the main fertilizers does not exceed 6-7 c / ha, subject to the full nutrition technology with the use of growth stimulants and complex fertilizers in the tillering and heading phase - the increase increases to 10 or even 20 c / ha due to an increase in the volume of the root system, improvement of physiological reactions in leaves, increase of assimilation of nutrients from soil and fertilizers by 15–20%, rapid recovery of plants under the influence of unfavorable conditions, increased re-utilization of reserve carbohydrates and their direction into the caryopsis.

Winter and spring barley- characterized by an even more intensive absorption of nutrients, which is associated with a short growing season. Due to heavy lodging, the dose of nitrogen fertilizers should be lower than for wheat. When growing malting barley, nitrogen fertilizers are not used, nor are they sown on early harvested predecessors that accumulate a lot of nitrogen. Barley is very sensitive to high soil acidity.

Rye... Rye is not very demanding on soils. She gives good harvests on sandy and loamy soils, and with proper care even on swampy soils. But its maximum yields are obtained on fertile black soil. Winter rye reacts strongly to fertilization.

Oats. Less picky about growing conditions. Compared to other cereals, it has a longer period of nutrient absorption. It makes good use of the aftereffect of fertilizers. Nitrogen fertilizers have a strong effect on all soils. Doses of fertilizers are the same as for barley. To increase the protein content, it is better to introduce nitrogen fractionally, as for wheat, and phosphorus-potassium - before sowing.

Millet. Before tillering, the growth and development of aboveground organs and the root system is slow, so the ability to assimilate nutrients from the soil is much less than that of other spring crops. The period of enhanced absorption of nutrients occurs later than in early spring crops and coincides with the warm period, when the processes of mobilization of nutrients are actively proceeding in the soil.

Mineral nutrition technologies for grain crops should take into account the biological characteristics of the cultivated crop, its needs for mineral nutrition elements in each phase of development and contribute to the maximum realization of the genetic potential of plants.

During critical periods of growth (laying of reproductive organs, flowering, grain filling), plants are most sensitive to the effects of favorable and unfavorable environmental factors that affect the mineral nutrition of plants.

Physiological metabolic disorders at these moments irreversibly reduce the utilization rate of basic fertilizers and, even with a high supply of nutrients, lead to a decrease in plant productivity. To prevent the negative impact of stress factors on the productivity of grain crops, fertilization should be based on regular soil analyzes, and foliar feeding- to precede the functional diagnostics of plants. While yield loss cannot be prevented, rapid laboratory diagnostics and modern foliar fertilization can help keep losses and damage to a minimum.

It is important to remember that the visual manifestation of the unfavorable state of plants occurs even with profound metabolic disorders. Yields and quality are greatly reduced before the visual symptoms of stress appear. Therefore, the effectiveness of mineral nutrition technologies is determined by the timely identification and reduction of the consequences of unfavorable environmental factors on plant metabolism.

This series of articles, one of the authors of which is James Cook, who was in Ukraine, known to readers of the Zerno magazine for his research, is adapted to Ukrainian realities and is offered to the reader-practitioner as an exhaustive array of information about the very modern technology and wheat growing methodology. Dear reader, you will receive the full amount of information if, starting from this issue, you collect all 12 issues in which this information will be published. (Published in # 7.2011)

In the first article, the authors focused on the biology, characteristics, cycles, and characteristics of the wheat plant. With each issue of the magazine "Zerno" you will be more and more interesting, and, we hope, our work will be useful in your agronomic practice.

Every healthy, fully developed wheat plant consists of a main stem with ears, internodes, nodes, leaves, roots and shoots. In turn, each shoot also consists of an ear, internodes, nodes, leaves, roots, and (potentially) secondary shoots. The roots that appear first as part of the seedling are the germinal or primary roots. And those that form later on the main stem and processes are nodal roots, sometimes they are called adventitious or secondary roots.

Before reaching full development and maturity, each wheat plant goes through successive stages of development: the seedling becomes the main stem with shoots, each of which elongates at about the same time, and then the ears and grain develop. The true stem in young plants is advanced at the point of growth through alternating layers of cells designed to become nodes (junctions) and internodes of long, stiff straw with a spike at the top. With the receipt of a signal - the sum of accumulated active temperatures, which is typical for most wheat varieties, or a signal from the duration of daylight hours, in the case of wheat sensitive to the length of the day, these extended internodes begin to lengthen, the nodes appear one after another, and, finally, an ear appears from the tube. During these stages, the main stem, shoots and associated nodal roots join together at a site known as the root collar. It consists of lower nodes and non-protruding internodes, which remain in a fixed position 2-5 cm below the soil surface. The stages of development and growth are described for the case when everything is going right: the plant is completely healthy, and the yield is genetically absolute (Fig. 1). In the following articles, we will describe what can go wrong and what needs to be done in such cases.

Rice. 1. Four levels of wheat productivity

Embryo

Inside each grain of wheat is an embryo, or germ of a wheat plant (Fig. 2). The embryo is the packaging for all the constituents necessary for the formation of a plant. It consists of several parts, namely:

1) scutellum - a modified leaf that absorbs sugar and other nutrients from the starch endosperm as it is cleaved by enzymes during germination;

2) ectoderm - a leaf-like structure that never develops into a real leaf;

3) coleoptile - another leaf-like structure that protects the first true leaf when it emerges from the soil;

4) undeveloped tissues (embryonic) for approximately the first three true leaves;

5) the future first root (embryonic root), covered with a protective layer of tissue;

6) from two to five embryos destined to become embryonic roots together with the primary root (they are not shown in Fig. 2).

Nodes

Nodes are where the wheat plant begins to grow. All roots, leaves and shoots originate in vegetative nodes on the stems. By analogy, all the spikelets that make up the spike originate in the reproductive nodes at the tops of the stems. These vegetative and reproductive nodes give rise to corresponding structures in a predetermined pattern, which can be easily described if the plant is analyzed according to its constituent nodes. Potentially, 9-14 vegetative nodes and 15-25 reproductive nodes form on the main stem of a fully developed winter wheat plant. Typically, a fully developed spring wheat plant has fewer vegetative and reproductive nodes than winter wheat and fewer lateral shoots than the main stem and older shoots.

Rice. 2

Rice. 2. View of the embryo of mature wheat (top), the incision is made in the middle along its entire length, and the placement of the embryo on the wheat seed and in the developmental stage (bottom)

The embryonic roots (but not the primary root) emerge from nodes in the ectoderm and scutellum of the embryo (Fig. 2). Typically, two root embryos are formed on either side of the scutellum node, and three root embryos are associated with the ectoderm node, that is, potentially only five embryonic roots (six with a primary root). So, the embryo has five nodes: corymbose (cotyledonous), ectodermic, coleoptile, as well as the first and second leaf nodes.

Vegetative parts

The order of development of the vegetative parts of wheat - leaves, main stem, shoots and roots (Fig. 3) can be traced visually. To do this, let's number each node. The node of the first leaf (the fourth node of the embryo) will be designated as node 1 (N1), and the first green leaf visible above the ground (the first true leaf), attached to N1, as L1 (Fig. 3). It contains a bud in its sinus and is called axillary shoot 1 (T1).

Rice. 3. Leaves, shoots and roots of the wheat plant

The second visible green leaf (L22) joins node 2 (N2) and contains a bud in its axil, which will become the second axillary shoot (T2). The coleoptile originates in the coleoptile node designated O (N0). The coleoptile, being a leaf-like structure, will be denoted by LO. The ectoderm originates at node -1 (N-1) and the scutellum at node -2 (N-2).

Nodal roots arise from one or more nodes of each stem starting at N1. From each such node, about four nodal roots can appear. Letters mark these four roots in accordance with the direction of their growth in relation to the midrib of the first leaf (L1 at N1). The roots that appear on the right and left sides of the midrib will be designated A and B, respectively. And the roots that appear in the direction to and from the midvein are like X and Y, respectively. The nodes on the shoots will also be denoted by numbers: consisting of two digits for nodes on the shoots, and three digits for nodes on secondary shoots. At the base of each shoot is a small, leaf-like structure - the bracts - that protects the young bud before it releases its first leaf to become a shoot. The bracts are analogous to the coleoptile and originate from their own node on the shoot. The bract contains a bud in its sinus, which will develop into a secondary shoot. Like the coleoptile and its node, the bracts and their nodes are designated 0. Since the first shoot is already T1 at N1, its bracts will be L10 at N10, and the bracts' shoot is a secondary shoot of T10. By analogy, the first true sheet on T1 will be L11 at N11, and the second true sheet on T1 -L12 at N12. These two leaves contain buds in their axils, designated T11 and T12. Likewise, the branch of the bracts on T10 will be a tertiary shoot, denoted as T100. In production crops at regular timeframes sowing very few secondary shoots and even fewer tertiary shoots form a full grain in the ear. At an early sowing date and with wide row spacings, wheat can form full grain even on secondary shoots.

The sum of active temperatures and the development of a wheat plant

The correct development of a wheat plant with leaves, main stem, shoots and secondary shoots is regulated by the accumulated heat units or the sum of active temperatures during the growing season (CAT). The number of active temperatures per day is the average temperature for that day minus the initial growth temperature. The initial temperature (biological zero) for wheat is 0 ° C. Early ripening glassy red-grain spring wheat requires approximately 1,475-1,500 CAT from the moment the seed first begins to absorb water until the grain ripens. Perhaps this is the minimum for wheat production in North America. Winter wheat needs 2,000-2,500 CAT, depending on the variety and sowing date. On average, wheat needs about 150 SAT for germination if sowing is carried out at a depth of 3.8 cm, 130 SAT - if the sowing depth is only 2.5 cm, and 230 SAT - if wheat is sown at a depth of 7.5 cm.Average 80 SAT is necessary for the seed to germinate, 50 SAT - for the shoot to reach the soil surface (for each centimeter of sowing depth - 20 SAT). A larger amount of the sum of active temperatures may be needed to obtain seedlings at a soil temperature of more than 27 ° C, since such temperatures are too high for seed germination, but they quickly accumulate in the calculation of the sum of active temperatures and can mislead the agronomist. The period between the successive appearance of leaves on the main stem and on the shoots is called phylochron, and like the emergence of seedlings, the formation of each leaf requires a certain minimum value of the sum of active temperatures during this period. Most varieties of glassy red-grain spring wheat grown in North Great Plains require 80 CAT per phylochron. Some very early maturing varieties of glassy red-grain spring wheat require less than 75 CAT per phylochron. Other early maturing cultivars require shorter phylochrones than conventional cultivars between emergence and heading because they produce fewer leaves on the main stem (eg seven leaves instead of eight). Varieties of soft white-grain winter wheat, bred for the northeastern Pacific coast, generally form 10-13 leaves on the main stem and require 90-100 CAT per phylochron. Winter wheat has a longer growing season than spring wheat and, accordingly, a higher potential yield. Winter wheat varieties grown in the relatively cool area of ​​the Pacific Northeast coast also have a higher yield potential than varieties grown in hot spring and early summer areas. Shortening the phylochron period or the formation of fewer leaves on the main stem (and shoots) helps to improve the maturation of the crop and in some years avoids exposure to high air temperatures during critical phases of development. With late sowing dates in winter wheat, the phylochron period is shortened, while the actual time for the photosynthesis process and the accumulation of dry matter is correspondingly reduced. For this reason, early maturing varieties and late seeded varieties tend to form plants with smaller leaves and spikelets and a lower potential yield. The plant, as it were, sacrifices its growth, but, despite this, it necessarily goes through each phase of its development. The phylochron period varies slightly in response to the rate of dry matter accumulation. For example, if the carbon absorbed from the products of photosynthesis is sufficient for the plant to develop before the end of the phylochron period, then this period may be slightly reduced to match the rate of carbon uptake. Conversely, if the accumulated carbon is insufficient, the phylochron period is slightly lengthened. The rate of plant development can be controlled by the input of carbon, and conversely, the input of carbon can be controlled by the rate of development of the plant. These processes are inextricably linked. In general, for the formation and enlargement of the shoot leaf, as well as the main stem, the same amount of sums of active temperatures is required. Knowing the phylochron period, it is possible to predict when the leaves will elongate, but it is impossible to predict their size at the end of this period, when the next leaf will begin to grow. The first shoot in the axil of the first leaf (L1) and each subsequent shoot in the axil of each subsequent leaf appear at intervals of 1 phylochron. By analogy, the leaves on these shoots appear at intervals of 1 phylochron. Subsequent shoots have fewer leaves (as a rule, each shoot contains one leaf less than its predecessor on the plant), so that when ripe, the difference in development between the main stem and the youngest associated shoot cannot be more than 50 CAT (2-3 days with an average value of daytime temperatures in the range of 15-25 ° C). Shoots may be delayed in development and maturation behind the main stem, but no more than 2-3 days. In ordinary varieties of glassy red-grain spring wheat, the stem begins to elongate approximately 5 phylochrones (about 400 CAT) after sowing, and in early ripening varieties, even after 370 CAT. Stem elongation is the plant's response to the accumulated amount of active temperatures over a certain growing season or to the length of the day. Winter wheat in North America usually enters the steming phase at about 4-4.5 phylochrones, or between 360 and 450 CAT, after January 1st. This period can be shorter with more early dates sowing. As soon as the stem elongation begins, any shoot with fewer than three leaves can be rejected by the plant. The stemming phase with fully developed leaves begins at 3 phylochrones after the development of stem elongation and lasts for 1 phylochron until the tip of the spikelet is shown. Common vitreous red spring wheat species reach this stage in about 715 CAT from germination. Early ripening varieties consume only 650 CAT. Soft white winter wheat in the Pacific Northwest reaches the stalk phase where approximately 1,400 CAT has accumulated after sowing on 15 September, but needs only 1,050-1,100 CAT when sown in October. A longer warm period with early sowing is used by the plant for additional vegetative development. This leads to the formation of more shoots, which potentially allows the plant to form more ears and, therefore, a greater yield, if all other factors vital to the plant are not limited. Heading lasts about 1 phylochron, and the flowering phase begins at 0.25-0.5 phylochron after the end of the heading phase, that is, roughly add another 100 CAT for spring wheat and 120-150 CAT for winter wheat. Vitreous red-grain spring wheat in the period from flowering to ripening requires another 630-770 CAT, and soft white-grain winter wheat requires 750-800 CAT. This brings the total accumulated heat units closer to 1.450-1.565 CAT for glassy red-grain spring wheat and 2.050-2.350 CAT for soft white-grain winter wheat, depending on the characteristics of ripening and sowing time of the crop. Naturally, these values ​​vary by variety and depend on other factors. The grain yield is a function of the total amount of accumulated carbon, expressed first as the maximum number of shoots with the widest leaves, then as the maximum number of spikelets in one spike, even later as the maximum number of flowers per spikelet, and finally, in the number of fully filled grains on every flower.

Shoot development

With the development of seedlings, a new leaf is simultaneously formed and the previous one is enlarged. However, the structure of young leaves develops faster than leaves grow to full size. Thus, a plant may have about 15 vegetative nodes, but by the time the growth point stops forming leaf buds and begins to produce reproductive nodes of future spikelets, only six or seven visible leaves can be formed. Typically, when winter wheat has 11 nodes, five of which contain visible leaves (L1-L5) and six are leaves awaiting elongation, spikelet (reproductive) nodes begin to form. Spring wheat and early varieties winter wheat can only have four visible leaves on the stem during the transition to the formation of reproductive nodes.

Root development

Germ roots

The first two embryonic roots are formed at the N2 and N1 nodes - the scutellum and epiblast nodes, respectively. These roots, designated -2A and -2B, elongate almost immediately after the onset of lengthening of the primary root. These two roots and the primary root make up the first three roots visible on a seedling dug out of the soil before it appears on the surface (Fig. 2). Only after these three roots have appeared and began to absorb water does the coleoptile elongate. After shoot emergence, the next two embryonic roots, designated -1A and -1B, elongate from the epiblast node (N1). A fifth germinal root (-1x) can emerge from N1 if the seedlings are particularly strong. Even the sixth embryonic root (-1y) can appear from the same node. The time when the germinal roots begin to elongate from nodes within the embryo, as well as the time when the leaves begin to elongate above the ground, is regulated by the sum of active temperatures or phylochrones. Embryonic roots -1A and -1B begin to elongate when coleoptile appears on the surface. The roots of OA and OV then elongate at the N0 node at about the same time as the coleoptile shoot begins to grow.

The time of emergence of roots of the first, second and third order is also regulated by the sum of active temperatures or phylochrones. In general, first-order shoots start branching at the germinal roots when three leaves are formed on the main stem. Second-order shoots start branching when 5-6 leaves appear on the main stem.

Nodal roots

Up to four nodal roots can develop at each node of the main stem and shoots. These four roots appear in two pairs, one called A and B, and the other X and Y. On some stems, more than four roots may be visible at the top nodes. Like embryonic roots, the time of emergence of nodal roots can be predicted from the accumulated sum of active temperatures. Roots 1A and 1B appear at node N1 on the main stem around the time T1 starts growing from the same node. The second pair of roots is formed from N1 (roots 1X and 1Y) approximately 2 phylochron after the appearance of the first two roots from the same node or at the time of elongation of TZ from N3. The sequence can continue until nodal roots appear at all nodes from N1 to N5 or N6 and until the growth point transforms from a vegetative to a reproductive node. A first-order branching of nodal roots from any given node begins when the shoot associated with that node has three leaves, and a second-order branching of nodal roots begins when the supporting shoot has five to six leaves.

Reproductive period

The growing point in the shoot of the main stem or lateral shoot of winter wheat stops producing vegetative nodes and starts producing reproductive nodes in early spring... The exact time of this transformation depends on the cultivar, the accumulated sum of active temperatures and the length of the day. The change from vegetative development to reproductive development is the result of hormonal signals in the plant. When growth points complete their vegetative mission and transition to reproductive, they go through a series of physical changes.

They elongate and produce reproductive nodes (bundles of undeveloped cells destined to become structures in the ear) about twice as fast as vegetative growth points develop. Single-apical tubercles (spikelet nodes) at the point of growth give rise to axillary buds, which form future spikelets. Thus, the embryo formed in the one-peaked phase of development of the growth point represents only the lower half of each future spikelet. The second row of the embryo (the embryo of the spikelet) develops later from the buds in the sinuses of the first row (the bimodal phase of the growth point development) (Fig. 4). In this phase, the plant accurately recorded the maximum number of spikelets. The future ear can yield no more than that established by the number of spikelets in the bimodal phase of the growth point development. In the future, as the plant develops, depending on the conditions, it can only be smaller. In this phase, the nodes are irreversibly rearranged into the reproductive phase. The upper half of the nodes of the future ear is formed at approximately twice the speed of the lower half, thus forming the final knot or the top of the spikelet.

By this time, the embryo of the first flower appears on more developed spikelets, which is located approximately in the middle part of the spike. During this phase, the final number of potential seeds is formed. Each spikelet can produce seven, eight, or even nine kernels (determined by the number of flowers), but most produce between one and five kernels. The development of an ear can be associated with the development of a seedling. For example, in winter wheat, the stages from the beginning of the single-peaked phase to the end of the two-peaked phase pass from the middle to the end of the tillering phase. In spring wheat, the spike is set at the time when the main stem has five and a half leaves. The last spikelet is formed at the end of the stem growth. Usually during this period the growth point is pushed to the soil surface. Flowers in a spike ripen during the period of emergence into the tube - the beginning of earing. By the beginning of flowering, all parts of the spikelets (with the exception of the grains) reach their full development.

Flowering and development of grains

Flowering - the phase when anther sacs appear and pollen begins to spill out of them. This happens immediately (approximately 0.5 phylochron) after earing and lasts approximately 3-5 days. Flowering is the transition from heading to the beginning of grain filling. It starts from about the middle of the spike and continues up and down in those areas and in the same sequence as the formation of double tops and spikelets. On the shoots, flowering occurs later than on the main stem, because they are slightly behind in development from the main stem.

Grain filling begins with the fertilization of the female ovules with pollen. For the total period of grain filling, 750-800 CAT is required. It can be divided into three phases: a hold phase, a constant pace phase, and a maximum weight phase. Approximately 150-200 CAT, or 1/4 units of heat, accumulates during the lag phase - the period of fertilization when the seeds begin to fill. The kernels can be poured in the middle of the spike, while the flowering is still continuing at the ends of the spike. The longer this phase and the greater the sum of active temperatures, the more grains there will be in one ear, since in this case there is time for the fertilization of more flowers. The maximum number of flowers is set at more than early stage, but some of them may not be fertilized, it depends on temperature, diseases and other factors. The delay phase ends when all flowers are fertilized. Another 500 SAT, or about 2/3 units of heat, are needed for filling grain - a phase of constant pace. During this period, the weight of the grain increases significantly at a constant rate. The actual speed and duration of this phase may vary depending on the variety and growing conditions. Moreover, factors or conditions associated with a higher rate of increase in grain weight are usually associated with a shorter phase of constant rate. In the third, final period - the phase of maximum weight, approximately 100-150 CAT are accumulated. In this phase, the grain loading rate decreases. During this period, the grain adds less than 10% of the final weight compared to 70-80% (6070% for spring wheat) in the phase of constant growth. The largest grains are usually found in the middle of the ear. Perhaps this is because grains fertilized in this zone have 2-3 days longer to pour than grains formed from flowers fertilized immediately before the end of the retention phase. The retention phase lasts longer and the caryopses are usually more abundant and larger in the head on the main stem than in the head on the shoot. The younger the shoot, the shorter the phase of delay in grain filling.

Wheat development scales

Standardized numbers are used for every phase of development that has the same meaning, regardless of year, region or type of wheat. Numeric notations take precedence over descriptive ones when information is entered into a computer. For this, several different types of scales have been developed. The most common are the Feekes scale (Fig. 5), the Haun scale and the Zadoks scale (Table 1). Each scale has certain advantages and disadvantages.

The Fickes scale is considered traditional and the most common. It denotes developmental stages on a scale of 1 to 11, in which stage 1 represents the seedlings (from awl to three leaves), and stage 11 represents the grain filling process (phases of constant rate and maximum weight). The Fickes scale is especially useful between stages 6 and 10.5, which corresponds to the period from the appearance of the first node at the beginning of stem elongation (stage 6) to the end of flowering (stage 10.5). Stem elongation is divided into five stages (stages 6-10), which are considered when considering the critical time for leaf fungicide application. According to the Haun scale, the development of cereals is divided into 16 stages - from 1 to 16. Stage 1 reflects the appearance of the first true leaf and coleoptile, and stage 16 - hardening of the grain. The Haun scale is based on the unfolding of leaves on the main stem and is therefore useful for dividing the stages of vegetative growth. On the Haun scale, stages 1-9 or higher represent, respectively, the full appearance of the first, second, third, and subsequent leaves (Li, L2, L3, etc.) on the main stem. Stages 6, 7, 8, and 9 or more represent the full appearance of the flag leaf on the main stem, depending on the number of leaves on the flag leaf. Usually it is 7 or 8 leaves on spring wheat, and 9 leaves on winter wheat. On this scale, there can be a minimum of 6 and a maximum of 10 leaves, depending on the variety and year. The numerical designations of spike appearance, flowering and subsequent stages of development until the grain hardens vary depending on the number of leaves on the main stem. The cultivar with 8 leaves on the main stem is at about 12 flowering stage, and the cultivar with 9 leaves on the main stem is at the 13th flowering stage. Haun's wheat development classification method is constant only during the vegetative growth stages, but does not provide a numerical designation of the grain filling stages. Since the emergence of shoots is followed by the appearance of leaves on the main stem in the correct and predictable order, the Haun scale indicates which shoots have formed (or should form) on the plant. The Haun scale has the advantage of being able to computerize the stages of wheat development.

According to the Zadoks scale, both stages are considered - vegetative and reproductive. This scale also lends itself better to computerization than the Fickes scale. The development of a wheat plant is divided into 10 primary stages (10, 20, 30, etc.), each of which, in turn, is divided into 10 secondary stages (1, 2, 3, etc.; 11, 12, 13, etc .; 21, 22, 23, etc.) to overall value 100 stages. The Zadoks scale allows more than one code to be used to describe one plant that may be problematic. A plant with 5 leaves on the main stem is at stage 15, but since it should have two shoots by this time, it can also be considered to be at stage 22, and if the main stem is elongated enough to open the first node, it is at 31 stages.

The growth and development of a wheat plant are shown in Figure 2 as the ratio of the masses of individual parts of the plant. The actual dry matter production by a part of a plant at a particular growth stage can vary depending on cultivar, season and geographic area.

We are grateful to the Agro-Soyuz company for their help in publishing the article.

Matt Liebman,

Adjunct Professor at the Faculty of Agronomy

Iowa State University

Charles L. Mohler,

Senior Research Fellow, Crop and Soil Science Department, Cornell University, Executive Editor, Weed Science

During the growing season, the following phases of growth and development are noted in cereal crops: shoots, tillering, stalking, stemming, earing (ear) or popping (sorghum, oats), flowering and ripening. In winter crops, the first two phases of development under favorable conditions occur in autumn, the rest - in spring and summer. next year; in spring crops - in spring and summer in the year of sowing.

The vegetation phases of cereal crops take up a fairly significant interval of time, during which the developing organs go through a number of stages. For development effective techniques mineral nutrition, it is important to know the stages of organogenesis, i.e. organ education. Several systems have been developed for naming growth and development stages. Among these systems, in Russia, the Kuperman scale is most often used, and all over the world, as a rule, the Fix, Zadoks (Z) or Naun systems (Feekes, Zadoks, Naun).

International classification of wheat development phases (according to Zadoks)

When the seeds swell, biochemical and physiological processes take place that promote germination. As the seeds swell, they begin to germinate. By the time 3-4 leaves are formed, the embryonic roots branch and penetrate into the soil to a depth of 30–35 cm, the growth of the stem and leaves temporarily stops, and the embryonic stem differentiates into nodes and internodes. During this period, there is a danger of damage to plants by root rot, especially if the seedlings are in a situation of waterlogging, low soil temperature, deep seeding. The stronger the plant, the less it will be influenced by pathogenic microorganisms.

The intensity of tillering depends on the growing conditions, species and varietal characteristics of grain crops. At optimal temperature(10–15 ° С) and soil moisture, the tillering period is extended, and the number of shoots increases. Under normal conditions, winter crops form 3-6 shoots, spring crops - 2-3. The number of shoots is also influenced by soil fertility, especially nitrogen before the onset of the steming phase.

The dynamics of the formation of tillering shoots and nodal roots in grain crops is not the same. In rye and oats, tillering and rooting occur simultaneously during the period when 3-4 leaves appear. In barley and wheat, tillering shoots appear before the onset of rooting, tillering occurs during the period of appearance of 3 leaves, and rooting - 4–5 leaves. In millet, tillering shoots are formed during the period of appearance of 5–6 leaves, in sorghum - 7–8 leaves. The nodal roots of these crops begin to develop when 3-4 leaves are formed. Simultaneously with the formation of lateral shoots, a secondary root system is formed, which is located mainly in the surface layer of the soil. During this period, the laying of the future harvest takes place - the formation of spikelet tubercles.

Shoots produced during the tillering phase must survive to maximize yield. Spike development and the beginning of stem elongation require a large amount of plant resources, so poorly formed shoots die off quickly. Drought, heat stress, frost during the period of stem elongation (steming phase) and in the phase of entering the tube increase the number of dead shoots due to the limited resources of the plant. Often, only the main shoot is left for reproduction in drought conditions. If the drought stops or additional nitrogen fertilization is applied during this period, the synchronization of plant development is disrupted and it produces many late-ripening ears, which is also a problem during harvesting.

The size of the yield also largely depends on the size of the ear and its grain size. An ear begins to form at the third stage of organogenesis (Z 25–29), which coincides in time with the tillering and stalking phases. During the tillering period, the plants should be sufficiently supplied with nutrients, especially nitrogen, which sharply increases the growth processes of the forming productive organs.

The fourth stage of organogenesis (beginning of tube emergence, Z 30) is practically determined by palpation of the first stem node, which is located at a height of 2–3 cm from the soil surface. This is a critical period for winter crops in terms of moisture and nutrition, when spikelets form, which determines the number of spikelets in an ear.

The fifth stage (Z 31–33) coincides with the middle of the tube entry phase and is characterized by the beginning of the formation and differentiation of flowers; the stamens, pistils and integumentary organs of the flower are laid. Its phenological feature is the appearance of a second stem node. At this stage of organogenesis, the number of flowers in spikelets potentially possible for the variety is finally determined.
Z 25–33, and the earlier it is carried out, the better the final result.

Tube outlet (Z 34-50)

The end of the differentiation of the growth cone falls on the sixth and seventh stages of organogenesis (Z 37–50), which coincides with the second half of the phase of entering the tube before heading (Gubanov V.Ya., 1986). During this period, plants absorb the greatest amount of nutrients, as a result of which the number of productive stems, spikelets and grains in an ear increases. At this time, a second dose of nitrogen fertilizers and foliar feeding are applied (the appearance of a flag leaf before flowering). Such feeding significantly increases the yield by increasing the viability of the pollen and the formation of grains in the ear. Flowering in cereals occurs during or shortly after earing. So, in barley, flowering takes place even before full earing, when the ear has not come out of the leaf sheath, in wheat - after 2-3 days, in rye - 8-10 days after earing.

Heading (Z 50-59)

Abiotic stresses before the appearance of the flag leaf can lead to the loss of spikelets of the developing spike. Under favorable conditions, up to 12 flowers can develop on each spikelet. However, late-formed flowers fall off and only two to four flowers remain on the spikelet, capable of producing grain. Flowering begins at the bottom of the ear and gradually spreads upward. Under extreme conditions, all the flowers of the spikelets at the top and bottom of the spike can die off even before flowering. The number of shoots and flowers that grow on wheat is usually much larger than the ears and grain that the plant can grow. As you know, a decrease in potential yield begins with the loss of shoots at the end of tillering and continues with the death of flowers even before flowering. Weather conditions during these periods, called critical, determine the magnitude of the loss of potential yield.

Flowering (Z 60-69)

The last adjustment to potential yield occurs during grain loading (Z 70–80), when grain size and weight are determined. Foliar dressing during this period (after flowering in the presence of assimilating leaves) increases the mass of the grain and improves its quality.

The duration of the ripening period directly correlates with the yield: the longer the accumulation of plastic substances takes place, the larger the caryopsis and the higher the grain harvest. High temperatures during this period lead to accelerated ripening, the formation of shrunken grains. Too low temperatures also negatively affect the yield, since they slow down the processes of the outflow of assimilates into the weevil, and the harvest time is delayed. Abundant rains lead to lodging of crops, germination of grain, a decrease in grain quality (runoff of gluten), and difficulty in harvesting. A delay in harvesting at high temperatures leads to a strong decrease in grain moisture, increased fracturing and shedding of grain.

Maturation stages

At each stage of the formation and growth of organs, the plant expends an enormous amount of energy. Providing the plant with nutrients, auxiliary products (amino acids, growth stimulants) at the right time and in the required amount for the smooth functioning of physiological reactions in metabolism contribute to the maximum realization of the plant's genetic potential.

Improving the conditions for passing one or another phase with the help of an appropriate agrophone, created using accurate calculations for the planned harvest, seed treatment and foliar dressing based on regular diagnostics with modern devices, increasing immunity to diseases and pests, we maintain an active root system, productive shoots, assimilating surface, flowers and providing a full-fledged filling of grain - we save the harvest!