Fertilizer application rates and recommendation for rapeseed

This macro stage develops from the first true leaf and continues up to nine or more true leaves. First, the rudimentary stem nodes and internodes are established. The plant needs sufficient supplies of macronutrients such as phosphorus and potassium. When exposed to environmental and anthropogenic influences, amino acids are needed to eliminate them.

Leaves originate on the sides of the shoot tip. A local concentration of cell divisions marks the very beginning of the leaf; these cells then enlarge to form a nipple-shaped structure called a leaf support. The cells of the leaf support can be derived from the sheath or from the sheath and the hull. The support then becomes more and more flattened in the transverse plane due to laterally oriented cell divisions and subsequent expansion on both sides.

After that, the prop becomes more and more flattened in the transverse plane due to laterally oriented cell divisions and subsequent expansion on both sides. The dividing zones are the marginal meristems, through the activity of which the leaf acquires its lamellar shape. In each meristem, the outer array of cells or marginal initials contribute to the epidermal layers by prolonged division. The cells below, the submarginal initials, provide the tissue of the inner part of the leaf.

Usually, a certain number of cell layers are defined in the mesophyll (the parenchyma between the epidermal layers of the leaf). Cell division is not limited to the region of the marginal meristems, but continues throughout the leaf in each of the layers, always in the same plane, until the final cell number is approached. Then the rate decreases, terminating in different layers at different times. The divisions usually end first in the epidermis, then in the lower layers of the leaf mesophyll.

During the development of the indicated macro stage, the differentiation of the main axis of the germinal inflorescence occurs. The actual number of flowers is determined. During the period of intensive development from the phase of formation of lateral shoots/bushing to the phase of flowering it is necessary to have enough of these types of reserves: macro-, meso- and microelements for the full development of all plant organs.

The shoots of most vascular plants branch out according to a sequential plan, with actually each new axis arising at an angle between the leaf and the stem, i.e. in the leaf axil. In some plants, buds may also be formed from older parts of the shoot or root distant from the main apices; these buds, called adventitious buds, do not follow the general plan. The apex of the lateral shoot begins on the sides of the main apex, but some distance below the point of emergence of the youngest leaf rudiment.

As in the origin of the leaf, usually the outer cell layers contribute to the surface tissues of the new apex, maintaining a consistent pattern of divisions. In some species, a sheath of more than one cell layer quickly forms, so that the new apex looks like a miniature version of the main one.

Alternatively, differentiation cannot become evident until a significant mass of the new initial state has been reached. In all cases, the new apex must reach a minimum volume before it can, in turn, begin to form its lateral rudiments and organize true axillary buds. When this size is reached, zoning occurs.

Like the beginning of the main apex, the formation of new rudiments is associated with the annular zone. From this point, the development of a lateral shoot is the same as the development of the main shoot, except that growth may not be as fast, because the main apex or leading bud dominates and absorbs most of the available nutrients.

Early axillary bud growth is quite vigorous until a certain number of leaf buds are formed; then the apex activity slows down. Cell division gradually ceases, and with it the associated syntheses; thus, there is no increase in DNA of meristem nuclei after the last division. The kidney essentially goes into a dormant state, even if external conditions for growth are favorable. This phenomenon is known as correlative bud oppression, because it is determined by the activity of the conducting bud of the shoot. If the main, i.e. leading bud is removed, the inhibited lateral buds restore growth, and with it all associated syntheses.

To disclose in detail this macro stage, it is necessary to indicate that here occurs the formation of second-order growth cones, the formation of the available number of flowers in the inflorescence with the laying down of flower covering organs, the formation of anthers (microsporogenesis) and stigmas (megasporogenesis), the formation of a larger number of synchronously developed productive stems. There is intensive growth of organs in length, formation of ovules and pollen grains.

Applying nitrogen and phosphorus fertilizers can increase the number of flowers in an inflorescence. Although the structural organization of the vascular plant is relatively loose, the development of different parts is well coordinated. Control depends on the movement of chemicals, including nutrients and hormones. An example of correlation is shoot and root growth. The increase in the aerial part is accompanied by an increased need for water, minerals and mechanical support, which are satisfied by the coordinated growth of the root system. Several factors seem to be involved in control, as the shoot and the root affect each other mutually. The root depends on the shoot for organic nutrients, just as the shoot depends on the root for water and inorganic nutrients, and thus the flow of ordinary nutrients must play a role. However, more specific control can be provided by supplying the nutrients needed in very small quantities.

The root depends on the shoot for certain vitamins, and changes in supply reflecting the metabolic state of the above-ground parts can also affect root growth. In addition, hormonal factors affecting cell division pass upward from the root to the stem; although the exact role of hormones has not yet been established with certainty, they may be one of the ways in which the root system can influence the activity of the shoot apex. Secondary thickening control is another important example of growth correlation. As the size of the shoot system increases, the need for both greater mechanical support and enhanced transport of water, minerals, and elements is met by increased coverage of the stem through the activity of the vascular cambium. As a rule, the cambium of trees in temperate zones is most active in spring, when buds are budding and shoots are sprouting, creating a need for nutrients.

Cell division begins on each shoot and then spreads out from it. The terminal bud stimulates the cambium to divide rapidly through the action of two groups of plant hormones: auxins and gibberellins.

Inhibition of lateral buds, another example of a correlated growth reaction, illustrates a reaction opposite to that occurring when controlling cambial activity. Lateral buds are generally depressed, as axillary shoots grow slower or do not grow at all, while the terminal bud is active. This so-called apical dominance is responsible for the characteristic unit of trunk growth observed in many conifers and herbaceous plants, such as the mallow. Weaker dominance leads to a form with multiple branching. This fact that the lateral or axillary buds become more active when the terminal bud is removed is evidence of hormonal control. The flow of auxin from the shoot apex is partially responsible for the inhibition of axillary buds.

The nutritional status of the plant also plays a role, as verticillium dominance is strong when mineral supply and light are insufficient. Since the axillary buds are released from inhibition by treatment with substances that stimulate cell division, also called cytokinins, it has been suggested that these substances are also involved in the regulation of bud’s activity.

In the above macro stage, the formation of all the organs of the inflorescence of the flower, development from the rudiments of already formed flowers, up to their opening, is completed. The largest upper internode continues to grow. Complex fertilizers with an emphasis on nitrogen and microelement such as zinc continue to be applied.

It is worth indicating that in terms of development, the flower can be considered as a determinate growth axis, but the lateral members occupy areas of the leaves that differentiate as floral organs, namely sepals, petals, stamens and uteri.

In the transition to flowering, the stems undergo characteristic changes, the most noticeable of which is the shape of the apical region, which is related to the type of structure to be formed, either already as a separate flower, such as in the tulip, or as a brush of flowers (inflorescence), as in the siren. The area of cell division extends to the whole apex, and the RNA content of the end cells increases. When the formation of a single flower occurs, in fact the lateral rudiments appear higher and higher on the sides of the apical dome, and the whole apex is absorbed in the described process, after which the apical growth ceases.