Fertilizer application rates and recommendation for grain crops

In the mentioned macro stage, the development starts from the first true leaf and continues up to nine or more true leaves. That is, rudimentary stem nodes and internodes are initiated. According to studies, every plant needs sufficient reserves 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, also called a leaf support. The cells of the leaf support can be derived from the sheath or from the sheath and its hull.

After that, the support becomes more and more flattened in the transverse plane due to laterally oriented cell divisions and subsequent expansion on both sides. We would like to point out that the dividing zones are marginal meristems, due to the activity of which the leaf acquires its lamellar shape.

In each meristem, the outer array of cells or marginal initials contributes to the epidermal layers by prolonged separation. The cells below are the submarginal initials, which provide the tissue of the inner part of the leaf. Usually, a certain number of cell layers are defined in the layer, which is called 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.

In this macro stage, differentiation of the main axis of the embryonic inflorescence occurs. The number of flowers is determined.

During the period of intensive development, from the phase of formation of lateral shoots/budding to the flowering phase, sufficient reserves of macro-, meso- and microelements are necessary for the full development of all plant organs.

The shoots of most vascular plants branch according to a sequential plan, with each new axis arising at the angle between the leaf and the stem, that is, in the axil of the leaf. In some plants, buds can also be formed from older parts of the shoot or root, distant from the main tops; these buds, called appendages, do not correspond to the general plan.

The apex of the lateral shoot begins on the sides of the main apex, but at some distance below the point of emergence of the bud of the youngest leaf. As in leaf origin, normally the outer cell layers contribute to the surface tissues of the new tip, maintaining a consistent pattern of divisions. In some species, a sheath of more than one cell layer is formed rapidly, so that the new tip looks like a miniature version of the main one. Alternatively, differentiation may not become apparent until a new initial state of significant mass has been reached. In all cases, the new apex must reach a minimum volume before it, in turn, can begin to form its own lateral buds and organize true axillary buds. When this volume is reached, zoning appears. As in the main apex, the formation of new buds is associated with the ring zone.

From this point, lateral shoot development is the same as that of the main shoot, except that growth may not be as rapid because the main shoot, or leading bud, dominates and absorbs most of the available nutrients. The early growth of the axillary bud proceeds quite vigorously until a certain number of leaf buds are formed; then the apical activity slows down. Cell division gradually stops, and with it the synthesis associated with it; thus, there is no increase in the DNA of the meristem nuclei after the last division. The bud, in fact, goes into a state of rest, even if the external conditions for growth are favorable. This phenomenon is known as correlative bud suppression, as it is determined by the activity of the leading shoot bud. If the leading bud is removed, stunted lateral buds resume growth.

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 this macro stage, the processes of formation of all the organs of the flower inflorescence are completed, the development from the rudiments of the flowers to their opening takes place. The largest upper internode continues to grow.

Application of complex fertilizers with an emphasis on nitrogen and trace elements – zinc.

From the point of view of development, a flower can be considered as the axis of a shoot of deterministic growth, with the lateral members occupying areas of leaves that differentiate as floral organs — sepals, petals, stamens, and pistils. In transition to flowering, the stem apex undergoes 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, whether it is a single flower, as in a tulip, or a cluster of flowers (inflorescence), as in a lilac. The area of ​​cell division extends to the entire tip, and the RNA content of the terminal cells increases. As a single flower forms, lateral primordia appear higher and higher on the sides of the apical dome, and the entire apex is absorbed in the process, after which apical growth ceases.