Potatoes occupy almost the main place in the human diet, yielding in consumption only to bread. But few people think about how complicated this plant is from a scientific point of view. It has unique features unique to it.
Biological features
Potato is one of the leading food crops. It not only ranks 1st among crops for protein production, but also has one of the highest fitness levels.
The homeland of the potato is the tropical zone of the continent of South America. The first centers of origin are located in Bolivia and Peru, in the Andean highlands (altitude 2000-4800 m above sea level), as well as in the temperate zones of Chile (0-250 m above sea level).
Man introduced the potato into culture over 8,000 years ago. Initially, the territories in which it was cultivated were in Southeast Peru and Northwest Bolivia. In Russia, this agricultural crop appeared during the reign of Peter I. It is thisthe ruler legalized the widespread cultivation of potatoes.
Aboveground
The potato plant is a bush that consists of 4-8 stems. Branching depends on the ripening period. In early ripening varieties, as a rule, there is a weak branching at the base of the stem, and in late ripening - strong. A large seed potato, or rather a tuber, forms a shoot with more stems than a small one.
Potato plants can also differ greatly in the number of leaves. The foliage may be weak, but there are also such shoots when the stems are almost invisible behind the numerous leaves. According to the shape of the bush, varieties with compact bushes, sprawling and semi-spreading bushes are distinguished. Based on the position of the stems, erect, sprawling and semi-sprawling bushes are distinguished.
Root system
As for the root system of potatoes, it is fibrous and in fact is a collection of root systems of individual stems. The penetration of roots into the soil largely depends on its type. But on average, the penetration depth ranges from 20 to 40 cm. In addition, in the arable layer, the roots grow to the sides by 50-60 cm.
Aerial part of the plant: potato leaf and flower
Sheet is a simple unpaired pinnately dissected type. If we consider its components, we can see several pairs of lobes, lobules and lobules, which are located in various combinations on the main petiole. And one leaf of potatoes endsunpaired share. The characteristic features of the leaf (the degree of dissection, the size and shape of the lobes, the size and position of the petiole) are important varietal characteristics. The leaf blade is always in a lowered position, the color varies from yellow-green to dark green.
Potato inflorescence is a set of fork-shaped divergent curls, the number of which is from 2 to 4. They are located on the peduncle, which is laid in the axil of the leaf (6-8). Potato flower is 5-membered, has a cleavage calyx and incompletely fused white, red-violet, blue-violet or blue corolla lobes. The number of stamens is 5. Their anthers are yellow or orange. Ovary superior, usually two-locular.
Mechanism of tuber formation
Potato tuber is an escape, but not aboveground, but underground. Its formation is as follows. Due to the increased concentration of nutrients in the upper part of the tuber, when planting, the buds of not all eyes germinate, but only those located in its upper part. The color of the sprouts depends on the variety and can be green, red-violet or blue-violet. When the plant reaches a height of 10-20 cm, the underground part of its stems gives rise to shoots - stolons, the thickness and length of which are 2-3 mm and 5-15 cm, respectively. Their ends gradually thicken, thus turning into tubers.
Structure of a tuber
The potato tuber is a shortened thickened stem, as evidenced by numeroussimilarities, especially noticeable at an early stage of development. This, in particular, is the presence of scaly leaves, in the axils of which resting buds are formed, the number of which varies from 2 to 4 in each eye. Also, the similarity lies in the similar alternation and arrangement of tissues and vascular bundles in tubers and stems. And the formation of chlorophyll in the tuber becomes apparent when it turns green under the influence of light. That is why in storage places poorly protected from light, green potato tubers are often found, which cannot be eaten.
The upper, youngest part of the tuber contains more eyes than the middle, and even more so the oldest, lower, or umbilical part. Therefore, the buds of the apical part develop stronger and more viable. It is known that most often in a single eye, the central kidney, which is the most developed, first of all germinates. If the sprout is removed, spare buds begin to develop and start growing, the plants from which will be weaker than from the central bud. Therefore, seed potatoes during winter storage should not be regularly freed from sprouts. This can lead to the fact that plants will not be formed from the central kidney, but from spare ones, that is, they will be weaker.
A young potato tuber covers the outer layer of the epidermis, which is subsequently replaced by a dense, breathable, integumentary tissue - the periderm. In the process of growth and development of the tuber, the skin of the tuber is formed from the outer layer. A special intensity of this process is observed when the tops are removed a few days before harvesting.
Respiration of tubers and evaporation of moisture is carried out with the help of lentils. Their laying under the stomata of the emerging tuber occurs simultaneously with the formation of the periderm. It is through them that oxygen enters the tuber and carbon dioxide and water vapor are removed.
Does tuber structure depend on potato variety
The structure of the potato tuber in early and late varieties may vary. For example, late varieties are characterized by the presence of denser cork tissue in the tubers.
Tubers can have a wide variety of shapes, depending on the variety and growing conditions. Shape options - round, elongated, oval, round-oval, turnip, barrel-shaped, etc.
The varieties with round tubers and superficial eyes have the greatest economic value. This shape is ideal for mechanized planting and harvesting, while the shallow position of the eyes facilitates mechanical peeling and washing.
The color of the tubers is very different - white, light yellow, pink, red, red and blue-violet. Thus, the external structure of a potato tuber is a varietal accessory. The flesh of the tubers also differs in shade: it can be white, yellow or light yellow.
Potato tuber: chemical composition
The deepest state of natural tuber dormancy is observed during the period of harvesting potatoes in autumn. As spring approaches, it gradually weakens, as growth inhibitors are alreadynot so active. At this time, the formation of substances that stimulate growth occurs. They encourage the growth of the kidney.
In winter, in a dry room with an air temperature of 1-3 ° C, potatoes are well stored without germinating for 6-7 months. After this time, with an increase in air temperature to 10-12 ° C and a sufficient supply of oxygen, growth processes begin.
Potato tuber contains a significant supply of nutrients that are necessary for the growth and development of the plant in the initial period of life. Its dry matter contains more than 26 different chemical elements. The composition may vary depending on the variety, soil, climatic conditions and fertilizers.
The average content of various substances in the chemical composition of tubers is as follows: water 75%, starch 20.4%, sugar 0.3%, crude protein 2%, fat 0.1%, fiber 1.1%, ash 1.1%.
Starch in potato tubers affects taste. The more starch, the tastier the potatoes. In the case of an increase in the concentration of crude protein, the palatability, on the contrary, deteriorates. By starchyness, the culinary properties of potatoes are judged. Its increase causes an increase in the flouriness of the pulp, an improvement in the digestibility.
Reproduction
Potato reproduction can be done in two ways - vegetatively and sexually.
The vegetative method of reproduction is the cultivation of potatoes from tubers. This method also includes reproduction using segments of stems, on which it must bethere is one apical or several lateral vegetative buds.
The most common way is growing potatoes from tubers. And stem cuttings are planted in cases where the number of tubers is limited, and some new valuable variety requires a quick introduction into practice.
The mechanism of potato sexual reproduction is more complex and is associated with the use of true seeds that form in fruits (tomatoes) that form on the stems of adult plant organisms. The peculiarity is that in the case of sexual reproduction, all daughter plants have genetic diversity. The seeds contained in one fruit can give rise to a wide variety of plant forms, but none of them will repeat the features of the mother plant.
