Potato in the human diet takes almost the main place, inferior only to bread in consumption. But few people think how complicated this plant is from a scientific point of view. It has unique features that are unique to it.
Biological features
Potato is one of the leading food crops. It takes not only the 1st place among agricultural crops for the production of protein, but also has one of the highest levels of fitness.
The birthplace of potato is a tropical zone of the continent of South America. The first centers of origin are located in Bolivia and Peru, in the highlands of the Andes (altitude 2000-4800 m above sea level), as well as in the temperate zones of Chile (0-250 m above sea level).
Man introduced potatoes into the culture more than 8000 years ago. Initially, the territories on which it was cultivated were located in Southeast Peru and Northwest Bolivia. In Russia, this crop appeared during the reign of Peter I. It was this ruler who legitimized the widespread cultivation of potatoes.
Aboveground part
A potato plant is a bush that consists of 4-8 stems. Branching depends on the maturity. In early-ripening varieties, as a rule, a weak branching is observed at the base of the stem, and in late-ripening - strong. Large seed potatoes, or rather tuber, forms an shoot with more stems than small ones.
By the number of leaves, potato plants can also vary greatly. Oblivost can be weak, but there are also such shoots when the stems are almost invisible behind numerous leaves. By the shape of the bush, varieties with compact bushes, spreading 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. 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: leaf and flower of potato
A leaf of a simple, unpaired, pinnate-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 the potato leaf ends in one unpaired share. Characteristic features of the leaf (degree of dissection, size and shape of the lobes, size and position of the petiole) are important varietal characters. The leaf plate is always in the lowered position, the color varies from yellow-green to dark green.
Potato inflorescence is a set of fork-like diverging curls, the number of which is from 2 to 4. They are located on the peduncle that is laid in the bosom of the leaf (6-8). The 5-membered potato flower has a spine-leaf cup and incompletely fused white,
red-violet, blue-violet or blue corolla lobes. The number of stamens is 5. Their anthers are yellow or orange. The ovary is upper, as a rule, two-celled.
Tuber formation mechanism
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, during planting, the germination of the kidneys is observed not in all the eyes, but only in the 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 off 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.
Tuber structure
Potato tuber is a shortened thickened stem, as evidenced by numerous similarities, especially noticeable at an early stage of development. This is, in particular, the presence of scaly leaves, in the sinuses of which dormant kidneys are formed, the number of which varies from 2 to 4 in each eye. Also, the similarity consists in a similar alternation and arrangement of tissues and vascular bundles in tubers and stems. And the formation of chlorophyll in a tuber becomes apparent when it turns green when exposed to light. That is why in storage places, poorly protected from light, green potato tubers are often found that 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 cord. Therefore, the kidneys 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, primarily grows. In case of removal of the sprout, spare buds begin to develop and start to grow in growth , plants from which will be weaker than from the central bud. Therefore, seed potatoes during the winter storage period should not be regularly freed from sprouts. This can lead to the fact that the plants will not form from the central bud, but from the spare, that is, they will be weaker.
A young potato tuber externally covers a layer of the epidermis, which is subsequently replaced by a dense, air-tight,
integumentary tissue - the periderm. In the process of tuber growth and development, the tuber peel is formed from the outer layer. The particular intensity of this process is observed when a leaf is removed a few days before harvesting.
Tubers are breathed and moisture is evaporated with 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 the structure of the tuber depend on the variety of potatoes
The structure of potato tubers in early and late varieties may vary. For example, late varieties are characterized by the presence of more dense cork in the tubers.
Tubers can have the most diverse form, depending on the variety and cultivation conditions. Shape options - round, elongated, oval, round-oval, turnip, barrel-shaped, etc.
The most valuable economically are varieties with round tubers and superficial eyes. This form is ideal for mechanized planting and harvesting, and the surface arrangement of the eyes facilitates mechanical peeling and washing.
The color of tubers is very different - white, light yellow, pink, red, red and blue-violet. Thus, the external structure of potato tubers is varietal affiliation. The pulp of the tubers is also different in hue: it can be white, yellow or light yellow.
Potato Tuber: Chemical Composition
The deepest state of the natural dormancy of tubers is observed during the period of harvesting potatoes in autumn. As spring approaches, it gradually weakens, since growth inhibitors are no longer so active. At this time, the formation of substances that stimulate growth occurs. They stimulate the growth of the kidney.
In winter, in a dry room with an air temperature of 1-3 ° C, potatoes are well stored, not 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 plants in the initial period of life. Its dry substance contains more than 26 different chemical elements. The composition may vary depending on the variety, soil, climatic conditions and fertilizers.
The average contents of various substances in the chemical composition of tubers are 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 palatability. The more starch, the better the potato. In the case of an increase in the concentration of crude protein, the taste is, on the contrary, worsened. By starchy judge the culinary properties of potatoes. Its increase causes an increase in the powderiness of the pulp, an improvement in digestibility.
Breeding
Potato propagation can be done in two ways - vegetative and sexually.
A vegetative method of propagation is the cultivation of potatoes from tubers. Also, this method includes propagation using segments of stems, on which there must be one apical or several lateral vegetative buds.
The most common way is to grow 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 sexual reproduction of potatoes is more complex and is associated with the use of true seeds that form in fruits (tomatoes), which are formed 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 large number of different forms of plants, but none of them will repeat the characteristics of the mother plant.