Potatoes - Botanical description and biological features. Potato is a plant of the nightshade family. The structure of a potato flower and its formula.
Potato belongs to the genus Solanum L . families Solanaceae (nightshades). This genus includes about 200 cultivated, primitive and wild potato species, including cultivated species S . tuberosum And
S . andigenum . The homeland of potatoes is Central and South America.
Potato is a perennial herbaceous plant propagated vegetatively: by tubers or parts thereof, sprouts, cuttings, layering. In agricultural practice, potatoes are used as an annual plant propagated by tubers. In breeding work, generative propagation by seeds is used.
5.1. Features of the structure of the potato plant
when grown from seeds and tubers
A potato plant can be obtained from seeds or vegetatively from parts of the mother plant - tubers.
Rice. 10. Development of a potato plant from a seed
A potato plant grown from seeds (Fig. 10) forms a sprout with two cotyledons (carried to the soil surface) and an embryonic root bearing numerous small roots. In addition to the embryonic root, secondary roots are also formed, which are laid at the base of the stem, in its nodes located underground.
When grown from seeds, the potato plant has a fairly long growing season of 80 - 100 days. By the end of the growing season, it forms a nodule weighing 20–30 g, which is poorly stored, so this method of potato propagation is not used in production.
A plant grown from a tuber (Fig. 11) develops a stem from its eye (bud). In this case, no embryonic root is formed. The tubers themselves do not bear normal roots, but secondary roots arise, as in the first case, in the nodes of the stem at its base or in the stolons and are usually located in groups, three to four together.
Rice. eleven. Development of a potato plant from a tuber
Root system potatoes - two types. In seedlings it consists of the main root, taproot and lateral roots. Vegetatively propagated plants have fibrous roots: germinal (primary), visible on light sprouts in the form of root tubercles; near-stolon roots, located in groups of four or five at the base of each stolon, and stolon roots, growing in groups along the length of the stolons.
The bulk of the roots are located at the depth of the arable layer, some go deep to 70-80 cm and only a small number of roots penetrate to a depth of 1.5-2 m. The development of roots depends on the biological characteristics of the variety and cultivation conditions. In early varieties, the depth of root penetration into the soil is less, in mid-season and late varieties it is greater. With sufficient moisture and good loosening of the soil, the power of the root system increases, which ensures high yields.
Tuber is a modified underground stem formed at the top of the stolon (Fig. 12). At an early age, small scaly leaves are observed on the tuber, which atrophy as it grows, and their leaf trail forms an eyebrow scar. In the axils of the scaly leaves, resting buds are formed, forming the so-called “eyes”. Each of them contains three or more buds, of which one germinates, and the rest develop only when the main one is damaged. The eyes on the tuber are located spirally, mainly in the upper part. Their number varies, depending on the variety, from 4-5 to 10-15 and directly correlates with the number of stems.
P 
The tuber point consists of a growth cone with the rudiments of the leaves of the axillary buds and the rudiments of the roots. When a tuber germinates, sprouts form from the dormant buds of the eyes. In the dark they are thin, long, etiolated, sometimes red-violet or blue-violet of varying intensity. In the light, short, strong shoots with anthocyanin characteristic of the variety are formed (see Fig. 12).
Rice. 12. The structure of the tuber and the light sprout of the tuber :
A- eyebrow; b- peephole; V- lentils; G- stolon trace.
Rostock: A- top; b-neck; V- base; G- root tubercles
The skin (periderm) of tubers (depending on the variety) is smooth thin, smooth thick, reticulated, flaky. The thickness of the peel, the size of its cells and layering are also determined by external conditions. The unilateral use of potassium and nitrogen fertilizers promotes the formation of a thin tuber skin, and phosphorus fertilizers - a thicker one. The cork tissue of the peel is impermeable to gases, so the tuber breathes through special organs - lentils, located in the form of points along the entire surface of the tuber. Lentils are laid in place of the stomata of a young tuber simultaneously with the formation of the peel.
When the soil becomes waterlogged and compacted, white tubercles appear on the lentils, consisting of loosely arranged thin-walled cells that allow outside air to pass into the underlying tissues. Increased growth of lentils indicates a possible disturbance in the respiration of tubers and damage to diseases, the pathogens of which more easily penetrate the tuber through the loose cells of the lentils.
The potato stem has wings - ribbon-like outgrowths between the nodes (Fig. 13). The number of stems in a bush varies by variety from 3-5 to 10-12. There is a certain relationship between the number of stems, the number and 
and the origin of tubers. Small-stemmed bushes have few tubers (5-10), but they
large; varieties with a large number of stems have more tubers - up to 20-25, but they are somewhat smaller, which is more economically feasible, since tubers weighing 50-150 g are more resistant to mechanical damage than large ones, and they are better stored in winter.
The potato leaf is discontinuous - odd pinnately dissected (Fig. 14). It consists of a single terminal leaflet, several pairs of lateral leaflets placed opposite each other, and smaller elements located between them - secondary leaflets. The lateral and secondary leaflets are attached by petioles to the stem, which passes into the leaf petiole.
The leaf, regardless of agricultural technology, is light green, dark green or grayish green (with strong pubescence). The petiole of the leaf, terminal and secondary leaflets, the veins are green or with anthocyanin color of varying degrees, which fades with age of the plant.
Potato flowers are collected in an inflorescence - a complex curl (Fig. 15). It consists of a peduncle, a peduncle and a flower. The shape of the inflorescences is compact or spreading.
Some varieties are characterized by the presence of small leaves called “top” leaves in the forks of the peduncles. Fig. 14. Structure of a potato leaf
The pedicels are divided by an articulation (cork ring) into upper and lower parts.
C 
potato branches consists of a calyx with five sepals, a corolla of five petals, five stamens collected in an anther column, and a pistil. The pointed tips of the sepals are broadly awl-shaped, narrowly awl-shaped and long leaf-shaped in shape.
Rice. 15. The structure of a potato inflorescence
A - peduncle; b- top leaves; V - cup; g - cork ring;
d - whisk; e- anther column; and - pestle; h - peduncle
Fetus potato - berry. The shape of the potato berry is often round, less often - somewhat elongated and pointed. The berry is bilocular and contains a large number of small seeds.
Seeds flattened, albuminous, with a bent embryo.
Potatoes have the following systematic position:
Department: Magnoliophyta - Magnoliaceae, or Anthophyta - Flowering plants, or Angiospermae - Angiosperms.
Class: Dicotyledoneae - Dicotyledons.
Order: Solanales - Solanaceae.
Family: Solanaceae - Solanaceae.
Genus: Solanum
View: Solanum tuberosum - Tuberous nightshade = Potato.
Potatoes are a self-pollinating plant; they reproduce vegetatively - by tubers or parts thereof. It is a perennial crop, but is cultivated as an annual crop. A potato plant grown from a tuber forms a bush of 2-4 or more stems. The number of stems in a bush depends on the variety and size of the planting tuber.
Stems herbaceous, green, tetrahedral, with weak lionfish. Depending on the number of stems, small-stem and multi-stem varieties are distinguished. Early ripening varieties usually branch weakly at the base of the stem, while late ripening varieties branch strongly.
Sheet intermittently unpaired pinnately dissected into lobes, lobules and lobules. The leaves on the stem are arranged in a spiral. The structure and color of the leaves is an important varietal characteristic.
Potato inflorescence- a complex curl with 2-5 flowers. The flower consists of a corolla calyx, stamens and pistil. The color of the flower is typical. The flower formula is as follows: Ca (5) Co (5) A 5 G (2), where you can see actinomorphy (multilateral symmetry), bisexuality, 5 fused sepals, 5 fused corollas, 5 unfused stamens, 2 fused pistils and a lower ovary.
Fetus- berry, two-locular, small-seeded (50-100 small white seeds), spherical, green. Typically, fewer berries are produced in dry years than in wet years. Removing buds and preventing berry formation can increase tuber yield by 10-15%.
Stolons- underground large-celled white shoots, at the end of which tubers are formed. Their length is 5-30 cm, and the shorter they are, the more compact the tubers are located in the nest, which is good for mechanized harvesting.
Root system fibrous, formed under the stolons. Most of the roots are located at a depth of 20-30 cm, and 5-7% of the roots penetrate into the layer of 60-80 cm. The bulk is located around the plant, occupying a diameter of 0.5 m. The development of the root system largely depends on the degree of soil cultivation.
Tuber potato is the thickened end of an underground shoot - the stolon and is a repository of reserve substances. Growth buds are located in the so-called eyes, located in a spiral in the tuber. Depending on the variety, the tubers vary greatly in shape - from elongated oval to round. The color of the pulp can be yellow, cream, white, and the peel can be light, purple, pink, red. During growth, the tuber has an easily erased epidermis, which by the time of maturity changes to a cork bark with lentils for gas exchange. One end of the tuber, which is attached to the stolon, is called the umbilical cord, the second - the apical one. Anatomical structure of the tuber: in a longitudinal section, a vascular ring is distinguished, approaching the eyes; in the middle part there is a core with a watery part. The outer layer consists of several layers of suberized periderm cells.
Rice. 91. Scheme of the structure of a potato leaf:
1 - final share; 2 - lateral lobe; 3 - slice.
Potatoes are a perennial herbaceous plant, but they are cultivated only as an annual crop. It is usually propagated by tubers, sometimes by their parts, sprouts, and cuttings. In breeding work, hybrid seedlings are grown from seeds.
Botanical description. The potato stem is erect or deviating to the side. A cultivated potato bush, depending on the variety and growing conditions, consists of 4-8 leafy stems. They can be branched or unbranched at the base. Early ripening varieties have unbranched stems. The later the variety, the more it branches.
From the axillary buds of the underground part of the stem, shoots develop - stolons, at the ends of which tubers are formed. In cultivated species, the length of stolons usually does not exceed 10 cm; in wild species, they can be up to 50 cm or more in length.
The leaves are discontinuously unpaired and pinnately dissected, consisting of a terminal lobe and 4-7 lateral lobes, between which there are smaller lobules (Fig. 91).
The flowers are quintuple, collected in an inflorescence in the form of a curl. The corolla is white, blue or red-violet in color with various shades. The flower has five stamens collected in a column (Fig. 92). Ovary superior.
The fruit is a two-lobed, multi-seeded green berry (Fig. 93). The seeds are very small, flattened, light yellow. The weight of 1000 seeds is about 0.5 g.
The root system is fibrous. The roots penetrate the soil relatively shallowly. When sowing seeds, a main root with numerous lateral branches develops from the rudimentary root of the seed.
The tuber is the thickened terminal part of the stolon. More than 3D of the tuber's weight is water and only about 1/4 is dry matter, of which mineral compounds are about 1%, proteins are about 2% and crude fiber is about 1%. The starch content in tubers of different varieties ranges from 12 to 24% and higher. Despite the strong variability under the influence of growing conditions, this indicator serves as a stable varietal trait.
On the tuber there are eyes located in a spiral, each of which has three buds. Since the tuber grows at the top, in its upper part the eyes are located more closely than in the middle and lower parts.
The shape and color of tubers are very diverse and are important varietal characteristics. Tubers are round, round-oval, elongated-oval, long, flat, etc. The color of the tubers is white, single, red or purple, depending on the color of the peel or pulp. Most varieties have white or slightly yellowish flesh, only in rare cases it is red or blue-violet.
Biological features. Potatoes are a plant of temperate climates, but due to their high plasticity they can be cultivated both in the south and far in the north. Depending on the variety and growing conditions, the growing season for potatoes lasts from 70 to 200 days. Based on this criterion, varieties are divided into five groups: early, mid-early, mid-ripening, mid-late and late.
Rice. 93. Potato berries. Below is a cross-section of the berry (a-seeds).
Potatoes are sensitive to low temperatures. In most varieties, the tops die during rapid cooling at a temperature of - 1°C. With a slow decrease in temperature, when sugars accumulate in plants, they can withstand short-term frosts down to -2°, -3°C, and in some cases even down to -4°C. For tubers, temperatures of -1°, -2°C are destructive.
The beginning of tuberization in most potato varieties coincides with the budding phase. The optimal temperature for tuber formation is 16°-18°C; at temperatures above 20°C, tuber growth stops. The best yield of potato tubers is formed in conditions of a short (12-hour) day.
Bloom. Potatoes are a self-pollinating plant. Some species and selected varieties are sterile. Sterility is determined genetically, and the degree of its manifestation is influenced by environmental conditions. For example, in the conditions of the Moscow region, the species S. curtilobum Juz. et Buk. It bears fruit every year, but near Leningrad it produces berries in rare years. In the Pamirs, almost all types of potatoes bear fruit well. Flowering occurs approximately 30-35 days after germination and continues for several days. The stigma usually ripens 3-4 days earlier than the anthers. Normally developed pollen, if properly snored, can remain viable for up to 6-7 days. Due to the sterility of the pollen, many varieties do not produce berries; some varieties do not bloom at all or only produce buds. The most favorable temperature for flowering is 13-22°C and light precipitation.
Rice. 92. Diagram of the structure of a potato flower: 1 - calyx; 2 - corolla; 3 - stigma; 4 - column; 5 - ovary; 6 - boot; 7 - filament; 8 - stamen; 9 - peduncle.
Today, potatoes occupy a significant niche in the diet in many parts of the world. Due to its nutritional value, relative cheapness and wide distribution, this vegetable is often called the “second bread”. Despite its apparent simplicity, the structure of potatoes is much more complex, and a detailed consideration of this issue will be useful for many agricultural producers and ordinary summer residents.
How did potatoes conquer Europe and Russia?
The homeland of potatoes is Central and Latin America. Spanish explorers began introducing potatoes to Europe in the late 16th century. At first, European kings and nobility appreciated only the flowers of the plant, which they used as a decorative decoration. Peasants zealously rejected this vegetable because they were poorly informed about the nutritional properties of the tubers themselves. Frequent poisonings from potato fruits and berries often led to the fact that, in a fit of anger, peasants simply uprooted the plants and burned them in the fire. The pleasant aroma of baked tubers obviously made people try them. So, gradually, the attitude of Europeans towards the new vegetable changed dramatically.
Potatoes appeared in Rus' during the time of Peter I. The Tsar, as a lover of everything European, brought a small batch of potatoes from Holland and ordered them to be handed over to the peasants for breeding. The lack of necessary knowledge had bitter consequences similar to what happened before to peasants in Europe. In addition, many clergy convinced illiterate people about the inadmissibility of growing foreign fruit and equated it with a sinful act.
Plant structure
Potatoes belong to the nightshade family. This is a perennial plant, however, for agricultural production purposes, potatoes are grown as an annual crop. The generally accepted method of propagation is planting tubers, however, experts also use seeds for selective work. The biological characteristics of potatoes as a crop lie in the specific formation of the root system, tubers and aerial parts of the plant.
Root system
There are two types of potato root system. A plant grown from seed has an embryonic taproot with a large number of small roots. Secondary roots are also formed at the base of the stem. Potatoes grown from a tuber have a fibrous root system consisting of sprout, near-stolon and stolon roots.
The usual depth of the potato root system is 25-40 cm, that is, the root mass is mainly located at the depth of the arable layer. In some cases, the roots can go to a depth of 80 cm or more. Late varieties have a more developed root system than their early counterparts.
Interesting facts: you can increase the yield by deepening the arable layer, for example, up to 70 cm. Thus, the number of tubers will increase significantly.
In addition to the usual roots, in the underground part of the plant there are stolons - shoots growing from the mother tuber. During development, the stolons grow and young tubers begin to form on young shoots. Stolons are easy to distinguish from roots: they are lighter in color and thicker.
Tuber
Many people believe that the tuber is the fruit of the potato. In fact, a tuber is part of an underground stem or stolon, and to be more precise, a tuber is a modified shoot. The plant accumulates starch, sugar and other useful substances necessary for further development.
The potato tuber has a unique structure and appearance. On the smooth and dense surface of the tuber there are always so-called “eyes”, small black dots and scars.
The eyes are the buds from which the plant stems sprout. The structure of the ocelli is quite interesting: near the main bud, in each of the ocelli there are always several additional buds, which are activated if the main one is damaged. Each tuber can have from 4 to 15 eyes. They are located on the upper half of the tuber.
The structure of a potato tuber also includes lentils - small points through which gas exchange occurs in the tubers. The formation of lentils occurs in parallel with the formation of the peel. If there is too much moisture in the soil or the soil is clogged, then loose white new growths appear on the lentils, which help absorb air. An increase in the size of the lentils is a bad signal, indicating that gas exchange in the tuber is impaired or it is affected by disease.
Scars that vaguely resemble eyebrows are atrophied scaly leaves that appear at an early stage of tuber development. It is in the axils of these leaves that buds later form.
The skin of the tubers themselves can be smooth, mesh or flaky, depending on the specific variety. The thickness of the periderm depends not only on the species, but also on weather and climatic conditions, soil quality and fertilizers. For example, the use of phosphorus-based fertilizers significantly thickens the peel, while potassium fertilizers, on the contrary, make the periderm thin.
Stem
The potato stem is formed from a tuber bud. Since there are always several buds, the stems also grow from 2-3 pieces or more, depending on the variety and size of the tuber itself. Several stems form a bush. In cross section they have a faceted shape (3-4 sides); much less often the stem looks rounded. Often the bushes reach a height of 80-90 cm, however, such luxurious plants often give a poor harvest, because all the strength goes into the development of the bush. Typically, this happens when there is an excess of fertilizers in the soil.
Each stem has wing-like appendages along its entire length.
Leaves
Each potato variety has its own characteristics, including the number, size and shape of leaves. An experienced gardener can easily identify the variety by the appearance of the green mass. The potato leaf is intermittently unpaired and pinnately dissected. On the main rod, between the paired lobes, smaller lobules are usually formed, and between them, in turn, there are lobules of even smaller size.
There are three degrees of dissection: weak, medium and strong. On a weakly dissected leaf there is one pair of lobules, but there are no lobules at all. The strongly dissected leaf has more than 2 pairs of lobules and many lobules.
The structure of the leaves also differs in the way the lobes, lobes and lobes are placed. If they overlap each other, creating the appearance of a continuous leaf, then this type is called densely divided. If the distance between the leaf elements is large enough, then we have a sparsely divided leaf type.
Flower
As you know, several centuries ago, a potato flower attached to clothing was considered a sign of belonging to the aristocracy.
Potato flowers have a rather complex structure. The inflorescence has the shape of a complex curl and can be spreading or compact. The peduncle, peduncle and flower form the inflorescence. In addition to these components, the inflorescence of some potato varieties contains top leaves.
The flower itself, the structure of which we are considering, consists of 5 sepals collected in a cup, 5 petals forming a corolla, 5 stamens and a pistil. The flower may have narrow, broadly awl-shaped and long leaf-shaped sepals.
The flower may be white, blue, purple or another color. After flowering is completed, the fruit ripens - a green poisonous berry, reaching 2 cm in diameter. The structure of the berry is quite simple: it is divided into two nests, each of which contains many small flattened seeds.
Despite the relatively low content of nutrients in potatoes, this root vegetable occupies an important place in the diet of many peoples. The advantages of the vegetable are the relative ease of cultivation, decent yield, and, of course, the excellent taste of potatoes.
A potato plant grown from a tuber forms a bush whose height is 50-80 cm. The number of stems in a bush (usually 3-6), their thickness, and ability to branch depend on the variety and growing conditions.
At the beginning of development, the stems are erect, later in most varieties they are curved. In cross section they are angular or rounded, up to 20 mm in diameter, often with straight or wavy, highly developed wing-like appendages. The color of the stems is green or with anthocyanin pigmentation. The underground shoots are called stolons. They thicken at the tops and form the beginning of new tubers. Each stem develops 6-7 or more stolons 15-20 cm long, in some varieties up to 40-50 cm. Depending on the length of the stolons, potato nests can be scattered (which makes caring for and harvesting plantings extremely difficult) and compact.
The structure of a potato tuber
A young tuber is covered with epidermis, a mature one is covered with suberized skin, smooth or mesh. The peel is impermeable to air, but there are holes in it - lentils, through which breathing occurs. Under the peel there are cortex cells filled with starch grains, then a layer of educational tissue (cambium), a ring of vascular-fibrous bundles and a core, also containing starch.
On the surface of the tubers, in recesses framed by a leaf scar or edge (a trace of a fallen underdeveloped leaf), there are eyes. They are arranged in a spiral. There are more of them at the top of the young part of the tuber than in the middle and lower parts. Each eye has 3-4 buds, but usually only one middle, most developed bud germinates, and only when the sprout is damaged does another bud begin to grow. The strongest sprouts come from the buds of the upper buds. Buds that sprouted in the dark form pale, elongated, thin sprouts called etiolated sprouts. In the light, shortened and dense shoots are formed. Depending on the variety, the shape of the base, color and pubescence of the sprouts are different.
Potato tubers
The color of the sprouts (green, red-violet and blue-violet) is better visible on tubers sprouted in low light. The basic shape of the tuber is round (rarely horn-shaped or ridge-shaped), elongated and oval; external color (white, yellow, pink, light red, red, blue) depends on the pigment contained in the cells of the bark or peel and the thickness of the suberized layer. The pulp can also be of different colors - white, cream, yellow, rarely red and blue. In Russia, the most common varieties are those with white-fleshed tubers.
The structure of the potato plant
The potato root system is fibrous, relatively poorly developed (its mass is 7-7.5% of the mass of the whole plant), branches up to the 3rd order; develops from the eyes of the tuber and from the buds of the stem nodes of the underground part of the stem and stolons. The bulk of the roots are located in the arable 25-centimeter layer, but individual strands can penetrate to a depth of 110-200 cm.
The structure of potatoes
A simple, unpaired, pinnately dissected potato leaf consists of several pairs of lobes, lobes and lobules, located in different combinations on the main petiole (stem), and ends with one unpaired lobe. The structure, degree of leaf dissection, size and shape of the lobes, length, position and shape of the petiole are important varietal characteristics. The leaf blade is always pubescent to varying degrees, the color ranges from yellow-green to dark green.
A potato inflorescence consists of 2-3, rarely 4 fork-shaped diverging curls located on a peduncle, which is laid in the axil of the 6-8th leaf and above (in later ripening varieties). Potato flowers are 5-membered with a cleavage calyx and incompletely fused white, red-violet, blue-violet or blue corolla lobes; 5 stamens with yellow or orange anthers; ovary superior, usually bilocular.
Potato flowers
Potatoes are self-pollinators; cross-pollination is rare. In many varieties, pollen grains are wrinkled and sterile (male sterility). The fruit is a spherical, oval or turnip-shaped juicy 2-locular berry containing a large number (sometimes more than 200) of very small seeds. Weight of 1000 seeds is 0.5-0.6 g.