2. The importance of vegetables in human nutrition
Vegetables have great importance in human nutrition. Eating right means correctly combining plant and animal foods in accordance with age, nature of work, and state of health. When we eat meat, fats, eggs, bread, cheese, acidic acids are formed in the body inorganic compounds. To neutralize them, you need basic, or alkaline, salts, which are rich in vegetables and potatoes. Green vegetables contain the largest amount of acid neutralizing compounds.
Consumption of vegetables helps prevent many serious diseases and increases human tone and performance. In many countries of the world during treatment various diseases In dietary nutrition, fresh vegetables occupy a leading place. They are rich in ascorbic acid (vitamin C), which ensures normal carbohydrate metabolism and promotes the removal of toxic substances from the body, resistance to many diseases, and reduction of fatigue. Many vegetables contain B vitamins, which affect human performance. Vitamins A, E, K, PP (nicotinic acid) are present in green peas, cauliflower and green vegetables. Cabbage contains vitamin and, which prevents the development peptic ulcer duodenum.
Organic acids, essential oils and vegetable enzymes improve the absorption of proteins and fats, enhance the secretion of juices, and promote digestion. Onions, garlic, horseradish, and radishes contain phytoncides that have bactericidal properties (they destroy pathogens). Tomatoes, peppers, and leaf parsley are rich in phytoncides. Almost all vegetables are suppliers of ballast substances - fiber and pectin, which improve intestinal function and help eliminate excess cholesterol and harmful digestive products from the body. Some vegetables, such as cucumber, have low nutritional value, but due to the content of proteolytic enzymes, they have a positive effect on metabolism when consumed. Green vegetables are of particular value. IN fresh They are not only better and more fully absorbed by humans, but also help (with enzymes) in the digestion of meat and fish in the body. At the same time, being cooked, the green ones lose a significant part useful properties.
To meet the need for vitamins, carbohydrates, proteins, acids, salts, an adult needs to consume more than 700 g (37%) of food of animal origin and more than 1200 g (63%) of plant origin, including 400 g of vegetables, daily. The annual need for vegetables per person varies depending on the region of the country and is 126-146 kg, including cabbage of various types 35-55 kg, tomatoes 25-32, cucumbers 10-13, carrots 6-10, beets 5-10, onions 6-10, eggplants 2-5, sweet peppers 1-3, green peas 5-8, melons 20-30, other vegetables 3-7.
Vegetables increase the digestibility of proteins, fats, and minerals. Added to protein foods and cereals, they enhance the secretory effect of the latter, and when consumed together with fat, they remove its inhibitory effect on gastric secretion. It is important to note that undiluted juices of vegetables and fruits reduce the secretory function of the stomach, and diluted ones increase it.
2.1Commodity characteristics of tubers
Tuber crops include potatoes, Jerusalem artichokes, and sweet potatoes.
Potatoes are the most common vegetable crop. Occupying one of the first places in nutrition. It is rightly called the second bread.
Homeland of potatoes - South America. Potatoes came to Russia at the end of the 17th century, Peter I sent a bag of tubers from Holland and ordered them to be planted in different regions. The peasants greeted the stranger with hostility; no one could really tell them about its merits. However, in subsequent centuries, potatoes not only took root in new places, but also found a second home in Russia.
Potato tubers are thickenings formed at the ends of the shoots of underground stems - stolons. The tuber is covered with bark, on the surface of which a plug called peel is formed. Under the bark there is pulp, consisting of a cambial ring, an outer and an inner pith. On the surface of the tuber there are eyes with two or three buds. The cork layer of bark protects the tubers from mechanical damage and the penetration of microorganisms, regulates water evaporation and gas exchange.
Potatoes contain: water - 70-80%; starch - 14-25%; nitrogenous substances - 0.5-1.8%; fiber - 0.9-1.5%; minerals - 0.5-1.8%; sugars - 0.4-1.8%; acids - 0.2-0.3%. It contains vitamins (in mg%): C – 4-35; B1- 0.1; B2- 0.05; PP - 0.9. Green and sprouted potatoes contain poisonous glycosides (corned beef and chaconine). Most of the glycosides are found in potato skins.
The nitrogenous substances in potatoes contain simple proteins - proteins. Potato proteins are complete and in terms of the combination of amino acids they are equal to proteins chicken eggs. As a result of enzymatic oxidation of the amino acid tyrosine, peeled potatoes darken in air. According to the ripening period, early potatoes are distinguished (ripening 75-90 days); average (90-120 days); late (up to 150 days).
According to their purpose, potato varieties are divided into table, technical, universal, and fodder.
Table varieties have large or medium tubers, thin skin, a small number of shallow eyes, are well preserved, and when peeled give smallest number waste; Their flesh is white, does not darken when cut and cooked, cooks quickly, but does not become mushy. When cooled, the potatoes do not darken and have a pleasant taste. Table potatoes are used directly for food, for the production of dried potatoes, potato flakes, frozen potato products, crisps (chips), and crackers. The most common early varieties of table potatoes are Nevsky, Svitanok, Lvovyanka, Skorospely, Early Rose, Epicurus; medium varieties: Stolovy 19, Ogonyok, Gatchinsky, Peredovik; To late varieties include Temp, Kievlyanka, Razvaristy, Komsomolets, Lorch.
Jerusalem artichoke (earthen pear). Jerusalem artichoke is grown in the southern regions of the country; it is a perennial crop. Jerusalem artichoke tubers are covered with large growths, have an elongated cylindrical shape, and are yellow-white, pink or purple in color; The pulp is white, juicy, sweet taste. Jerusalem artichoke contains up to 20% inulin; it also contains nitrogenous substances (1.5-3%) and sucrose (2-5%). Jerusalem artichoke is used as livestock feed, to obtain alcohol, inulin, and fried directly for consumption.
Yam (sweet potato). Grown in the south. In appearance it is similar to potatoes. Sweet potato is classified as a tuber crop conditionally, since it consists of overgrown lateral roots. The skin is white, yellow or red, the flesh is juicy or dry. Sweet potatoes contain (in%): starch-20, sugars-2-9, nitrogenous substances-2-4. Bata is used boiled, fried, for preparing first and second courses, for producing flour, and also for drying.
Potato
Variety "Svitanok"
Jerusalem artichoke
Variety "European"
Vegetables as food products occupy a special place in the human diet. Their nutritional benefits are due to the content of carbohydrates, proteins, fats, vitamins, enzymes, hormones, minerals and other substances. According to the methods of consumption, all vegetable crops are divided into three groups: vegetables consumed mainly raw; vegetables consumed both raw and processed; vegetables consumed mainly in processed form (heat treatment, canning, drying, freezing).
Mostly salad vegetables are eaten raw: leaf lettuce, head lettuce, all types of chicory, watercress, watercress, radish, radish, leaves of onion plants, horseradish, katran.
In raw and processed form they eat: tomatoes, cucumbers, melons, watermelons, peppers, carrots, white cabbage, Chinese cabbage, kohlrabi, turnips, rutabaga, onions, garlic, leeks, peas, herbs, parsley, celery and root, spinach, sorrel.
In processed form they use: pumpkin, zucchini, squash, beans, asparagus, rhubarb, eggplant, parsnips, root parsley, mushrooms.
Vitamins. This is a group of biologically active organic compounds, contained in very small quantities and necessary for the normal functioning of the human body. From water-soluble vitamins vegetables contain vitamin C ( ascorbic acid) - an important component of redox processes in the body, increasing its protective reactions; vitamin PP (niacin, nicotinic acid), which regulates digestion, liver function, cholesterol metabolism and the formation of red blood cells. Green peas, carrots, potatoes, and red peppers are especially rich in vitamin PP. Vitamin B c (folic acid) is involved in the work of hematopoietic organs, the synthesis of nucleic acids and choline, increases resistance to chemicals. Found mainly in green vegetables and beans.
Vitamins B, (thiamine), B, (riboflavin), B 3 (pantothenic acid), H (biotin) participate in the regulation of carbohydrate and fat metabolism, specific effects on the digestive organs, oral mucosa, and digestive tract. These vitamins are found in green peas, leeks, cauliflower and red cabbage.
Vegetables also contain vitamin-like substances: vitamin B 4 (choline), which is involved in fat metabolism, vitamin B 8 (inositol), which normalizes metabolism in nervous tissue, stimulates intestinal activity, and reduces cholesterol in the blood. Vitamin U (methylmethionine sulfonium chloride), contained in cabbage juice, is used in the treatment of peptic ulcers gastrointestinal tract.
Fat-soluble vitamins in vegetables are represented by p-carotene, which is converted in the liver into retinol (provitamin A), necessary for growth and development, normal functioning of mucous membranes and tissues. Contained mainly in orange-colored vegetables: carrots, red peppers, pumpkin, as well as spinach, garlic leaves, dill, lettuce, parsley.
Vitamin E (tocopherol, the reproduction vitamin), which is rich in green peas, onion and parsley leaves, spinach and leeks, is an active antioxidant involved in metabolism in the liver and supports the reproduction function.
Minerals. Vegetables are the main suppliers of alkaline elements. Consuming them neutralizes the acid reaction of digestion. Vegetables contain: calcium, which regulates physiological and biochemical processes; magnesium, which normalizes heart activity and nervous system and stimulating bile secretion and removal of waste from the body; potassium, which regulates cardiac activity and water-salt regime; phosphorus. Vegetables are an important supplier of iron, iodine, molybdenum, fluorine, zinc, manganese, copper and other trace elements.
Protein. Vegetable crops are relatively poor in proteins, but many vegetables contain all the essential amino acids. The richest in proteins are beans, green peas, beans, Brussels sprouts and cauliflower, kohlrabi, parsley, and spinach. In terms of protein yield per unit area, certain vegetable crops are superior to grain crops.
Carbohydrates. Contained in all vegetable crops. They are represented mainly by mono- and disaccharides, and to a lesser extent by starch (potatoes, sweet potatoes and green peas). The carbohydrate content ranges from 2.2% for lettuce to 19.7% for potatoes. Carbohydrates mainly determine the energy value of vegetables. An important component of vegetables is polysaccharides: fiber (cellulose) and pectin. Both compounds belong to the group plant fibers. Fiber contained in vegetable crops (from 0.3% in zucchini to 3.5% in dill) and pectin substances stimulate intestinal motility, bind and remove from the body harmful products, including carcinogenic, toxic substances formed as a result of digestion and the activity of microorganisms.
Organic acids. Vegetables contain mainly citric, oxalic and malic acids. When vegetables are consumed, they quickly decompose and do not neutralize the alkaline salts contained in the product. Acids give a pleasant taste to vegetables and their processed products and, in sufficient quantities, prevent the development of botulinum bacteria in processed products.
Oxalic acid, with excessive consumption of vegetables containing it (sorrel, spinach, rhubarb), can be an anti-nutritional factor that counteracts the absorption of calcium, magnesium, manganese Essential oils, aromatic substances. There are two groups of essential oils in vegetables: those containing and those that do not contain sulfur. Sulfur-free oils are found in vegetable plants of the Celery (parsley, carrot, dill, fennel, parsnip, lovage, etc.), Asteraceae (tarragon) and Lamiaceae (mint, lemon balm, hyssop, darter, marjoram, etc.) families. Essential oils containing sulfur are divided into nitrogen-containing and nitrogen-free. The former are present mainly in vegetables of the Brassica (horseradish, radish, cabbage, turnip, rutabaga) and Allium (garlic, onion) families. Asparagus, leeks and chives contain nitrogen-free substances. Essential oils and other aromatic substances improve the taste of vegetable dishes, give them piquancy, increase appetite, and improve food absorption.
Energy value(calorie content) of vegetables. The energy value of vegetables is low. The highest rates are found in potatoes, green peas, beans, Brussels sprouts and beets. The low calorie content of vegetables makes them a valuable product for the prevention of obesity.
Phytoncides. Many vegetables of the Cabbage, Onion, Lamiaceae, and Asteraceae families contain phytoncides, essential oils and other compounds that have a pronounced antimicrobial effect. The most strongly phytoncidal effect is expressed in horseradish, onions and garlic, radishes and radishes, and mint. Vegetables are superior to others food products(meat, bread, milk) according to their ability to increase excretion in humans gastric juice. The adaptogenic and stimulating effect of vegetables on the human body, especially in stressful situations, is generally recognized. Many vegetable plants were introduced into cultivation as medicinal ones.
Harmful substances. In addition to substances beneficial to the human body, due to biological characteristics and violations of agricultural technology, vegetables may contain harmful components (anti-food toxic substances). Anti-nutritional substances also include chemical compounds that are non-toxic to the body and impair the absorption of other nutrients.
Toxic substances include toxic amino acids, nitrates and nitrites included in proteins, which accumulate in vegetables under unbalanced nitrogen nutrition of plants and other conditions unfavorable for protein synthesis (low light, overheating). When soil is contaminated, vegetables are capable of accumulating large amounts of radionuclides (strontium-90, cesium-137), as well as heavy metal salts. Radionuclides accumulate especially in large quantities in plant leaves.
Fruits and vegetables contain vitamins, mineral salts, carbohydrates, proteins, and vegetable fats necessary for human life. Each type of fruit and vegetable has certain biologically active substances: some of them improve the metabolic process, neutralize acids formed during the digestion of meat, dairy and flour foods, normalize blood pressure, others strengthen the walls of blood vessels, give them elasticity, and reduce cholesterol in the blood and fluids in the body.
Fruits and vegetables consumed fresh contain the most vitamins.
Provitamin A (carotene) is a growth vitamin. There is a lot of it in carrots, spinach, tomatoes, onion leaves, parsley, in the fruits of sea buckthorn, plums, and rose hips. In the human body, carotene is converted into vitamin A. With its deficiency, eye disease (night blindness) develops and the body's resistance to other diseases decreases.
B vitamins (Bi, Br, Bb, PP, etc.) promote metabolism in the body, slowing down the development of sclerotic phenomena in blood vessels. With a lack of vitamin Bi, a disease known as “beriberi” develops, which is characterized by a severe disorder of nervous and cardiac activity. Vitamin Br is part of a number of enzymes involved in carbohydrate and protein metabolism. With its deficiency, growth retardation or weight loss, weakness, weakened vision and the formation of cataracts, skin and nervous disorders. Vitamin PP takes an active part in metabolism. With its deficiency, the functions of the gastrointestinal tract and central nervous system are disrupted. Sources of vitamins Bi, Br and PP are apples, pears, carrots, tomatoes, cabbage, spinach, onions, and potatoes.
Vitamin C (ascorbic acid) protects against scurvy, nervous system disorders and general loss of strength. The main sources of this vitamin are rose hips, sea buckthorn, black currants, strawberries, apples, peppers, kohlrabi, white cabbage (fresh and pickled), horseradish, spinach, lettuce, onion leaves, dill and parsley, potatoes. Vitamin U contained in cabbage juice has been discovered. It helps treat stomach and duodenal ulcers.
Some vegetables contain aromatic substances that increase appetite and promote the absorption of food (dill, tarragon, cumin, basil, marjoram, savory, parsley, celery, onion, garlic, etc.); phytoncides that have a detrimental effect on pathogens (onions, garlic, peppers, radishes, horseradish).
Rational human nutrition consists of food of animal and plant origin. Physiological norm consumption, the favorable temperature for growth, development and fruiting of heat-loving vegetable crops is 20-30 °C.
Less demanding of heat are cabbage of all types, carrots, beets, turnips, rutabaga, radishes, radishes, parsley, celery, onions, garlic, lettuce, spinach, dill, peas, and beans. Their seeds germinate at temperatures below 10 °C. These crops grow well, develop and form a productive part at 17-20 °C.
Winter-hardy vegetable plants include sorrel, rhubarb, horseradish, and perennial onions. In plants of this group, growth begins at 1-2 °C. Vegetating plants can tolerate frosts down to -10 °C. Being at rest, they overwinter painlessly in the open ground.
During the period of growth and development, the requirements for temperature conditions in vegetable plants change. During swelling and germination of seeds, more heat, and when seedlings appear, it is lower. Therefore, in protected ground with elevated temperature and lack of light, stretching of plants is often observed. During the flowering and fruiting period, the temperature should be elevated.
When storing vegetables and fruits it is necessary low temperature- about 0 ° C to slow down the processes of respiration and breakdown of nutrients.
Light. In natural conditions sunlight- the only source of energy that provides the process of photosynthesis. In the light, the leaves of vegetative plants synthesize organic substances from carbon dioxide in the air, water and minerals coming from the soil. The need for lighting is determined by the species and varietal characteristics of plants, the growing season, as well as the regime of other meteorological, soil and agrotechnical factors.
Garden plants react differently to light: some need intense lighting and, with a lack of light, grow poorly and sharply reduce yield (cherry), others are shade-tolerant (actinidia). Reproductive organs (inflorescences, flowers, fruits) require the highest light intensity. In the absence of light they do not develop. Deviation from the optimum illumination leads to leaf shredding. With insufficient lighting, many physiological processes are disrupted (accumulation and metabolism, differentiation of tissues and cells, pollination and fertilization, formation of fruits and seeds, etc.). For normal growth and high productivity of plants, it is necessary that all vegetative and reproductive organs that make up the crown are provided with an optimal amount of light. Poor lighting inside the crown reduces the longevity of the fruiting organs, their productivity, and the quality of the fruit. Assimilation, that is, the absorption by the plant of substances entering it from the external environment, is directly dependent on the intensity of lighting. As the latter improves, it increases. In gardening practice, pruning is used to lighten the crowns of trees and shrubs; if the planting is too dense, the plants are thinned out.
Vegetable crops are divided into short-day plants (tomatoes, eggplants, peppers, beans, zucchini, squash, pumpkin, cucumber varieties intended for cultivation in open ground) and long-day plants (root vegetables, cabbage, onions, garlic, green crops, some greenhouse varieties cucumbers). First for more rapid growth and development requires a day length of less than 12 hours, but in good light, the second requires more than 12 hours, and they tolerate partial shading.
By artificially shortening or lengthening daylight hours, you can get higher yields of some vegetable crops and products best quality. For example, by creating a short daylight hours for radishes, lettuce, dill and spinach, you can delay their development, that is, the transition to bolting and flowering, and get a higher yield of the productive part (root crops, leaves), and of improved quality. Under natural conditions, this is achieved by early spring and late autumn sowing dates, when daylight hours are shorter. In the winter months, with short daylight hours and low lighting in greenhouses, from the moment the seedlings emerge until the seedlings are planted in a permanent place, artificial supplementary lighting with electric lamps is used.
Excessive thickening of crops and plantings should not be allowed, both in protected and open ground, since in this case the plants shade each other, stretch out, weaken and subsequently reduce productivity. It is necessary to maintain the optimal density of sowing and planting, thin out the plantings if they are thickened, and destroy weeds.
Water makes up 75-85% of the wet weight of plants. A huge amount of water is spent on the formation of roots, shoots, leaves, fruits and other plant organs. So, to create 1 kg of dry matter, plants consume 300-800 kg of water. Most of it is spent on transpiration, which promotes the movement of water through the vessels of the stem from the roots to the leaves.
The main source of water for the plant is soil moisture. Garden, vegetable and ornamental plants grow and produce best when soil moisture is 65-80% of full moisture capacity. With higher humidity, the oxygen necessary for the normal functioning of roots is displaced from the soil; with lower humidity, the plants lack moisture and their growth is inhibited.
In the Non-Chernozem Zone, with an annual precipitation of 550-700 mm, natural moisture is considered sufficient. However, every year certain months, and sometimes the entire growing season, are dry, as a result of which the normal growth and productivity of fruit, vegetable and ornamental plants is impossible without artificial irrigation. This is especially true for moisture-loving plants grown on light sandy and sandy loam soils, where constant watering is required.
If there is a lack of water for irrigation during the dry period, it is recommended to loosen the soil more often between the rows. Loosening prevents the formation of a soil crust, destroys the capillaries through which water flows from the lower layers of the soil to the upper ones, which significantly reduces its evaporation from the soil.
It is not recommended to water plants during the daytime in sunny weather, as most of the poured water will quickly evaporate. Watering is best done in evening hours- 2-3 hours before sunset or early in the morning. In cloudy weather, watering during the daytime is also acceptable.
Fruit and berry plants require more water during the period of intensive growth of roots and shoots and during the formation of fruits (May - July), less - during the period of attenuation of growth and ripening of fruits (August - September). In dry weather, in the first period it is necessary to carry out abundant watering, in the future it can be limited, since a decrease in humidity at this time contributes to the ripening of shoots, preparing them for winter, ripening of fruits, improving their taste and color. Excessive amounts of moisture in the soil are also harmful: root growth is inhibited, shoot growth is delayed, fruits and berries crack. Trees and shrubs grow best when the groundwater level is at least 1-1.5 m from the soil surface. According to the degree of resistance to excess water in the root layer of the soil, fruit and berry plants are arranged in the following descending order: currants, gooseberries, apple trees, pears, plums, cherries, raspberries, strawberries.
Vegetable plants are demanding of moisture. IN different periods This exactingness varies depending on their growth and development. Cabbage, cucumbers, turnips, radishes, radishes, lettuce, and spinach are especially moisture-loving. A lot of moisture is required for seed germination (from 50 to 150% of their mass). Plants also need a lot of moisture at seedling age. Plants in adulthood and especially during the formation of productive organs need less frequent, but more abundant watering, capable of moistening the soil to the entire depth of the bulk of the roots (up to 20-30 cm). Plants must be watered regularly so that the moisture content of the root layer of soil is 70-80% of the total moisture capacity. A sharp transition from an arid state to excessive soil moisture leads to cracking of fruits, heads of cabbage and root crops, causing their consumer qualities to sharply decrease.
All heat-loving vegetable crops (especially cucumbers and tomatoes) need to be watered warm water(20-25°C). Watering cold water(6-10°C) leads to plant disease.
In greenhouses and greenhouses, water for irrigation is heated artificially. In conditions open ground The water is heated in the sun, for which it is poured in advance into barrels, bathtubs, tanks, and into small pools specially built in the areas.
Maintaining a certain air humidity is also important for vegetable plants. For example, the relative air humidity when growing cucumbers should be at least 85-90%, for tomatoes no more than 60-65%. Such a sharp difference in air humidity requirements does not allow growing cucumbers and tomatoes in the same greenhouse or greenhouse.
Atmospheric air consists mainly of oxygen (21%), carbon dioxide (0.03%) and nitrogen (78%). Air is the main source of carbon dioxide for photosynthesis occurring in plants, as well as oxygen necessary for their respiration (especially for the root system). Thus, adult plants per 1 hectare daily absorb more than 500 kg of carbon dioxide, which, if its content in 1 m3 of air is 0.03%, corresponds to more than 1 million m3. To ensure the normal functioning of plants, it is necessary to constantly replenish the air in the area where they are located with carbon dioxide. An artificial increase in the carbon dioxide content in the air to 0.3-0.6% (10-20 times more than natural) helps to increase plant productivity. The introduction of manure and other organic fertilizers into the soil helps enrich the ground layer of air with carbon dioxide. In greenhouses, this is achieved by fermenting cow or bird droppings in barrels, using liquefied gas cylinders, special burners, and “dry ice” (solid carbon dioxide).
The oxygen content in the soil air is somewhat less, and the carbon dioxide content is many times higher than in the atmosphere. Soil aeration has a great influence on the supply of oxygen to plant roots. To improve it, you need to frequently loosen the soil and keep it free of weeds.
Nutrition. Plants use minerals from the air to build their organs and produce crops ( carbon dioxide) and soil (macro- and microelements dissolved in water). Different nutrients play different roles in plant life. Thus, carbon, oxygen, nitrogen, phosphorus, sulfur and magnesium are used to build organs and tissues. Iron, copper, zinc, manganese, cobalt are part of biocatalysts that promote the absorption of minerals by plants. Nitrogen, potassium, phosphorus, calcium, magnesium, sulfur are required by the plant in large quantities and are called macroelements, other elements are needed in small quantities and are called microelements. Of the macroelements, plants use nitrogen, phosphorus and potassium the most. Each of these elements is part of organic substances and plays a specific role in physiological processes.
Nitrogen is part of proteins and other organic substances. The largest amount of it goes to the formation of leaves, shoots, vegetative and flower buds, flowers, fruits and seeds. The nitrogen content in these organs changes noticeably during the growing season. So, in the spring (in initial period growth) in leaves and shoots it is increased. The source of nitrogen during this period is the reserves deposited in the plant in the fall. Then the amount of nitrogen decreases significantly. By autumn, the nitrogen content increases again and it flows into wintering organs.
A long-term lack of nitrogen leads to starvation of plants, which is reflected in the suspension of the growth of shoots and roots, the formation of smaller and paler leaves, and the shedding of fruits and berries. A sufficient amount of nitrogen ensures active growth of shoots, the formation of large dark green leaves, earlier entry of plants into fruiting, intensive flowering and increased fruit set.
Excess nitrogen with a lack of phosphorus and potassium in the soil can negatively affect the development of young plants. In this case, there is a delay in the growth of annual shoots and a later onset of a period of relative dormancy. In fruit-bearing trees, excess nitrogen causes insufficient ripening of fruits, their pale color, a decrease in sugar content and keeping quality, and a decrease in winter hardiness and frost resistance of fruit trees.
Nitrogen enters plants mainly through the roots from the soil, where it accumulates as a result of the application of organic and mineral fertilizers, as well as due to the activity of bacteria that fix it from the air.
Phosphorus compounds provide intermediate reactions associated with photosynthesis and plant respiration. Phosphorus is part of complex proteins. Its deficiency weakens the growth of shoots, branching of roots, and the formation of flower buds. Phosphorus in soil can be in the form of organic and mineral compounds. During the decomposition of organic compounds, it is mineralized and becomes available to plant roots. Most of the mineral phosphorus compounds are sparingly soluble and inaccessible to plants. Different fruit species have different assimilation capacity of roots. The roots of an apple tree, for example, absorb phosphorus from sparingly soluble compounds better than the roots of strawberries, currants, and gooseberries.
Potassium promotes the assimilation of carbon dioxide, the absorption of water by the plant, and metabolism. It ensures normal division of cells and tissues, growth of shoots and roots, formation of leaves and fruits, and increases the frost resistance of plants. Its deficiency leads to a change in the color of the leaves - their edges first turn yellow and then become covered with brown spots. In soil, potassium is found in organic and mineral compounds. Sandy soils are poor in potassium. Its main source is organic forms after their mineralization.
As for other macroelements, they are found in garden soils in quantities sufficient for plants.
Iron plays an important role in the formation of chlorophyll. If there is a deficiency of it, plants develop chlorosis (light yellow and even white leaves are formed).
Magnesium is part of chlorophyll. Its deficiency causes stunting of shoot growth, chlorosis or brown spotting, premature death and falling of leaves.
Zinc is an integral part of a number of vital enzymes; it influences the formation of growth substances (auxins) and plays an important role in redox processes in plants. If it is deficient, apple trees develop rosettes (instead of normal side shoots, they form rosettes with small deformed leaves).
Since these and other elements are needed by plants in small quantities, their needs are almost always met by the reserves that are available in the soil. An acute lack of microelements can be eliminated by adding them directly to the soil or spraying plants (foliar feeding).
- The importance of fruits and vegetables in human nutrition
The importance and role of vegetables in human nutrition is enormous, because they have a beneficial effect on digestion. However, you should not think that you need to eat only plant foods, as vegetarians believed. Modern science The basis for healthy human nutrition is a harmonious combination of plant and animal foods.
According to scientists, the average daily norm vegetables for an adult is 300-400 g - 110-150 kg per year. The same amount of potatoes is needed.
The most important feature of vegetables is their high content of vitamins. This makes them indispensable in human nutrition.
Vitamins are special substances that regulate the vital functions of the body. More than 20 of them are now known. The most important vitamins for humans are vitamins A, B, Bi, B2, B12, C, D, E, K, and PP.
Vitamin A is found in animal products ( fish oil, cow butter), but its main amount enters the human body in the form of carotene when consuming tomatoes, lettuce, spinach, carrots, pumpkin, zucchini, cauliflower, green leaf vegetables In any case is important action any gardener
Vitamin A promotes the growth of a young body, improves vision, and also strengthens the activity of the glands internal secretion. Its deficiency reduces the body's resistance various diseases, colds and causes eye disease (night blindness).
Vitamins Bi and Br are found in cabbage, tomatoes, potatoes, carrots, leafy vegetables and legumes. The first of them helps improve cardiac activity and the nervous system, and the second - metabolic processes and activity gastrointestinal tract. A lack of vitamin Bi in food can lead to muscle weakness and even paralysis of the legs.
Vitamin C is found in cabbage, tomatoes, peas, peppers, green onions, horseradish, lettuce, spinach, dill, parsley, potatoes and many other vegetables. This vitamin protects the body from many diseases (scurvy), accelerates the healing of wounds, fractures, improves the absorption of carbohydrates, proteins and fats, promotes normal liver function, recovery from pneumonia, diphtheria and whooping cough. The reserves of vitamin C in our body are insignificant. Therefore, we should consume fresh or canned vegetables throughout the year. Fresh greens are especially useful in winter.
Vitamin B is found in onions, spinach, green peas, rhubarb and other vegetables. This vitamin favors proper development bones and teeth in a young body. In its absence, rickets develops and muscles weaken.
Vitamin E is found in all green parts of vegetables and especially in leafy ones. It helps improve the functioning of the nervous system, treat cardiovascular diseases and takes part in fat metabolism.
Vitamin K is found mainly in leafy vegetables, tomatoes and carrots; it promotes blood clotting and accelerates wound healing.
Vitamin PP B large quantities found in cauliflower, tomatoes and carrots, takes part in the metabolism of carbohydrates and proteins, regulates the activity of the nervous system and prevents gout.
With a lack of vitamins, the normal operation body, general weakness begins, caused by lack of appetite; all this leads to serious illnesses. In addition, when eating bread, meat, fish, butter, cheese, eggs in digestive organs harmful acids are formed. To neutralize them, you need to eat vegetables, which, in addition to vitamins, also contain mineral salts.
Some vegetables (onions, garlic, horseradish) contain special substances - phytoncides, which have an inhibitory effect on bacteria and thereby disinfect the digestive organs.
The importance of vegetables in the human diet. There are more than 1,200 species of vegetable plants around the globe, belonging to 78 botanical families. About half of them are cultivated, and the rest grow wild.
About 70 species of vegetable plants are grown in our country. The nutritional value of vegetables is determined by their high content of easily digestible carbohydrates, organic acids, vitamins, aromatic and mineral substances, a varied combination of which determines the taste, color and smell of these healthy products. The main indicator of the quality of vegetables is the biochemical composition. They contain up to 96-97% water and, despite this, are of great importance in human nutrition. This is due to the fact that the small amount of dry matter found in vegetables contains many biologically important compounds that are required for the normal functioning of the body.
The main part of the dry matter is starch and sugar. There is a lot of starch in legumes and root vegetables; Sugars - in carrots, peas, onions. In table beets, sucrose predominates, and in cabbage, cucumbers, and pumpkins, glucose predominates. The dry matter also includes fiber, pectic nitrogenous substances, mainly proteins, and glucose.
In addition, there are organic acids - citric/malic, tartaric, oxalic, etc. They have a beneficial effect on the taste of vegetables and contribute to their better absorption. Vegetable essential oils (onion, parsley, dill) have phytoncidal properties. It is known that phytoncides have long been used in medicine: they protect humans from many infectious diseases. Vegetables are an important source of mineral salts. Parsley leaves, green peas, onions, cabbage, and parsnips are rich in phosphorus; leafy vegetables and root vegetables - potassium; lettuce, spinach, beets, cucumbers, tomatoes - iron; cauliflower, lettuce, spinach - calcium.
The high content of vitamins and their diverse composition make vegetables irreplaceable food products, playing a decisive role in regulating amino acid, fat and carbohydrate metabolism in the human body. The daily requirement of an adult for various vitamins is, mg: A - 3-5, B1, B2 - 2-3, B3 - 5-10, PP - 15-25, C - 50-70, etc. To satisfy the need in vitamin C, for example, you need to eat 200 g of fresh white cabbage or 300 g of sauerkraut, 50 g of sweet pepper or parsley, 250 g of tomatoes or radishes, 70 g of dill or horseradish per day.
Carotene (provitamin A) deficiency can be compensated by 40-50 g of carrots, spinach, dill, parsley, 300 g of tomatoes or radishes, 80 g of green onions, 75 g of sorrel. Vitamin C (ascorbic acid) protects the body from scurvy and anemia. Most of it is found in sweet peppers, parsley, dill, white cabbage, and cauliflower.
Vitamin A is involved in redox processes, increases the glycogen content in the muscles of the heart and liver, ensures the normal condition of the epithelium, cornea and lacrimal glands of the eyes, skin, respiratory tract, digestive tract. The human body can fill the need for vitamin A both with vitamin A itself and with its predecessor, provitamin A (carotene). The most valuable sources of provitamin A are sweet peppers (red and green), tomatoes, pumpkin, and carrots from root vegetables.
Compounds with A-vitamin activity can accumulate in the human body and persist for up to a year. Therefore, it is very important to consume as many vegetables rich in carotene as possible during the summer season. In winter, they can be replaced with tomato puree, tomato paste and tomato juice. Vitamin B1 (thiamine) is part of many enzymes that play an important role in the conversion of carbohydrates. Insufficient intake of vitamin B1 from food leads to the accumulation of toxic products; incomplete oxidation of glucose, increased content of pyruvic acid in tissues, resulting in diseases of the nervous system.
Legumes and spinach have the highest vitamin B content. A lack of vitamin B2 (riboflavin) reduces the rate of conversion of fats and carbohydrates in the human body, impairs the absorption of protein received from food, impairs the ability to form glycogen in the liver, which leads to weakness, eye damage and skin, increased blood sugar.
A large amount of vitamin B2 is found in green peas, beans, Brussels sprouts, spinach, green onions, sweet peppers, and parsley root. Pea and bean pods are also rich in vitamin B6, which plays an important role for the normal functioning of the nervous system. Vitamin PP is essential for normalizing the functioning of the liver. An important source in everyday nutrition nicotinic acid are, first of all, tomatoes, onions, carrots, spinach.
Vitamins of group K are necessary for normal blood clotting. They are found in spinach, cauliflower and white cabbage, and tomatoes. Vegetables contain a lot of physiologically important salts of iron, potassium, calcium, magnesium and phosphorus. During digestion, minerals form compounds with alkaline properties. Vegetable foods help maintain a slightly alkaline blood reaction and neutralize the harmful effects of acidic substances contained in meat, bread and fats.
The inclusion of vegetables in the diet makes it harmonious and prevents the occurrence of gastrointestinal and other diseases. 2.
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This topic belongs to the section:
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