Table cultural forms of organisms and their origin. Centers of origin of cultivated plants
Centers of origin of cultivated plants- * centers of cultivated plant origin areas of the globe in which certain types of cultivated plants originated and where their greatest genetic diversity is observed. Theory of C. P. K. R. developed by N. ... ... Genetics. encyclopedic Dictionary
centers of origin of cultivated plants- centers of origin of cultivated plants, areas of the globe in which certain plant species were introduced into cultivation and where their greatest genetic diversity is concentrated. Theory of C. P. K. R. developed by N. I. Vavilov ... ... Agriculture. Big encyclopedic dictionary
CENTERS OF ORIGIN OF CULTIVATED PLANTS- areas of the globe, in which were introduced into the culture determined. types of districts and where the most is concentrated. their genetic diversity. Theory of C. P. K. R. developed by N.I. Vavilov (1926-39), which, on the basis of materials on the world grows. allocated resources... Agricultural Encyclopedic Dictionary
Geographical centers of genetic diversity of cultivated plants. The doctrine of Ts. p. k. r. arose in connection with the need for source material for breeding and improving varieties of cultivated plants. It was based on the idea of Ch. Darwin ... ...
Cultivated plants, territories (geographical areas) within which a species or other systematic category of agricultural crops was formed and from where they spread. N. I. Vavilov discovered 8 main centers of origin ... ... Ecological dictionary
Centers of origin of plants (according to Vavilov)- the territory (s) within which a species or other systematic category was formed before their more widespread. There are 12 such centers of origin of cultivated plants, which are macroareas, inside them they are distinguished ... ... Beginnings of modern natural science
The introduction (attraction) of plant species or varieties to places, areas where they have not been encountered before. The term has been used since the 2nd half of the 19th century. Theory of I. river. was first substantiated in 1855 by A. Decandol (See. Decandol), and then developed and ... ... Great Soviet Encyclopedia
center of origin- Geographic centers of genetic diversity of cultivated plants, located mainly in the mountainous regions of the tropics, subtropics and partly temperate zone (Russian scientist N.I. Vavilov discovered eight such centers) ... Geography Dictionary
Wikipedia has articles about other people with that surname, see Vavilov. Vavilov Nikolai Ivanovich ... Wikipedia
Cultivated plants on the globe are predominantly angiosperms (flowering) plants. They have undergone a versatile genetic, physiological and biochemical evolution. Many organic compounds are characteristic of ... ... Biological Encyclopedia
Books
- Geography and ecology of plants. Textbook, Rodman Lara Samuilovna. Information about floristic geography is presented: the concept of flora, areas, floristic kingdoms. Peculiarities of cultural flora, centers of origin of cultivated plants are considered. Are given…
- Plant geography and ecology: a textbook, L. Rodman. Information about floristic geography is presented: the concept of flora, areas, floristic kingdoms. Peculiarities of cultural flora, centers of origin of cultivated plants are considered. Are given…
There are 4 types of tasks in the proposed practical work. in the first task, compare plants with their centers, the second task is to work with a contour map. the third task is to compare the centers of cultivated plants with a description of the geographical location. The fourth task is to give a complete answer to the questions posed.
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"Practical work on the topic: "Centers of origin of cultivated plants" Grade 11"
Practical work on the topic:
"Centers of origin of cultivated plants" Grade 11
Exercise 1. Sort the plants into centers (each option distributes all 48 plant names to their centers).
| 1st option South Asian tropical; Abyssinian; South American. | 2nd option East Asian; Mediterranean; Central American. | 3rd option Southwest Asian; South American; Abyssinian. |
| Plant names: |
||
| 1) sunflower; | 17) hemp; | 44) pumpkin; |
Task 2. Working with the map . On the contour map, mark all centers of origin of cultivated plants, indicate geographical position centers.
Task 3.Fill the table. Match centers with geographic location and cultivated plants.
| plant centers | Geographical position | cultivated plants |
| Abyssinian | ||
| South Asian tropical | ||
| East Asian | ||
| Southwest Asian | ||
| Mediterranean | ||
| Central American | ||
| South American |
Ethiopian Highlands of Africa
Southern Mexico
Task 4. Answer the questions with full and detailed answers.
1. Why do most cultivated plants propagate vegetatively?
2. Why are breeders trying to create polypoid plants?
3. What is the essence of the law of homological series in the hereditary theory of N.I. Vavilov?
4. What is the difference between domesticated plants and cultivated ones?
5. For what purpose are mutagens used in breeding?
ANSWERS TO PRACTICAL WORK.
Table 1. Centers of origin of cultivated plants (according to N.I. Vavilov)
| Center name | Geographical position | cultivated plants |
| South Asian tropical | Tropical India, Indochina, South China, islands South-East Asia | Rice, sugarcane, cucumber, eggplant, black pepper, banana, sugar palm, sago palm, breadfruit, tea, lemon, orange, mango, jute, etc. (50% of cultivated plants) |
| East Asian | Central and Eastern China, Japan, Korea, Taiwan | Soybean, millet, buckwheat, plum, cherry, radish, mulberry, kaoliang, hemp, persimmon, Chinese apples, opium poppy, rhubarb, cinnamon, olive, etc. (20% of cultivated plants) |
| Southwest Asian | Asia Minor, Central Asia, Iran, Afghanistan, Southwest India | Soft wheat, rye, flax, hemp, turnip, carrot, garlic, grape, apricot, pear, pea, bean, melon, barley, oat, cherry, spinach, basil, walnut, etc. (14% of cultivated plants) |
| Mediterranean | Countries along the shores of the Mediterranean | Cabbage, sugar beet, olive (olive), clover, one-flowered lentil, lupine, onion, mustard, swede, asparagus, celery, dill, sorrel, cumin, etc. (11% of cultivated plants) |
| Abyssinian | Ethiopian Highlands of Africa | durum wheat, barley, a coffee tree, grain sorghum, bananas, chickpeas, watermelon, castor beans, etc. |
| Central American | Southern Mexico | Corn, long-staple cotton, cocoa, pumpkin, tobacco, beans, red pepper, sunflower, sweet potato, etc. |
| South American | South America along the west coast | Potatoes, pineapple, cinchona, cassava, tomatoes, peanuts, coca bush, garden strawberry and etc. |
| 1st option South Asian tropical; | 2nd option East Asian; | 3rd option Southwest Asian; |
| Plant names: |
||
| 1) sunflower; | 17) hemp; | 33) peas; |
| Answers: |
||
| 1st option South Asian Tropical: | 2nd option East Asian: | 3rd option Southwest Asian: |
| Center name | Geographical position | cultivated plants |
| South Asian tropical | Tropical India, Indochina, South China, the islands of Southeast Asia | |
| East Asian | Central and Eastern China, Japan, Korea, Taiwan | |
| Southwest Asian | Asia Minor, Central Asia, Iran, Afghanistan, Southwest India | |
| Mediterranean | Countries along the shores of the Mediterranean | |
| Abyssinian | Ethiopian Highlands of Africa | |
| Central American | Southern Mexico | |
| South American | South America along the west coast | |
Among the flora of the globe, there is a significant group of plants (more than 2500) species cultivated by man and called cultivated. Cultivated plants and agrophytocenoses formed by them have replaced meadow and forest communities. They are the result of human agricultural activity, which began in some peoples 7-10 millennia ago.
Wild plants passing into cultivation inevitably reflect a new stage in their life. The branch of biogeography that studies the distribution of cultivated plants, their adaptation to soil and climatic conditions in various regions of the globe and includes elements of the economics of agriculture is called the geography of cultivated plants.
According to their origin, cultivated plants are divided into three groups: the youngest group, field weed species and the most ancient group.
The youngest group of cultivated plants comes from species that still live in the wild. For plants of this group, it is not difficult to establish the center of the beginning of their cultivation. These include fruit trees (apple, pear, plum, cherry, gooseberry, currant, raspberry, strawberry), all melons, beets, rutabaga, radishes, turnips, etc.
Field weed plant species became objects of culture where the main crop, due to unfavorable natural conditions, gave low yields. So, with the advancement of agriculture to the north, winter rye replaced wheat; Camelina, an oil-bearing crop widespread in Western Siberia, used to produce vegetable oil, is a weed in flax crops.
For the most ancient cultivated plants, it is impossible to establish the time of the beginning of their cultivation, since their wild ancestors have not been preserved. These include sorghum, millet, peas, beans, beans, lentils, etc.
The need for source material for breeding and improving varieties of cultivated plants led to the creation of the doctrine of the centers of their origin. The doctrine was based on the idea of Charles Darwin about the existence of geographical centers of origin of biological species. For the first time, the geographical areas of origin of the most important cultivated plants were described in 1880 by the Swiss botanist A. Decandol. According to his ideas, they covered quite vast territories, including entire continents. The most important research in this direction half a century later was carried out by the remarkable Russian geneticist and botanical geographer N. I. Vavilov (1887-1943), who studied the centers of origin of cultivated plants on a scientific basis.
N. I. Vavilov proposed a new method, which he called differentiated, of establishing the initial center of origin of cultivated plants, which consists in the following. The collection of the plant of interest collected from all places of cultivation is studied using morphological, physiological and genetic methods. Thus, the area of concentration of the maximum diversity of firms, characteristics and varieties of a given type is determined. Ultimately, it is possible to establish the centers of the introduction of a particular species into the culture, which may not coincide with the territory of its wide cultivation, but are located at considerable (several thousand kilometers) distances from it. Moreover, the centers of the emergence of cultivated plants currently cultivated on the plains of temperate latitudes are in mountainous regions.
In an effort to put genetics and selection at the service of the national economy of the country, N. I. Vavilov and his associates during numerous expeditions in 1926-1939. collected a collection of about 250 thousand samples of cultivated plants. As the scientist emphasized, he was mainly interested in plants of the temperate zones, since, unfortunately, the huge plant wealth of South Asia, Tropical Africa, Central America and Brazil can only be used in our country on a limited scale.
An important theoretical generalization of N. I. Vavilov’s research is the the doctrine of homologous series(from Greek homologos - corresponding). According to the law of homological series of hereditary variability formulated by him, not only genetically close species, but also genera of plants form homological series of forms, i.e., there is a certain parallelism in the genetic variability of species and genera. Close species due to the great similarity of their genotypes (almost the same set of genes) have similar hereditary variability. If all known trait variations in a well-studied species are placed in certain order, then almost all the same variations in the variability of characters can be found in other related species. For example, the variability of the ear awn is approximately the same in soft, durum wheat and barley (Fig. 9).
The law of homological series of hereditary variability makes it possible to find the necessary characters and variants in an almost infinite variety of forms of various species of both cultivated plants and domestic animals, and their wild relatives. It makes it possible to successfully search for new varieties of cultivated plants and breeds of domestic animals with certain required traits. This is the enormous practical significance of the law for crop production, animal husbandry and selection. Its role in the geography of cultivated plants is comparable to the role of the Periodic Table of Elements of D. I. Mendeleev in chemistry. By applying the law of homologous series, it is possible to establish the center of origin of plants by related species with similar characters and forms, which probably develop in the same geographical and ecological setting.
For the emergence of a large center of origin of cultivated plants, N. I. Vavilov considered the presence of an ancient agricultural civilization to be a necessary condition, in addition to the richness of wild-growing flora with species suitable for cultivation.
The scientist came to the conclusion that the vast majority of cultivated plants are associated with seven main geographical centers of their origin: South Asian tropical, East Asian, Southwest Asian, Mediterranean, Ethiopian, Central American and Andean(Fig. 10).
Rice. Fig. 9. Parallel variability of ear awns in soft wheat (a), durum wheat (b) and barley (c)
Outside these centers, there was a significant territory that required further study in order to identify new centers of domestication of the most valuable representatives of wild flora. The followers of N. I. Vavilov - A. I. Kuptsov and A. M. Zhukovsky continued research on the study of the centers of cultivated plants. Ultimately, the number of centers and the area covered by them increased significantly (Fig. 11). Let us give a brief description of each of the centers.
Rice. 10. The main centers of origin of cultivated plants (according to N. I. Vavilov):
1 - South Asian tropical; 2 - East Asian; 3 - Southwest Asian; 4 - Mediterranean; 5 - Ethiopian; 6 - Central American; 7 - Andean
Sino-Japanese. World crop production owes East Asia the origin of many cultivated species. Among them are rice, multi-row and naked barley, millet, chumiza, naked oats, beans, soybeans, radish, many types of apple trees, pears and onions, apricots, very valuable types of plums, oriental persimmon, possibly orange, mulberry tree, sugar cane Chinese, tea tree, short staple cotton.
Indonesian-Indochinese. This is the center of many cultivated plants - some varieties of rice, bananas, breadfruit, coconut and sugar palms, sugar cane, yams, manila hemp, the largest and tallest species of bamboo, etc.
Australian. Australia's flora has given the world the fastest growing woody plants - eucalyptus and acacia. 9 wild-growing species of cotton, 21 species of wild-growing tobacco and several kinds of rice. In general, the flora of this continent is poor in wild edible plants, especially those with juicy fruits. At present, crop production in Australia is almost entirely based on foreign-origin cultivated plants.
Rice. 11. Origin of cultivated plants (according to Zhukovsky, 1974):
primary centers: / - Sino-Japanese; 2 -Indonesian-Indochinese; 3 - Australian; 4 - Hindustani; 5 - Central Asian; 6 - Western Asian; 7-Mediterranean; 8 - African (a - Ethiopian); 9 - European-Siberian; 10- Central American; // - South American; 12 - North American
Hindustani. The Hindustan Peninsula was of great importance in the development of crop production in ancient Egypt, Sumer and Assyria. This is the birthplace of spherical wheat, the Indian subspecies of rice, some varieties of beans, eggplant, cucumber, jute, sugar cane, Indian hemp, etc. In the mountain forests of the Himalayas, wild species of apple, tea tree and banana are common. The Indo-Gangetic Plain is a huge plantation of cultivated plants of world importance - rice, sugar cane, jute, peanut, tobacco, tea, coffee, banana, pineapple, coconut palm, oil flax, etc. The Deccan Plateau is known for the culture of orange and lemon.
Central Asian. On the territory of the center - from the Persian Gulf, the Hindustan peninsula and the Himalayas in the south to the Caspian and Aral Seas, o.ch. Balkhash in the north, including the Turan lowland, fruit trees are of particular importance. Since ancient times, apricot, walnut, pistachio, sucker, almond, pomegranate, fig, peach, grapes, wild types of apple trees have been cultivated here. Some varieties of wheat, onion, primary types of carrots and small-seeded forms of legumes (peas, lentils, horse beans) also arose here. The ancient inhabitants of Sogdiana (modern Tajikistan) developed high-sugar varieties of apricots and grapes. Wild apricot still grows in abundance in the mountains Central Asia. Varieties of melons bred in Central Asia are the best in the world, especially the Chardjou melons, which remain suspended throughout the year.
Pseudo-Asian. The center includes Transcaucasia, Asia Minor (except for the coast), the historical region of Western Asia, Palestine and the Arabian Peninsula. Wheat, two-row barley, oats, the primary crop of peas, cultivated forms of flax and leeks, some types of alfalfa and melons originate from here. This is the primary center of the date palm, the birthplace of quince, cherry plum, plum, cherry and dogwood. Nowhere in the world is there such an abundance of wild wheat species. In the Transcaucasus, the process of the origin of cultivated rye from field weeds, which still clog wheat crops, has been completed. As wheat moved north, winter rye, as a more winter-hardy and unpretentious plant, became a pure crop.
Mediterranean. This center includes the territory of Spain, Italy, Yugoslavia, Greece and the entire northern coast of Africa. Western and Eastern Mediterranean - the birthplace of wild grapes and the primary center of its culture. Wheat, legumes, flax, and oats evolved here (in the wild in Spain, on sandy soils, Avena strigosa oats with strong immunity to fungal diseases have been preserved). In the Mediterranean, the cultivation of lupine, flax, and clover began. A typical element of the flora is olive Tree, which became a culture in ancient Palestine and Egypt.
African. It is characterized by a variety of natural conditions from moist evergreen forests to savannahs and deserts. In crop production, at first only local species were used, and then those already introduced from America and Asia. Africa is the birthplace of all types of watermelon, the center for the cultivation of rice and millet, yams, some types of coffee, oil and date palms, cotton and other cultivated plants. The origin of the kulebasy gourd, cultivated everywhere in Africa, but unknown in the wild, raises a question. A special role in the evolution of wheat, barley and other cereal plants belongs to Ethiopia, on the territory of which their wild ancestors did not exist. All of them were borrowed by farmers already cultivated from other centers.
European-Siberian. It covers the territory of all of Europe, except for the Iberian Peninsula, the British Isles and the tundra zone, in Asia it reaches the lake. Baikal. It is associated with the emergence of sugar beet crops, red and white clovers, northern alfalfa, yellow and blue. The main significance of the center lies in the fact that European and Siberian apple trees, pear, cherry, forest grapes, blackberries, strawberries, currants and gooseberries were cultivated here, wild relatives of which are still common in local forests.
Central American. It occupies the territory of North America, bounded by the northern borders of Mexico, California and the Isthmus of Panama. In ancient Mexico, intensive crop production developed with the main food crop being corn and some types of beans. Pumpkin, sweet potato, cocoa, pepper, sunflower, Jerusalem artichoke, shag and agave were also cultivated here. Nowadays, wild types of potatoes are found in the center.
South American. Its main territory is concentrated in the Andes mountain system with rich volcanic soils. The Andes is the birthplace of ancient Indian types of potatoes and various types of tomatoes, peanut crops, melon tree, cinchona, pineapple, Hevea rubber, Chilean strawberries, etc. Potato (Solarium tuberosum) was cultivated in ancient Araucania, which probably comes from the island Chiloe. Neither Peruvian nor Chilean potatoes are known in the wild and their origin is unknown. In South America, a culture of long-staple cotton arose. There are many wild types of tobacco here.
North American. Its territory coincides with the territory of the United States. It is of particular interest primarily as a center a large number wild grape species, many of which are resistant to phylloxera and fungal diseases. Over 50 wild-growing herbaceous species of sunflower and the same number of lupine species, about 15 plum species live in the center, large-fruited cranberries and tall blueberries have been cultivated, the first plantations of which have recently appeared in Belarus.
The problem of the origin of cultivated plants is quite complicated, since it is sometimes impossible to establish their homeland and wild ancestors. Often a cultivated plant occupies large areas and is of great importance in crop production not in the center of cultivation, but far beyond its borders. In this case, one speaks of secondary centers of cultivated plants. For rye from the Caucasus and Chilean potatoes, this is the temperate zone of Eurasia. Peanuts from Northern Argentina are now bred in Tropical Africa. Manchurian soybean in the USA covers an area of about 20 million hectares. Peruvian long-staple cotton has taken a leading place in crop production in Egypt.
As noted by A. I. Kuptsov (1975), cultivated plants are a young group of species that have significantly pressed wild flora on Earth. Among them are the three "main breads of mankind" (rice, wheat and corn) and minor cereal plants (barley, oats, rye, millet, sorghum). Large areas are occupied by starch-bearing plants (potatoes in countries with a temperate climate, sweet potatoes, yams, taro, and others in more southern regions).
Leguminous crops (beans, peas, lentils, etc.) and sugar-bearing crops (sugar beet and sugar cane) are widespread. Fibrous plants (cotton, flax, hemp, jute, kenaf, etc.) provide a person with clothing and technical fabrics. The modern human diet is unthinkable without dishes prepared from fruit, berry aromatic and tonic plants, which are also widespread. Plants, which are sources of rubber, medicines, tannins, cork, etc., play a large role in everyday life and industry. Modern animal husbandry is based on the cultivation of fodder plants.
Cultivated plants develop under the control of man, whose breeding work leads to the emergence of new varieties.
N. I. Vavilov’s research on the centers of origin of cultivated plants was of great importance for establishing the places where the first animals were domesticated. According to S. N. Bogolyubsky (1959), the domestication of domestic animals probably took place in different ways: the natural rapprochement of man with animals, the forced domestication of young, and then adults.
The time and place of domestication of the first animals are judged mainly by the excavations of the settlements of primitive man. In the Mesolithic era, a dog was domesticated, in the Neolithic era - a pig, a sheep, a goat and cattle, and later - a horse. The hypothetical centers of origin of domestic animals are determined by the ranges of their likely wild relatives. However, the question of the wild ancestors of domestic animals is not completely clear. It is assumed that the wild ancestors of cattle were rounds, sheep - wild sheep, common on the islands of Corsica and Sardinia, in Western, Central and Central Asia, goats - markhorn and bezoar goats, horses - Przewalski's horse and tarpan, domestic camel (Bactrian) - wild camel (haptagai), llamas and alpacas - guanaco, domestic goose - gray goose, etc.
It is easy to establish the places of origin and domestication of those animals whose ancestral ranges were small, for example, the yak. For animals such as dogs, pigs and cattle, whose wild ancestors were widespread in Eurasia and Africa, it is difficult to establish the alleged centers of origin. Probably, the first centers of origin of domestic animals were the Near and Near East, and then the areas of ancient cultures in the basins of the river. Nile, Tigris, Euphrates, Ganges, Indus, Amu Darya, Huang He, in the upper reaches of the Yenisei, where agriculture first arose.
The process of domestication of wild animals is not over yet. At present, spotted deer, arctic foxes, sables, foxes, nutrias, red deer, elk, etc. are in the transitional stage from wild to domestic animals. this case to establish the centers of their domestication is not particularly difficult: the domestication of these animals is carried out, as a rule, in the areas of their modern distribution.
plant breeding
Breeding is the science of creating new and improving existing breeds of animals, plant varieties, strains of microorganisms.
Selection is based on methods such as hybridization and selection. The theoretical basis of selection is genetics.
Breeds, varieties, strains are populations of organisms artificially created by man with hereditarily fixed features: productivity, morphological, physiological characteristics.
Development pioneer scientific foundations breeding work was N. I. Vavilov and his students. N. I. Vavilov believed that selection is based on the right choice for the work of the original individuals, their genetic diversity and influence environment on the manifestation of hereditary traits during hybridization of these individuals.
For successful work, the breeder needs a varietal diversity of the source material, for this purpose N.I. Vavilov collected a collection of cultivated plant varieties and their wild ancestors from all over the globe. By 1940, the All-Union Institute of Plant Growing had 300,000 specimens.
In search of starting material for obtaining new plant hybrids, N. I. Vavilov organized in the 20-30s. 20th century dozens of expeditions around the world. During these expeditions, N. I. Vavilov and his students collected more than 1,500 species of cultivated plants and a huge number of their varieties. Analyzing the collected material, N. I. Vavilov noticed that in some areas there is a very large variety of varieties of certain types of cultivated plants, while in other areas there is no such diversity.
Centers of origin of cultivated plants
N. I. Vavilov suggested that the region of the greatest genetic diversity of any kind of cultivated plant is the center of its origin and domestication. In total, N. I. Vavilov established 8 centers of ancient agriculture, where people first began to grow wild plant species.
1. The Indian (South Asian) center includes the Indian subcontinent, South China, and Southeast Asia. This center is home to rice, citrus fruits, cucumbers, eggplants, sugar cane and many other types of cultivated plants.
2. The Chinese (East Asian) center includes Central and Eastern China, Korea, and Japan. Millet, soybeans, buckwheat, radishes, cherries, plums, and apple trees were cultivated in this center.
3. The Southwest Asian center covers the countries of Asia Minor, Central Asia, Iran, Afghanistan, Northwest India. This is the birthplace of soft varieties of wheat, rye, legumes (peas, beans), flax, hemp, garlic, grapes.
5. The Mediterranean center includes European, African and Asian countries located along the shores of the Mediterranean Sea. Here is the birthplace of cabbage, olives, parsley, sugar beet, clover.
6. The Abyssinian center is located in a relatively small area of modern Ethiopia and on the southern coast of the Arabian Peninsula. This center is the birthplace of durum wheat, sorghum, bananas, and coffee. Apparently, of all the centers of ancient agriculture, the Abyssinian center is the most ancient.
7. The Central American center is Mexico, the islands of the Caribbean Sea and part of the countries of Central America. Here is the birthplace of corn, pumpkin, cotton, tobacco, red pepper.
8. The South American center covers the western coast of South America. This is the birthplace of potatoes, pineapple, cinchona, tomatoes, beans.
All these centers coincide with the places of existence of the great civilizations of antiquity - ancient egypt, China, Japan, Ancient Greece, Rome, Mayan and Aztec states.
Centers of origin of cultivated plants
|
Centers of origin |
Location |
cultivated plants |
|
1. South Asian tropical 2. East Asian 3. Southwest Asian 4. Mediterranean 5. Abyssinian 6. Central American 7. South American |
Tropical India, Indochina, islands of Southeast Asia Central and Eastern China, Japan, Korea, Taiwan Asia Minor, Central Asia, Iran, Afghanistan, Southwest India Countries along the shores of the Mediterranean Abyssinian highlands of africa Southern Mexico West coast of South America |
Rice , sugarcane, citrus, eggplant, etc. (50% of cultivated plants) Soybean, millet, buckwheat, fruit and vegetable crops - plum, cherry, etc. (20% of cultivated plants) Wheat, rye, legumes, flax, hemp, turnip, garlic, grapes, etc. (14% of cultivated plants) Cabbage, sugar beets, olives, clover (11% of cultivated plants) Durum wheat, barley, coffee tree, bananas, sorghum Corn, cocoa, pumpkin, tobacco, cotton Potatoes, tomatoes, pineapple, cinchona. |
9. Basic plant breeding methods
1. Mass selection for cross-pollinated plants (rye, corn, sunflower). Selection results are unstable due to random cross-pollination.
2. Individual selection for self-pollinating plants (wheat, barley, peas). The offspring from one individual is homozygous and is called a pure line.
3. Inbreeding (closely related crossing) is used for self-pollination of cross-pollinated plants (for example, to obtain corn lines). Inbreeding leads to "depression" as recessive unfavorable genes become homozygous!
Aa x Aa, AA + 2Aa + aa
4. Heterosis ("life force") - a phenomenon in which hybrid individuals significantly exceed parental forms in their characteristics (yield increase up to 30%).
Stages of obtaining heterotic plants
1. Selection of plants that give the maximum effect of heterosis;
2. Preservation of lines by inbreeding;
3. Obtaining seeds as a result of crossing two inbred lines.
Two main hypotheses explain the effect of heterosis:
Dominance hypothesis - heterosis depends on the number of dominant genes in the homozygous or heterozygous state: the more pairs of genes that have dominant genes, the greater the effect of heterosis.
Hypothesis of overdominance - a heterozygous state for one or more pairs of genes gives the hybrid superiority over parental forms (overdominance).
Cross-pollination of self-pollinators is used to produce new varieties.
Cross-pollination of self-pollinators makes it possible to combine the properties of different varieties.
6. Polyploidy. Polyploids are plants that have an increase in the chromosome set, a multiple of the haploid one. In plants, polyploids have a larger mass of vegetative organs, larger fruits and seeds.
Natural polyploids - wheat, potatoes, etc., varieties of polyploid buckwheat, sugar beet have been bred.
The classic method for obtaining polyploids is the treatment of seedlings with colchicine. Colchicine destroys the spindle and the number of chromosomes in the cell doubles.
7. Experimental mutagenesis is based on the discovery of the effects of various radiations to produce mutations and on the use of chemical mutagens.
8. Remote hybridization - crossing plants belonging to different species. But distant hybrids are usually sterile, since they have impaired meiosis.
In 1924, the Soviet scientist G.D. Karpechenko received a prolific intergeneric hybrid. He crossed radish (2n = 18 rare chromosomes) and cabbage (2n = 18 cabbage chromosomes). The hybrid has 2n = 18 chromosomes: 9 rare and 9 cabbage, but it is sterile, does not form seeds.
With the help of colchicine, G.D. Karpechenko obtained a polyploid containing 36 chromosomes; during meiosis, rare (9 + 9) chromosomes were conjugated with rare, cabbage (9 + 9) with cabbage. Fertility has been restored.
In this way, wheat-rye hybrids (triticale), wheat-couch grass hybrids, etc. were subsequently obtained.
9. Use of somatic mutations.
By vegetative propagation, a beneficial somatic mutation can be maintained. In addition, only with the help of vegetative propagation, the properties of many varieties of fruit and berry crops are preserved.
10 . Technological scheme for obtaining potato concentrate
Scientists from the Republican Unitary Enterprise "Scientific and Practical Center of the National Academy of Sciences of Belarus for Food" simplified the technological scheme for obtaining potato concentrate, reduced energy costs and labor intensity of its production (patent of the Republic of Belarus for invention No. 15570, IPC (2006.01): A23L2 / 385; authors of the invention : Z.Lovkis, V.Litvyak, T.Tananaiko, D.Khlimankov, A.Pushkar, L.Sergeenko; applicant and patent holder: the above-mentioned RUP). The invention is intended to provide a potato concentrate used in the formulations of non-alcoholic, low-alcohol and alcoholic beverages with improved organoleptic characteristics.
The proposed method for obtaining potato concentrate includes several stages: preparation of potato raw materials, which are fresh potatoes and (or) good-quality dry and mashed potato waste; its thermal and subsequent two-stage treatment with amylolytic enzymes; separating the resulting precipitate by filtration; concentration of the filtrate by evaporation; acidifying it with one or more organic acids; subsequent thermostating.
After thermostating, water and (or) water-alcohol infusions of aromatic plants are added to the resulting concentrate in a certain amount until the final dry matter content is 70 ± 2%. The range of these plants is wide: cumin, purple echinacea, hyssop officinalis, coriander, sweet clover, oregano, immortelle, balsamic tansy, peppermint, tarragon tarragon and others.
A. S. Konkov
Obviously, cultivated plants did not appear in nature by themselves, but with the participation of man on the basis of some wild forms. This is supported by the fact that cultivated plants often have properties that are useful for humans, but not at all useful for the plants themselves in the wild. Such a quality, for example, is the inability to shed seeds in many cultivated cereals. Many qualities in cultivated plants are clearly hypertrophied - for example, the fruit pulp is too thick in garden plants- and unnecessary to exist in the wild. As a result, many (though not all) agricultural plants die or are quickly replaced by other species in natural habitats.
In addition, crops are not necessarily grown in the same places where they were originally domesticated. According to modern estimates, approximately 70% of the cultivated crops that provide food for the local population are grown outside their original ancestral home.
How did the domestication of the wild progenitors of cultivated plants take place? Were such centers of origin of cultivated plants concentrated in narrow zones, or did their domestication occur over a wide area? If the zones of origin of cultivated plants were territorially limited, then there were many narrow-local foci independent for each individual plant, or could they unite entire complexes of potential domesticated species? Well, and a particularly intriguing question is whether the botanical advantages of certain areas could give some advantage to local societies, stimulating their social development? Could they, for example, contribute to such phenomena as the Neolithic revolution described? It is entirely possible that this process and similar processes in other regions of the world began to spread precisely from places that were more fortunate than others with potential domestics in the local flora.
The first researcher who tried to answer these questions was the Swiss botanist Alphonse Louis Decandol. He established putative geographic areas of origin for individual cultivated plants from their wild relatives. Decandol revealed the multiplicity of such centers. He combined these studies in the great work "Origine des plantes cultivées", . However, Louis Decandol believed that all the differences in the ancestral home of the origin of individual cultivated plants can only be explained by two reasons: 1) climatic zonality 2) differences in the set of species in different floristic regions and provinces (which arises due to the long-term geological isolation of these regions from each other ). In the first case, different plants come from different adaptation zones. In the second case, different groups of plants arose in the course of a long isolation and independent evolution of individual floristic regions over many millions of years. Decandol's research denied the existence of any narrow local foci of domestication. He believed that the zones of cultivation of wild progenitors of agricultural plants covered wide areas.
Map of natural zones of the Earth
Map of the floristic regions of the Earth
The first researcher who tried to answer these questions was the Swiss botanist Alphonse Louis Decandol. He established putative geographic areas of origin for individual cultivated plants. Decandol revealed the multiplicity of such centers. He combined these studies in the great work "Origine des plantes cultivées" ("The Origins of Cultivated Plants"). However, Decandol believed that all differences in the ancestral home of the origin of individual cultivated plants can only be explained by two reasons: climatic zoning and differences in the set of species in different floristic regions and provinces (which arises due to the long-term geological isolation of these regions from each other). In the first case, different plants come from different adaptation zones. In the second case, different groups of plants arose in the course of a long isolation and independent evolution of individual floristic regions over many millions of years. Decandol's research denied the existence of any narrow local foci of domestication. He believed that the zones of cultivation of wild progenitors of agricultural plants covered wide areas.
The indisputable merit of Decandole is that he found the approximate origins of many species (albeit within wide geographical boundaries), and that he postulated the very idea of the plurality of such breeding areas for different cultivated plants. But a real revolution in the views on the nature of the origin of cultivated plants was made by our compatriot, the outstanding geneticist of the 20th century, Nikolai Ivanovich Vavilov. Having made about 180 expeditions to different parts of the world, Vavilov established that climatic causes and floristic division are far from the only factors that determined the history of the emergence of cultivated plants. In the world flora, there are breeding bundles that unite entire complexes of species that are responsive to selection. Moreover, within these zones, not 1-2 species are concentrated, but a whole palette of potential domestics and wild relatives of cultivated plants, and the number of these centers is limited. When new places were settled, secondary foci with their own unique varieties and cultures could also arise, but the initial impulse came precisely from the primary centers. From there, the very spread of the producing economy and the most important food crops began. And this happened due to the fact that the centers of origin of plants were not just centers of speciation and variety formation, but also centers of a particularly high diversity of ancestors of cultivated plants (i.e., species responsive to human selection).
Initially, Nikolai Ivanovich Vavilov singled out 7 primary geographical centers of origin of cultivated plants [Vavilov 1939].
4 centers are in Eurasia :
- South Asian Tropical Center
(rice, sugarcane, citrus fruits, cucumber, mango, eggplant, black pepper).
- East Asian Center
(soy, buckwheat, millet, chumiza, radish, cherries, plums)
- Southwest Asian Center
(wheat, rye, barley, fig, pomegranate, quince, cherry, almond, sainfoin)
- mediterranean center
(olive tree, cabbage, mustard, carrot)
1 center is located in sub-Saharan Africa :
- Abyssinian center
(teff, coffee, watermelon)
2 independent centers located in the New World:
- Central American Center
(corn, beans, avocado, cocoa, tobacco)
- Andean (South American) center
(potatoes, pineapple, quinoa, tomatoes)
In Australia not a single primary center of origin of plants arose.
Centers of origin of cultivated plants, originally identified by N. I. Vavilov
After the appearance of new data, Vavilov's students E. N. Sinskaya and P. M. Zhukovsky not only clarified the history and geography of secondary centers, but also identified new primary centers, and some old foci, which in earlier studies seemed to be the same, were divided. Thus, the South-West Asian center was divided into the Near East and Central Asian, and the South Asian tropical center broke up into the Hindustan center, located in India and the Indo-Malay center, connected with the countries of Indochina and the islands of Indonesia. As a result, the list of primary centers increased to 12 for Zhukovsky and 10 (included in 5 large communities) for Sinskaya. It should be noted that Vavilov himself hesitated about the need to single out the Indochinese and Central Asian centers as independent centers of domestication.
Over time, thanks to the work of foreign researchers, special independent centers of plant domestication, different from the Ethiopian, were discovered in Africa in the western part of the Black Continent. An independent primary breeding center was also found in North America. It is possible that a separate center of domestication, different from the Andean, existed in the Amazon basin. Also isolated from the rest of the world, a center of domestication of agricultural plants was found in New Guinea, whose influence remained limited to a small area of \u200b\u200bthis island and had little effect on other regions of the World except Melanesia.
Centers of plant origin in Western Eurasia
Western Asian early agricultural center - the most ancient of all hearths of the world. Its territory included Asia Minor, Levant, Zagros mountains in the Iran-Iraq border, Transcaucasia. The transition to a productive economy took place here in the 9th-7th millennium BC. e. Wheat, barley, rye, lentils, figs, pomegranate, quince, almonds were developed here.
The domestication zone covers territories with a rainfall of 300–500 mm per year in the foothill zone of local uplands and approximately corresponds to the oak-pistachio forest-steppe zone. However, wild barley and some legumes are found in a more arid zone with a rainfall of 200 mm per year, entering the steppe regions of the plain. For the wild Asian ancestors of cultivated cereals, in addition to the general norm of moisture, their confinement to a certain time is very important, namely, to the winter season, which should precede their ripening in the spring. After a period of rain, wild cereals give abundant thickets, where you can collect up to 2 kg of grain per hour by hand, which should have given an incentive to collect these cereals. Perhaps that is why legume remains are very rare in Early Neolithic paleobotanical collections.
A single Western Asian center arose due to the merger into one whole of 5-6 local microcenters. These include Eastern Mediterranean (Palestine, Southwestern Syria), North Syriac , southeastern Anatolian , South Anatolian , Zagrossky(from Northern Iraq to Southwestern Iran), Transcaucasian microfoci.
- IN Eastern Mediterranean emmer and two-row barley were domesticated in the microcenter, and lentils and peas were domesticated from legumes.
IN North Syrian in the outbreak - einkorn wheat, barley, and, as in the first outbreak, lentils and peas.
IN southeast anatolian In the center - local varieties of emmer and einkorn wheat, lentils and peas.
IN Zagrossky micro-center - its own varieties of einkorn wheat, emmer, two-row barley, but this center is distinguished by a low role of legumes.
IN South Anatolian - einkorn wheat, barley and lentils, peas, rank, chickpeas. Rye was also domesticated here.
IN Transcaucasian- local varieties of millet and wheat.
The last two foci may be secondary, but this issue requires additional research. The completion of the formation of a single Western Asian focus caused a new stage of breeding, when multi-row barley and tetraploid and hexaploid wheat were bred in the Middle East region.
Areas of wild relatives of cereals in Western Asia
The influence of the Asiatic focus not only had a huge impact on a significant part of the Old World - it contributed to the emergence of secondary centers based on the cultures of this center in Western and Eastern Europe, North Africa, Arabia, the Caucasus, Iran, Central Asia and North India. It was from this region that the Neolithic revolution in Western Eurasia began. And although, of course, it would be wrong to reduce all its causes solely to geobotany factors, there is no doubt that the advantages of the local flora played a significant role.
The connections of the Near East Center with mediterranean center . Of the local cereals, only oats were tamed here. But the local flora provided many new domesticates, giving rise to great wealth. vegetable crops: radish, cabbage, parsnip, mustard, carrot, carob and olive tree. Despite this, modern evidence suggests that agriculture did not originate here independently, but under the influence of a Middle Eastern impulse. Middle Eastern cultures became the basis of food here, and the very selection of local crops was initiated and stimulated by Middle Eastern influence. Vavilov included some western parts of the Western Asian focus in the area of the Mediterranean focus, suggesting that they could be genetically related to the more western foci of Europe, while more eastern regions The Central Asian focus, including the Levant, was initially isolated from the history of Mediterranean agriculture. He considered different forms of wheat to be one of the key differences between the Mediterranean and Near East centers: independent breeding in the Mediterranean center led to the emergence of large-seeded tetraploid wheat varieties, and in the Near Asian center - small-seeded hexaploid varieties. However, modern genetic data indicate that these processes were more complex. Probably, the Levantine center of domestication should be considered simply as part of the Near East center. And all the centers of domestication in Europe and North Africa - as its secondary child centers. Therefore, although this goes against Vavilov's original scheme, the Mediterranean center must be excluded from the list of primary zones of origin of cultivated plants.
Central Asian focus
is distinguished by a very high diversity of varieties of agricultural plants, which makes it justified to distinguish it as an independent center. It occupies the territory from Turkmenistan to the Indus basin and from Badakhshan to Iran. Here, in the course of selection by local farmers, cross-bred varieties of wheat, pears, and apricots were bred. Over time, some East Asian plants also came here, which led to the appearance of local varieties of persimmon and plum. The time of the emergence of this center dates back to the 6th millennium BC. e. However, the Central Asian center is secondary and is derived from the Near East, since most of the local cultivated plants come from Middle Eastern cultures. Probably, the spread of agriculture here began from the south of the region - from southern Afghanistan and Balochistan. In the north, in modern Turkmenistan and Central Asia, a manufacturing economy appears later. Also, the Central Asian center undoubtedly includes North-West India, where a special variety of round-grain wheat was bred on the basis of Middle Eastern crops, which became the main crop in local irrigated agriculture.
Centers of origin of plants in South Asia
The origin of most of the cultivated crops is traditionally associated with this region. The center of domestication is located in the mountainous regions of the Indochinese Peninsula, South China south of the Yangtze River and the northeastern part of Hindustan. Rice, sugar cane, bananas, citrus fruits, durian, taro, eggplant and most of the plants that are sources of classic spices have been introduced into cultivation here.
In the territory Hindustan agriculture is secondary to other regions. The local flora provided a number of cultivated plants, but Indian domestics played a supporting role and did not become the main livelihood of the societies of this region. These include mung bean and cucumber. The origins of agriculture and most crops in India are connected with other regions of Eurasia and even sub-Saharan Africa. In the first half of the II millennium BC. e. millet, barley, wheat, flax penetrated into India, obviously coming here from Asia Minor. Rice penetrated from the Indo-Malay center to Hindustan (it is found in the period of the Harrap civilization). And from Africa, bypassing the Middle East (apparently through South Arabia) - sorghum, dagussa, lobia. These crops became the basis of agriculture on the Deccan Plateau.
Indo-Malay Center , on the contrary, played a major role in the domestication and selection of the ancestors of cultivated plants. Initially, this region was considered as a periphery, on the territory of which agriculture and domestics spread from other centers. Vavilov was one of the first to change his mind about the local flora and appreciate its great potential. However, he included it only as a very species-rich local focus within the framework of the general South Asian center, along with the Hindustan one. Later botanical studies not only confirmed, but also strengthened the point of view about the richness and diversity of the wild and cultivated flora of Indochina, the southern regions of China and northeastern India. Therefore, it is expedient to present the Indo-Malay center as the primary center of plant domestication in South Asia, and consider the Hindustan and local centers of domestication in Indonesia as its derivative centers.
The main crops of the Indo-Malay center, which played a special role in the development of local agriculture and farming in other regions, were rice, taro and South Asian forms of yams.
Taro and Asian forms of yam are starchy tubers that are analogous to similar crops in other parts of the world: sweet potato, potato and cassava in the New World and African yam in the Black Continent. The advantages of taro are in its greater unpretentiousness, the disadvantage is in lower yields and demands for very high humidity. It can be cultivated only where the annual rainfall is between 1000 and 5000 mm per year. The advantages of the yam are in its greater yield, less demanding on moisture, the disadvantages are in the short harvest period and the greater capriciousness of this crop. Probably, the yam was introduced into the culture after the taro and by those groups of the population that already had the skills of selection and agriculture.
Rice domestication took place in the north of the Indochinese Peninsula with the inclusion of certain territories of Northeast India and the extreme south of China. It is here that wild relatives of rice (Oryza rufipogon, Oryza nivara) live. In cultivated rice, there are two main most common varieties: Indian rice (Oryza sativa indica) with long and non-glutinous grains and Japanese rice (Oryza sativa japonica) with short and sticky grains. Japanese rice is more frost-resistant, which allowed this variety to spread in the mountainous regions of Southeast Asia and India, and later in the temperate climate of Korea, Japan and Northern China.
Due to the fact that these varieties are so markedly different morphologically that it is difficult to cross between them (which is rare in plants even in the case of interspecific hybridization), it has even been assumed that they were domesticated in different regions. But geneticists have established that all cultivated forms of rice descended from the same ancestors about 8200 thousand years ago in the region south of the Yangtze River, and the separation of Japanese and Indian rice occurred 3900 years ago. In the Ganges and Huang He valleys, rice culture is secondary and appears late. The sterility of hybrids between these subspecies is associated not with some of their systematic remoteness, but with an imbalance in the work of genes that inhibit programmed cell death - apoptosis in the ovules, which causes seed sterility.
Rice cultivation area
Rice is a hydrophilic plant that requires a high humidity of 1000 mm per year, so the introduction of rice into the culture could only take place in the humid zone.
Rice also has upland varieties that are cultivated in the highlands far from rivers and allow it to be grown without the use of irrigation. However, botanical data indicate that these varieties are secondary, have a later origin and cannot be primitive forms. In the breeding of rice, as in the breeding of wheat and corn, for its transformation from a wild form into a cultivated one, it was important that the seeds do not crumble on their own, because this would allow the crop to be preserved. It is curious that the change in this trait was associated with the mutation of only one sh4 gene, which starts the entire process of formation of the separating layer on the peduncle. Perhaps for this reason, the domestication of rice occurred faster and was less extended in time than that of wheat.
The general history of the formation of the Indo-Malay center of domestication and the emergence of a producing economy suggests several scenarios. Some authors believe that agriculture originally arose on the basis of the cultivation of tubers, such as taro and yams, and only at the next stage did the transition to intensive rice cultivation occur. This point of view seems more plausible, but alternative hypotheses must also be taken into account, according to which rice could have been introduced into the culture before tubers. A special look at the origin of the manufacturing economy in Southeast Asia belongs to Sauer. According to his model of domestication, in this region, the domestication of not purely food species, but plants of multifunctional use (such as pandanus, cordiline) initially began. Other crops gradually entered the economy as companion crops, and already at the next stage, after a certain selection, they occupied central location in the life support structure. It is difficult to say which of these hypotheses is more plausible, but agriculture in Southeast Asia most likely originated among semi-sedentary fishermen who cultivated moisture-loving crops near their villages. Considering that relatives of some of the plants (sago, taro, banana) had to be domesticated in the zone of very humid tropics, and others (yams, sugar cane) - in the zones of the monsoon climate, which allows the alternation of drier and wetter seasons, it is obvious that here , as well as in Western Asia, the center of domestication was formed due to the merger of several territorially close microfoci].
Impulses from the primary Indomalayan center led to the emergence of secondary foci in India, the islands of Indonesia and Taiwan. From these last two centers, plants bred in the Southeast Asian center spread to the island of Madagascar, as well as to Polynesia and other islands of the Pacific Ocean, creating the basis of agriculture in Oceania.
It is characteristic that if tropical tubers spread to the south and southeast, rice spread first of all to the west and north.
Centers of origin of plants in East Asia
East Asian Primary Center located in Northern China in the middle reaches of the Yellow River. Chumiza was the basis of his agriculture before rice came here from the south. Asian millet, daikon radish, plum, persimmon and a number of other crops were also domesticated here. Vavilov assumed that the core of this center was closer to the Yangtze basin. But according to modern concepts, the Yangtze basin is included in the area of the Indo-Malayan center.
It is interesting that the local agricultural complex was actively supplemented by introducers, i.e., new crops from the Indo-Malayan and Central Asian focus (such as wheat and rice) at a time when the transition to a productive economy was not only over in the Yellow River basin, but a developed statehood had already arisen. (in the II millennium BC). This significantly distinguishes these processes from those that took place in the Indo-Malay region, where, on the contrary, the state did not arise for a long time even after the transition to developed agriculture.
On the basis of the East Asian primary center, a Korean-Japanese secondary focus , where, in addition to East Asian plants and rice, some new crops from local flora have been domesticated, such as local varieties of yams (Dioscorea japonica).
Centers of origin of plants in the Americas
On the North American continent in the mountainous regions of Mexico, a Central American Center . In it, corn, beans, amaranth, and pumpkin were introduced into the culture. Probably, here, as well as in the Western Asian center, there was a merger of several local microfoci. An interesting feature of this center was the unusually long transition to sustainable agriculture. If its beginnings arose only a little later than in the earliest centers of the Old World, in the 9th millennium BC. e. - then its final design took place only in the III - II millennium BC. e. The reasons for this slow transition need to be elucidated in future research.
Shortly thereafter, the production economy and its accompanying domesticates began to spread into the lowlands of Mexico and Central America, and then spread to the United States. Here a very large child arose Arizona-Sonora hearth .
Interestingly, in the east of the United States in the II - I millennium BC. e. began to form its own independent center of domestication, which was based on the cultivation of cyclaena, canary grass, mountaineer and mari. However, a small initial set of species did not allow it to become a major center. And local plants in the 1st - early 2nd millennium AD. e. were driven out by Central American domesticates, forming a secondary focus - Alabama-Illinois .
Range of wild relatives of cultivated plants in North America
On the South American continent, in the mountainous zone of the Andes, a South American (Andean) Center . Potatoes, pineapple, quinoa, tomatoes were domesticated here. There was a very clear vertical zonality in the development and selection of ancestral species of agricultural plants. Potatoes and quinoa were domesticated in the high mountain zone, while pumpkins and legumes were domesticated in the middle mountains. This center was formed in the III - II millennium BC. e. A great stimulus for the development of local agriculture was provided by corn introduced from the Central American center.
On the coast of South America, during the transition to agriculture in the mountainous regions, intensive fishing dominated, and the appropriating economy did not immediately give way to the producing one. However, it gradually fell into the sphere of influence of the mountain zone, cultivated plants from the Andes zone spread here and its secondary focus was formed.
Somewhat less clear is the situation with the area of cultivation of cassava, which is grown by many peoples of the Amazon and Orinoco basins. It is widely believed that it could have arisen under the influence of Andean agriculture in the foothill zone, transitional to the selva. However, this assumption requires proof, and the possibility of an independent origin of this focus in the Amazon is not ruled out.
Range of wild relatives of cultivated plants in South America
Centers of origin of plants in Africa
Several centers of primary domestication have sprung up in Africa. Vavilov connected the origin of agriculture and the domestication of African cultures with the Ethiopian Highlands. It is now clear that there were also other breeding centers for the ancestors of cultivated plants in the west of the continent. But in relation to the Ethiopian center, some authors admit its initial formation not with the mountainous regions, but rather with the adjacent regions of the Sahara, from where these cultures spread to the highland zone later.
Porter identified several centers of plant cultivation in Sub-Saharan Africa:
- Nilo-Abyssinian , corresponding to the Ethiopian Vavilov Center,
- West African
- East African
- Central African.
Because of this problem, the American botanist Harlan proposed for Africa a special model of domestication, where there are no narrow local centers. According to his concept, various types of plants were cultivated here in various places, often quite remote friend from each other, but then a single communication network for the exchange of cultivated plants united remote regions of this continent. To describe it, he created the term "uncenter". A number of Soviet researchers demonstrated similar views and considered the whole of Africa as a single global non-localized macro-range of plant domestication.
And yet, despite the vague boundaries and wide areas of domestication of many native species, several zones can be distinguished in Africa, corresponding to cultural centers in other regions. First hearth associated with the cultivation of African cereals and associated with the savanna zone that extends south of the Sahara between Senegal and the Nile Valley. Sorghum, pearl millet and African rice were domesticated here. Second hearth associated with the cultivation of the African yam in the borderland of the forest zone, oil palm and kola nut were also domesticated here. It is possible that the second center could have arisen under the influence of the first, and together they form a single West African center. Third center occupies the mountainous regions of Ethiopia and / or the flat regions of the Sahel close to it. Teff, dagussa, ensette, watermelon and coffee were domesticated here.
Under the influence of the Ethiopian and West African macrofoci, subsidiary centers appeared in East and Central Africa.
Unlike animal husbandry, Middle Eastern domestics have had a limited impact on the sub-Saharan African crop mix, except in some areas in northeast Africa. This is due to the fact that the ancestors of many Western Asian plants were domesticated in the winter rains and are not suitable for African agriculture, which requires adaptation to the summer rains. Interestingly, in those regions of Eurasia where there is a zone of summer rains (as on the Deccan Plateau), on the contrary, there was an active development and introduction of African crops: dagussa, lobia, pearl millet. Since this spread bypassed the Levant, the Fertile Crescent and Iran, the mediation in the spread of African cultures must be connected with South Arabia.
Range of wild relatives of cultivated plants in Africa
Domestication in Oceania
A significant part of cultivated plants in Oceania is of Asian origin (mainly from the Indo-Malayan focus). And on Easter Island, even American influence is allowed due to the presence of American varieties of sweet potato and gourd.
For a long time it was believed that agriculture was brought to the islands of the Pacific Ocean entirely from outside and arose here along with the appearance of the Lapita archaeological culture, which is associated with the first groups of proto-Polynesians. The ancestors of the Polynesians did indeed bring many agricultural plants from Asia to Oceania. But due to the fact that this group of the population was the first to start developing the outlying islands of the Pacific Ocean, which had not previously been inhabited by humans, it is quite natural that plants from Asian centers of domestication predominate in a significant part of the archipelagos of this region. However, recent evidence has accumulated that some farming skills may have originated in the region without the influence of cultural innovations brought by Polynesian migrants from Asia. So local varieties of sago, breadfruit, yam, and sugarcane were domesticated in New Guinea independently. Data on the domestication of the Oceanian variety of taro are somewhat contradictory, which could have been domesticated either independently or brought from the Indo-Malayan center. Archaeological data are in agreement with these data. In the mountainous regions of New Guinea (in Kaviafana), traces of irrigation or drainage channels have been found that date back to the 9th millennium BC. e. According to palynological analysis, reliable traces of plant cultivation date back to the middle of the 2nd millennium BC. e. But one way or another, in New Guinea, a narrow local center of primary domestication really arose, which appeared completely independently of other centers.
New Guinea Center - the only center of primary domestication in the world ecumene, which did not have any large-scale impact on other regions of the world (it had a limited effect only through a series of borrowings on some islands of Melanesia) and was preserved within the narrow zone of its ancestral home. But apparently this exceptional fact can be explained by several simple reasons. Agriculture originated here within a very large island (the second largest in the world after Greenland), which has a high diversity of landscapes. Domestication took place within a large mountainous region in its center, which was limited from the coast, which delayed influences from the interior of the island to the outside world and, conversely, inhibited influences from the outside world into inner part islands. At the moment when agriculture was fully mastered in the interior of New Guinea, it was actively spreading from Asia to other regions of Oceania. Therefore, just as New Guinean agriculture could not displace Asiatic agriculture on other islands, so Asiatic agriculture was not able to displace New Guinean agriculture. The domestication of cultivated plants in the New Guinea center took place on the basis of species taxonomically close to the species of the Indo-Malay center (sago, yam, breadfruit), therefore, neither New Guinean nor Indomalayan domesticates had an advantage over each other for borrowing (except, perhaps, taro) . Because of this, it was expedient to use ready-made complexes of cultivated plants independently developed in New Guinea and the Indo-Malayan center.
Distribution of Asian plants along with Polynesian migrations
Conclusion
Now, about a century after the appearance of the first results in Vavilov's largest study, it is clear that his theory and views on the origin of cultivated plants are correct, although significant adjustments have been made to his original scheme for identifying basic primary centers. Without a doubt, agriculture originated, not in one, but in several independent centers of origin of cultivated plants. Therefore, any monocentric theories are untenable. Domestication and selection of wild progenitors took place in relatively narrow zones, which united entire complexes of such species.
Modern ideas about the primary centers of domestication of cultivated plants
and their distribution to other regions
The earliest ancient center of origin of cultivated plants, which arose in time before all the others, is the Near East Center, which was formed as a result of the union of several local microfoci.
The existence of the Mediterranean Center as an independent center needs to be reconsidered. Its eastern Syro-Palestinian part can be considered as one of the centers that flowed into the Near East center, and it is appropriate to consider it as part of the Near East center of domestication. The western regions connected with the Balkans and the western Mediterranean are undoubtedly secondary centers that were formed during the spread of agriculture from the Near East center to Southern Europe. However, the local flora also provided excellent breeding material, and under the influence of the Middle Eastern impulse, a considerable number of local plants were domesticated and introduced into cultivation.
The Central Asian center, as well as the Mediterranean center, is secondary. It arose on the basis of Middle Eastern cultures that spread from the Near East center to the east. This secondary center, in addition to Iran and the southern regions of Central Asia, also covered the western part of Hindustan in the Indus Valley.
Views on the development of agriculture and domestication in South Asia also need to be reconsidered. The initial centers of South Asian agriculture and the domestication of local plants are not in India, but on the territory of Indochina. Indian agriculture arose due to the joint influence of the Near East and Indo-Malayan centers and African centers of agriculture. In Hindustan itself, not many species of native flora have been domesticated, and the Hindustan center must be regarded as secondary. The Indo-Malay center, on the contrary, is clearly the primary center. In the past, it was he who was the main incubator of the domestication of South Asian plants. It is especially interesting that, despite the antiquity of this center and the exceptional wealth of agricultural crops, in the zone of the Indomalayan center, unlike many other primary and secondary centers, originated very late public entities and urban civilization, which in some ways makes this situation similar to that observed in America.
The East Asian center, together with the Near East and Indo-Malay centers, is the third basic primary center of Eurasia, where, unlike the Mediterranean, Hindustan and Central Asia, agriculture originated independently without any outside influence. Modern data localize the geographical position of this center in the Huang He basin, i.e., to the north than Vavilov assumed.
In Africa, agriculture developed in the most peculiar and unlike manner in comparison with other continents. There were several initially isolated, but early united centers, geographically remote from each other (which distinguishes it from the Middle East focus, where such protocenters are located close): in Ethiopia, the Western Sahel and in the tropics of West Africa. It is possible that a global sub-Saharan network of diffuse interconnected microcenters could have arisen here, which united into one broad community, forming a pan-African non-localized focus. This is a unique feature of this region. But he draws attention to the fact that in Africa, as in other regions, the zones of domestication of many plants gravitate either to mountainous areas (in Ethiopia, the Guinean mountains), or in the rough terrain of the borders between different biotopes: savannahs and semi-deserts, savannahs and tropical forests, which in West Africa are close to each other. And here, nevertheless, the cores of domestication are indicated in the Sahel, in the Ethiopian Highlands and Guinea. But of course, a detailed study of the zones of domestication of cultivated plants in Africa is still waiting in the wings.
Three primary centers arose in the New World. Two of them, the Andean in South America and the Central American in North America, have become important, influencing neighboring regions of North, Central and South America. Both of these centers had a limited influence on each other. The third center of domestication of the New World - East North American - was not identified by Vavilov. But this center, although it arose completely independently, was not rich in potential domestics, and as a result was absorbed by cultures from subsidiary secondary centers derived from the primary Central American center. With regard to the Amazonian center, it is still not very clear how independent it is, whether it arose as a primary center or as a secondary center on the periphery of the Andean. An important feature of the development of the New World is that here, unlike in Eurasia and Africa, the development of agriculture did not lead to bright "Neolithic revolutions" and the process of transition to more complex societies here, in contrast to the Old World, was slowed down.
In Oceania, in New Guinea, an independent center of domestication of agricultural plants arose, isolated from the rest of the world, where agriculture originated independently, but remained locked within a limited territory.
It is very important that all the primary centers of origin of cultivated plants identified by Vavilov and most of the newly discovered centers are confined to the mountainous regions of the subtropical and tropical belt. This is due to the wide diversity in mountain landscapes, which creates a very wide range of adaptations to very different conditions within a close area, and also creates structured populations with a high level of drift in subpopulations, which also contributes to the emergence and spread of rare variants. In some cases, as in West Africa and in the Yellow River valley, the clear pattern of linking the origin of cultivated plants to mountainous areas is still violated. However, here, too, domestication took place in the border zone of very different and dissimilar ecosystems, contributing to population diversity. Therefore, here the diversity of domesticates was influenced by the same reasons as in the mountainous regions.
How the diversity of selective species has affected the social and demographic advantages of the population living in them, and what genetic data can tell about this, will be discussed in the next publication.
Bibliography
Vavilov N. I. Centers of origin of cultivated plants. - L .: Type. them. Gutenberg, 1926
Vavilov N.I. The doctrine of the origin of cultivated plants after Darwin: (report at the Darv. session of the Academy of Sciences of the USSR. November 28, 1939) // Sov. the science. 1940. No. 2. S. 55–75
Dekandol A. Location of cultivated plants. St. Petersburg: Publishing House of K. Rikker, 1885. 490 p.
Zhukovsky P. M. Cultivated plants and their relatives. Systematics, geography, cytogenetics, ecology, origin, use. 3rd ed. L.: Kolos, 1971. 752 p.
Sinskaya EN Historical geography of cultural flora (At the dawn of agriculture). L.: Kolos, 1969. 480 p.
Shnirelman VV Emergence of a productive economy. - M.: Nauka, 1989. - 448 p.
Ballard, C., Brown, P., Bourke, R. M., Harwood T. The Sweet Potato in Oceania: A Reappraisal // Oceania Monograph 56/Ethnology Monographs 19. 2005. Sydney: University of Sydney.
Bellwood, P. S. 1979. Man's Conquest of the Pacific: The Prehistory of Southeast Asia and Oceania. New York: Oxford University Press.
Bellwood P. The Prehistory of Oceania // Curr. Anthropol. 1975. V. 16. No. 1. S. 9.
Childe V. G. The Dawn of European Civilization // Am. Hist. Rev. 1926. V. 31. No. 3. S. 499.
Green, R. A range of disciplines support a dual origin for the bottle gourd in the Pacific // J. Polyn. soc. 2000 Vol. 109. P. 191–198.
Grivet L. et al. A review of recent molecular genetic evidence for sugarcane evolution and domestication // Ethnobot. Res. Appl. 2004. V. 2. No. 0. S. 9–17.
Harlan J. R. Agricultural origin: centers and noncentres // Science. 1971. V. 174. No. 4008. P. 468–474
Khoury C. K., Achicanoy H. A. Origins of food crops connect countries worldwide // Proc. R. Soc. B. 2016, vol. 283, pp. 468–74.
Kjær A. et al. Investigation of genetic and morphological variation in the sago palm (Metroxylon sagu; Arecaceae) in Papua New Guinea // Ann. Bot. 2004. V. 94. No. 1. S. 109–117.
Li C., Zhou A., Sang T. Rice Domestication by Reducing Shattering // Science (80-.). 2006. V. 311. No. 5769. S. 1936–1939.
Malapa R. et al. Genetic diversity of the greater yam (Dioscorea alata L.) and relatedness to D. nummularia Lam. and D. transversa Br. as revealed with AFLP markers // Genet. resource. Crop Evol. 2005. V. 52. No. 7. S. 919–929.
Molina J. et al. Molecular evidence for a single evolutionary origin of domesticated rice. //Proc. Natl. Acad. sci. U.S.A. 2011, vol. 108, no. 20, pp. 8351–6.
Porteres R. Primary cradle of agriculture in the African continent, 1970. Pappers in the African prehistory. 1970 Cambridge.
Smith B. D. Eastern North America as an independent center of plant domestication. //Proc. Natl. Acad. sci. U. S. A. 2006, vol. 103, no. 33, pp. 12223–12228.
Spriggs, M. 1984. The Lapite cultural complex: origins, distribution, contemporaries, and successors. In Out of Asia: Peopling the Americas and the Pacific. R. Kirk and E. Szathmary, eds., pp. 202-223. Canberra: The Journal of Pacific History.
Shaw, T. C. 1980. Agricultural origins in Africa. In The Cambridge Encyclopedia of Archaeology. A. Sherratt, ed., pp. 179-184. New York: Crown.
Tanno K.-I., Willcox G. How fast was wild wheat domesticated? // Science. 2006. V. 311. No. 5769. S. 1886.
Yang J. et al. A Killer-Protector System Regulates Both Hybrid Sterility and Segregation Distortion in Rice // Science (80-.). 2012. V. 337. No. 6100. S. 1336–1340.
Zerega N. J. C., Ragone D., Motley T. J. Complex origins of breadfruit (Artocarpus altilis, Moraceae): Implications for human migrations in Oceania // Am. J. Bot. 2004. V. 91. No. 5. S. 760–766.
