If you put the task: "Call center of origin", many people who are not related to the hybridization will not be able to cope with it.This article contains information explaining.
Terminology
center of origin - a specific geographic "hot spots."They focused genetic diversity of agricultural varieties.Center of origin are the primary - they include areas where wild and domesticated forms originally grew, and secondary.The last - the centers, which were formed by subsequent distribution polukulturnyh, cultivated species of plants and their further breeding.
Historical information
phenomenon of crop, emerged long before the onset of AD.Initially, development occurred, regardless of the surrounding flora species, five geographically isolated areas of the planet.Basically floral structure types who tried to domesticate was endemic in most areas.This forced to resort to the use of the local flora.Human civilization continues to develop ... A period of flourishing marine and land communications between peoples living in different geographical areas.These processes could accelerate the spread of endemic fruits and seeds of domesticated plants.For this reason it is difficult to establish the home of a cultural type.Progress of domestication, which took place in different geographical areas of certain conditions, was subject to the laws of evolution.For example, the plants originate phenomena such as random mating, fold increase in the number of chromosomes in the background of natural hybridization.There have been different types of mutations.
Research conclusion
Based on Charles Darwin's discoveries about the geographic centers of origin of different species formed a certain direction in the study of hybridization.In the XIX century A. de Candolle published his study, which identified center of origin and the area of their original appearance.In his works these areas belonged to the vast continent, as well as other large-scale areas.For almost fifty years after the publication of De Candolle working knowledge center of origin have expanded considerably.It has been published several monographs, which covered agricultural varieties from different countries, as well as on certain types of materials.Later this issue come to grips with Vavilov.On the basis of information on the flora of the world's resources, he identified the main center of origin.A total of seven: East Asia, the Mediterranean, Central American, South Asia, South-West Asian, Ethiopian and Indian.In each of them grow from a certain percentage of the total species diversity of agricultural varieties.
Adjustments
Some researchers, such as AI Kuptsov and PM Zhukovsky, continued the work of Vavilov.They have made some changes to its conclusion.For example, South-West Asian center was divided into the Persian and Sredneaziatsy and Indochina and tropical India emerge as two separate geographical focus.Pool of the Yellow River is considered the foundation of the East Asian center.First it was the Yangtze River, but on this site the Chinese - the people engaged in farming - settled much later.New Guinea and Western Sudan are also identified as areas of agriculture.
Note that fruit crops, including berry orehoplodnye and have extensive habitat.They spread far beyond the borders of the territories of origin.This phenomenon is more in tune with the teachings of de Candolle than the others.The reason is justified mainly forest origin, not foothill, which corresponds to the field and vegetable varieties.Also key is the selection.Center of origin is now more clearly defined.Among them are the European-Siberian and Australian pockets.Formed and North American Center.
General
In the past, some species have been introduced into the culture outside the main foci.However, their number is relatively small.Previously, the main centers of ancient agricultural crops have been considered to be the valley of the Nile, Euphrates, Tigris, Ganges and other major rivers.According to research by Vavilov, a lot of agricultural varieties appeared in the mountainous areas of the temperate zone, the tropics and subtropics.The initial center of origin are closely related to floristic diversity and ancient civilizations.
Chinese site
This area includes the mountainous areas of western and central parts of the country, with the surrounding low-lying areas.The basis of this center are the latitude temperate zone, located on the Yellow River.The conditions here are inherent characteristics such as moderate growing season, a very large degree of moisture and high temperature.The hearth is a natural habitat for soybeans, angular bean, sorghum, millet, rice, oats, payzy, broomcorn, Tibetan barley and many other plants.
South-East Asian section
Indo-Malaysian origin agricultures center complements the Indian region.It includes areas such as Indochina, all the Malay Archipelago, and the Philippines.Hindustan and Chinese center of origin has some effect on this area.Local conditions are characterized by a year-round vegetation, extremely high humidity and temperature.The area is a natural habitat for the nutmeg, allspice, cardamom, orange, bergamot, black pepper, mangosteen, betel, lime and many other species.
Indian land
He also called Hindustan hearth and includes the Indian state of Assam, Burma and the entire Indian subcontinent, with the exception of the north-western states of India.The climate contributes to a long growing season, high temperature and humidity levels.The area has been influenced by the Indo-Malayan center.On the territory grow citrus, sugar cane, rice and many other representatives of flora.
Central Asian land
in this center includes the land of the Western Tien Shan, Tajikistan, northern Pakistan, Uzbekistan, Afghanistan and north-western part of India.Local conditions are characterized by a moderate duration of the growing season, high temperatures with strong seasonal and daily fluctuations and very low humidity.This area has experienced a strong impact Peredneaziatski and Chinese centers.For this reason, it is a secondary center for the majority of local fruit varieties.
Anterior portion
The center is located in the Near East.Its area includes the mountainous territory of Turkmenistan, the whole Caucasus, the Fertile Crescent, Iran and the interior of Asia Minor.The climate is characterized by long drought periods, high temperatures and very low humidity.This area has experienced the impact of the Central Asian and Mediterranean areas.The boundaries of these three foci are closely intertwined, so it is virtually impossible to establish.
South American center of origin
These areas include mountain areas and highlands of Bolivia, Ecuador, Colombia and Peru.Local conditions characterized by insufficient moisture and very high fever.Central American Center had on this area some impact.
