The term "centre of origin" refers to a specific geographical area where a particular group of organisms, whether they are domesticated or wild, originally originated on Earth. While many have assumed that these centres of origin are also hubs of biodiversity, it's important to note that centres of diversity may not necessarily coincide with the origin of crop plants. Although a few species may have independently originated in multiple places, most species had their initial origin in a specific location and then spread to other regions. In simpler terms, a crop plant typically originates in one primary location, whereas centres of diversity may be scattered in multiple locations. Determining the exact origin of species is often speculative and relies on indirect evidence.
Understanding the origins of crop plants holds significance in the field of plant breeding as it helps locate wild relatives, related species, and new genetic traits. This knowledge is crucial for preventing genetic erosion, which occurs when germplasm is lost due to the disappearance of ecotypes and their natural habitats.
The Russian scientist Nikolai Ivanovich Vavilov and his colleagues conducted extensive research in various countries, collecting a vast array of crop plants and their wild counterparts. They utilized this collection in Russia's breeding programs to develop improved crop varieties. Vavilov's conclusions were based on evidence from various fields such as morphology, anatomy, cytology, genetics, plant geography, and distribution.
He posited that significant centres of origin were consistently situated in the lower mountainous and hilly regions of tropical and subtropical areas. Additionally, he identified secondary centres of origin where multiple species had crossed with one another. These secondary centres of origin represented places where natural and artificial selection processes occurred sequentially. Vavilov emphasized that the domestication of plants was not a random event but rather a continuous and deliberate process.
In 1926, he published his findings and developed a theory regarding the centres of origin of cultivated plants.
He proposed the existence of eight distinct centres of origin for crop plants, each characterized by specific details:
Our expanding knowledge of cultivated plants has led to certain modifications in Vavilov's views, as they have revealed limitations in his perspective:
160 videos|140 docs
|
|
Explore Courses for UPSC exam
|