Pure line Theory | Agriculture | Pure Line Theory in Plant Breeding | Dr Vijay Kamal 

A pure line is the progeny of a single self-fertilized homozygous plant.
The concept of pureline was proposed by Johannsen on the basis of his studies with beans (Phaseolus vulgaris) variety called Princess. He obtained the seeds from the market and observed that the lot consisted of a mixture of larger as well as smaller size seeds. Thus, there was variation in seed size. Johannsen selected seeds of different sizes and grown them individually. Progenies of larger seeds produced larger seeds and progenies from smaller seeds produced small seeds only.
This clearly showed that there is variation in seed size in the commercial lot and it has a genetic basis. He studied nineteen lines altogether. He concluded that the market lot of the beans is a mixture of pure lines. He also concluded that whatever variation observed within a line is due to environment only.