Pure Line Theory and Pure line Selection

Pure Line Theory and Pure line Selection

1. SAM HIGGIN BOTTOM UNIVERSITY OF AGRICULTURE, TECHNOLOGY & SCIENCES, NAINI, ALLAHABAD DEPARTMENT OF PLANT BREEDING AND GENETICS TOPIC: PURE LINE THEORY AND PURE LINE SELECTION PRESENTED BY P. NIKHIL 19MSCGPB177 SUBMITTED TO: Dr.B.G.SURESH DEPT OF GENETICS AND PLANT BREEDING

2. Started experiments in 1901.Established 19 pure lines by selection of individual beans from the mixed seed lot of 8kg.(named those as A,B,...,T) Followed selection among these purelines too and selected the smallest and largest beans (seeds).planted those selected seeds. Pure Line Theory Johannsen developed concept of pure line while working with princess bean ( Phaseolus vulgaris nana).Princess bean exhibits self -pollination Procedure:

3. Johannsen’s theory and conclusions: Continuous inbreeding ( selfing ) leads to homozygosity . Variation with in a pure line results from environment only . Selection with in pure line is not effective because all the plants in a pure line have some genotype . Selection in the original population is effective because the plants have genetic variation.

4. PURE LINE SELECTION INTRODUCTION: A pure line is the progeny of a single homozygous, self pollinated plants. In pre line selection a large number of plants are selected from a self pollinated crop and harvested individually; individual plants progeny from them are evaluated and the best progeny is released as a pure line variety. All the individuals within a pure line have identical genotype and any variation present within a pure line solely due to environment.

5. Characteristics of Purelines : All the plants within a Pureline have the same genotype as the plant from which the pureline was derived since the parent plant was homozygous and self-fertilized . Variation present within a pureline is due to the environment and non heritable. Purelines become genetically variable with time due to mechanical mixture, natural hybridization and mutations.

6. Uses of Purelines As a variety As Parents in hybridization programme . In studies on mutation Pure lines are used for studying mutations and other biological investigations such as medicine, immunology, physiology, and biochemistry.

7. Application of Pureline selection Improvement of local varieties. Selection in introduced varieties. Improvement of old Pureline varieties. Selection for a new characteristic in a pureline .

8. Pure line selection Procedure:

9. Advantages of Pureline Selection It achieves the maximum possible improvement over the original variety. Pureline varieties are extremely uniform; they are therefore preferred by farmers and consumers to a less uniform variety developed through mass selection. Due to extreme uniformity, the variety is easily identified in seed certification programmes .

10. Disadvantages of Pureline Selection The varieties developed through Pureline selection generally do not have the wide adaptation and stability in the production possessed by the local varieties from which they are developed. Pureline selection requires more time, space and expensive yield trials than mass selection. The improvement is dependent on the genetic variation present in the original population. The breeder has to devote more time to pureline selection than to mass selection.

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