Difference Between Mass Selection and Pure Line Selection

Key Difference – Mass Selection vs Pure Line Selection
 

Plant breeding procedures deal with the alteration of genetic composition and the genotype, which results in a beneficial improved crop plant. This is achieved by developing different procedures. Mass selection and Pure line selection are two important aspects in plant breeding. In pure line selection, development of the variety is highly uniform with the involvement of a single plant. In mass selection, several pure lines are mixed to develop a heterozygous variety with genetic variations. This is the key difference between Mass selection and Pure Line selection

CONTENTS

1. Overview and Key Difference
2. What is Mass Selection 
3. What is Pure Line Selection
4. Similarities Between Mass Selection and Pure Line Selection
5. Side by Side Comparison – Mass Selection vs Pure Line Selection in Tabular Form
6. Summary

What is Mass Selection?

In the context of crop development and improvement, mass selection is one of the oldest methods practiced. In this method, plants which contain similar phenotypic characters are selected in large quantities, and the seed of the plants are harvested and mixed in order to create a new variety. Mass selection can be practiced in both self-pollinating and cross-pollinating plants. Even though the originally selected plant population is homozygous, the product variety is heterozygous with genetic variations. A progeny test is not carried out when conducting mass selection procedure. This process can be done in two methods; Hallets Method and Rimpar Method.

In Hallet’s method, ideal environmental conditions are provided for a crop with ample water and fertilizers; then, the mass selection procedure is carried out. In Rimpar method, mass selection is carried out once a crop is provided with unfavorable environmental conditions, with a less amount of water and fertilizers. Mass selection can be applied for improvement of local varieties and for purification of existing pure line varieties. Improvement of local varieties is important in order to eliminate inferior plants with low-yielding capacities. This will increase the stability and the adaptability. Due to various factors like mutations, natural hybridization, etc., pure line plants have a tendency to variate over time. Mass selection is an important aspect during purification of existing pure line variations.

The mass selection method is advantageous due to certain aspects. Due to the selection of a large number of crops, the resulted variety by mass selection consists of high adaptability than pure line selection method. The mass selection method is quick since no progeny test is carried out and there is no controlled pollination. The genetic variation developed through mass selection can be further improved through another mass selection process carried out a few years later. Since a progeny test is not carried out, we cannot determine whether the plant possesses homozygous characteristics or whether the variety developed within a short time. These aspects are the disadvantages of the mass selection process.

What is Pure Line Selection?

The theory of Pure Line selection was put forward by Johansson, a Danish botanist. He conducted experiments on the plant Phaseolus vulgaris which is a species that self-pollinates. During the pure line selection process, a large quantity of self-pollinating crop plants are selected and harvested individually. Progenies of each harvested crop plants are evaluated in order to select the most beneficial plant crop and selected as a pure line. Since this procedure involves a single crop variety, it is also referred to as individual plant selection. The plants in pure line selection consist of the same genotype as the parent plant used for the creation of the pure line. Phenotypic differences present within the plants of pure line are environmental and will not transfer to the next generation. Due to certain mutations and mechanical mixture, pure line plants become genetically variable with time. Pure line plants can be utilized in order to develop new varieties by hybridization. Pure line could also be utilized in the study of mutations and in the context of biological investigations. The procedure of pure line selection is of 03 steps; selection of plants (source of mixed population), evaluation of the progeny and yield trials.  Advantages of pure line selection include the development of a plant crop with the highest variety when compared with the original plant variety.

What is the Similarity Between Mass Selection and Pure Line Selection?

• Both processes are involved in the formation of new varieties of crop plants

What is the Difference Between Mass Selection and Pure Line Selection?

Summary – Mass Selection vs Pure Line Selection

Mass selection and pure line selection are two important plant breeding techniques. It involves the alteration of genotypes in order to develop a more beneficial plant crop. In pure line selection, development of the variety is highly uniform with the involvement of a single plant. In mass selection, several pure lines are mixed to develop a heterozygous variety, with genetic variations. Pure line selection is time-consuming with respect to the development of the variety when compared with the mass selection. This is the differences between mass selection and pure line selection.

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Reference:

1. Baydar, H., et al. “Pure line selection for improved yield, oil content and different fatty acid composition of sesame, Sesamum indicum.” Plant Breeding, Blackwell Publishing Ltd, 28 June 2008, Available here. Accessed 19 Sept. 2017
2. Zhong, Xiaoxiao, et al. “Genetic Variation and Breeding Signature in Mass Selection Lines of the Pacific Oyster (Crassostrea gigas) Assessed by SNP Markers.” PLOS ONE, Public Library of Science, Available here.0150868. Accessed 19 Sept. 2017