Prinnciples of Pure Line Selection

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  Pure Line Selection   Pure line selection is one of the oldest and most important methods of plant breeding. It is mainly used for the improvement of self-pollinated crops. In agriculture, many crop plants show natural variation in characters such as plant height, maturity, grain size, seed colour, disease resistance, and yield. A plant breeder studies this variation and selects the best plant from the available population. When the selected superior plant is self-pollinated generation after generation, its progeny becomes highly uniform and stable. This uniform and genetically similar group of plants is called a pure line.   The concept of pure line selection has played a major role in the development of improved crop varieties. It helped breeders convert variable local populations into uniform and high-performing varieties. The method is simple, scientific, and economical, so it has remained a fundamental topic in plant breeding courses. For undergraduate stud...
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Oedogonium Practical

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 Sample A2

1. Supplied specimen appears as unbranched or sparingly branched filaments. The thallus is multicellular, filamentous and unbranched. Filaments are typically composed of cylindrical cells arranged end-to-end.

 

2. The filament is differentiated into three types of cells according to their position : (i) basal, (ii) intercalary and (iii) apical.

 

3. The basal cell of a filament serves as an anchor. The lowest section of the holdfast might take the form of either a disc or a finger-like structure. The upper portion is predominantly wide and curvaceous. The basal region of the cell typically lacks chlorophyll and is consequently devoid of green coloration, in contrast to the other cells within the filament.

 

4. The cell located at the apex of the filament is referred to as the apical cell. The free surface of the object is curved.

 

5. The cells located between the basal and apical cells are known as intercalary cells. These have characteristic cellular morphology. The average cell has a cylindrical shape. The cell wall is characterized by its substantial thickness and consists of three distinct layers.

 

6. A reticulate chloroplast runs parallel to the cell's long axis inside the cell wall.

 The chloroplast contains a large number of pyrenoids.

 

7. The cell contains only one nucleus. The nucleus is positioned adjacent to the cell wall and is supported by slender and fragile cytoplasmic strands.

 

8. Mature and old cells show 'cap cells' at their upper end.

……………………………..Hence The specimen is Oedogonium  sp

 

Systematic Position:

Division: Chlorophyta

          Class: Chlorophyceae

                  Order: Oedogoniales

                        Family:  Oedogoniaceae

                                    Genus:  Oedogonium





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