Types of Centres of Diversity of Crops


Types of Centres of Diversity of Crops

The centres of crop diversity of three types viz:

1) Primary centres of diversity,
2) Secondary centres of diversity
3) Micro –Centres.

These are briefly discussed below:

1. Primary Centres of Diversity:

Primary centres are regions of vast genetic diversity of crop plants. These are original homes of the crop plants which are generally uncultivated areas like, mountains , hills, river valleys, forests, etc. Main features of these centres are given below:

1. They have wide genetic diversity.
2. Have large number of dominant genes.
3. Mostly have wild characters.
4. Exhibit less crossing over.
5. Natural selection operates.

2. Secondary Centres of Diversity:

Vavilov suggested that values forms of crop plants are found for away from their primary area of origin, which he called secondary centres of origin or diversity. These are generally the cultivated areas and have following main features.

1. Have lesser genetic diversity than primary centres.
2. Have large number of recessive genes.
3. Mostly have desirable characters.
4. Exhibit more crossing over
5. Both natural and artificial selections operate.

3. Microcenters:

In some case, small areas within the centres of diversity exhibit tremendous genetic diversity of some crop plants. These areas are referred to as micro-centres. Microcenter is important sources for collecting valuable plant forms and also for the study of evolution of cultivated species. The main features of micro centres are given below:

1. They represent small areas within the centres of diversity.
2. Exhibit tremendous genetic diversity.
3. The rate of natural evolution is faster than larger areas.
4. They are important sites for the study of crop evolution.