Principles of Plant Breeding (2+1)

Conservation

• Conservation refers to protection of genetic diversity of crop plants from genetic erosion. There are two important methods of germplasm conservation or preservation, viz.

In-situ Conservation:
Conservation of germplasm under natural habitat is referred to as in situ conservation. It requires establishment of natural or biosphere reserves, national parks or protection of endangered areas or species.

Ex-situ Conservation:
• It refers to preservation of germplasm in gene banks. This is the most practical method of germplasm conservation.

Advantages
1. It is possible to preserve entire genetic diversity of a crop species at one place.
2. Handling of germplasm is easy.
3. This is a cheap method of germplasm conservation.
The germplasm is conserved either in the form of seed or in the form of meristem cultures.
The seeds can be conserved under long term (50 to 100 years), medium term (10 to 15 years) and short term (3-5 years) storage conditions. Roberts (1973) has classified seeds into two groups for storage Purpose; viz. (1) Orthodox and (2) Recalcitrant.

1. Orthodox
Seeds which can be dried to low moisture content and stored at low temperature without losing their viability are known as orthodox seeds. Eg. Rice, Carrot, Beetroot, Papaya, Chickpea, Soybean, Cotton and sunflower These seeds can be dried and stored at low temperatures for long periods of time.

2. Recalcitrant
Seeds which show very drastic loss in viability with a decrease in moisture content below 12 to 13% are known as recalcitrant seeds. Eg. Cocoa, Coconut, Jackfruit, Mango and Jamun. Seeds cannot be conserved in seeds banks and, therefore, requirein-situ conservation.