Principles of Plant Breeding (2+1)

Degrees of inbreeding depression

• Various plant species exhibit different degrees of inbreeding depression. The depression may be from very high to nil. Based on degree of depression, the plant species can be grouped into 4 broad categories.

1. High inbreeding depression: E.g. Lucerne, Carrot. Inbreeding leads to severe depression and exhibit lethal effects. After 3 or 4 generations of selfing it is hard to maintain lines.

2. Moderate inbreeding depression: E.g. Maize, Jowar, Bajra. Though lethal effects are there, lines can be separated and maintained.

3. Low inbreeding depression: E.g. Cucurbits, Sunflower. Only a small degree of inbreeding depression is observed.

4. No inbreeding depression: The self-pollinated crops do not show inbreeding depression.