About Lesson
Undesirable effects
- Reduction in Diversity:
- Plant breeding leads to reduction in diversity.
- The uniform varieties are more prone to the new races of pathogen than land races which have high genetic diversity.
- Narrow genetic base:
- Uniform varieties have narrow genetic base. Such varieties generally have poor adaptability.
- Danger of Uniformity:
- Most of the improved varieties have some common parents in the pedigree which may cause danger of uniformity.
- Undesirable combinations:
- Sometimes, plant breeding leads to undesirable combinations. The examples of man-made crops having undesirable combination of characters are Raphanobrassica and Pomato.
- Increased susceptibility to minor diseases and pests:
- Due to emphasis on breeding for resistance to major diseases and insect pests often resulted in an increased susceptibility to minor diseases and pests.
- These have gained importance and, in some cases, produced severe epidemics.
- The epidemic caused by Botrytis cinerea (grey mold) in chickpea during 1980-82 Punjab, Haryana.
- The severe infection by Karnal bunt (Tilletia sp.) on some wheat varieties, infestation of mealy bugs in Bt cotton.