শুক্রবার, ৮ আগস্ট, ২০১৪

In previous post name of the principals of heterosis fixation was listed now a short note on that principals will be discussed:
a. Vegetative Propagation: Vegetative cell is diploid & it's production depends on mitosis. So heterosis can be easily conserved in vegetatively propagated crops. Example- Sugarcane, sweet potato, banana, potato etc.
b. Apomixis: Seeds are developed without fertilization in apomixis. Sothe apomictic progeny is identical to the mother plant. Example- Citrus, blackberries, roses & many other flowering plants.
c.Balanced lethal system: This principal lead the fixation process in some plants. Only heterozygotes survive because homozygous are lethal hence they die. Example- Oenothera spp.
d. Polyploidy: Especially in interspecific and intergeneric hybrids heterosis can also be fixed by chromosome doubling or polyploidy. Example- Wheat-rye cross is sterile, which becomes fertile after doubling chromosome and exhibit heterosis.

Inbreeding: It is the mating between individuals related by descent.

Inbreeding depression: It can be defined as the reduction or loss in vigor & fertility due to close inbreeding. It stars from the second generation.

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