Question

Heterosis (hybrid vigor) desirable in vegetatively propagated plants, because
A) Heterosis maintains longer duration.
B) These plants are easy to cultivate.
C) Vegetative reproduction helps in faster multiplication.
D) It is due to homozygosity.

Answer 1

Hint:Heterosis is referred to as the enhancement in the biological qualities like size, fertility rate, growth rate, biomass and yield due to mating of parents resulting in a mix of genetic contributions. These qualities are greater than those already present in parents.

Complete answer:
Characteristics of Vegetatively propagated plants
>Vegetative propagation is a type of asexual reproduction.
>A new plant is grown from vegatative parts of plants like root, stem and leaves or it can n=be grown from a fragment of the parent plant.
>It maintains the genetic characteristics of the plants over many generations i.e the offspring is a clone.
>Same traits can be maintained indefinitely.
>High quality plants can be grown.
>Maintains the consistency of traits.
Let us analyse all the options to find the correct answer
>Option A: In Heterosis two pure lines are crossed in which the first generation shows the desirable traits but the vigour can reduce in following generations. Therefore, vegetatively propagated plants are used to maintain the vigour for longer duration. THis helps in getting the desired traits consistently. Hence, this is the correct answer.
>Option B, C and D - All these options are irrelevant and incorrect, therefore, this is the incorrect option.

Additional information :
>Heterosis was observed for the first time in tobacco hybrids by Koelreuter.
>Species like Pearl. Millet and Rye which pollinate naturally show heterosis.
>Heterosis also provides better adaptation to the environment, resistance against pests and high tolerance.
>Metabolic, molecular, epigenetic and metabolomic changes are also seen due to heterosis.

Thus the correct answer is option (A) Heterosis maintains longer duration.

Note:Heterosis is an outbreeding enhancement where F1 generation shows is more vigorous than parents. The greater quality of traits can be due to both mendelian and non-mendelian inheritance.