Read the given passage and answer the questions that follow:-
Plant breeders aim to create new and improved varieties by crossing different species, and sometimes even genera, to combine desirable traits. To achieve successful crossbreeding, it is crucial to ensure that only the intended pollen grains are used for pollination, while also protecting the stigma from any unintended contamination. This careful selection and controlled pollination process helps breeders create commercially superior varieties with specific traits.
Given below are two statements:
Statement I: If the female parent produces unisexual flowers, the female flower buds are bagged after the flowers open.
Statement II: Pollen grains of a large number of species can be stored for years in liquid nitrogen and used in crop breeding programmes.
In the light of the above statements, choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Statement I is incorrect but Statement II is correct.
Emasculation is needed only when the female parent bears bisexual flowers. With unisexual flowers there are no anthers to remove, but the stigma must still be kept away from unwanted pollen.
Statement I: If the female parent produces unisexual flowers, the female flower buds are bagged after the flowers open. — False. The female flower buds are bagged before the flowers open. Bagging after opening would let unwanted pollen reach the stigma first.
Statement II: Pollen grains of a large number of species can be stored for years in liquid nitrogen and used in crop breeding programmes. — True. Such stored pollen works as a pollen bank, similar to a seed bank.
So Statement I is incorrect and Statement II is correct.
NCERT Extract:
Pollination – “If the female parent produces unisexual flowers, there is no need for emasculation. The female flower buds are bagged before the flowers open. When the stigma becomes receptive, pollination is carried out using the desired pollen and the flower rebagged.”
Stamen, Microsporangium and Pollen Grain – “… It is possible to store pollen grains of a large number of species for years in liquid nitrogen … Such stored pollen can be used as pollen banks, similar to seed banks, in crop breeding programmes.”