Question

In sunflower, self pollination is avoided by
A. Protogyny
B. Unisexuality
C. Self sterility
D. Protandry

Answer 1

Hint: Pollination is the process where the pollen grains are transferred from another to stigma and it is of again two types namely, self pollination and cross-pollination.

Complete answer:
Classification of pollination
1. Autogamy: Transfer of pollen grains from the anther to the stigma of the same flower or same plant is called as autogamy or self pollination
Methods that promoting autogamy includes
> Bisexuality: The presence of male and female reproductive organs in the same flower is called bisexuality and all flowers which possess bisexuality are called hermaphrodite.
> Homogamy: Maturation of anther and stigma at the same time.
> Cleistogamy: when pollination and fertilization occurs in the open bud flowers
> Chasmogamy: Opening of flowers only after the completion of pollination is called chasmogamy
> Position of Anthers: In some species, the stigma of anthers are arranged in such a way to initiate self pollination.
2. Allogamy: Transfer of pollen grains from another one plant and to the stigma of another plant then it is called allogamy or cross-pollination.
Methods that promoting the cross-pollination are
> Dicliny: if refers to the unisexual flowers, they are again divided into 2 types
i. Monoecy: If male and female flowers are present on the same plant, examples such as mango, castor, etc
ii. Dioecy: In this type, staminate and pistillate flowers are present on different plants, examples include the papaya, hemp, etc.
> Dichogamy: Maturation of the anthers and stigma of the flowers at different times. They are again of 2 types
i. Protandry: If anthers mature, before the pistil, example are sunflower, sugar beets
ii. Protogyny: If pistil matures before anther then it is protogyny, an example is pearl millet
> Herkogamy: stopping the self pollination by barriers
> Hetrostyle: when style and filaments of the anther are different heights
> Self-incompatibility: Inability of fertile pollen to fertilize the same ovum.
> Male sterility: If pollen grains are not mature and not fertile

So from the above explanation, the sunflower is the correct answer.

Note:
The mode of pollination plays an important role in plant breeding. It has an impact on five important aspects such as gene action, genetic constitution, adaptability, genetic purity, and transfer of genes.