Question

Maturation of stigma and anthers at different times in the same flower is
A. Heterostyly
B. Dichogamy
C. Dicliny
D. Herkogamy

Answer 1

Hint: Outbreeding devices are the devices or features of plants which discourage self pollination and encourages cross pollination. These devices or features prevent the loss in genetic variation or inbreeding depression.

Complete answer:
Dichogamy is the maturation of stigma and anthers at different times in the same flower. There are two conditions which fall under the Dichogamy:
> Protandrous: The pollen is released before the stigma becomes receptive, e.g., Sunflower and cotton.
> Protogynous: The stigma becomes receptive before the release of pollen, e.g., Ficus and aristolochia.
> Heterostyly: It is the condition in which 2-3 types of flowers within the same plant and such flowers have the difference in length of style and stamens.
> Herkogamy: It is the condition in which the pollen grains fail to reach the stigma. In some flowers, a mechanical barrier exists between the compatible pollen and stigma.
> Dicliny: It is the presence of only one kind of reproductive whorl in a flower. It is also known as unisexuality. There are two conditions of dicliny:
> Monoecious plants: In this, male and female flowers are produced on the same plant. This condition prevents autogamy, e.g., castor and maize.
> Dioecious plants: In the, male and female flowers are produced on the different plants. It prevents autogamy as well as geitonogamy, e.g., papaya.

So the correct answer is option B.

Note: Self-incompatibility is also a type of outbreeding devices or techniques. In this technique pollen grains fail to fertilize the ovule by inhibiting pollen germination and pollen tube growth in the pistil. It is a genetically controlled mechanism.