Breeding of Fruit and Plantation Crops

Parthenocarpy and Seedlessness

• In the recent years, the consumer preference towards seedless fruits is increasing among the consumers. The seedless nature of certain fruits is due to the phenomenon of ‘parthenocapy’ which refers to the development of fruits without fertilization or even without the stimulus that comes from pollination. Parthenocarpic fruits are usually seedless but need not be always.

Vegetative parthenocarpy

• If a fruit develops even without the stimulus of pollination, then the phenomenon is referred to as vegetative parthenocarpy (automatic) eg. Banana and Japanese persimmon.

Stimulative parthenocarpy

• If a fruit develops from the mere stimulus of the pollination (but without fertilization), the phenomenon is known as stimulative parthenocarpy. The female flowers of triploid watermelon require the pollen grains of diploid varieties to develop into a seedless fruit.


• Diploid pollen grain gives a stimulus to the ovary of guava when self pollinated, which result in the development of parthenocarpic fruit due to the stimulation provided by pollen hormones. E.g) Thompson Seedless variety of Grapes and papaya

Steno-spermocarpy

• In Black Corinth variety of grapes, pollination and fertilization take place but the embryo gets aborted subsequently resulting in seedlessness. This phenomenon of development of seedless fruits is referred to as ‘steno-spermocarpy’. The seedlessness or parthenocarpic fruits are advantageous since there is a greater preference among the consumers for the seedless fruits of the same kind (e.g. seedless grapes, guava or oranges).
  


• Besides the problem of unfruitfulness due to pollination failure, sterility and incompatibility may not arise if a fruit develops parthenocarpically and the grower is assured of good crop (e.g. banana). One drawback with the seedless fruits is that they are usually small in size (e.g. Black Corinth variety of grapes) and irregular in shape (guava).