Question

Parthenocarpic tomato fruits can be produced by
(a) Treating the plants with phenylmercuric acetate
(b) Removing androecium of flowers before pollen grains are released.
(c) Treating the plants with low concentrations of gibberellic acid and auxins
(d) Raising the plants from vernalized seeds.

Answer 1

Parthenocarpy is the production of fruits without fertilization of ovules. It may be natural or artificially induced. These fruits do not produce any viable seeds, which improve the quality. The plant growth regulators are natural and fruits grown are larger in size.

Complete solution:
Parthenocarpy is desirable in the production of food crops that are difficult to pollinate or fertilize.
Gibberellic acid and auxins are stimulatory plant growth regulators. When low concentrations of these plant hormones are sprayed on the flower, it stimulates the development of parthenocarpic fruit. This type of parthenocarpy is artificial.
The plant hormones are seldom used commercially to produce parthenocarpic fruit. Some gardeners also spray auxins on their tomatoes to assure fruit production. They are used for the growth and development of fruits and an increase in the long shelf life.

Additional information:
Phenylmercuric acetate is used as a fungicide. When sprayed on the leaves of plants, it induces stomatal closure, which reduces the amount of water lost through transpiration. Hence, PMA reduces the rate of transpiration.
Removal of the androecium of flowers before pollen grains is released called emasculation. Emasculation is used in various plant hybridization techniques.
Vernalized seeds are seeds that were exposed to low temperatures to stimulate flowering or enhance seed production.

So, the correct answer is 'Treating the plants with low concentrations of gibberellic acid and auxins'.

Note:
When sprayed on flowers, Gibberellic acid promotes the fruit set, and auxins complete the fruit's development process. Another plant hormone, cytokinin, also stimulates the development of parthenocarpic fruits.