Question

Parthenocarpic fruit cannot be produced by the application of
A. IAA
B. 2,4-D
C. ABA
D. IBA

Answer 1

Hint: In botany and horticulture, parthenocarpy is the natural or artificially induced development of fruit without the fertilization of ovules, which renders the fruit seedless.

Complete Answer:
- Varieties of pineapple, banana, cucumber, grape, orange, grapefruit, persimmon and breadfruit exemplify naturally occurring parthenocarpy.
- In non-parthenocarpic varieties and in naturally parthenocarpic varieties, seedless parthenocarpic fruit can be induced out of season by a form of artificial pollination with dead or modified pollen or by pollen of a different type of plant.
- The use of synthetic growth substances in paste form, by injection or by spraying also induces parthenocarpy development.Unpollinated ovaries reacted to GA3 and to different auxins [indole-3-acetic acid, naphthaleneacetic acid and 2,4-dichlorophenoxyacetic acid (2,4-D)], with 2,4-D being the most effective.
- GA3-and 2,4-D-induced fruits had different internal morphology, with low locular tissue development in the case of GA, and pseudo-embryo development in the case of 2,4-D. Interestingly, the use of NPA to pollinated ovaries prevented their development, likely due to supra-optimal IAA accumulation.
- Parthenocarpic fruit growth of unpollinated ovaries was also caused by plant decapitation and inhibition of auxin transport by NPA from the apical shoot. Application of IAA to the severed stump negated the effect of plant decapitation, suggesting that the apical shoot prevents unpollinated ovarian growth by IAA transport.
- Abscisic acid (ABA) is a plant hormone. ABA functions in many plant growth processes, including seed and bud dormancy, organ size control, and stomatal closure. It is particularly important for plants to react to environmental stress, including drought, soil salinity, cold tolerance, freezing tolerance, heat stress and heavy metal ion tolerance.

Thus the correct answer is option(C) ABA.

Note: Effects of ABA
- Inhibits ripening of fruit.
- Responsible for dormant seed by inhibiting cell growth – prevents seed germination.
- Inhibits Kinetin nucleotide synthesis.
- Regulates the enzymes required for photosynthesis.
- Acts on endodermis to avoid root growth when exposed to salty conditions.
- Delays the division of cells.