Q.Define parthenocarpy and explain how it can be induced artificially, with one example.

Seedless fruits are produced by parthenocarpy (fruit development without fertilization), so the Reason correctly explains the Assertion; both are true.

• Assertion (A): Some fruits are seedless and their demand is rising — true (e.g. seedless banana, grapes, watermelon are commercially valued).
• Reason (R): These fruits are produced without fertilization — true. Parthenocarpy is the formation of fruit without fertilization; because fertilization is bypassed, no seeds develop, giving seedless fruits. Parthenocarpy can also be induced with growth hormones.

Since the absence of fertilization is exactly what makes such fruits seedless, R is the correct explanation of A.

A standard NCERT/CBSE Class 12 Biology assertion–reason board question on parthenocarpy.

Parthenocarpy is the formation of a fruit from the ovary without fertilization taking place, resulting in a seedless fruit; it can be natural or artificially induced using the growth hormone auxin.

Normally, fruit development follows fertilization of the ovule(s) inside the ovary — the ovary wall develops into the pericarp (fruit wall) while the fertilised ovules become seeds. Parthenocarpy is the exception to this: it is the development of the ovary into a fruit WITHOUT fertilization ever occurring, so the resulting fruit is seedless.

Occurrence:

• Naturally seedless fruits, such as banana, are parthenocarpic.
• Parthenocarpy can also be induced artificially by treating unpollinated flowers/ovaries with auxins (a plant growth regulator). Commercially, this technique is used to produce seedless tomatoes — spraying an auxin such as PAA (phenylacetic acid) or 2,4-D on unpollinated tomato flowers stimulates the ovary to develop into a fruit even without fertilization.

Parthenocarpy is of horticultural importance because seedless fruits (grapes, bananas, some citrus, tomatoes) are generally preferred by consumers, so understanding and artificially inducing this auxin-mediated response is a useful application of plant growth regulators in agriculture and horticulture.