Which one of the PGRS would you use if you are asked to?

(a) 'Bolt' a rosette plant

(b) Induce immediate stomatal closure in leaves

(c) Induce parthenocarpy in tomatoes

(d) Elongation and improvement in shape of apple

(a)- Gibberellic acid ,(b) ABA , (c) auxin (d) Gibberellic acid

The correct answer is Option (3) -(a)- Gibberellic acid ,(b) ABA , (c) auxin (d) Gibberellic acid

Auxins also induce parthenocarpy, e.g., in tomatoes. They are widely used as herbicides. 2, 4-D, widely used to kill dicotyledonous weeds, does not affect mature monocotyledonous plants. It is used to prepare weed-free lawns by gardeners. Auxin also controls xylem differentiation and helps in cell division.

Gibberellins also promotes bolting (internode elongation just prior to flowering) in beet, cabbages and many plants with rosette habit. Their ability to cause an increase in length of axis is used to increase the length of grapes stalks. Gibberellins, cause fruits like apple to elongate and improve its shape. They also delay senescence .

abscisic acid (ABA) was discovered for its role in regulating abscission and dormancy. But like other PGRs, it also has other wide ranging effects on plant growth and development. It acts as a general plant growth inhibitor and an inhibitor of plant metabolism. ABA inhibits seed germination. ABA stimulates the closure of stomata and increases the tolerance of plants to various kinds of stresses.