Question

The onset of seed germination , the digestive enzyme amylase is produced by the action of-
A. Auxins
B. Gibberellins
C. Cytokinins
D. Ethylene

Answer 1

Hint: Plant hormones (also referred to as phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pathogen defense, stress tolerance and thru to reproductive development. Unlike in animals (in which hormone production is restricted to specialized glands) each plant cell is capable of manufacturing hormones.

Complete answer:
Gibberellins break seed dormancy of buds and tubers. But in root tubers, it inhibits the development of root tubers. It enhances seed germination by enhancing alpha amylase synthesis and thus results in breaking seed dormancy. Thus, the production of digestive enzymes like alpha amylase is an action of gibberellin. Some seeds that are sensitive to light like tobacco and lettuce exhibit poor germination within the absence of sunlight. Germination begins rapidly if the seeds are exposed to the sunlight. If the seeds are treated with gibberellic acid, the light requirement can be overcome.The buds that are formed in autumn stay dormant until next spring. This dormancy is often overcome by treating them with gibberellin.Gibberellins have almost no effect on the expansion of roots. However, some inhibition of growth can occur at a better concentration during a few plants.

Hence, the correct answer is option (B).

Note: Synthetic plant hormones or PGRs are utilized in a variety of techniques involving plant propagation from cuttings, grafting, micropropagation and tissue culture. Most commonly they're commercially available as "rooting hormone powder". Gibberellin is commercially obtained from fungi. It is used to facilitate the germination of seeds.It is sprayed on the grapevines and used to enlarge them.It is used on cucumber plants to produce all-male flowers. This helps the farmers to obtain pollen of desired characteristics to be used for hybridization.