How does a flower bloom after plucking it out of the plant?
POOJA S. KUMAR
Thiruvananthapuram
Flowers are the reproductive organs of a flowering plant. Flowering normally occurs when sufficient vegetative growth ( i.e leaves, roots) has taken place to support and feed the reproductive parts.
Flowering is influenced by photoperiod (the time of exposure to sunlight), temperature and humidity. These factors mainly influence the number of pollinators, their concentration and formation of seeds. They also decide the blooming mechanism.
Blooming is often preceded or accompanied by an increase in the soluble sugars in the petals. The receptors present in the leaves, namely phytochromes, will send the signals to direct more nutrients, carbohydrates and water to the petals.
This results in a surge in the osmotic gradient and the cells present in the petals expand on receiving more water. Cell walls get loosened and expand considerably and blooming takes place.
Flowering hormones (Florigens C and T) will rush to the bud in high proportion just before blooming. The flowering hormones include Gibberellic acid, and in some plants ethylene, IAA and cytokinins.
Inhibitors also play an important role in the blooming mechanism. These inhibitors are again controlled by photoperiod, temperature and humidity. It's only when the inhibitor concentration falls below a critical level that buds start developing. So, when all the above conditions are satisfied blooming will happen.
Hence, only the buds that have reached appropriate maturity will bloom after we pluck them because by that time the concentration of sugars, water in their cells, florigens must have reached the required level.
Inhibitor concentration too must have fallen below the critical value. The buds too must have enough reserves of nutrients for blooming even after plucking. Exogenous application of Gibberillic acid can induce immediate flowering and blooming irrespective of photoperiod.
DR. T. BHAVANI
Bengaluru
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