Difference between vernalisation and photoperiodism.
Answers
Difference between Photoperiodism and Vernalization
Sl. No. Photoperiodism Vernalization
1 Photoperiodism is the induction of flowering in plants by exposing them to appropriate photoperiods (light and dark periods). Vernalization is the process of induction of flowering in plants by exposing them to cold temperature.
2 Photoperiodism provides both the stimuli and the induction of flowering. Vernalization only prepares the plant for perceiving the flowering stimuli. It does not induce flowering.
3 The stimuli induced by light in photoperiodism are received only by the green leaves. The stimuli induced by the cold treatment in the vernalization are received by leaves, meristem and embryos.
4 The photoperiodism is mediated through a hypothetical hormone called Florigen. Vernalization is mediated through a hypothetical hormone vernalin which is known to induce the synthesis of florigen in plants.
5 The exposure of 2 to 3 appropriate photoperiods is enough to induce flowering in plants. The exposure to low temperature (below -2oC to 12oC) for about 50 days is needed to induce flowering through vernalization.
6 Photoperiodic induction cannot be nullified or reverted by exposure to unfavorable photoperiods. Vernalized plants can be devernalized by exposing them to high temperature (40oC).
7 Gibberellic Acid (GA) can replace the exposure to long photoperiods in long-day plants only. GA can replace cold treatment to induce vernalization in all plants.
Answer:
Photoperiodism can be termed as the response of plants to periods of day/night. It is theorized that the hormonal substance that is responsible for flowering, is formed in the leaves which subsequently migrates to the shoot apices and alters them into flowering apices. This process of photoperiodism helps in studying the response of flowering in different crop plants when the duration of exposure of light is considered.
Vernalisation is the phenomena where the process of flowering in some plants is either quantitatively or qualitatively dependent on the exposure to lower temperatures. In particular, it refers to promoting the flowering process by a period of lower temperatures. The process prevents precocious reproductive development late in the growing season which thereby enables the plant to have sufficient time to attain maturity.