Photoperiodism and vernalization | Long Day | Short Day | Neutral Plants

Photoperiodism and vernalization: The response of a plant to the relative lengths of light and dark periods is known as photoperiodism. In plants, most significant photoperiodic response is the initiation of flowering. It has been first observed in Maryland Mammoth variety of tobacco (Nicotiana tabacum). From the observation of Garner and Allard all the plants do not require the same length of light and dark periods for flowering. Plants require specific period of light and darkness for flowering. It is known as critical period. Plants are classified into three classes 1. The plants requiring longer exposure to light than their critical period are known as long day plants eg. wheat and oats. 2. The plants requiring light for a shorter period than their critical period are known as short day plants eg. tobacco and Chrysanthemum. 3. The plants in which flowering is unaffected by the photoperiod are known as day neutral plants eg. sunflower and maize. Vernalization: The term vernalization was first introduced by a Russian scientist T.D. Lysenko in 1920. Many species, especially biennials and perennials are induced to flower at low temperature range of 1oC to 10oC. This is known as vernalization. The response to the cold temperature stimulus is not uniform in all plants. Plants, which are vernalized, are called inductive types. Those nonvernalized are called noninductive types. Techniques of vernalization: The following are the steps to be taken to induce vernalization. Seeds are allowed to germinate and subjected to cold treatment for varying period of time depending on the species. Germinated seeds after this treatment are allowed to dry for sometime and then sown. Devernalization: Reversal of the effect of vernalization is called Devernalization. Subjecting the plants to higher temperature after a cold treatment brings about devernalization. Practical application of vernalization: Russian scientists have used vernalization to shorten the time of crop maturity by hastening the flowering processes which are brought about by cold treatment. Disclaimer This channel does not promote or encourage any illegal activities. All contents provided by this channel for general and education purpose only. Copyright disclaimer under section 107 of the copyright act 1976,allowance is made for "fair use policy" for purposes such as criticism, comment, news reporting,teaching,scholarship and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use.