Importance of dark period, Biology

Importance of Dark Period

For quite sometime the role of light period (photoperiod) was emphasised in flowering? However, based on certain experiments it was realised that it is the dark period that is more important than the light period for inducing a plant to flower. In fact, as early as 1912, from his experiments on flowering, Julien Tournois concluded that flowering occurred "not so much by shortening of day as by lengthening of nights". We describe below an experiment, which was done much later by Hamner and Bonner (1936) that proved this point. A short-day plant was taken that required 16 hours of darkness and 8 hours of light to flower. If the dark period was reduced, plants did not flower. Interestingly, if the dark period of 16 hours was interrupted by light, again there was no flowering. However, if the light period was interrupted by dark period, or if plant8 were kept less than 8 hours in light there was no effect on flowering. It was clear that altering the light period had no effect but if the dark period was less than 16 hours, the plants would not flower. A look at Figure will further clarify this experiment and confirm that dark period is more important for inducing plants to flower. This concept has now been well established. The role of dark period is to bring about some changes which trigger the development from the vegetative to the flowering state. The role of light period is to realise this change and help in bringing about maximum flowering.

433_Importance of Dark Period.png

Figure: Experiments to show that dark period is important for flowering. If dark period is interrupted (3) SDP do not flower but if light period is interrupted (4) or shortened (5) there is no effect on flowering in LDP

Posted Date: 1/17/2013 7:20:36 AM | Location : United States







Related Discussions:- Importance of dark period, Assignment Help, Ask Question on Importance of dark period, Get Answer, Expert's Help, Importance of dark period Discussions

Write discussion on Importance of dark period
Your posts are moderated
Related Questions
List 7 different types of information that must be recorded for every item of evidence collected from a crime scene.

A genetic trait which is considered to be harmful in the present day might prove to be beneficial in future. For example by removing the trait for sickle cell we may increase the s

Q. Protein Requirement during congestive cardiac failure? Protein: The protein requirements remain the &me as healthy adult men and women, About 0.8 - lg of protein per kg

VITAMIN - D Also known as Calciferol / Anti ricket vitamin / sun shine vitamin. It is necessary for bones & teeth. It is synthesized in presence of UV rays of sunl

Determine about the Psychological tests The construct of attention has been found to comprise several interrelated elements that the paediatric neuropsychologist can consider i

Explain the Feeding process for Preschoolers? The word preschool children, you may be aware, is used for children less than six years of age. After the first year, there is a s

Q. What is the difference between rough and smooth endoplasmic reticulum? The endoplasmic reticulum is a delicate membranous structure contiguous to the nuclear membrane as wel

Q. How to Recover from Blood Pressure? The rate of the systolic blood pressure drop during recovery is usually fairly rapid after maximum exercise, although a rebound with a te

Agro Industrial-Incriminating factors in feeds There are many anti-nutritional factors present in feeds and fodders which affect the utilization of nutrients. Some of these are

Define the term Archenteron ? The name given to the primitive gut, the first tube that runs through the developing embryo and is open to the external environment. Formed during