the Role of the photoperiod and temperature in growth regulation. Influence of lunar and artificial light on photoperiodic reaction

you are: the Role of the photoperiod and temperature in growth regulation

Low light exposure of an order 0,1 lk can influence the photoperiodic account of time at many plants and animals at night. Intensity of light in a full moon in cloudless night at width 50 ° sometimes reaches 0,3 lk, and in tropical areas - three times it is more (fig. 12.20). This fact has induced E.Bjunninga and its employees to find out, whether can break a moonlight time account. To the surprise, they have found out that some plants possess adaptive mechanisms which, probably, interfere with moonlight influence on fotoperiodizm.

Recollect that as photoperiod receptors leaves serve. At bean plants (a soya, a peanut, a clover) sleepy movements change position of leaves: in the afternoon it horizontal, and at night the vertical. It reduces intensity of light falling on a surface of leaves from suspended at the top of bulb (' the artificial moon '), on 85-95%, i.e. To the level which is not influencing not so into the account of time. At some niktinasticheskih plants (Albizzia, Samanea and Cassia) leaves not only are guided at night vertically, but also turn about the axis so that pair leaflets develop together, shading each other (fig. 12.1 see). It is very interesting whereas the top surface is more sensitive to light, than bottom.

Some plants of short day blossom is better at a weak night-time lighting (approximately 0,5 lk), instead of at full darkness at night. At these plants the moonlight, possibly, increases number tsvetkov, formed at a short bottom. Though it is yet clear, why weak light favours to flowering more, than darkness, these facts, probably, underlie poverja that certain seeds need to be sowed by the light of the full moon: then the following full moon could render beneficial effect on flowering.

On the other hand, street and room illumination can break the photoperiodic control at many plants. For example, it can detain an induction of rest at a rhododendron, a cornel and other trees and bushes, reducing thereby chances of a survival in severe winters. the lamps which light is enriched by red beams are especially harmful and consequently supports in plants high level of Fdk. This fact needs to be considered at the device of external illumination.