Photoperiodism

So in the scientific language is called a complex of phenomena caused by a change in illumination. Photoperiodism is the biological reaction of a plant organism to these changes.

Days have different lengths depending on the season. The increase or decrease in the duration of the light period of the day serves as a signal for the plant to include certain growth and development processes. The plant is genetically "programmed" not for actual age changes( especially since many species every spring seem to begin to live anew), depending exclusively on the time of the type through so many days - the sprout, through some more - the first pair of leaves and so onFurther. They, depending on climatic factors, simply would not survive under such condition. Even the temperature itself is not an exhaustive parameter: there are very cold years, there are warm, there are with an unpredictable change of cold and warm fronts, etc. Only one year after year is the cycles of illumination. They, then, became the basis of the main life program for plants.

Until the length of the light day reaches a certain( so-called "critical") length, the plant will not bloom. If it is exceeded, too. But after all, for flower-growing plants, the most important thing is a flower, and therefore one should not know or forget about this feature.

The photoperiodic reaction of many plant species is so precise that the difference between the length of the period of illumination at which it blooms and at which it will not bloom for anything is only fifteen to twenty minutes. In this case, it is often important not the absolute length of the light day, namely, comparative to the day preceding, whether it will be shorter or longer than a certain critical period.

According to the requirements for the light regime, the flowers are divided into short-range, long-day and neutral( which, however, are also not completely neutral).

Moreover, with some plants there are almost no tricks! We include a chandelier at night - and for a long-day plant, one minute of light at night on a short day is enough to make the

bloom, while a short-day blossom in response to this "pulse" of light will blossom flatly. Both the period of continuous light and the period of continuous darkness are almost equally important.

The origin of the plant will play a decisive role here. Suffice it to recall the geography at the level of the secondary school to answer: can a light day in the equatorial zone reach 16 hours or at least 14 hours in two weeks.

Short-day plants bloom in the spring or( sometimes - in the autumn), long-day plants in the summer.

Some are sufficiently single-use, others require a longer exposure: these "slow-witted" react to the change in lighting after a few weeks.

In one of the greenhouses of our city, where chrysanthemums were being grown for sale, one day there was a "total nightmare": huge chic flowers blossomed on the stems. .. only about fifteen centimeters long. The reason was simple: a problem with lighting. A loss. .. Comments are superfluous.

Plants that have been in a long day have higher stems than plants in a short day.

And again, as always, none of the life manifestations is something isolated: everything is interconnected in nature.

It is associated with photoperiodism and the so-called vernalization( keeping the seeds at a certain, usually close to freezing, temperature): thanks to it, you can turn a long-day plant into a short-day plant, and vice versa. Vernalized winter rye becomes a typical long-day plant, spinach - short-day, clover generally loses the dependence of flowering on the length of the day. This fact does not yet have a direct practical significance for floriculture: experiments have been conducted mainly with agricultural crops, but just in case it can be remembered. And for general erudition, and for experiments that can open up new opportunities in growing flowers.