Have you noticed the wonderful synchronization of living things? Every year, plants grow, grow and bloom according to the calendar. Not everyone follows the same schedule: some bloom in spring, some in summer and others in autumn and early winter. But each species knows the right time to perform its different activities.

The same goes for animals. They reproduce, reproduce, go dormant, migrate and perform other functions as if following a specific schedule. Think of insects that rest in a dormant state called diapause. In late summer, while the weather is still warm, they stop feeding and reproduce and begin to settle down in their dormant state. How do you know winter is coming?

There are also birds that migrate to the tropics to spend the winter. With the arrival of spring in the north, they return home. Since the temperature in the tropics is about the same as when the birds arrived, how do you know it's getting warmer in your homes? Many asked such questions. You have?

The wonderful time device

The main synchronization mechanism for living things is assumed to be easy. In general, seasonal variations in temperature are thought to trigger different reactions in plants and animals. But the temperature varies; it is inconsistent from year to year. Light, on the other hand, is reliable. Every day of the year, daylight will be the same. It never varies. Thus, a living organism receives accurate information about the progress of the season.

This does not mean that temperature or other factors can not affect the seasonal rhythm of plants and animals. Extremely yes. But the main time device seems to be the length of daylight. That the activities of living things are programmed with this wonderful clock is a relatively new discovery.

An important investigation

In 1920, researchers studied a variety of tobacco called Maryland Mammoth. They tried to determine why the flowering was delayed when growing near Washington, DC. Although the plant was ready to bloom for several days, something prevented it from doing so until the end of the season to seed ripen.

Many experiments were performed, but they did not reveal the cause of the delay in flowering. Finally, the greenhouse plants artificially had a reduced daily exposure to light. He did it! The plants bloomed earlier than those that grew outside. This provided some insight into why the Maryland mammoth does not bloom until the end of the season near Washington, DC, as it was not until late summer that daylight was shortened to just the right length for this plant to bloom.

Does light affect other plants in the same way? Further research from these researchers has shown that this is the case. It turned out that plants can be divided into three groups, depending on their reaction to the duration of daylight.

First, it is the group that includes plants, such as tomatoes and cucumbers, that do not require much of a day's duration. A second group is called "short day" plants. These will bloom only when the daily light dose is less than a certain number of hours. The third group is called "long-day" plants. They bloom when daylight exceeds a certain number of hours.

The conclusions from Findings

These surveys answered many questions. They explain why plants of a certain species can be planted at different times of the year, but all bloom at the same time. And they reveal why some plants bloom in some neighborhoods, but do not bloom in others.

Farmers now regularly determine the plant's lighting needs. Some of them have very specific daylight needs. For example, several varieties of onions and soybeans only work best when grown within a width range of 150 km. If grown in the northern or southern part of this region, they can fail as a crop.

Plants, from daylight to plants, can disappoint flower lovers. When traveling, a person can buy a variegated plant for their garden, but it cannot bloom at home. Why? The daylight you live in may not be long enough for the plant to bloom.

For example, there is the garden plant Sedum telephium that grows in southern Vermont. But he does need a daily dose of 16 hours or more of light to develop. You can find it in Vermont. But if you take it too far south it won't bloom because of the lack of daylight.

On the other hand, a person in northern Maine might be grateful that there is little to no ragweed there. Ragweed doesn't bloom until the daylight fades at half past two. This doesn't happen until August 1st in North Maine, so the seeds don't have enough time to ripen before the cold weather arrives.

How plants recognize light

Knowing these facts about how plants respond to daylight made it more obvious. The plants must contain something that can sense the change in daylight and make them react accordingly. This substance, called "phytochrome", has recently been isolated.

Phytochrome is a light-sensitive bluish pigment that absorbs red light. It has been shown that many plants mature faster when exposed to the red wavelength of light. In either case, light acts on the phytochrome to regulate changes in the growth of a plant from seed to maturity. But we don't know how to do it.

Manipulate the light

Many gardeners now use this knowledge to their advantage of how plants react to light. By adjusting the exposure you can make a plant bloom whenever you want. In winter, they appreciate flowers that normally only grow in summer, and those that normally bloom in fall may have flowers in other seasons.

For example, a chrysanthemum is usually a plant that blooms in the fall. But it can bloom in summer. Simply cover with a cardboard box in the late afternoon and remove in the morning. The long darkness makes the chrysanthemums react like autumn and bloom with summer flowers.

On the other hand, a person might want to enjoy winter flowers that normally only bloom in summer. The daily application of artificial light at the end of the day allows these plants to react as if the long summer days had come. Therefore, they bloom on short winter days.

Effect on animals

After the remarkable effects of daylight duration on plants were discovered, an investigation was conducted to see if the animals were affected in the same way. As a result, it also appeared that many animals performed their seasonal routines after the day.

The first experiments with birds were carried out with starlings. Starlings usually mate in the spring when the days get longer. However, the short December days were artificially lengthened and lit candles on the birds after dark. Within a few days, the falls began to melt and take on the colorful plumage of the spring mating season. Your breeding program lasted four months and increased the duration of your daily light exposure!

Similar experiments have been carried out with ferrets, which are usually also bred in spring or early summer. These small animals also mate in winter when exposed to additional periods of light. Starlings and ferrets are creatures. They are among those creatures that react sexually to long periods of light.

But many other animals such as goats, sheep and deer breed in the fall. The short duration of the day affects them sexually. Therefore, sheep farmers who want lambs in spring can limit the daylight exposure of their animals in late summer. By keeping the sheep in dark stalls all day in July and August, the rearing process starts earlier.

Many interesting experiments have also been carried out with insects, including silkworms. The eggs laid in autumn spend the winter in a resting position. They develop into larvae or worms in spring. The larvae later quickly transform into young and adult moths. Eggs laid in early summer do not go through a resting phase.

Experiments show that it is the length of daylight that determines why eggs laid in early summer do not go to rest, unlike eggs laid in autumn. Through artificial regulation of light, silkworms can be stimulated to reproduce generation after generation without any of their eggs entering a dormant phase. When the exposure time changes, the butterflies lay eggs that become inactive.

As with plants, it is obvious that there is a mechanism in animals that triggers their different responses to the duration of light. A hormone is thought to be involved. However, there are few details on how short messages are received or sent.

Although man has learned much about the many wonders of creation, he is constantly reminded of how much mystery he still has. The study of the effects of light on living beings clarifies this again.