Can Plants tell Time? (Long, but neat stuff)

I discovered this on another forum that I belong to, Makes for an Interesting Read!

"This first article is base knowledge but relevant for those adjusting light schedules in a common or uncommon manner.

How plants tell time

Plants of the same species tend to flower, fruit and go to seed with remarkable synchronicity. How are they able to keep such rigid schedules?

Gardeners often marvel at how plants of the same species tend to flower, fruit and go to seed with remarkable synchronicity, as if on cue. Some flowers even follow a strict daily routine, opening their petals at dawn’s light and closing at dusk. How are plants able to keep such rigid schedules? The secret lies in a kind of vegetative internal clock that has fascinated CALS plant scientists for decades. Here’s what they’ve learned about how it works:

See the light. The primary component of plants’ internal clock is a light-absorbing molecule known as phytochrome. A turquoise-colored pigment that can exist in two different forms, phytochrome inter-converts between a “Pr” form, which absorbs red light, and a “Pfr” form, which absorbs far-red light.

The sun winds the clock. In full sunlight, plants’ leaf cells contain equal amounts of phytochrome’s two forms—50 percent Pr and 50 percent Pfr.

The clock counts down at night. When it’s dark, phytochrome molecules that are in the Pfr form start converting to Pr at a slow, steady rate. Because this rate is constant, the amount of Pfr remaining in the leaf cells at any given time is a direct reflection of the number of hours a plant has sat in darkness. In this way, plants use phytochrome to count the hours of the night—they don’t directly measure day length—and use that information to dictate when they sprout, flower, fruit and go to seed during the growing season.

Plants got rhythm. The phytochrome clock enables plants to establish a 24-hour circadian rhythm. For plants that open their flower petals at dawn and close them at dusk, the phytochrome clock allows them to anticipate the sun’s rise and set. In fact, when placed in a dark closet, these plants will continue to open and close their flowers right on schedule for a number of days, until the circadian rhythm finally dampens.


What plants do all night will surprise you

In 2010, biologists studying Arabidopsis metabolism at an independent scientific research center discovered something very interesting: Their experimental plants seemed to use up their starch reserves at a very steady rate, every night using roughly 95% of what they started with.

If you remember your high school biology, during daylight hours, plants use sunlight to convert carbon dioxide and water (through photosynthesis) into carbohydrate compounds—AKA starches. Then, at night, they break down these stored starches to power their continued metabolism and growth.

What the team at the John Innes Centre had been doing was growing Arabidopsis in 12 hours of daylight followed by 12 hours of darkness. Throughout the 24-hour cycle, they measured both how much starch the plants produced and how much starch they consumed. They found that the rates were pretty linear, increasing and decreasing fairly steadily. You're probably thinking, "Big whoop. A steady metabolism rate. What's exciting about that?"

Well, read on. After four weeks of 12 hours light/12 hours dark, the researchers mixed things up. The very next day, they turned out the lights early for some of the plants—after only 8 hours of daylight instead of 12. Thus, the plants had only been making starch for 8 hours, not the usual 12. Then, 16 hours of darkness later, the scientists turned the lights back on. Notice this is still a 24-hour cycle, it's just skewed toward more darkness than light. So you might expect that these plants, accustomed to having their food last for 12 hours, would now run out when the night was 4 hours longer. But they didn't! They still had about 5% left—so, again, they used up about 95% of their reserves!

Meaning they changed the rate at which they were consuming starch to account for the changed conditions! And other plants that were given more light than they were accustomed to—now 16 hours of light followed by 8 hours of dark—also had 95% of reserves left at dawn. They had sped up their starch consumption, to account for the shorter night!

What did all this mean? The team concluded that plants must have a 24-hour biological clock that tells them how many hours of darkness to expect after a certain number of hours of light. Knowing how long your food has to last gives you a chance to pace how fast you eat. Who knew plants could do this?

The last segment below is from the same team of plant physiologists, who now think they have a mechanism for how plants determine their nighttime consumption rates. They're calling it molecular math. And though plants aren't really doing arithmetic, it is useful to think of it a type of calculation:

Amount of stored starch ÷ length of upcoming night = optimal rate of consumption.


Can plants do math?

This is Sandra Tsing Loh with the Loh Down on Science, saying maybe they can ..

See, during the day, plants use sunlight to convert carbon dioxide into sugars and starches. At night, they use these to maintain life and growth. But how do they pace their consumption so they don't run out before dawn?

Plant biologists in the U.K. have developed a model of the process. It's like a math problem: amount of stored starch divided by the number of hours of darkness equals consumption rate.

The model seems to match what they're finding in the lab. When they make the night artificially shorter or longer? Each change triggers a different "calculation." Short night ahead? Plants use starch more rapidly. Long night ahead? Use it more slowly.

The plants aren’t really doing division of course . . . the key is likely a biological clock, which helps them estimate the time til dawn. The biologists are calling it "molecular math."
END"
What do Y'all think?

 

Thank you Homesteater!
Interesting for sure...a bit over my head though, but I have it book marked for reference!
Thanks again!