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Light Duration (Photoperiod)

Light Duration (Photoperiod)

Plant Science Topics:

 

-Short-day crops

-Long-day crops

-Extending photoperiods in greenhouse with supplemental light

-How light color (quality) can impact photoperiod responses

-How light intensity (quantity) can impact photoperiod responses

 

Recommendations to Apply the Science:

 

-Using timers to control photoperiod

-Night interruption strategies

-Photoperiod manipulation

-Sunrise and sunset settings on Phantoms

 

Product References:

 

-Various Timers (Digital & Analog)

-Autopilot PX1

-Active Eye Green LED Flashlight

-Active Eye Green Work Light

-Active Eye Green Cap Light

-powerPAR Red LED

-Solar System Controller

-Solar System 550

 

Science

 

-Intro. Photoperiod, define. And brief talk about nuances of light quality and light quantity.

-Define short day, and long day. Obligate vs not obligate. Vs stress flowering.

-Difference of practical application in greenhouse vs indoors

-Additional factors. Light quality.

-Practical applications for night work lights, or extending photoperiod range with simulated sunrise/sunset functions.

 

Episode 2, Photoperiod

 

The first of the Three fundamental factors in horticultural lighting: photoperiod,

 

Duration of light

 

Review:

 

-Long-day crops

-Short-day crops

 

By controlling when a plant flowers you can increase plant size before flower. In cornell study in 2008, researchers observed a significant difference in flower bud size between sunrich orange sunflower plants that were immediately exposed to short days to stimulate flowering or those that had flowering delayed by starting with long days. This initial burst helped the plants gain more energy, get more established before flowering.

 

Some plants like spinach, a grower might never want it to flower, by keeping them

Spinach (some types) critical day length: 13 hrs.

 

How can a grower practically use photoperiod manipulation

 

-In a greenhouse can control with block out curtains

-Extending photoperiods in greenhouse with supplemental light

A variety of lighting options for interrupting the dark cycle, that can low intensity lights like incadescent, Compact fluorescents or can be high intensity option that can not only distrupt the night cycle, but also provide energy for photosynthesis to improve crop growth. This is often powerful high bay LEDs or high pressure sodium lights like these 1000W double ended HPS lights.

 

-Indoors it is much easier to control. Analog timers, digital timers and light controllers are all options. Some lighting controllers give the option of Sunrise/sunset simulation settings, like this PX1 which can ramp-up and down at both ends of your photoperiod, many growers use this strategy to flower short day plants with 13 or more hours. Plants that use to be flowered at 12, are being flowered with longer photoperiods using this sunrise/sunset simulation setting, providing more light to the plants for growth while keeping plants flowering.

Programmable LED lights with spectrum control light this SolarSystem 550 can not only similate sunrise/sunset by ramping up and down intensity, it can also manipulate spectrum to simulate the natural change in spectrum seen during sunrise and sunset. Sunsets have a spectrum shifted towards red and far red. In Episode 6 & 7 we’ll look at how that affects plant physiology.

 

Photoperiodic responses are greatly affected by spectrum or the color of light, which in the horticultural world is traditionally called light quality. Light quality is the second fundamental factor of horticultural lighting which we cover in depth in the following episodes. Some colors create a strong photoperiodic response while others may induce little to no photoperiodic response in a crop. And there is one other factor that can affect photoperiodic responses, the light intensity of the specific colors. Low intensity green might not induce a photoperiodic response, but high intensity might… join me in the next episode of Plants & Light as we begin our journey through the light spectrum, traveling through the rainbow of colors. I’m Farmer Tyler, and the more your know, the better you grow.














 

Episode 2 - Plants and Light: Photoperiod

 

Plant Science Topics:

 

-Short-day crops

-Long-day crops

-Extending photoperiods in greenhouse with supplemental light

-How light color (quality) can impact photoperiod responses

-How light intensity (quantity) can impact photoperiod responses

 

Recommendations to Apply the Science:

 

-Using timers to control photoperiod

-Night interruption strategies

-Photoperiod manipulation

-Sunrise and sunset settings on Phantoms

 

Product References:

 

-Various Timers (Digital & Analog)

-Autopilot PX1

-Active Eye Green LED Flashlight

-Active Eye Green Work Light

-Active Eye Green Cap Light

-powerPAR Red LED

-Solar System Controller

-Solar System 550

 

Video Production Direction:

-Tyler in front of white screen with graphics popping up

-Tyler in greenhouse

-Cutting between Tyler giving info on white screen, greenhouse, and white screen with graphics

-Tyler pointing/physicalizing.

-Side-by-side timelapse showing short day crops with and without night interruption

-Show Autopilot PX1 controller’s ability to simulate sunrise and sunset

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