The photosynthesis of aquatic plants, we can almost see its breathing

 

What is DLI?

Daily Light Integral (DLI) is the total number of photosynthetically active radiation (PAR) photons (traditionally those between 400-700 nm) incident on an area over the course of a day

 

DLI: is the PPFD throughout the day. It is measured in moles/sq. meter/day, or mol/m2/day

 

DLI calculation method: average PPFD（μmol/m²/s) * illumination time (s) / 1000000

 

For example: PPFD=700μmol/m²/s, light time is 12 hours (3600 seconds per hour)

Daily light integral DLI=700x12x3600/1000000=30.24mol/m²/day

 

*1,000,000 μmols = 1 Mol of light

 

 

What is PAR (photosynthetically available radiation)?

Photosynthetically active radiation (PAR) is the range of light wavelengths that enables photosynthesis in plants. The actual range is from 400 to 700nm. It basically coincides with the visible spectral range of the human eye

 

Photosynthetically active radiation spectrum (PAR)

 

In fact, the wavelength range of the light source to promote plant growth is wider than the wavelength range of photosynthetically available radiation(PAR),

which is roughly in the range of 300nm to 800nm. This part of the radiation is called physiological radiation. In addition to promoting photosynthesis, it also affects other physiological activities of plants.

 

For example:

UVA radiation is important in inducing production of phenolics, anthocyanins (coloration), antioxidants and vitamins that inhibit mold growth.

UV-A 385nm-400nm has been shown to increase THC, CBD, and terpene production in cannabis plants.

FR730nm can stretch plants, fully grow stems, adjust node spacing, promote flowering, and higher yields

 

 

What is PPF？

Photosynthetic Photon Flux (PPF). The total light emitted by the light source per second (photons in the PAR spectral range). PPF tells us how much PAR is emitted by a light source. Measured in “micromoles per second” and expressed as μmol/s.

 

 

What is PPFD?

Photosynthetic photon flux density (PPFD) is defined as the photon flux density of PAR.

PPFD is the amount of light photons that hit a surface (your plant canopy) in one second. It’s measured in units called micromoles (μmols).  it’s the strength of the light that reaches your plants.

The light loses strength as it travels from source to endpoint (from grow light to plant). You’ll notice on grow light intensity charts, the PPFD numbers decrease with increased distance from the light.

 

What is the light compensation point (LCP)?

The (light) compensation point is the light intensity on the light curve where the rate of photosynthesis exactly matches the rate of cellular respiration. At this point, the uptake of CO2 through photosynthetic pathways is equal to the respiratory release of carbon dioxide, and the uptake of O2 by respiration is equal to the photosynthetic release of oxygen.

Light Compensation Point(LCP):

The Light Compensation Point, whose unit is µmol/m²/s, is the amount of light intensity on the light curve where the rate of photosynthesis exactly matches the rate of respiration.

 

 

What is the light saturation point(LSP)?

More light usually equates to a higher level of photosynthesis. However, as the light intensity increases, the photosynthesis rate will eventually reach its maximum. The point where the light intensity does not increase the rate of photosynthesis is called the light saturation point.

Light Saturation Point(LSP):

In a certain intensity range, plant photosynthetic rate increased with increasing light intensity. When light intensity increases to a certain value, the photosynthetic rate of illumination did not further increase, where the point is called Light Saturation Point of PPFD.

 

Illumination requirements of several plants: photosynthetic photon flux density PPFD, daily light integral DLI, light compensation point LCP and light saturation point LSP

 

Recommended Daily Light Integral (DLI) for some Cultivated crops

 

Illumination requirements of several plants: photosynthetic photon flux density PPFD, daily light integral DLI, light compensation point LCP and light saturation point LSP

Recommended Daily Light Integral (DLI) for some cultivated plants

 

Coriander, Chives, Cilantro, Honey Dew, Kale, Lavender, Strawberry, Leafy Greens, Lemon Balm, Lavender, Mint, Oregano, Parsley, Pea, Pumpkin, Rosemary, Spearmint, Spinach, Swiss Chard, Thyme, Watercress, Watermelon, Zucchini, and other crops light requirements, PPFD, DLI, PAR, PPF, LCP, LSP.