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Hi sorry to bother you, I am contacting you after reading this article on your site:

click here

I was hoping that you would able to answer a few quick questions I have about a project I am thinking about doing for the BT young scientist.

1) Do different spectra of light effect the growth of plants differently? (Ignoring green)

2) Do specific combinations of light i.e. red, yellow and blue of an equal intensity to solar light effect plants' growth?

3)Does the effectiveness of the light on photosynthesis vary throughout the day? If so do different spectra affect this?

The above questions are to aid in setting a baseline for experiments, as I haven't been able to find any definitive proof online.

Thank you for your time,
Answer 1:

1) Do different spectra of light effect the growth of plants differently? (Ignoring green) Higher-energy light, toward the blue-violet end of the spectrum would potentially give plants more energy, but different plants have different pigments for capturing the light. Also, as the answer you read mentioned, light in the red end of the spectrum may be a cue to flower.

There’s a good article on this at:
what light do plants need

2) Do specific combinations of light i.e. red, yellow and blue of an equal intensity to solar light effect plants' growth? I’m not sure what you’re asking. Are you thinking that blocking some wavelengths decreases the total amount of light, and boosting the intensity of other wavelengths to compensate? That would be good scientific thinking. Different combinations of light would be interesting to test.

3) Does the effectiveness of the light on photosynthesis vary throughout the day? If so do different spectra affect this? Are you asking about whether the plant’s response changes throughout the day, or whether changes in the angle of the sun influences the amount of light available to the plant? If you are asking about the plant, plants that evolved in dry places usually close their stomata (leaf holes) when they get too dry. This keeps reduces the amount of water that evaporates, but keeps them from letting in the CO2 they need for photosynthesis.

If you are asking about the angle of the sun, the intensity will be highest around noon.

The above questions are to aid in setting a baseline for experiments, as I haven't been able to find any definitive proof online. Just a reminder, we can never prove our hypothesis is true. We can only support it. I hope this helps.

Good luck with your experiments.


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