Abstract
Despite decades of research, the effects of spectral quality on plant growth, and development are not well understood. Much of our current understanding comes from studies with daily integrated light levels that are less than 10% of summer sunlight thus making it difficult to characterize interactions between light quality and quantity. Several studies have reported that growth is increased under fluorescent lamps compared to mixtures of wavelengths from LEDs. Conclusions regarding the effect of green light fraction range from detrimental to beneficial. Here we report the effects of eight blue and green light fractions at two photosynthetic photon fluxes (PPF; 200 and 500 μmol m-2 s-1; with a daily light integral of 11.5 and 29 mol m-2 d-1) on growth (dry mass), leaf expansion, stem and petiole elongation, and whole-plant net assimilation of seven diverse plant species. The treatments included cool, neutral, and warm white LEDs, and combinations of blue, green and/or red LEDs. At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively, but there was no statistically significant effect on radish, soybean, lettuce or wheat. At the lower PPF (200), increasing blue light reduced growth only in tomato (41%). The effects of blue light on growth were mediated by changes in leaf area and radiation capture, with minimal effects on whole-plant net-assimilation. In contrast to the significant effects of blue light, increasing green light in increments from 0 to 30% had a relatively small effect on growth, leaf area and net assimilation at either low or high PPF. Surprisingly, growth of three of the seven species was not reduced by a treatment with 93% green light compared to the broad spectrum treatments. Collectively, these results are consistent with a shade avoidance response associated with either low blue or high green light fractions.
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Claims 13
Claim · model-written summary
At PPF 500, increasing blue light from 11 to 28% reduced tomato growth by 22%.
- Taxon
- tomato
Solanum lycopersicume1 - Treatment
- increasing blue light in increments from 11 to 28%e1
- Outcome
- growthe1
- Direction
- reducede1
- Value
- 22e1
- Qualifier
- higher PPF (500)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively”
Claim · model-written summary
At PPF 500, increasing blue light from 11 to 28% reduced cucumber growth by 26%.
- Taxon
- cucumber
Cucumis sativuse1 - Treatment
- increasing blue light in increments from 11 to 28%e1
- Outcome
- growthe1
- Direction
- reducede1
- Value
- 26e1
- Qualifier
- higher PPF (500)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively”
Claim · model-written summary
At PPF 500, increasing blue light from 11 to 28% reduced pepper growth by 14%.
- Taxon
- peppere1
- Treatment
- increasing blue light in increments from 11 to 28%e1
- Outcome
- growthe1
- Direction
- reducede1
- Value
- 14%e1
- Qualifier
- higher PPF (500)e1
Not reportedComparator
Verbatim
e1“At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively”
Claim · model-written summary
At PPF 500, increasing blue light had no statistically significant effect on radish growth.
- Taxon
- radish
Raphanus sativuse2 - Treatment
- increasing blue light in increments from 11 to 28%e1
- Outcome
- growthe1
- Direction
- no statistically significant effecte2
- Qualifier
- higher PPF (500)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively”
e2“but there was no statistically significant effect on radish, soybean, lettuce or wheat”
Claim · model-written summary
At PPF 500, increasing blue light had no statistically significant effect on soybean growth.
- Taxon
- soybean
Glycine maxe2 - Treatment
- increasing blue light in increments from 11 to 28%e1
- Outcome
- growthe1
- Direction
- no statistically significant effecte2
- Qualifier
- higher PPF (500)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively”
e2“but there was no statistically significant effect on radish, soybean, lettuce or wheat”
Claim · model-written summary
At PPF 500, increasing blue light had no statistically significant effect on lettuce growth.
- Taxon
- lettuce
Lactuca sativae2 - Treatment
- increasing blue light in increments from 11 to 28%e1
- Outcome
- growthe1
- Direction
- no statistically significant effecte2
- Qualifier
- higher PPF (500)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively”
e2“but there was no statistically significant effect on radish, soybean, lettuce or wheat”
Claim · model-written summary
At PPF 500, increasing blue light had no statistically significant effect on wheat growth.
- Taxon
- wheat
Triticum aestivume2 - Treatment
- increasing blue light in increments from 11 to 28%e1
- Outcome
- growthe1
- Direction
- no statistically significant effecte2
- Qualifier
- higher PPF (500)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively”
e2“but there was no statistically significant effect on radish, soybean, lettuce or wheat”
Claim · model-written summary
At PPF 200, increasing blue light reduced tomato growth by 41%; no other species responded.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- increasing blue lighte1
- Outcome
- growthe1
- Direction
- reducede1
- Value
- 41%e1
- Qualifier
- lower PPF (200)e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At the lower PPF (200), increasing blue light reduced growth only in tomato (41%)”
Claim · model-written summary
Increasing green light from 0 to 30% had a relatively small effect on growth, leaf area and net assimilation at low or high PPF.
Verbatim
e1“increasing green light in increments from 0 to 30% had a relatively small effect on growth, leaf area and net assimilation at either low or high PPF”
e2“whole-plant net assimilation of seven diverse plant species”
Claim · model-written summary
Growth of three of the seven species was not reduced by 93% green light compared with broad spectrum treatments.
Verbatim
e1“Surprisingly, growth of three of the seven species was not reduced by a treatment with 93% green light compared to the broad spectrum treatments”
Claim · model-written summary
The effects of blue light on growth were mediated by changes in leaf area and radiation capture.
Verbatim
e1“The effects of blue light on growth were mediated by changes in leaf area and radiation capture, with minimal effects on whole-plant net-assimilation”
e2“whole-plant net assimilation of seven diverse plant species”
Claim · model-written summary
Blue light had minimal effects on whole-plant net assimilation.
Verbatim
e1“The effects of blue light on growth were mediated by changes in leaf area and radiation capture, with minimal effects on whole-plant net-assimilation”
e2“whole-plant net assimilation of seven diverse plant species”
Claim · model-written summary
Responses to low blue or high green light are consistent with a shade avoidance response.
Verbatim
e1“Collectively, these results are consistent with a shade avoidance response associated with either low blue or high green light fractions”
e2“whole-plant net assimilation of seven diverse plant species”
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See all 300 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.