Abstract
Abstract An experiment was conducted to find out how humic substances affected nutrient uptake of plants. The test plants, oregano, thyme, and basil, were grown in nutrient film technique at two pH levels (4.5 and 6.5), in two substrates (peat and perlite), and at three levels of humic substance that was a peat extract (control, low, and high concentration). Nutrient uptake of potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined by elemental contents in aerial parts of the plant and its weight. Humic substance had no effect on K, Ca, and Mg uptake but lowered the uptake of Fe, Mn, Zn, and Cu for the three test plants, more pronounced with perlite than peat and more at low pH than at high pH. The lowering of the uptake might be caused by complexation of Fe, Mn, Zn, and Cu by the humic substance and the lower availability of these metals in complexed form than as a cation or as EDTA‐chelate in the case of Fe. It is not clear why the effect of the humic substance on micro‐element uptake is larger at low than at high pH. The complexation is expected to be stronger at pH 6.5 than at pH 4.5. At low pH, the high concentration of humic substance caused a low fresh weight of the shoots, perhaps caused by a toxicity of the humic substance at low pH. This was less pronounced at high pH.
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Claims 9
Claim · model-written summary
oregano showed no change in K, Ca, and Mg uptake with humic substance.
- Taxon
- oregano
Origanum vulgaree0 - Treatment
- Humic substancee1
- Outcome
- K, Ca, and Mg uptakee1
- Direction
- no effecte1
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The test plants, oregano, thyme, and basil, were grown in nutrient film technique at two pH levels (4.5 and 6.5), in two substrates (peat and perlite), and at three levels of humic substance that was a peat extract (control, low, and high concentration)”
e1“Humic substance had no effect on K, Ca, and Mg uptake but lowered the uptake of Fe, Mn, Zn, and Cu for the three test plants, more pronounced with perlite than peat and more at low pH than at high pH”
Claim · model-written summary
thyme showed no change in K, Ca, and Mg uptake with humic substance.
- Taxon
- thyme
.JPG?width=60)
Thymus vulgarise0 - Treatment
- Humic substancee1
- Outcome
- K, Ca, and Mg uptakee1
- Direction
- no effecte1
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.JPG?width=500)
Verbatim
e0“The test plants, oregano, thyme, and basil, were grown in nutrient film technique at two pH levels (4.5 and 6.5), in two substrates (peat and perlite), and at three levels of humic substance that was a peat extract (control, low, and high concentration)”
e1“Humic substance had no effect on K, Ca, and Mg uptake but lowered the uptake of Fe, Mn, Zn, and Cu for the three test plants, more pronounced with perlite than peat and more at low pH than at high pH”
Claim · model-written summary
basil showed no change in K, Ca, and Mg uptake with humic substance.
- Taxon
- basil
Ocimum basilicume0 - Treatment
- Humic substancee1
- Outcome
- K, Ca, and Mg uptakee1
- Direction
- no effecte1
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The test plants, oregano, thyme, and basil, were grown in nutrient film technique at two pH levels (4.5 and 6.5), in two substrates (peat and perlite), and at three levels of humic substance that was a peat extract (control, low, and high concentration)”
e1“Humic substance had no effect on K, Ca, and Mg uptake but lowered the uptake of Fe, Mn, Zn, and Cu for the three test plants, more pronounced with perlite than peat and more at low pH than at high pH”
Claim · model-written summary
oregano had reduced Fe, Mn, Zn, and Cu uptake with humic substance, especially with perlite and low pH.
- Taxon
- oreganoOriganum vulgaree0
- Treatment
- Humic substancee1
- Outcome
- uptake of Fe, Mn, Zn, and Cue1
- Direction
- lowerede1
- Qualifier
- more pronounced with perlite than peat and more at low pH than at high pHe1
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The test plants, oregano, thyme, and basil, were grown in nutrient film technique at two pH levels (4.5 and 6.5), in two substrates (peat and perlite), and at three levels of humic substance that was a peat extract (control, low, and high concentration)”
e1“Humic substance had no effect on K, Ca, and Mg uptake but lowered the uptake of Fe, Mn, Zn, and Cu for the three test plants, more pronounced with perlite than peat and more at low pH than at high pH”
Claim · model-written summary
thyme had reduced Fe, Mn, Zn, and Cu uptake with humic substance, especially with perlite and low pH.
- Taxon
- thymeThymus vulgarise0
- Treatment
- Humic substancee1
- Outcome
- uptake of Fe, Mn, Zn, and Cue1
- Direction
- lowerede1
- Qualifier
- more pronounced with perlite than peat and more at low pH than at high pHe1
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The test plants, oregano, thyme, and basil, were grown in nutrient film technique at two pH levels (4.5 and 6.5), in two substrates (peat and perlite), and at three levels of humic substance that was a peat extract (control, low, and high concentration)”
e1“Humic substance had no effect on K, Ca, and Mg uptake but lowered the uptake of Fe, Mn, Zn, and Cu for the three test plants, more pronounced with perlite than peat and more at low pH than at high pH”
Claim · model-written summary
basil had reduced Fe, Mn, Zn, and Cu uptake with humic substance, especially with perlite and low pH.
- Taxon
- basilOcimum basilicume0
- Treatment
- Humic substancee1
- Outcome
- uptake of Fe, Mn, Zn, and Cue1
- Direction
- lowerede1
- Qualifier
- more pronounced with perlite than peat and more at low pH than at high pHe1
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The test plants, oregano, thyme, and basil, were grown in nutrient film technique at two pH levels (4.5 and 6.5), in two substrates (peat and perlite), and at three levels of humic substance that was a peat extract (control, low, and high concentration)”
e1“Humic substance had no effect on K, Ca, and Mg uptake but lowered the uptake of Fe, Mn, Zn, and Cu for the three test plants, more pronounced with perlite than peat and more at low pH than at high pH”
Claim · model-written summary
Humic substance may lower micronutrient uptake through metal complexation and reduced availability.
- Taxon
- oregano, thyme, and basilOcimum basilicumOriganum vulgareThymus vulgarise1
- Compound
- Fe, Mn, Zn, and Cue0
- Outcome
- lowering of the uptakee0
- Qualifier
- might be caused by complexatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The lowering of the uptake might be caused by complexation of Fe, Mn, Zn, and Cu by the humic substance and the lower availability of these metals in complexed form than as a cation or as EDTA‐chelate in the case of Fe”
e1“oregano, thyme, and basil”
Claim · model-written summary
At low pH, high humic substance concentration caused low shoot fresh weight.
- Taxon
- oregano, thyme, and basilOcimum basilicumOriganum vulgareThymus vulgarise1
- Organ / stage
- shootse0
- Treatment
- high concentration of humic substancee0
- Outcome
- fresh weight of the shootse0
- Direction
- lowe0
- Qualifier
- At low pHe0
- Comparator
- controle2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At low pH, the high concentration of humic substance caused a low fresh weight of the shoots, perhaps caused by a toxicity of the humic substance at low pH”
e1“oregano, thyme, and basil”
e2“three levels of humic substance that was a peat extract (control, low, and high concentration)”
Claim · model-written summary
The reduction in shoot fresh weight at high humic substance concentration was less pronounced at high pH.
- Taxon
- oregano, thyme, and basilOcimum basilicumOriganum vulgareThymus vulgarise2
- Outcome
- fresh weight of the shootse1
- Direction
- less pronouncede0
- Qualifier
- high pHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This was less pronounced at high pH”
e1“At low pH, the high concentration of humic substance caused a low fresh weight of the shoots”
e2“oregano, thyme, and basil”
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