Abstract
The mechanism by which humic substances stimulate plant biological activities is not clear. To study effects of humic acid on N metabolism and growth of lettuce (Lactuca sativa L.) a hydroponic experiment was conducted under greenhouse conditions. Humic acid (HA) at 0, 100, or 1000 mg·L−1 was added with a nutrient solution to plants. HA accelerated uptake of N and NO3 and accelerated N metabolism by enhancing nitrate reductase activity, which resulted in production of protein. HA did not affect P absorption and proline content of leaves. The photosynthetic activity of lettuce increased with all levels of HA due to enhancement of chlorophyll content and mesophyll conductance. HA can stimulate N metabolism and photosynthesis activity of lettuce to improve yield.
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Claims 8
Claim · model-written summary
Humic acid accelerated lettuce uptake of N and NO3.
- Taxon
- lettuce
Lactuca sativae0 - Treatment
- HAe1
- Outcome
- uptake of N and NO3e1
- Direction
- acceleratede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lettuce (Lactuca sativa L.)”
e1“HA accelerated uptake of N and NO3”
Claim · model-written summary
Humic acid enhanced nitrate reductase activity in lettuce.
- Taxon
- lettuceLactuca sativae0
- Treatment
- HAe1
- Gene
- nitrate reductasee1
- Outcome
- nitrate reductase activitye1
- Direction
- enhancinge1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lettuce (Lactuca sativa L.)”
e1“accelerated N metabolism by enhancing nitrate reductase activity”
Claim · model-written summary
Humic acid promoted protein production in lettuce.
- Taxon
- lettuceLactuca sativae0
- Treatment
- HAe2
- Outcome
- production of proteine1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lettuce (Lactuca sativa L.)”
e1“which resulted in production of protein”
e2“HA accelerated uptake of N and NO3”
Claim · model-written summary
Humic acid did not affect lettuce P absorption.
- Taxon
- lettuceLactuca sativae0
- Treatment
- HAe1
- Outcome
- P absorptione1
- Direction
- did not affecte1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lettuce (Lactuca sativa L.)”
e1“HA did not affect P absorption and proline content of leaves.”
Claim · model-written summary
Humic acid did not affect proline content of lettuce leaves.
- Taxon
- lettuceLactuca sativae0
- Organ / stage
- leavese1
- Treatment
- HAe1
- Outcome
- proline content of leavese1
- Direction
- did not affecte1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lettuce (Lactuca sativa L.)”
e1“HA did not affect P absorption and proline content of leaves.”
Claim · model-written summary
All humic acid levels increased lettuce photosynthetic activity.
- Taxon
- lettuceLactuca sativae0
- Treatment
- HAe0
- Outcome
- photosynthetic activitye0
- Direction
- increasede0
- Qualifier
- all levelse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The photosynthetic activity of lettuce increased with all levels of HA”
Claim · model-written summary
Humic acid enhanced lettuce chlorophyll content and mesophyll conductance.
- Taxon
- lettuceLactuca sativae0
- Treatment
- humic acide2
- Outcome
- chlorophyll content and mesophyll conductancee1
- Direction
- enhancemente1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lettuce (Lactuca sativa L.)”
e1“due to enhancement of chlorophyll content and mesophyll conductance”
e2“To study effects of humic acid on N metabolism and growth of lettuce”
Claim · model-written summary
The authors concluded humic acid improves lettuce yield through stimulation of nitrogen metabolism and photosynthesis.
- Taxon
- lettuceLactuca sativae0
- Treatment
- HAe0
- Outcome
- yielde0
- Qualifier
- N metabolism and photosynthesis activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“HA can stimulate N metabolism and photosynthesis activity of lettuce to improve yield.”
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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.