Abstract
Excessive nitrogen fertilization results in nitrate accumulation in leafy vegetables. Reducing the dose of mineral nitrogen or using alternate fertilizers lowers the nitrate accumulation; however, a critical minimum level of mineral nitrogen is necessary to maintain yield and nutritional quality. The aim of this study was to evaluate the effect of two levels of mineral nitrogen (100% and 50%) and three levels of an amino acid solution (0, 0.3, and 0.9%) in the nutrient solution of two baby lettuce cultivars (green and red) grown in a floating system. Nitrogen reduction did not affect yield (12.9–13.4 and 11.0–11.3 g/plant, respectively) but reduced nitrate accumulation (by 43 and 19%, respectively) in both green and red lettuce, while enhancing phenolic content (by 28%) and antioxidant capacity (by 69%) in green lettuce and soluble solid (by 7%) and total chlorophyll content (by 9%) in red lettuce. Although nitrate accumulation was prevented (< 355 mg/kg FW) and most nutritional components increased in both lettuce types by amino acids supplementation, plant growth was negatively affected, especially in red lettuce, in both concentrations of amino acids (reduction by 9 and 35% in 0.3 and 0.9%, respectively). In both lettuce types, proline content increased by 0.9% amino acids supplementation (by 45%), implying a probable induction of a stress condition. Mineral nutrients were slightly affected by nitrogen reduction, which was probably perceived as an abiotic stress.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 13
Claim · model-written summary
Nitrogen reduction did not affect green or red lettuce yield.
- Treatment
- Nitrogen reductione0
- Outcome
- yielde0
- Direction
- did not affecte0
- Value
- 12.9–13.4 and 11.0–11.3 g/plante0
Not reportedTaxonComparator
Verbatim
e0“Nitrogen reduction did not affect yield (12.9–13.4 and 11.0–11.3 g/plant, respectively)”
Claim · model-written summary
Nitrogen reduction lowered nitrate accumulation in green lettuce by 43%.
Not reportedTreatmentComparator
Verbatim
e0“reduced nitrate accumulation (by 43 and 19%, respectively) in both green and red lettuce”
Claim · model-written summary
Nitrogen reduction lowered nitrate accumulation in red lettuce by 19%.
Not reportedTreatmentComparator
Verbatim
e0“reduced nitrate accumulation (by 43 and 19%, respectively) in both green and red lettuce”
Claim · model-written summary
Nitrogen reduction raised green lettuce phenolic content by 28%.
Not reportedTreatmentComparator
Verbatim
e0“enhancing phenolic content (by 28%) and antioxidant capacity (by 69%) in green lettuce”
Claim · model-written summary
Nitrogen reduction raised green lettuce antioxidant capacity by 69%.
Not reportedTreatmentComparator
Verbatim
e0“enhancing phenolic content (by 28%) and antioxidant capacity (by 69%) in green lettuce”
Claim · model-written summary
Nitrogen reduction raised red lettuce soluble solids by 7%.
Not reportedTreatmentComparatorDirection
Verbatim
e0“soluble solid (by 7%) and total chlorophyll content (by 9%) in red lettuce”
Claim · model-written summary
Nitrogen reduction raised red lettuce chlorophyll by 9%.
Not reportedTreatmentComparatorDirection
Verbatim
e0“soluble solid (by 7%) and total chlorophyll content (by 9%) in red lettuce”
Claim · model-written summary
Amino acid supplementation prevented nitrate accumulation and increased most nutritional components.
- Taxon
- lettuce
Lactuca sativae0 - Treatment
- amino acids supplementatione0
- Outcome
- nitrate accumulatione0
- Direction
- preventede0
- Value
- < 355 mg/kg FWe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate accumulation was prevented (< 355 mg/kg FW) and most nutritional components increased in both lettuce types by amino acids supplementation”
Claim · model-written summary
Amino acid supplementation increased most nutritional components in both lettuce types.
- Taxon
- lettuceLactuca sativae0
- Treatment
- amino acids supplementatione0
- Outcome
- most nutritional componentse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“most nutritional components increased in both lettuce types by amino acids supplementation”
Claim · model-written summary
Amino acids at 0.3% lowered red lettuce growth by 9%.
Not reportedComparator
Verbatim
e0“plant growth was negatively affected, especially in red lettuce, in both concentrations of amino acids (reduction by 9 and 35% in 0.3 and 0.9%, respectively)”
Claim · model-written summary
Amino acids at 0.9% lowered red lettuce growth by 35%.
Not reportedComparator
Verbatim
e0“plant growth was negatively affected, especially in red lettuce, in both concentrations of amino acids (reduction by 9 and 35% in 0.3 and 0.9%, respectively)”
Claim · model-written summary
Amino acids at 0.9% increased proline content by 45% in both lettuce types.
- Taxon
- lettuceLactuca sativae0
- Treatment
- 0.9% amino acids supplementatione0
- Outcome
- proline contente0
- Direction
- increasede0
- Value
- 45%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both lettuce types, proline content increased by 0.9% amino acids supplementation (by 45%)”
Claim · model-written summary
Nitrogen reduction slightly affected mineral nutrients.
Not reportedTaxonComparatorDirection
Verbatim
e0“Mineral nutrients were slightly affected by nitrogen reduction”
The same questions in other papers
nitrogen · yield · Lactuca sativa (garden lettuce)Positive and negative results
17 papers in the same direction as this paper · 61 in the opposite direction
- positive
- positive
- positive
75 papers more in this group
See all 79 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.