Abstract
Mature `Picual' olive ( Olea europaea L.) trees growing in two different localities of Córdoba and Jaén provinces, southern Spain, were subjected to annual applications of 0, 0.12, 0.25, 0.50, or 1.0 kg N/tree in the Cordoba's experiment, and to 0 or 1.5 kg N/tree in the Jaén's experiment. Nitrogen was applied 50% to the soil and 50% through foliar application in Córdoba, and 100% to the soil in Jaén. Three years after the initiation of treatments, when the trees showed differences among them in nitrogen content, fruit were sampled at maturity from each experimental tree during six consecutive seasons to determine the effect of nitrogen fertilization on olive oil quality. Tree nitrogen status was always above the threshold limit for deficiency even in control trees, indicating that most treatments caused nitrogen over fertilization. Nitrogen in excess was accumulated in fruit and, consequently, polyphenol content, the main natural antioxidants, significantly decreased in olive oil as nitrogen increased in fruit. The decrease in polyphenols induced a significant decrease in the oxidative stability of the oil and its bitterness. Tocopherol content, on the contrary, increased with nitrogen application, mainly by an increase in α-tocopherol, the main component in the olive oil. No effect was found on pigment content, particularly carotenoid and chlorophyllic pigments, neither on fatty acid composition.
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Claims 8
Claim · model-written summary
Even control olive trees exceeded the threshold for nitrogen deficiency.
- Taxon
- olive
Olea europaeat0 - Outcome
- Tree nitrogen statuse0
- Direction
- abovee0
- Comparator
- threshold limit for deficiencye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tree nitrogen status was always above the threshold limit for deficiency even in control trees”
t0“Olive Oil Quality Decreases with Nitrogen Over-fertilization”
Claim · model-written summary
Excess nitrogen accumulated in olive fruit.
- Taxon
- oliveOlea europaeat0
- Organ / stage
- fruite0
- Outcome
- Nitrogen in excesse0
- Direction
- accumulatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen in excess was accumulated in fruit”
t0“Olive Oil Quality Decreases with Nitrogen Over-fertilization”
Claim · model-written summary
Olive oil polyphenol content decreased significantly as fruit nitrogen increased.
- Taxon
- oliveOlea europaeat0
- Organ / stage
- fruite0
- Compound
- nitrogene0
- Outcome
- polyphenol contente0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“polyphenol content, the main natural antioxidants, significantly decreased in olive oil as nitrogen increased in fruit.”
t0“Olive Oil Quality Decreases with Nitrogen Over-fertilization”
Claim · model-written summary
Lower polyphenols caused lower olive oil oxidative stability.
- Taxon
- oliveOlea europaeat0
- Compound
- polyphenolse0
- Outcome
- oxidative stability of the oile0
- Qualifier
- decrease in polyphenolse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The decrease in polyphenols induced a significant decrease in the oxidative stability of the oil and its bitterness.”
t0“Olive Oil Quality Decreases with Nitrogen Over-fertilization”
Claim · model-written summary
Lower polyphenols caused lower olive oil bitterness.
- Taxon
- oliveOlea europaeat0
- Compound
- polyphenolse0
- Outcome
- bitternesse0
- Qualifier
- decrease in polyphenolse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The decrease in polyphenols induced a significant decrease in the oxidative stability of the oil and its bitterness.”
t0“Olive Oil Quality Decreases with Nitrogen Over-fertilization”
Claim · model-written summary
Nitrogen application raised olive oil tocopherol content, mainly alpha-tocopherol.
- Taxon
- oliveOlea europaeat0
- Treatment
- nitrogen applicatione0
- Outcome
- Tocopherol contente0
- Direction
- increasede0
- Qualifier
- mainly by an increase in α-tocopherole0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tocopherol content, on the contrary, increased with nitrogen application, mainly by an increase in α-tocopherol, the main component in the olive oil.”
t0“Olive Oil Quality Decreases with Nitrogen Over-fertilization”
Claim · model-written summary
Nitrogen application did not affect olive oil pigment content.
- Taxon
- oliveOlea europaeat0
- Treatment
- Nitrogen Over-fertilizationt0
- Outcome
- pigment contente0
- Direction
- No effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No effect was found on pigment content, particularly carotenoid and chlorophyllic pigments, neither on fatty acid composition.”
t0“Olive Oil Quality Decreases with Nitrogen Over-fertilization”
Claim · model-written summary
Nitrogen application did not affect olive oil fatty acid composition.
- Taxon
- oliveOlea europaeat0
- Treatment
- Nitrogen Over-fertilizationt0
- Outcome
- fatty acid compositione0
- Direction
- No effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No effect was found on pigment content, particularly carotenoid and chlorophyllic pigments, neither on fatty acid composition.”
t0“Olive Oil Quality Decreases with Nitrogen Over-fertilization”
The same questions in other papers
nitrogen · physiology: pigments · Olea europaea (common olive)Positive and negative results
1 in the opposite direction
- positive
nitrogen · quality: oil · Olea europaea (common olive)Positive and negative results
1 paper in the same direction as this paper · 4 in the opposite direction
- positive
- no effect
- positive
2 papers more in this group
See all 6 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.