Abstract
(pp. 9–16) Nitrate is a major form of uptake and storage of nitrogen for upland plants. However, nitrate is harmful to human health · ingestion of a large quantity can lead to cancer or methemoglobinemia. The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study. Fertilizer application can be controlled effectively by drip fertigation. Field experiments were conducted in September 2002 and June 2003 at the National Agricultural Research Center for Hokkaido Region. Two spinach cultivars were grown in each cultivation in a plastic greenhouse, and the plants were treated with 4, 8 or 12 g N m−2 of fertilizer applied by drip fertigation, and with 8, 12 or 16 g N m−2 of fertilizer applied as basal application. The nitrogen was applied at the rate of 0.15 g m−2 per day for the first 15 days, and 0.25 g m−2 for the following 23 days in 8 g N m−2 treatment of drip fertigation. The rate of growth and nitrogen absorption of spinach in the early growth stages was very slow, but they increased quickly from around day 23 after sowing. The amount of nitrogen absorbed by spinach was close to the amount applied in 8 g N m−2 treatment. This treatment resulted in spinach with a low nitrate concentration without reduction in yield. Although the same results were obtained by treatment with 8 g N m−2 of fertilizer by basal application, there was a tendency for nitrate concentration to fall further with drip fertigation. The rate of nitrate-nitrogen to total-nitrogen rose sharply when the total-nitrogen concentration was higher than 42 g kg−1 DW in leaf blade and 18 g kg−1 DW in leaf petiole. The total-nitrogen concentration was lowered a little and for that reason the rate of nitrate-nitrogen to total-nitrogen was lower in spinach treated with 8 g N m−2 of drip fertigation than in spinach treated with 8 g N m−2 of basal application. Thus, drip fertigation was considered to reduce nitrate more stably.
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Claims 8
Claim · model-written summary
The 8 g N m−2 drip fertigation treatment gave spinach a low nitrate concentration.
- Taxon
- spinach
Spinacia oleraceae0 - Treatment
- 8 g N m−2 treatment of drip fertigatione2
- Outcome
- nitrate concentratione1
- Direction
- decreaseinferrede1
- Setting
- National Agricultural Research Center for Hokkaido Regione3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study”
e1“This treatment resulted in spinach with a low nitrate concentration without reduction in yield”
e2“in 8 g N m−2 treatment of drip fertigation”
e3“Field experiments were conducted in September 2002 and June 2003 at the National Agricultural Research Center for Hokkaido Region”
Claim · model-written summary
The 8 g N m−2 drip fertigation treatment did not reduce spinach yield.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- 8 g N m−2 treatment of drip fertigatione2
- Outcome
- yielde1
- Direction
- without reductione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study”
e1“This treatment resulted in spinach with a low nitrate concentration without reduction in yield”
e2“in 8 g N m−2 treatment of drip fertigation”
Claim · model-written summary
Nitrate concentration tended to fall further with drip fertigation than with basal application.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- drip fertigatione3
- Outcome
- nitrate concentratione3
- Direction
- fall furthere3
- Comparator
- basal applicatione4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study”
e3“there was a tendency for nitrate concentration to fall further with drip fertigation”
e4“Although the same results were obtained by treatment with 8 g N m−2 of fertilizer by basal application”
Claim · model-written summary
The rate of nitrate-nitrogen to total-nitrogen rose sharply once total-N exceeded 42 g kg−1 DW in leaf blade and 18 g kg−1 DW in leaf petiole.
- Taxon
- spinachSpinacia oleraceae0
- Organ / stage
- leaf bladee5
- Outcome
- rate of nitrate-nitrogen to total-nitrogene5
- Direction
- rose sharplye5
- Value
- 42 g kg−1 DW in leaf blade and 18 g kg−1 DW in leaf petiolee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study”
e5“The rate of nitrate-nitrogen to total-nitrogen rose sharply when the total-nitrogen concentration was higher than 42 g kg−1 DW in leaf blade and 18 g kg−1 DW in leaf petiole”
Claim · model-written summary
The rate of nitrate-nitrogen to total-nitrogen was lower with 8 g N m−2 drip fertigation than with 8 g N m−2 basal application.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- 8 g N m−2 of drip fertigatione6
- Outcome
- rate of nitrate-nitrogen to total-nitrogene6
- Direction
- lowere6
- Comparator
- 8 g N m−2 of basal applicatione6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study”
e6“The total-nitrogen concentration was lowered a little and for that reason the rate of nitrate-nitrogen to total-nitrogen was lower in spinach treated with 8 g N m−2 of drip fertigation than in spinach treated with 8 g N m−2 of basal application”
Claim · model-written summary
Drip fertigation appears to reduce nitrate more stably.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- drip fertigatione7
- Outcome
- nitratee7
- Direction
- reducee7
- Qualifier
- more stablye7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study”
e7“Thus, drip fertigation was considered to reduce nitrate more stably”
Claim · model-written summary
Growth and nitrogen absorption of spinach were very slow early and increased quickly from around day 23 after sowing.
- Taxon
- spinachSpinacia oleraceae0
- Organ / stage
- early growth stagese2
- Outcome
- rate of growth and nitrogen absorptione2
- Direction
- increased quicklye2
- Qualifier
- from around day 23 after sowinge2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study”
e2“The rate of growth and nitrogen absorption of spinach in the early growth stages was very slow, but they increased quickly from around day 23 after sowing”
Claim · model-written summary
Nitrogen absorbed by spinach was close to the amount applied in the 8 g N m−2 treatment.
- Taxon
- spinachSpinacia oleraceae0
- Outcome
- amount of nitrogen absorbede3
- Comparator
- amount appliede3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effectiveness of drip fertigation for reducing nitrate in spinach was investigated in this study”
e3“The amount of nitrogen absorbed by spinach was close to the amount applied in 8 g N m−2 treatment”
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