Abstract
Soybean is traditionally grown in soil, where root symbiosis with Bradyrhizobium japonicum can supply nitrogen (N), by means of bacterial fixation of atmospheric N2. Nitrogen fertilizers inhibit N-fixing bacteria. However, urea is profitably used in soybean cultivation in soil, where urease enzymes of telluric microbes catalyze the hydrolysis to ammonium, which has a lighter inhibitory effect compared to nitrate. Previous researches demonstrated that soybean can be grown hydroponically with recirculating complete nitrate-based nutrient solutions. In Space, urea derived from crew urine could be used as N source, with positive effects in resource procurement and waste recycling. However, whether the plants are able to use urea as the sole source of N and its effect on root symbiosis with B. japonicum is still unclear in hydroponics. We compared the effect of two N sources, nitrate and urea, on plant growth and physiology, and seed yield and quality of soybean grown in closed-loop Nutrient Film Technique (NFT) in growth chamber, with or without inoculation with B. japonicum. Urea limited plant growth and seed yield compared to nitrate by determining nutrient deficiency, due to its low utilization efficiency in the early developmental stages, and reduced nutrients uptake (K, Ca, and Mg) throughout the whole growing cycle. Root inoculation with B. japonicum did not improve plant performance, regardless of the N source. Specifically, nodulation increased under fertigation with urea compared to nitrate, but this effect did not result in higher leaf N content and better biomass and seed production. Urea was not suitable as sole N source for soybean in closed-loop NFT. However, the ability to use urea increased from young to adult plants, suggesting the possibility to apply it during reproductive phase or in combination with nitrate in earlier developmental stages. Root symbiosis did not contribute significantly to N nutrition and did not enhance the plant ability to use urea, possibly because of ineffective infection process and nodule functioning in hydroponics.
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
Urea limited soybean growth relative to nitrate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Urea limited plant growth and seed yield compared to nitrate”
t0“Soybean”
Claim · model-written summary
Urea limited soybean seed yield relative to nitrate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Urea limited plant growth and seed yield compared to nitrate”
t0“Soybean”
Claim · model-written summary
Urea led to nutrient deficiency through low early utilization efficiency.
- Taxon
- Soybean
Glycine maxt0 - Treatment
- Ureae0
- Outcome
- nutrient deficiencye0
- Qualifier
- low utilization efficiency in the early developmental stagese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Urea limited plant growth and seed yield compared to nitrate by determining nutrient deficiency, due to its low utilization efficiency in the early developmental stages”
t0“Soybean”
Claim · model-written summary
Urea reduced K, Ca and Mg uptake throughout the growing cycle.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- Ureae0
- Outcome
- nutrients uptake (K, Ca, and Mg)e0
- Direction
- reducede0
- Comparator
- nitratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Urea limited plant growth and seed yield compared to nitrate by determining nutrient deficiency, due to its low utilization efficiency in the early developmental stages, and reduced nutrients uptake (K, Ca, and Mg) throughout the whole growing cycle”
t0“Soybean”
Claim · model-written summary
B. japonicum inoculation did not improve soybean performance under either nitrogen source.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- Root inoculation with B. japonicume0
- Interactor
- B. japonicum
Bradyrhizobium japonicume0symbiont - Outcome
- plant performancee0
- Direction
- did not improvee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root inoculation with B. japonicum did not improve plant performance, regardless of the N source”
t0“Soybean”
Claim · model-written summary
Soybean nodulation increased with urea versus nitrate fertigation.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- fertigation with ureae0
- Outcome
- nodulatione0
- Direction
- increasede0
- Comparator
- nitratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nodulation increased under fertigation with urea compared to nitrate”
t0“Soybean”
Claim · model-written summary
Increased nodulation under urea did not raise leaf N content.
- Taxon
- SoybeanGlycine maxt0
- Organ / stage
- leafe0
- Outcome
- leaf N contente0
- Direction
- did not result in highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this effect did not result in higher leaf N content and better biomass and seed production”
t0“Soybean”
Claim · model-written summary
Increased nodulation under urea did not improve biomass or seed production.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- biomass and seed productione0
- Direction
- did not result in highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this effect did not result in higher leaf N content and better biomass and seed production”
t0“Soybean”
Claim · model-written summary
Soybean ability to use urea increased from young to adult plants.
- Taxon
- SoybeanGlycine maxt0
- Organ / stage
- young to adult plantse0
- Outcome
- ability to use ureae0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the ability to use urea increased from young to adult plants”
t0“Soybean”
Claim · model-written summary
The authors judged urea unsuitable as sole N source in closed-loop NFT.
- Taxon
- soybeanGlycine maxe0
- Outcome
- not suitable as sole N sourcee0
- Setting
- closed-loop NFTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Urea was not suitable as sole N source for soybean in closed-loop NFT”
Claim · model-written summary
The authors suggest urea during reproduction or with nitrate earlier.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- apply it during reproductive phase or in combination with nitrate in earlier developmental stagese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the possibility to apply it during reproductive phase or in combination with nitrate in earlier developmental stages”
t0“Soybean”
Claim · model-written summary
Root symbiosis did not significantly contribute to soybean N nutrition.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- N nutritione0
- Direction
- did not contribute significantlye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root symbiosis did not contribute significantly to N nutrition”
t0“Soybean”
Claim · model-written summary
Root symbiosis did not enhance soybean urea use.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- plant ability to use ureae0
- Direction
- did not enhancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“did not enhance the plant ability to use urea”
t0“Soybean”
The same questions in other papers
Bradyrhizobium japonicum · yield · Glycine max (soybean)Positive and negative results
6 papers in the same direction as this paper · 54 in the opposite direction
- positive
- positive
- positive
57 papers more in this group
See all 61 papers →nitrogen · nutrient: content · Glycine max (soybean)Results differ
20 papers in the same direction as this paper · 73 in the opposite direction
- positive
- positive
- positive
90 papers more in this group
See all 94 papers →nitrogen · symbiosis · Glycine max (soybean)Positive and negative results
58 papers in the same direction as this paper · 86 in the opposite direction · 1 reporting no difference from an alternative
- negative
- negative
- negative
142 papers more in this group
See all 146 papers →nitrogen · growth · Glycine max (soybean)Positive and negative results
35 papers in the same direction as this paper · 117 in the opposite direction
- positive
- positive
- positive
149 papers more in this group
See all 153 papers →fertilization · symbiosis · Glycine max (soybean)Positive and negative results
141 papers in the same direction as this paper · 50 in the opposite direction
- positive
- negative
- negative
188 papers more in this group
See all 192 papers →nitrogen · yield · Glycine max (soybean)Positive and negative results
97 papers in the same direction as this paper · 318 in the opposite direction
- positive
- positive
- positive
412 papers more in this group
See all 416 papers →inoculation · yield · Glycine max (soybean)Positive and negative results
74 papers in the same direction as this paper · 491 in the opposite direction
- positive
- positive
- positive
562 papers more in this group
See all 566 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.