Abstract
Ammoniacal fertilizers can cause seedling damage. The present aims were to characterize spatial and temporal, root morphological NH 3 /NH 4 + toxicity symptoms, assess the extent of the toxicity zone, and relate species‐specific responses to their root architecture. Wheat ( Triticum aestivum L.) and canola ( Brassica napus L.) were exposed to seed and deep placed urea. Faba ( Vicia faba L ) seedlings were grown above organic amendments. Time‐sequential images of canola root apex and root hair die‐back, discoloration, and accelerated lateral rooting were captured with soil‐buried, high resolution digital scanners. Seed‐placed urea stunted wheat shoot and root radicles, while slow‐release urea reduced these symptoms. Primary axes of all three species were damaged by encountering the deep fertilizer zones. The multiple seminal axes and lateral root growth away from the fertilizer allowed greater wheat seedling survival, while toxicity‐damage to a single tap root of the germinating canola and faba often resulted in seedling mortality. Urea and chicken manure developed expanded NH 3 /NH 4 + toxicity zones 1.5 to 5 cm, eliciting similar toxicity symptoms initiated at the root apex. Within 3 d after planting, canola tap root elongation stopped, followed by progressive basal directed necrosis and shrinking of the root axis, root hairs. These characteristic symptoms may be used for future toxicity diagnostics of soil‐grown plants. Elevated pH in the soil zone above the chicken manure suggested NH 3 gas transported through soil pores followed by H + consumption and elevated NH 4 + . Ammonia gas toxicity and species‐specific root system architecture should be considered in N placement and source selection. Core Ideas NH 3 /NH 4 + toxicity initiates at the root apex and moves basipetally. Symptoms include tissue discoloration, axis shrinkage, root hair disfigurement, and seedling death. Toxicity zones ranged from 1 to 5 cm from the ammonia sources. Putative upward movement of ammonia raised soil pH and NH 4 + above chicken manure. Most wheat axes avoided NH 3 /NH 4 + toxicity zones, improving survival over tap‐rooted species.
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Claims 12
Claim · model-written summary
Canola roots exhibited apex and root hair die-back, discoloration, and accelerated lateral rooting.
- Taxon
- canola
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Brassica napus var. napuse0 - Outcome
- root apex and root hair die‐back, discoloration, and accelerated lateral rootinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Time‐sequential images of canola root apex and root hair die‐back, discoloration, and accelerated lateral rooting were captured with soil‐buried, high resolution digital scanners.”
Claim · model-written summary
Seed placed urea stunted wheat shoots and root radicles.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- Seed‐placed ureae0
- Outcome
- wheat shoot and root radiclese0
- Direction
- stuntede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seed‐placed urea stunted wheat shoot and root radicles, while slow‐release urea reduced these symptoms.”
Claim · model-written summary
Slow release urea reduced the wheat stunting symptoms.
- Taxon
- wheatTriticum aestivume0
- Treatment
- slow‐release ureae0
- Outcome
- symptomse0
- Direction
- reducede0
- Comparator
- Seed‐placed ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seed‐placed urea stunted wheat shoot and root radicles, while slow‐release urea reduced these symptoms.”
Claim · model-written summary
Deep fertilizer zones damaged primary root axes of wheat, canola, and faba.
- Taxon
- WheatTriticum aestivume1
- Treatment
- deep fertilizer zonese0
- Outcome
- Primary axes of all three species were damagede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Primary axes of all three species were damaged by encountering the deep fertilizer zones.”
e1“Wheat ( Triticum aestivum L.) and canola ( Brassica napus L.) were exposed to seed and deep placed urea. Faba ( Vicia faba L ) seedlings were grown above organic amendments.”
Claim · model-written summary
Wheat seedling survival was greater as multiple seminal axes and lateral roots grew away from fertilizer.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- multiple seminal axes and lateral root growthe0
- Outcome
- greater wheat seedling survivale0
- Direction
- greatere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The multiple seminal axes and lateral root growth away from the fertilizer allowed greater wheat seedling survival”
Claim · model-written summary
Damage to canola taproots often caused seedling mortality.
- Taxon
- canolaBrassica napus var. napuse0
- Organ / stage
- single tap roote0
- Outcome
- seedling mortalitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“toxicity‐damage to a single tap root of the germinating canola and faba often resulted in seedling mortality.”
Claim · model-written summary
Damage to faba taproots often caused seedling mortality.
Verbatim
e0“toxicity‐damage to a single tap root of the germinating canola and faba often resulted in seedling mortality.”
Claim · model-written summary
Urea developed an expanded ammonia toxicity zone of 1.5 to 5 cm.
- Taxon
- wheatTriticum aestivume1
- Treatment
- Ureae0
- Outcome
- NH 3 /NH 4 + toxicity zonese0
- Direction
- expandede0
- Value
- 1.5 to 5 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Urea and chicken manure developed expanded NH 3 /NH 4 + toxicity zones 1.5 to 5 cm, eliciting similar toxicity symptoms initiated at the root apex.”
e1“Seed‐placed urea stunted wheat shoot and root radicles”
Claim · model-written summary
Chicken manure developed an expanded ammonia toxicity zone of 1.5 to 5 cm.
Verbatim
e0“Urea and chicken manure developed expanded NH 3 /NH 4 + toxicity zones 1.5 to 5 cm, eliciting similar toxicity symptoms initiated at the root apex.”
e1“Faba ( Vicia faba L ) seedlings were grown above organic amendments.”
Claim · model-written summary
Canola taproot elongation stopped within three days, followed by necrosis and shrinking of root axis and hairs.
- Taxon
- canolaBrassica napus var. napuse0
- Outcome
- tap root elongatione0
- Direction
- stoppede0
- Value
- 3 de0
- Qualifier
- progressive basal directed necrosis and shrinking of the root axis, root hairse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Within 3 d after planting, canola tap root elongation stopped, followed by progressive basal directed necrosis and shrinking of the root axis, root hairs.”
Claim · model-written summary
Elevated pH above chicken manure suggested upward ammonia transport with increased ammonium.
Verbatim
e0“Elevated pH in the soil zone above the chicken manure suggested NH 3 gas transported through soil pores followed by H + consumption and elevated NH 4 + .”
e1“Faba ( Vicia faba L ) seedlings were grown above organic amendments.”
Claim · model-written summary
Ammonia toxicity and root architecture should be considered when selecting nitrogen placement and source.
- Taxon
- WheatTriticum aestivume1
- Outcome
- N placement and source selectione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ammonia gas toxicity and species‐specific root system architecture should be considered in N placement and source selection.”
e1“Wheat ( Triticum aestivum L.) and canola ( Brassica napus L.) were exposed to seed and deep placed urea.”
The same questions in other papers
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- no effect
- negative
- negative
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See all 54 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.