Abstract
Abstract The mechanism whereby plants growing on aerated and neutral to basic soils obtain adequate amounts of iron is, in spite of several experimentally observed iron stress responses, not yet clear. We have evaluated the currently held models of iron mobilization, and have discussed whether they could, as they presently stand, explain a very old observation, namely the contact phenomenon according to which mere physical contact between plant roots and iron‐containing solid particles enhances the uptake of iron by plant roots. It seems that in aerated well‐buffered soils, the iron mobilization mechanisms such as H+ efflux, reduction of iron, or chelation by organic ligands can be operational to an effective and significant extent only if these chemical processes take place in domains isolated from the chemical reactions taking place in the soil milieu. It is shown that roots of corn attach themselves firmly to sand particles and build extensive root hairs at the contact sites. In the two‐phase experiments in which the nutrient phase lacked iron, corn plants with roots in contact with quartz sand containing traces of iron impurities grew better and absorbed more Fe, Cu, and Mn than plants with roots suspended in nutrient solution. When iron was present in the nutrient phase, however, the roots’ contact with quartz sand had no effect on the plant's growth and the content of the above nutrients. It is postulated that protected micropockets, formed at the root and solid interfaces and sealed off from the rest of the soil milieu by mucigel plugs, shelter a chemical environment favorable to nutrient mobilization. The nutrients thus mobilized diffuse to the root cell membrane but cannot leak out and are not accessible to other roots.
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Claims 9
Claim · model-written summary
Corn roots attached to sand and formed root hairs at contact sites.
- Taxon
- corn
Zea mays subsp. mayse0 - Organ / stage
- rootse0
- Outcome
- attach themselves firmly to sand particles and build extensive root hairs at the contact sitese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“roots of corn attach themselves firmly to sand particles and build extensive root hairs at the contact sites”
Claim · model-written summary
With iron absent from the nutrient phase, sand contact improved corn growth.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- roots in contact with quartz sand containing traces of iron impuritiese0
- Outcome
- grewe0
- Direction
- bettere0
- Qualifier
- nutrient phase lacked irone0
- Comparator
- plants with roots suspended in nutrient solutione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the two‐phase experiments in which the nutrient phase lacked iron, corn plants with roots in contact with quartz sand containing traces of iron impurities grew better and absorbed more Fe, Cu, and Mn than plants with roots suspended in nutrient solution”
Claim · model-written summary
Corn absorbed more Fe with sand contact.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- roots in contact with quartz sand containing traces of iron impuritiese0
- Outcome
- Fee0
- Direction
- moree0
- Comparator
- plants with roots suspended in nutrient solutione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“corn plants with roots in contact with quartz sand containing traces of iron impurities grew better and absorbed more Fe, Cu, and Mn than plants with roots suspended in nutrient solution”
Claim · model-written summary
Corn absorbed more Cu with sand contact.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- roots in contact with quartz sand containing traces of iron impuritiese0
- Outcome
- Cue0
- Direction
- moree0
- Comparator
- plants with roots suspended in nutrient solutione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“corn plants with roots in contact with quartz sand containing traces of iron impurities grew better and absorbed more Fe, Cu, and Mn than plants with roots suspended in nutrient solution”
Claim · model-written summary
Corn absorbed more Mn with sand contact.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- roots in contact with quartz sand containing traces of iron impuritiese0
- Outcome
- Mne0
- Direction
- moree0
- Comparator
- plants with roots suspended in nutrient solutione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“corn plants with roots in contact with quartz sand containing traces of iron impurities grew better and absorbed more Fe, Cu, and Mn than plants with roots suspended in nutrient solution”
Claim · model-written summary
With iron in the nutrient phase, sand contact had no effect on plant's growth.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- roots’ contact with quartz sande0
- Outcome
- plant's growthe0
- Direction
- no effecte0
- Qualifier
- iron was present in the nutrient phasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When iron was present in the nutrient phase, however, the roots’ contact with quartz sand had no effect on the plant's growth and the content of the above nutrients”
e1“roots of corn attach themselves firmly”
Claim · model-written summary
With iron in the nutrient phase, sand contact had no effect on content of the above nutrients.
- Taxon
- cornZea mays subsp. mayse1
- Treatment
- roots’ contact with quartz sande0
- Outcome
- content of the above nutrientse0
- Direction
- no effecte0
- Qualifier
- iron was present in the nutrient phasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When iron was present in the nutrient phase, however, the roots’ contact with quartz sand had no effect on the plant's growth and the content of the above nutrients”
e1“roots of corn attach themselves firmly”
Claim · model-written summary
The authors propose that protected root micropockets favor nutrient mobilization.
- Taxon
- cornZea mays subsp. mayse1
- Outcome
- nutrient mobilizatione0
- Qualifier
- protected micropocketse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It is postulated that protected micropockets, formed at the root and solid interfaces and sealed off from the rest of the soil milieu by mucigel plugs, shelter a chemical environment favorable to nutrient mobilization”
e1“roots of corn attach themselves firmly”
Claim · model-written summary
The authors propose that mobilized nutrients reach the root membrane without escaping.
- Taxon
- cornZea mays subsp. mayse1
- Outcome
- diffuse to the root cell membranee0
- Qualifier
- cannot leak out and are not accessible to other rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The nutrients thus mobilized diffuse to the root cell membrane but cannot leak out and are not accessible to other roots”
e1“roots of corn attach themselves firmly”
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