Abstract
A comparative study has been made of the uptake by and translocation from roots of intact barley plants of six herbicides and a systemic fungicide (four triazines, diuron, 2,4-dichloro phenoxyacetic acid (2,4-D) and ethirimol). Relationships between uptake and transpiration rate are discussed in the light of the physico-chemical properties of these compounds, notably their partition coefficients in oil/water systems and their dissociation constants. Apart from 2,4-D, sorption of these compounds appears to be a passive process. At pH4 the uptake of 2,4-D seems to be influenced by metabolism ; not only may the concentration of this compound in the transpiration stream be considerably greater than that in the medium surrounding the roots but absorption by roots is markedly reduced at low temperatures and by sodium azide. The initial rate of uptake of these compounds correlates reasonably well with their partition coefficients in olive oil/water or w-dodecane/water systems ; likewise the concentration in the transpiration stream is greater for lipophilic than for lipophobic substances. Whereas the hydrogen ion and calcium concentrations of the ambient medium appear to have no effect on the uptake of compounds with low pK's, the uptake of those substances which protonate between pH4 and pH6 is affected by them. These findings are discussed from the viewpoint that the pathways of transport of lipophilic and lipophobic compounds across the roots may differ. Although there is some evidence that retention by roots can limit transport to shoots, there is no simple inverse correlation between the total concentration of the different sub stances in the roots and that in the transpiration stream. This question is discussed in a subsequent paper.
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Claims 11
Claim · model-written summary
Sorption was apparently passive except for 2,4-D.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaret0 - Outcome
- sorption of these compoundse0
- Qualifier
- passive processe0
- Comparator
- 2,4-De0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Apart from 2,4-D, sorption of these compounds appears to be a passive process”
t0“intact barley plants”
Claim · model-written summary
At pH4, 2,4-D uptake appears influenced by metabolism.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- uptake of 2,4-De0
- Qualifier
- influenced by metabolisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At pH4 the uptake of 2,4-D seems to be influenced by metabolism”
t0“intact barley plants”
Claim · model-written summary
2,4-D concentration in the transpiration stream can exceed its concentration around roots.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- concentration of this compound in the transpiration streame0
- Direction
- considerably greatere0
- Comparator
- medium surrounding the rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the concentration of this compound in the transpiration stream be considerably greater than that in the medium surrounding the roots”
t0“intact barley plants”
Claim · model-written summary
Low temperature reduced 2,4-D absorption by roots.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- low temperaturese0
- Outcome
- absorption by rootse0
- Direction
- markedly reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“absorption by roots is markedly reduced at low temperatures and by sodium azide”
t0“intact barley plants”
Claim · model-written summary
Sodium azide reduced 2,4-D absorption by roots.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- sodium azidee0
- Outcome
- absorption by rootse0
- Direction
- markedly reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“absorption by roots is markedly reduced at low temperatures and by sodium azide”
t0“intact barley plants”
Claim · model-written summary
Initial uptake rate correlated with oil or dodecane partition coefficients.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- these compoundse0
- Outcome
- initial rate of uptakee0
- Qualifier
- correlates reasonably welle0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The initial rate of uptake of these compounds correlates reasonably well with their partition coefficients in olive oil/water or w-dodecane/water systems”
t0“intact barley plants”
Claim · model-written summary
Lipophilic substances reached higher transpiration stream concentrations than lipophobic substances.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- concentration in the transpiration streame0
- Direction
- greatere0
- Comparator
- lipophobic substancese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the concentration in the transpiration stream is greater for lipophilic than for lipophobic substances”
t0“intact barley plants”
Claim · model-written summary
Ambient hydrogen and calcium did not affect uptake of low-pK compounds.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- hydrogen ion and calcium concentrationse0
- Outcome
- uptake of compounds with low pK'se0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the hydrogen ion and calcium concentrations of the ambient medium appear to have no effect on the uptake of compounds with low pK's”
t0“intact barley plants”
Claim · model-written summary
Ambient hydrogen and calcium affected uptake of substances protonating at pH4–6.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- hydrogen ion and calcium concentrationse0
- Outcome
- uptake of those substances which protonate between pH4 and pH6e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the hydrogen ion and calcium concentrations of the ambient medium appear to have no effect on the uptake of compounds with low pK's, the uptake of those substances which protonate between pH4 and pH6 is affected by them”
t0“intact barley plants”
Claim · model-written summary
Root retention could limit transport to shoots.
- Taxon
- barleyHordeum vulgaret0
- Organ / stage
- rootse0
- Outcome
- transport to shootse0
- Direction
- limite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“retention by roots can limit transport to shoots”
t0“intact barley plants”
Claim · model-written summary
Root concentration and transpiration stream concentration had no simple inverse correlation.
- Taxon
- barleyHordeum vulgaret0
- Organ / stage
- rootse0
- Outcome
- total concentration of the different sub stances in the rootse0
- Qualifier
- no simple inverse correlatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there is no simple inverse correlation between the total concentration of the different sub stances in the roots and that in the transpiration stream”
t0“intact barley plants”
The same questions in other papers
calcium atom · nutrient: content · Hordeum vulgare (barley)Positive and negative results
10 papers in the same direction as this paper · 15 in the opposite direction
- positive
- positive
- positive
22 papers more in this group
See all 26 papers →sodium azide · nutrient: content · Hordeum vulgare (barley)Results agree
2 papers in the same direction as this paper
- negative
- no effect
cold · nutrient: content · Hordeum vulgare (barley)Positive and negative results
5 papers in the same direction as this paper · 1 in the opposite direction
- positive
- negative
- negative
3 papers more in this group
See all 7 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.