Abstract
In bean, Phaseolus vulgaris L. (Contender), the directly measured hydraulic resistance of the xylem pathway between roots and primary leaf pulvinal junctions increased rapidly and progressively from 21 to 28 days after planting. These increases in xylem resistance (+390%) were specifically located in the pulvinal junction of the primary leaf. Moreover, they occurred just prior to the onset of primary leaf yellowing. Developmental increases in xylem hydraulic flow resistance and stomatal resistance, as well as subsequent primary leaf yellowing, were completely prevented by detopping the shoots above the primary leaves at 21 days. Thus, the onset of these senescence-associated symptoms was correlatively controlled. In short-term investigations of the mechanisms involved, flow between petiole and cut tip of excised leaves was rapidly reduced by infiltration of 20 picomoles of soluble dextran into the xylem. Moreover, imbibition of approximately 120 picomoles of dextran by excised leaves increased stomatal resistances. A programmed secretion of hormonal concentrations of similar polysaccharides into specific xylem sections in vivo might provide a mechanism for regulating the partitioning of essential xylem supplies between leaves, thus inducing sequential leaf senescence.
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Claims 9
Claim · model-written summary
Bean root-to-primary-leaf xylem resistance increased rapidly from day 21 to day 28.
- Taxon
- Phaseolus vulgaris L.
Phaseolus vulgarise0 - Material
- Contendere0
- Outcome
- hydraulic resistance of the xylem pathwaye0
- Direction
- increased rapidly and progressivelye0
- Qualifier
- from 21 to 28 days after plantinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In bean, Phaseolus vulgaris L. (Contender), the directly measured hydraulic resistance of the xylem pathway between roots and primary leaf pulvinal junctions increased rapidly and progressively from 21 to 28 days after planting.”
Claim · model-written summary
Primary leaf pulvinal-junction xylem resistance increased 390%.
Verbatim
e0“These increases in xylem resistance (+390%) were specifically located in the pulvinal junction of the primary leaf.”
t0“bean”
Claim · model-written summary
The xylem resistance increases preceded primary-leaf yellowing.
- Taxon
- beant0
- Organ / stage
- primary leafe0
- Outcome
- primary leaf yellowinge0
- Qualifier
- just prior to the onsete0
Not reportedDirection
Verbatim
e0“they occurred just prior to the onset of primary leaf yellowing”
e1“These increases in xylem resistance (+390%)”
t0“bean”
Claim · model-written summary
Detopping at day 21 prevented developmental increases in xylem hydraulic resistance.
- Taxon
- beant0
- Treatment
- detopping the shoots above the primary leaves at 21 dayse0
- Outcome
- xylem hydraulic flow resistancee0
- Direction
- completely preventede0
Not reportedComparator
Verbatim
e0“Developmental increases in xylem hydraulic flow resistance and stomatal resistance, as well as subsequent primary leaf yellowing, were completely prevented by detopping the shoots above the primary leaves at 21 days.”
t0“bean”
Claim · model-written summary
Detopping at day 21 prevented developmental increases in stomatal resistance.
- Taxon
- beant0
- Treatment
- detopping the shoots above the primary leaves at 21 dayse0
- Outcome
- stomatal resistancee0
- Direction
- completely preventede0
Not reportedComparator
Verbatim
e0“Developmental increases in xylem hydraulic flow resistance and stomatal resistance, as well as subsequent primary leaf yellowing, were completely prevented by detopping the shoots above the primary leaves at 21 days.”
t0“bean”
Claim · model-written summary
Detopping at day 21 prevented primary-leaf yellowing.
- Taxon
- beant0
- Treatment
- detopping the shoots above the primary leaves at 21 dayse0
- Outcome
- primary leaf yellowinge0
- Direction
- completely preventede0
Not reportedComparator
Verbatim
e0“Developmental increases in xylem hydraulic flow resistance and stomatal resistance, as well as subsequent primary leaf yellowing, were completely prevented by detopping the shoots above the primary leaves at 21 days.”
t0“bean”
Claim · model-written summary
Infiltration of 20 picomoles soluble dextran rapidly reduced flow through excised leaves.
- Taxon
- beant0
- Treatment
- infiltration of 20 picomoles of soluble dextran into the xyleme0
- Outcome
- flow between petiole and cut tip of excised leavese0
- Direction
- rapidly reducede0
- Value
- 20 picomolese0
Not reportedComparator
Verbatim
e0“flow between petiole and cut tip of excised leaves was rapidly reduced by infiltration of 20 picomoles of soluble dextran into the xylem.”
t0“bean”
Claim · model-written summary
Imbibition of about 120 picomoles dextran increased stomatal resistance in excised leaves.
- Taxon
- beant0
- Treatment
- imbibition of approximately 120 picomoles of dextrane0
- Outcome
- stomatal resistancese0
- Direction
- increasede0
- Value
- approximately 120 picomolese0
Not reportedComparator
Verbatim
e0“imbibition of approximately 120 picomoles of dextran by excised leaves increased stomatal resistances.”
t0“bean”
Claim · model-written summary
The authors propose polysaccharide secretion into xylem as a possible mechanism for sequential leaf senescence.
Verbatim
e0“A programmed secretion of hormonal concentrations of similar polysaccharides into specific xylem sections in vivo might provide a mechanism for regulating the partitioning of essential xylem supplies between leaves, thus inducing sequential leaf senescence.”
t0“bean”
The same questions in other papers
pruning · disease · Phaseolus vulgaris (common bean)Positive and negative results
3 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
1 paper more in this group
See all 5 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.