Abstract
The mechanism by which O2, C2H4, KCN and NaN3 stimulate germination was examined using completely after-ripened, non-dormant upper seeds of Xanthium pensylvanicum Wallr. in which secondary dormancy was induced by presoaking. Although the presoaked seeds had lost the ability to respond to these chemicals applied singly, they were highly responsive to C2H4 alone, but not to O2 alone, when pretreated with KCN or NaN3. Transfer of seeds exposed to KCN or NaN3 to C2H4 under O2 enrichment was the best practice for breaking secondary dormancy. Both O2 and C2H4 stimulated total respiration of untreated seeds by increasing the ratio of alternative path flux (Valt) to cytochrome path flux (Vcyt), which had been very low during the secondary dormancy stage. Maximal values of Valt and Vcyt were obtained when O2and C2H4 were applied together. The respiration surge induced by O2 or C2H4 was also produced when the seeds were pretreated with KCN or NaN3, but it did not occur until KCN or NaN3 treatment was continued beyond 32 h. This time corresponds to that required for complete restoration of C2H4 responsiveness. The respiration surge did not occur when the KCN solution was renewed, suggesting that the operation of the cytochrome system, even if restricted, was required to develop the alternative path. In order to observe the respiration-enhancing action of C2H4 in seeds pretreated with KCN or NaN3, C2H4 had to be applied in combination with O2. This combination led to maximal fluxes of both Vcyt and Valt, although it did not significantly increase the Valt/Vcyt ratio. O2 enrichment was ineffective in stimulating germination of these seeds and in increasing the Valt/Vcyt ratio, since it stimulated the flux via the cytochrome path rather than the alternative one. It is concluded that both the large increase of Valt and the high Valt/Vcyt ratio are required for seed germination and that KCN, NaN3, O2 and C2H4 exert their actions on the germination by increasing either or both.
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Claims 10
Claim · model-written summary
Presoaked seeds responded to ethylene after KCN or NaN3 pretreatment but not to oxygen alone.
- Taxon
- Xanthium pensylvanicum Wallr.
Xanthium strumariumt0 - Treatment
- C2H4 alonee0
- Outcome
- highly responsivee0
- Comparator
- O2 alonee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“they were highly responsive to C2H4 alone, but not to O2 alone, when pretreated with KCN or NaN3”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
KCN or NaN3 pretreatment followed by ethylene under oxygen enrichment best broke secondary dormancy.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Treatment
- seeds exposed to KCN or NaN3 to C2H4 under O2 enrichmente0
- Outcome
- breaking secondary dormancye0
- Direction
- beste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transfer of seeds exposed to KCN or NaN3 to C2H4 under O2 enrichment was the best practice for breaking secondary dormancy”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
Oxygen and ethylene stimulated total respiration by increasing the alternative-to-cytochrome flux ratio.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Treatment
- O2 and C2H4e0
- Outcome
- total respiratione0
- Direction
- stimulatede0
- Comparator
- untreated seedse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both O2 and C2H4 stimulated total respiration of untreated seeds by increasing the ratio of alternative path flux (Valt) to cytochrome path flux (Vcyt)”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
Together oxygen and ethylene produced maximal Valt and Vcyt fluxes.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Treatment
- O2and C2H4e0
- Outcome
- Valt and Vcyte0
- Direction
- Maximale0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximal values of Valt and Vcyt were obtained when O2and C2H4 were applied together”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
KCN or NaN3 pretreatment also produced a respiration surge after treatment continued beyond 32 hours.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Treatment
- pretreated with KCN or NaN3e0
- Outcome
- respiration surgee0
- Direction
- producede0
- Qualifier
- beyond 32 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The respiration surge induced by O2 or C2H4 was also produced when the seeds were pretreated with KCN or NaN3, but it did not occur until KCN or NaN3 treatment was continued beyond 32 h”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
Renewing KCN solution prevented the respiration surge.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Treatment
- KCN solution was renewede0
- Outcome
- respiration surge did not occure0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The respiration surge did not occur when the KCN solution was renewed”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
Ethylene enhanced respiration after KCN or NaN3 pretreatment only with oxygen.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Treatment
- C2H4 had to be applied in combination with O2e0
- Outcome
- respiration-enhancing actione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In order to observe the respiration-enhancing action of C2H4 in seeds pretreated with KCN or NaN3, C2H4 had to be applied in combination with O2”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
Oxygen enrichment failed to stimulate germination of pretreated seeds.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Treatment
- O2 enrichmente0
- Outcome
- germinatione0
- Direction
- ineffectivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“O2 enrichment was ineffective in stimulating germination of these seeds”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
Oxygen enrichment failed to increase Valt/Vcyt ratio.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Treatment
- O2 enrichmente0
- Outcome
- Valt/Vcyt ratioe0
- Direction
- ineffectivee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“O2 enrichment was ineffective in stimulating germination of these seeds and in increasing the Valt/Vcyt ratio”
t0“Xanthium pensylvanicum Wallr.”
Claim · model-written summary
Large Valt and high Valt/Vcyt ratio were deemed necessary for seed germination.
- Taxon
- Xanthium pensylvanicum Wallr.Xanthium strumariumt0
- Outcome
- seed germinatione0
- Qualifier
- large increase of Valt and the high Valt/Vcyt ratioe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both the large increase of Valt and the high Valt/Vcyt ratio are required for seed germination”
t0“Xanthium pensylvanicum Wallr.”
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See all 9 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.