Abstract
Seed germination rates (GR =inverse of time to germination) are sensitive to genetic, environmental, and physiological factors. We have compared the GR of tomato (Lycopersicon esculentum Mill.) seeds of cultivar T5 to those of rapidly germinating L. esculentum genotypes PI 341988 and PI 120256 over a range of water potential (ψ). The influence of seed priming treatments and removal of the endosperm/testa cap enclosing the radicle tip on germination at reduced ψ were also assessed. Germination time-courses at different ψ's were analysed according to a model that identified a base, or minimum, ψ allowing germination of a specific percentage (g) of the seed population (ψb(g)), and a ‘hydrotime constant’ (θH) indicating the rate of progress toward germination per MPa.h. The distribution of ψb(g) determined by probit analysis was characterized by a mean base ψ (b) and the standard deviation in ψb among seeds (σψb). The three derived parameters, b, σψb) and θH, were sufficient to predict the time-courses of germination of intact seeds at any ψ. A normalized time-scale for comparing germination responses to reduced ψ is introduced. The time to germination at any ψ(tg(ψ)) can be normalized to be equivalent to that observed in water (tg(0)) according to the equation tg(0)=[l−(ψ/ψb(g))]tg(ψ). PI 341988 seeds were more tolerant of reduced ψ and had a more rapid GR than T5 seeds due to both a lower b and a smaller θH. The rapid germination of PI 120256, on the other hand, could be attributed entirely to a smaller θH. Seed priming (6 d in −1.2 MPa polyethylene glycol 8000 solution at 20 °C followed by drying) increased GR at all ψ>ψb(g), but did not lower the minimum ψ allowing germination; i.e. priming reduced θH without lowering ψb. Removing the endosperm/testa cap (cut seeds) markedly increased GR and lowered the mean ψ required to inhibit germination by 0.7 to 0.9 MPa. However, this resulted primarily from downward adjustment in b during the incubation of cut seeds at low ψ in the test solutions. The difference in b between intact and cut seeds incubated at high ψ was much less (0.l MPa), indicating that at the time of radicle protrusion, the endosperm had weakened to the point where it constituted only a small mechanical barrier. In the intact seed, endosperm weakening and the downward adjustment in embryo b ceased at ψ < −0.6 MPa, while the reduction in θH associated with priming proceeded down to at least −1.2 MPa. Based on these data and on the pressure required to push the embryos from the seeds at various times after imbibition, it appears that the primary effect of priming was to shorten the time required for final endosperm weakening to occur. However, as priming increased GR even in cut seeds, priming effects on the embryo may control the rate of endosperm weakening.
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Claims 14
Claim · model-written summary
Three hydrotime parameters predicted germination time courses of intact tomato seeds at any water potential.
- Taxon
- tomato (Lycopersicon esculentum Mill.)
Solanum lycopersicume1 - Outcome
- predict the time-courses of germination of intact seedse0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The three derived parameters, b, σψb) and θH, were sufficient to predict the time-courses of germination of intact seeds at any ψ.”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
PI 341988 seeds tolerated lower water potential and germinated faster than T5 seeds.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Material
- PI 341988e0
- Outcome
- more tolerant of reduced ψ and had a more rapid GRe0
- Direction
- more tolerante0
- Comparator
- T5e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PI 341988 seeds were more tolerant of reduced ψ and had a more rapid GR than T5 seeds”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
PI 341988 had lower mean base water potential and a smaller hydrotime constant than T5.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume2
- Material
- PI 341988e1
- Outcome
- b and a smaller θHe0
- Direction
- lowere0
- Comparator
- T5e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“due to both a lower b and a smaller θH”
e1“PI 341988 seeds were more tolerant of reduced ψ and had a more rapid GR than T5 seeds”
e2“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Rapid germination of PI 120256 was attributed to a smaller hydrotime constant.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Material
- PI 120256e0
- Outcome
- rapid germinatione0
- Qualifier
- smaller θHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rapid germination of PI 120256, on the other hand, could be attributed entirely to a smaller θH.”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Priming increased germination rate at water potentials above the base potential.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Treatment
- Seed priming (6 d in −1.2 MPa polyethylene glycol 8000 solution at 20 °C followed by drying)e0
- Outcome
- GRe0
- Direction
- increasede0
- Qualifier
- at all ψ>ψb(g)e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seed priming (6 d in −1.2 MPa polyethylene glycol 8000 solution at 20 °C followed by drying) increased GR at all ψ>ψb(g)”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Priming did not lower the minimum water potential permitting germination.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Treatment
- priminge0
- Outcome
- minimum ψ allowing germinatione0
- Direction
- did not lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“did not lower the minimum ψ allowing germination; i.e. priming reduced θH without lowering ψb.”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Priming reduced the hydrotime constant.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Treatment
- priminge0
- Outcome
- θHe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“priming reduced θH without lowering ψb.”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Removing the endosperm and testa cap increased germination rate.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Treatment
- Removing the endosperm/testa cape0
- Outcome
- GRe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Removing the endosperm/testa cap (cut seeds) markedly increased GR”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Removing the endosperm and testa cap lowered the mean inhibitory water potential by 0.7 to 0.9 MPa.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Treatment
- Removing the endosperm/testa cape0
- Outcome
- mean ψ required to inhibit germinatione0
- Direction
- lowerede0
- Value
- 0.7 to 0.9 MPae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Removing the endosperm/testa cap (cut seeds) markedly increased GR and lowered the mean ψ required to inhibit germination by 0.7 to 0.9 MPa.”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
The base water potential difference between intact and cut seeds at high water potential was 0.l MPa.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Outcome
- difference in be0
- Direction
- much lesse0
- Value
- 0.l MPae0
- Comparator
- intact and cut seedse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The difference in b between intact and cut seeds incubated at high ψ was much less (0.l MPa)”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Endosperm weakening and downward adjustment in embryo base potential ceased below −0.6 MPa in intact seeds.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Outcome
- endosperm weakening and the downward adjustment in embryo b ceasede0
- Qualifier
- ψ < −0.6 MPae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the intact seed, endosperm weakening and the downward adjustment in embryo b ceased at ψ < −0.6 MPa”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Priming-associated reduction in hydrotime constant continued to at least −1.2 MPa.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Treatment
- priminge0
- Outcome
- θHe0
- Direction
- reductione0
- Qualifier
- down to at least −1.2 MPae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the reduction in θH associated with priming proceeded down to at least −1.2 MPa”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
The authors interpreted priming as shortening the time required for final endosperm weakening.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Treatment
- priminge0
- Outcome
- time required for final endosperm weakeninge0
- Direction
- shortene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it appears that the primary effect of priming was to shorten the time required for final endosperm weakening to occur”
e1“tomato (Lycopersicon esculentum Mill.)”
Claim · model-written summary
Priming also increased germination rate in cut seeds.
- Taxon
- tomato (Lycopersicon esculentum Mill.)Solanum lycopersicume1
- Treatment
- priminge0
- Outcome
- GRe0
- Direction
- increasede0
- Qualifier
- even in cut seedse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“priming increased GR even in cut seeds”
e1“tomato (Lycopersicon esculentum Mill.)”
The same questions in other papers
seed treatment · growth · Solanum lycopersicum (tomato)Positive and negative results
9 papers in the same direction as this paper · 121 in the opposite direction
- no effect
- positive
- positive
127 papers more in this group
See all 131 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.