Abstract
The smooth germination of mature Hybrid rose achenes is hampered by (i) hardseededness (HS), (ii) primary dormancy (PD) and (iii) germination polymorphism (GP). HS is owing to the hard pericarp. PD is, in principle, a natural phenomenon that protects the seeds from precocious germination. For germination, PD must be lifted by after-ripening. When the process of after-ripening is interrupted seeds become secondary dormant (SD). When SD both seeds and naked embryos are highly recalcitrant to germination. After-ripening of Hybrid rose seeds consists of two steps (i) softening the pericarp, (ii) hydrolysing and/or antagonizing the inhibitor ABA, present in the testa and/or embryo. The ratio ABA:GA (present or newly synthesized) controls readiness for germination. Imbibing previously cold-stratified Hybrid seeds in GA 3 , enhanced the even emergence and germination percentage. Likely owing to their unique descent, Hybrid roses bear achenes that are less recalcitrant to breaking PD than those of many rose species. Different levels of PD, occurring between the rose species, can be traced back to adaptation to their natural habitat. Comparing the after-ripening requirements of Hybrid seeds with those of rose species is a false position. GP is caused by varying temperatures during fruit ripening, is promoted by prolonged pollination periods, effects variation in dormancy and as such contributes to uneven germination of Hybrid seeds. PD of Hybrid seeds is deeper as mean ambient temperatures during the last 30 days of fruit ripening were lower. Hence, lower temperatures in autumn, as commonly set in glasshouses, cause deeper PD. Rose seeds may germinate without any after-ripening when harvested unripe. Each year, breeders should compose the best protocol for cold stratification/germination of Hybrid rose seeds from the elements: (i) the period of pollination, (ii) the temperatures during 30 days prior to hip ripening, (iii) the storage of achenes between extraction from the hip and sowing, (iv) the intended warm period prior to stratification and (v) the temperatures set for stratification.
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Claims 16
Claim · model-written summary
Hardseededness hampers mature hybrid rose achene germination.
Verbatim
e0“The smooth germination of mature Hybrid rose achenes is hampered by (i) hardseededness (HS)”
Claim · model-written summary
Primary dormancy hampers mature hybrid rose achene germination.
Verbatim
e0“The smooth germination of mature Hybrid rose achenes is hampered by (i) hardseededness (HS), (ii) primary dormancy (PD)”
Claim · model-written summary
Germination polymorphism hampers mature hybrid rose achene germination.
Verbatim
e0“(iii) germination polymorphism (GP)”
t0“hybrid rose”
Claim · model-written summary
Hardseededness is attributed to the hard pericarp.
Verbatim
e0“HS is owing to the hard pericarp”
t0“hybrid rose”
Claim · model-written summary
Interrupted after-ripening makes seeds secondarily dormant.
Verbatim
e0“When the process of after-ripening is interrupted seeds become secondary dormant (SD)”
t0“hybrid rose”
Claim · model-written summary
Secondarily dormant seeds and naked embryos are highly recalcitrant to germination.
Verbatim
e0“When SD both seeds and naked embryos are highly recalcitrant to germination”
t0“hybrid rose”
Claim · model-written summary
After-ripening softens the pericarp.
Verbatim
e0“After-ripening of Hybrid rose seeds consists of two steps (i) softening the pericarp”
Claim · model-written summary
After-ripening hydrolyses or antagonizes ABA inhibitor.
Verbatim
e0“(ii) hydrolysing and/or antagonizing the inhibitor ABA, present in the testa and/or embryo”
t0“hybrid rose”
Claim · model-written summary
The ABA:GA ratio controls readiness for germination.
Verbatim
e0“The ratio ABA:GA (present or newly synthesized) controls readiness for germination”
t0“hybrid rose”
Claim · model-written summary
GA 3 imbibition enhanced even emergence and germination percentage after cold stratification.
- Taxon
- Hybrid roset0
- Treatment
- GA 3e0
- Outcome
- even emergence and germination percentagee0
- Direction
- enhancede0
Not reportedComparator
Verbatim
e0“Imbibing previously cold-stratified Hybrid seeds in GA 3 , enhanced the even emergence and germination percentage”
t0“hybrid rose”
Claim · model-written summary
Hybrid rose achenes are less resistant to breaking primary dormancy than achenes of many rose species.
Verbatim
e0“Hybrid roses bear achenes that are less recalcitrant to breaking PD than those of many rose species”
Claim · model-written summary
Varying temperatures during fruit ripening cause germination polymorphism.
Verbatim
e0“GP is caused by varying temperatures during fruit ripening”
t0“hybrid rose”
Claim · model-written summary
Prolonged pollination periods promote germination polymorphism.
Verbatim
e0“GP is caused by varying temperatures during fruit ripening, is promoted by prolonged pollination periods”
t0“hybrid rose”
Claim · model-written summary
Lower mean temperatures during the last 30 days of fruit ripening deepen primary dormancy.
Verbatim
e0“PD of Hybrid seeds is deeper as mean ambient temperatures during the last 30 days of fruit ripening were lower”
t0“hybrid rose”
Claim · model-written summary
Unripe rose seeds may germinate without after-ripening.
Verbatim
e0“Rose seeds may germinate without any after-ripening when harvested unripe”
Claim · model-written summary
Breeders should tailor annual stratification and germination protocols to pollination, ripening temperature, storage and stratification conditions.
Verbatim
e0“Each year, breeders should compose the best protocol for cold stratification/germination of Hybrid rose seeds from the elements”