The Control of Dormancy

Bewley, J. Derek; Black, M.

doi:10.1007/978-3-642-68643-6_4

Cited by 40 publications

(63 citation statements)

References 193 publications

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Section: Introductionmentioning

confidence: 99%

“…However, as the temperature rises further above this range, the promotive effect of a short exposure to light also disappears (4,21), although continuous light has been reported to induce more germination (90%) than a single light exposure (32%) at 29°C (21). The latter finding suggests that the loss of effectiveness of short term irradiation may be related to a rapid thermal reversion of Pfr to Pr prior to the completion of phytochrome action.…”

mentioning

confidence: 96%

“…Germination of lettuce seeds is nearly 100% in the dark at temperatures up to approximately 20°C, although the actual permissive temperature range varies among cultivars or even different seed lots ofthe same cultivar (4,16,27,29 percentage declines with increase in temperature (thermoinhibition) to reach zero at approximately 25 to 35°C depending on the seed lot and cultivar (16,22,27,29). Seeds held at such supraoptimal temperatures in an ungerminated state eventually lose their ability to germinate even when returned to a permissive temperature, thus entering a secondary dormancy termed 'thermodormancy' (4).…”

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confidence: 99%

“…Over a limited temperature range, thermoinhibition of lettuce seed germination can be alleviated by briefly exposing the imbibed seeds to light (4,6). However, as the temperature rises further above this range, the promotive effect of a short exposure to light also disappears (4,21), although continuous light has been reported to induce more germination (90%) than a single light exposure (32%) at 29°C (21).…”

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Control Processes in the Induction and Relief of Thermoinhibition of Lettuce Seed Germination

et al. 1989

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Germination of lettuce seeds (Lactuca sativa L. cv Grand Rapids) in the dark was nearly 100% at 200C but was inhibited at 270C and higher temperatures (thermoinhibition). A single 5-minute exposure to red light completely overcame the inhibition at temperatures up to 280C, above which the effectiveness of single light exposures gradually declined to reach a negligible level at 320C. However, the promotive effect of light could be extended to 340C by repeated irradiations. At any one temperature, increased frequency of irradiations increased germination percentage, and with each degree increase in temperature, increasingly frequent irradiations were necessary to elicit maximal germination. Loss of the effectiveness of single irradiations with increase in temperature may result either from acceleration of the thermal reversion of the far red-absorbing form of phytochrome or decrease in seed sensitivity toward a given percentage of the far red-absorbing form of phytochrome. Using continuous red light to induce germination, the role of endogenous C2H4 in germination at 32°C was studied. Ethylene evolution from irradiated seeds began to increase 2 hours prior to radicle protrusion, whereas the dark-incubated (nongerminating) seeds produced a low, constant amount of C2H4 throughout the 24 hour incubation period. Inhibition of C2H4 synthesis with 2-aminoethoxyvinyl glycine and/or inhibition of C2H4 action with 2,5-norbomadiene blocked the promotive effect of light. Exogenous C2H4 overcame these blockages. The results showed that participation by endogenous C2H4 was essential for the light-induced relief of thermoinhibition of lettuce seed germination. However, light did not act exclusively via C2H4 since exogenous C2H4 alone in darkness did not promote germination.Germination of lettuce (Lactuca sativa L.) seeds is strongly influenced by temperature. Germination of lettuce seeds is nearly 100% in the dark at temperatures up to approximately 20°C, although the actual permissive temperature range varies among cultivars or even different seed lots ofthe same cultivar (4,16,27,29).

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 96%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Control Processes in the Induction and Relief of Thermoinhibition of Lettuce Seed Germination

et al. 1989

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“…Under natural conditions, phenolic compounds are present in the seed coat, cotyledons etc. and have been imphcated in dormancy (Bewley & Black, 1982). They are also available through soil from where they produce allelochemic effects.…”

Section: -8±0-4nsmentioning

confidence: 99%

REVERSAL BY PHENOLIC COMPOUNDS OF ABSCISIC ACID‐INDUCED INHIBITION OF IN VITRO ACTIVITY OF AMYLASE FROM SEEDS OF TRITICUM AESTIVUM L.

Sharma

1986

New Phytologist

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SUMMARYEffects of abscisic acid and certain phenolic compounds have been studied, individually and in combination, on in vitro amylase activity from Triticum aestivum L. seeds. ABA suppressed the amylase activity, in vitro, while salicylic acid, cinnamic acid and ferulic acid applied alone promoted it; vanillic acid caused a slight inhibition. Irrespective of their individual effects, all the phenolic compounds studied reverted the inhibitory action of ABA on amylase activity. This behaviour suggests that phenolic compounds could have a role in regulating mobilization of carbohydrates through degradation of starch, and in turn some role in tbe regulation of seed germination.

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Value of the mucilaginous pellicle to seeds of the sand-stabilizing desert woody shrub Artemisia sphaerocephala (Asteraceae)

Huang

Gutterman

Osborne³

2004

Trees

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Seeds (achenes) of certain desert species (Artemisia) deposit considerable amounts of fixed carbon into an external polysaccharide pellicle that has a high capacity for holding water and can be hydrated and dehydrated many times. One function is considered to be the adhesion of the seed to sand particles during dew which protects from predation by ants. We have questioned whether the germinating embryo could utilize this pellicle as a nutrient source in the poor desert soil. Embryo extracts from dry imbibing and germinating seeds were assayed for a number of specific endo-glycosylase and exo-glycosylase activities and for the ability of these enzymes to degrade preparations of isolated pellicle. No evidence was found for any enzymic cleavage or hydrolysis of the pellicle or for any products to be available for utilization during germination of the seeds. Of commercial enzymes tested only polygalacturonase released reducing sugars from pellicle preparations after long incubation times indicating the high level of resistance of pellicle to enzymic cleavage. Comparisons of the water holding capacity of seeds with or minus their pellicles showed that periods of hydration were extended after dew deposition if pellicle was present. We suggest that a value of pellicle at low water availability is the provision of an enhanced opportunity for metabolic events in the embryo including those of DNA repair, the maintenance of genomic integrity and sustained viability in the seed bank.

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The Control of Dormancy

Cited by 40 publications

References 193 publications

Control Processes in the Induction and Relief of Thermoinhibition of Lettuce Seed Germination

Control Processes in the Induction and Relief of Thermoinhibition of Lettuce Seed Germination

REVERSAL BY PHENOLIC COMPOUNDS OF ABSCISIC ACID‐INDUCED INHIBITION OF IN VITRO ACTIVITY OF AMYLASE FROM SEEDS OF TRITICUM AESTIVUM L.

Value of the mucilaginous pellicle to seeds of the sand-stabilizing desert woody shrub Artemisia sphaerocephala (Asteraceae)

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