Secondary dormancy in light-sensitive lettuce seeds incubated anaerobically or at elevated temperature

1975 ◽  
Vol 53 (22) ◽  
pp. 2557-2560 ◽  
Author(s):  
William Vidaver ◽  
A. I. Hsiao
Keyword(s):  
Elevated Temperature ◽  
Red Light ◽  
Lettuce Seeds ◽  
Secondary Dormancy ◽  
Phytochrome System ◽  
Temperature Induction ◽  
Dormancy Induction

Light-sensitive lettuce seeds become secondarily dormant within 8–10 days if initial germination is suppressed by far-red light or incubation at elevated temperature (≥30 °C). When germination is suppressed by temperature, induction of dormancy occurs in both red and far-red irradiated seeds and the process is, therefore, independent of the phytochrome system. Dormancy induction requires oxygen, but reversion of phytochrome from the far-red- to the red-absorbing form appears to take place anaerobically.

ACTION AND INTERACTION OF MONOCHROMATIC LIGHT ON PHOSPHATE METABOLISM OF GERMINATING LETTUCE SEEDS

1962 ◽  
Vol 40 (7) ◽  
pp. 965-974 ◽  
Author(s):  
Kenneth Surrey
Keyword(s):  
Energy Flow ◽  
Spectral Band ◽  
Red Light ◽  
Monochromatic Light ◽  
Lettuce Seed ◽  
Phosphate Metabolism ◽  
Lettuce Seeds ◽  
Phytochrome System ◽  
Lettuce Seed Germination ◽  
Partial Suppression

A previously described photoresponse of lettuce seed germination to red and far-red light is shown to be paralleled by a response of phosphate metabolic activity: (1) When seeds were continuously irradiated, red light accelerated and far-red suppressed their phosphate uptake and esterification. (2) The influence of monochromatic light on phosphate metabolism of seeds, determined after 36 and 64 hours of germination, respectively, indicated maximum potentiation between 550 and 650 mμ, maximum suppression beyond 700 mμ, and partial suppression at 475 mμ. Stimulation was encountered at 400 mμ, but with shorter wavelengths of the ultraviolet spectrum, suppression appeared again. (3) Photoactivation of phosphate metabolism in response to each of the three loci (550, 600, and 650 mμ, i.e., green, orange, and red light, respectively) of the potentiating spectral band was reversed by far-red (750 mμ) light. These activations and inhibitions could be reversed several times in an alternating sequence. Complete reversibility depended entirely upon the magnitudes of the radiant flux for the two counteracting wavelengths, and this was characteristic for each pair of antagonistic wavelengths. In view of the association of phytochrome with the isolated mitochondria and of the specific manner in which their phosphorylation activity is influenced by light, it is suggested that a part of the energy flow required for cellular development may be channeled through the mitochondrial–phytochrome system.

scholarly journals Induction of Dormancy in Nondormant Seeds

1994 ◽  
Vol 119 (3) ◽  
pp. 408-413 ◽  
Author(s):  
Anwar A. Khan
Keyword(s):  
Abscisic Acid ◽  
Lycopersicon Esculentum ◽  
Gibberellic Acid ◽  
Lactuca Sativa ◽  
Daucus Carota ◽  
Apium Graveolens ◽  
Lettuce Seeds ◽  
Moist Chilling ◽  
Dormancy Induction ◽  
Ga Biosynthesis

A gibberellic acid (GA) biosynthesis inhibitor, tetcyclacis, induced dormancy in nondormant seeds of lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), pepper (Capsicum annuum L.), carrot [Daucus carota var. sativus (Hoffn.)], onion (Allium cepa L.), celery (Apium graveolens L.), and impatiens (Impatiens novette), as most of the seeds failed to germinate after washing under conditions that permitted germination before dormancy induction. In lettuce seeds, tetcyclacis and paclobutrazol were more effective in inhibiting germination in light than in darkness. A 16- to 24-h soak treatment with tetcyclacis was sufficient to induce dormancy in nearly all seeds. Tetcyclacis failed to induce dormancy if applied after 6 h presoak in water. Dormancy induced by tetcyclacis was released by GA4+7 (a mixture of gibberellin A4 and A7), light, and moist-chilling treatments. When GA4+7 was applied with tetcyclacis, dormancy induction was prevented under both favorable, e.g., 25C, and unfavorable, e.g., 5C, or low water potential (Ψ), germination conditions. Unlike tetcyclacis, abscisic acid (ABA) failed to induce dormancy in lettuce seeds. Thermodormancy induction in lettuce seeds at 35C was prevented by fluridone. However, neither ABA nor tetcyclacis countered its effect. Dormancy was also induced in lettuce seeds by ancymidol, flurprimidol, or paclobutrazol. Dormancy induced by tetcyclacis in pepper, tomato, carrot, and onion seeds was released by GA4+7, but not by irradiation or moist-chilling. Chemical names used: 5-(4-chlorophenyl)-3, 4, 5, 9, 10-pentaazatetracyclo [5.4.102,6.08,11]-dodeca-3, 9-diene (tetcyclacis); 1-(4-chlorophenyl)-4, 4-dimethyl-2-(1H-1, 2, 4-triazole-1-yl)-3-pentanol (paclobutrazol); α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine methanol (ancymidol); α-(1-methyl)-α-[4-(trifluoromethoxy) phenyl]-5-pyrimidine-methanol (flurprimidol); 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4 (1H)-pyridinone (fluridone).

The growth physics and water relations of red-light-induced germination in lettuce seeds

Planta ◽  
1971 ◽  
Vol 101 (1) ◽  
pp. 1-25 ◽  
Author(s):  
Murray W. Nabors ◽  
Anton Lang
Keyword(s):  
Water Relations ◽  
Red Light ◽  
Lettuce Seeds

scholarly journals Differential Control of Embryo Growth Potential in Lettuce and Tomato Seeds

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 527A-527 ◽  
Author(s):  
Gokhan Hacisalihoglu ◽  
Anwar A. Khan
Keyword(s):  
Germination Rate ◽  
Growth Potential ◽  
Physical Factors ◽  
Release Process ◽  
Aging Period ◽  
Lettuce Seeds ◽  
Tomato Seeds ◽  
Chemical Solutions ◽  
Differential Control ◽  
Dormancy Induction

The effects of chemical or physical factors during pregermination imbibition phase, or on dry seeds, on embryo growth potential (EGP) was studied in lettuce (Grand Rapids and Mesa 659) and tomato (H-9889) seeds in relation to dormancy, invigoration, and vigor loss. Embryos were excised from treated seeds (washed if imbibed in chemical solutions) and their growth rate (a measure of EGP) followed at 25°C at high magnification (X55). Treated seeds were also germinated at 25°C. In lettuce seeds, dormancy inducing treatments, i.e., a 2-day dark soak at 25°C with 50–100 μM tetcyclacis (TCY) or a 2-day dark soak in water at 35°C, reduced the subsequent embryo growth and germination rate at 25°C. The reduction was prevented by 1 mM GA4+7 or irradiation applied during dormancy induction. A -d osmoconditioning (OC) at 15C with -1.2 MPa PEG-8000 solution in light or in dark with added GA4+7 enhanced the EGP; addition of TCY reduced the EGP and the TCY inhibition reversed by GA4+7. A progressive reduction in EGP occurred with increase in vigor loss. In tomato seeds, a soak with 100 μM TCY in light or dark for 2 days at 30°C induced a dormancy, but had little effect on EGP. Application of GA4+7 plus TCY prevented dormancy induction without affecting EGP. A 4-day matriconditioning (MC) at 25°C in light or dark with moist Micro-Cel E enhanced the EGP; TCY and/or GA added during MC, had little effect on EGP. EGP progressively decreased as the aging period increased. Thus, in lettuce, the EGP is coupled with the reversible –GA/+GA or phytochrome-controlled dormancy induction/release process, enabling germination, its inhibition, or its enhancement. In tomato, the EGP is not subject to light or GA control. Reduction in EGP, accompanying vigor loss in both seeds, is independent of light or GA action.

scholarly journals (421) Light and Temperature Interactions in Promoting Lettuce Seed Germination

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1021E-1022
Author(s):  
Samuel Contreras ◽  
David Tay ◽  
Mark Bennett
Keyword(s):  
Red Light ◽  
Light Treatment ◽  
Effect Of Temperature ◽  
Lettuce Seed ◽  
Lettuce Seeds ◽  
Radicle Emergence ◽  
Lettuce Seed Germination ◽  
Temperature Interactions ◽  
Soaking Temperature ◽  
Light Break

Lettuce seeds (Lactuca sativavar. acephalacv. Tango) were used with the objective of determining the effect of temperature, light, and their interactions in promoting germination. Under standard op-timal conditions (20 °C, light), the seed presented 100% germination (radicle emergence 5 d after sowing). Different treatments evaluated germination under dark conditions, with or without a red light break (LB, 28.8 mmol·m-2) 48 h after sowing, and with different combination of temperatures pre- (soaking temperature, ST) and post- (germination temperature, GT) the LB. Germination at constant 20 °C without LB was less than 5%, and with LB, it was around 30%. However, germination was close to 100% at GT of 20 °C when LB was applied after a ST of 10 °C, and around 50% under the same conditions, but without LB. When GT was 30 °C and LB was applied, germination was less than 3% with ST = 30 °C, less than 10% with ST = 20 °C, and around 100% when ST = 10 °C. With ST and GT of 10 °C and 30 °C, respectively, and no LB, germination was less than 5%. Germination at 10 °C constant, with and without LB, was around 90% and 0%, respectively. When ST was 40 °C and LB was applied, germination was around 40% at GT= 20 °C, but less that 3% with GT= 30 °C. In summary, a severe inhibition of germination was observed when seeds were germinated in dark, which was partially reversed by either a light treatment or soaking at 10 °C, and fully reversed when both treatments were applied together. Inhibition of lettuce germination at 30 °C was observed when this temperature was applied after a light treatment, but not when applied before. Possible implications of these results for the phytochrome mechanism of action are discussed.

Growth physics and water relations of red-light-induced germination in lettuce seeds

Planta ◽  
1981 ◽  
Vol 152 (2) ◽  
pp. 131-136 ◽  
Author(s):  
Nicholas C. Carpita ◽  
Murray W. Nabors
Keyword(s):  
Water Relations ◽  
Red Light ◽  
Lettuce Seeds
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