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 (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.

scholarly journals Preventing thermoinhibition in a thermosensitive lettuce genotype by seed imbibition at low temperature

2003 ◽  
Vol 60 (3) ◽  
pp. 477-480 ◽  
Author(s):  
Warley Marcos Nascimento
Keyword(s):  
Seed Germination ◽  
Low Temperature ◽  
High Temperatures ◽  
Lactuca Sativa ◽  
Lettuce Seed ◽  
Temperature Dependent ◽  
Lettuce Seeds ◽  
Lactuca Sativa L ◽  
Lettuce Seed Germination ◽  
Dark Green

Lettuce (Lactuca sativa L.) seed germination is strongly temperature dependent and under high temperatures, germination of most of genotypes can be erratic or completely inhibited. Lettuce seeds of 'Dark Green Boston' (DGB) were incubated at temperatures ranging from 15° to 35°C at light and dark conditions. Other seeds were imbibed in dark at 20°; 25°; 30°; and 35°C for 8 and 16 hours and then transferred to 20 or 35°C, in dark. Seeds were also incubated at constant temperature of 20° and 35 °C, in the dark, as control. In another treatment, seeds were primed for 3 days at 15°C with constant light. DGB lettuce seeds required light to germinate adequately at temperatures above 25°C. Seeds incubated at 20°C had 97% germination, whereas seeds incubated at 35°C did not germinate. Seeds imbibed at 20°C for 8 and 16 hours had germination. At 35°C, seeds imbibed initially at 20°C for 8 and 16 hours, had 89 and 97% germination, respectively. Seeds imbibed at 25°C for 16 hours, germinated satisfactory at 35°C. High temperatures of imbibition led to no germination. Primed and non-primed seeds had 100% germination at 20°C. Primed seeds had 100% germination at 35°C, whereas non-primed seeds germinate only 4%. The first hours of imbibition are very critical for lettuce seed germination at high temperatures.

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.

The effect of lettuce seed extracts on lettuce seed germination

1975 ◽  
Vol 53 (7) ◽  
pp. 593-599 ◽  
Author(s):  
Henry L. Speer ◽  
Dorothy Tupper
Keyword(s):  
Abscisic Acid ◽  
Liquid Chromatography ◽  
Seed Germination ◽  
Seed Coat ◽  
Gas Liquid Chromatography ◽  
Lettuce Seed ◽  
Lettuce Seeds ◽  
Grand Rapids ◽  
Lettuce Seed Germination ◽  
Seed Extracts

Lettuce seeds (Lactuca sativa var. Grand Rapids) were found to contain inhibitory substances, one of which is probably abscisic acid. Extracts from seeds were characterized by gas–liquid chromatography, and peaks coincident with abscisic acid were found.The germination water surrounding seeds made secondarily dormant was subjected to gas–liquid chromatography and was also found to contain peaks coincident with abscisic acid. It was also determined that the inhibitory substances are localized in the embryo but not in the endosperm or seed coat.

Persistence of phytochrome-mediated germination control in lettuce seeds for 1 year following a single monochromatic light flash

1972 ◽  
Vol 50 (4) ◽  
pp. 687-689 ◽  
Author(s):  
William Vidaver ◽  
A. I-hsiung Hsiao
Keyword(s):  
Light Flash ◽  
Red Light ◽  
Monochromatic Light ◽  
Entire Period ◽  
Lettuce Seeds ◽  
Light Flashes

The effects of red or far-red light flashes on partially hydrated lettuce seeds were found to be undiminished by subsequent dry, dark storage for more than 1 year before germination. Upon rehydration of the seeds photoreversal of the latent response could be induced by a red or far-red light flash at any time during the entire period.

scholarly journals RELATIONSHIP BETWEEN THE SEED COAT AND EMBRYO IN REGULATING THE EFFECT OF HEAT AND SALT STRESS ON LETTUCE SEED GERMINATION

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1156b-1156
Author(s):  
James Dunlap ◽  
Brian Scully ◽  
Dawn Reyes
Keyword(s):  
Seed Coat ◽  
Turgor Pressure ◽  
Physiological Mechanism ◽  
Nacl Stress ◽  
Lettuce Seed ◽  
Embryo Germination ◽  
Critical Range ◽  
Lettuce Seeds ◽  
Lettuce Seed Germination ◽  
Expansion Force

Poor germination of lettuce seeds exposed to heat and salinity is attributed to a reduction in the capacity for embryo expansion. Ethylene and kinetin are proposed to overcome these stresses by increasing the expansion force of the embryo which ruptures the seed coat barrier to growth. To better understand the physiological mechanism regulating thermodormancy in the embryo, germination was determined for intact and decoated seeds from thermosensitive and thermotolerant varieties subjected to a critical range of temperature and salt (NaCl) stress. Although more tolerant of stress, the response of decoated seeds to ACC and kinetin was similar to the response of intact seeds. No interaction between ACC and kinetin was detected in decoated seed except under the most severe stress and in the thermosensitive variety. Heat and salt tolerance appear to be governed by the same physiological mechanism. We propose that the seed coat plays no qualitative role in the expression of lettuce seed thermodormancy. The response occurs exclusively in the embryo and may result from an inability to generate sufficient turgor pressure at supraoptimal temperatures for cell expansion.

scholarly journals 402 Lettuce Seed Germination and Endo-mannanase Activity are Stimulated by Ethylene at High Temperature

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 513B-513 ◽  
Author(s):  
Warley M. Nascimento ◽  
Daniel J. Cantliffe ◽  
Donald J. Huber
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
Enzyme Regulation ◽  
Seed Priming ◽  
Lettuce Seed ◽  
Endosperm Cell ◽  
Lettuce Seeds ◽  
Mannanase Activity ◽  
Lettuce Seed Germination

Temperatures above 30 °C may delay or inhibit germination of most of commercial lettuce cultivars. Ethylene enhances lettuce seed germination at high temperatures. Enzyme-mediated degradation of endosperm cell walls appears to be a crucial factor for lettuce germination at high temperature. The galactomannan polysaccharides in lettuce endosperm cell wall are mobilized by endomannanase. The role of endo-mannanase during germination of lettuce seeds at high temperature (35 °C) and the possible role of etlene in enzyme regulation were investigated. Seeds of thermotolerant (`Everglades'-EVE) and thermosensitive (`Dark Green Boston'-DGB) lettuce genotypes were incubated at 20 and 35 °C in water, 10 mM of 1-aminocyclopropane-1-carboxylic acid (ACC), or 20 mM of silver thiosulphate (STS). Also, seeds were primed in an aerated solution of polyethylene glycol (PEG), or PEG+ACC, or PEG+STS. Untreated seeds germinated 100% at 20 °C. At 35 °C, EVE germinated 100%, whereas DGB germinated only 33%. Seed priming or adding ACC during imbibition increased germination of DGB to 100% at 35 °C. Adding STS during imbibition led to a decrease in germination at 35%C in EVE and completely inhibited germination of DGB. Priming with STS led to reduced germination at 35%C of both genotypes. EVE produced more ethylene than DGB during germination at high temperature. Providing ACC either during priming or during germination led to an increase in endo-mannanase activity, whereas STS inhibited mannanase activity. Higher endo-mannana activity was observed in EVE than DGB seeds. The results suggest that ethylene might overcome the inhibitory effect of high temperature in thermosensitive lettuce seeds via weakening of endosperm due to increased endo-mannanase activity.

scholarly journals The effects of three plasma-activated water generation systems on lettuce seed germination

2021 ◽  
Author(s):  
rouzbeh abbaszadeh ◽  
Pegah KHOSRAVİ NİA ◽  
Mahsa Fattahi ◽  
Hamid Ghomi
Keyword(s):  
Water Treatment ◽  
Electrical Discharge ◽  
Water Surface ◽  
Germination Rate ◽  
Lettuce Seed ◽  
New Approach ◽  
Lettuce Seeds ◽  
Mean Germination Time ◽  
Lettuce Seed Germination ◽  
Plasma Activated Water

Irrigation water treatment using plasma technology is a new approach to improve productivity. In this study the generation of plasma-activated water (PAW) as a novel subject in agriculture is investigated. Three water treatment systems were designed and evaluated: 1<sup>st</sup> PAW generation from vapor and injection into the water, 2<sup>nd</sup> PAW generation using electrical discharge on the water surface and 3<sup>rd</sup> PAW generation in the aeration path into the water. The lettuce seeds were irrigated with PAW. The germination rate and mean germination time were measured after 6 days. The seedlings weight and the number of seedlings with a length of more than 3 cm were also recorded after 8 days. The results showed that PAW had a significant effect on the germination rate and length of seedlings. Electrical discharge on the water surface had the best results. Germination rate and the number of seedlings with a length of more than 3 cm increased by 11 and 36% respectively. While injection of plasma-treated air into the water significantly reduced the number of seedlings longer than 3 cm, compared to the control. In conclusion, the PAW application can improve some attributes of lettuce germination depending on the PAW system.  

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