scholarly journals SEASON OF SEED DEVELOPMENT AFFECTS GERMINATION OF LETTUCE SEED WITH HIGH TEMPERATURE

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1148g-1149
Author(s):  
Margaret Mnichowicz ◽  
Janice Coons ◽  
John McGrady
Keyword(s):  
Electrical Conductivity ◽  
Seed Germination ◽  
High Temperatures ◽  
Lettuce Seed ◽  
Lactuca Sativa L ◽  
Relative Tolerance ◽  
Percent Germination ◽  
Early Fall ◽  
Measured Field ◽  
Petri Dishes

Lettuce (Lactuca sativa L.) seed germination is inhibited at temperature higher than 25-30C. The extent of this inhibition varies between seed lots. Our objective was to determine how the season during which seed develops affects the ability of seeds to germinate and establish a stand at high temperatures. Lettuce seed, `Empire', was produced during 2 summers and 2 winters (1988 and 1989) in Yuma, AZ. These seeds were germinated at 20, 25, 30 or 35C in petri dishes or in growth pouches to determine percent germination or root lengths, respectively. Electrical conductivity of seed leachates was measured. Field emergence of seeds was tested with early fall plantings in Yuma, AZ. Percent seed germination was greater and root lengths were longer for the seeds produced in summer than in winter. Conductivity will be correlated with relative tolerance to high temperatures of the different seed lots. In the field, percent emergence of seed lots from summer and winter averaged 60% and 38%, respectively.

scholarly journals SEASON OF SEED DEVELOPMENT AFFECTS GERMINATION OF LETTUCE SEED WITH HIGH TEMPERATURE

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1148G-1149
Author(s):  
Margaret Mnichowicz ◽  
Janice Coons ◽  
John McGrady
Keyword(s):  
Electrical Conductivity ◽  
Seed Germination ◽  
High Temperatures ◽  
Lettuce Seed ◽  
Lactuca Sativa L ◽  
Relative Tolerance ◽  
Percent Germination ◽  
Early Fall ◽  
Measured Field ◽  
Petri Dishes

Lettuce (Lactuca sativa L.) seed germination is inhibited at temperature higher than 25-30C. The extent of this inhibition varies between seed lots. Our objective was to determine how the season during which seed develops affects the ability of seeds to germinate and establish a stand at high temperatures. Lettuce seed, `Empire', was produced during 2 summers and 2 winters (1988 and 1989) in Yuma, AZ. These seeds were germinated at 20, 25, 30 or 35C in petri dishes or in growth pouches to determine percent germination or root lengths, respectively. Electrical conductivity of seed leachates was measured. Field emergence of seeds was tested with early fall plantings in Yuma, AZ. Percent seed germination was greater and root lengths were longer for the seeds produced in summer than in winter. Conductivity will be correlated with relative tolerance to high temperatures of the different seed lots. In the field, percent emergence of seed lots from summer and winter averaged 60% and 38%, respectively.

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.

Influence of Heat on Seed Germination of Cistus Laurifolius and Cistus Ladanifer

1992 ◽  
Vol 2 (1) ◽  
pp. 15 ◽  
Author(s):  
L Valbuena ◽  
R Tarrega ◽  
E Luis
Keyword(s):  
Seed Germination ◽  
High Temperatures ◽  
Exposure Time ◽  
Germination Rate ◽  
Heat Exposure ◽  
Cistus Ladanifer ◽  
Different Temperatures ◽  
Petri Dishes ◽  
Germinated Seeds

The influence of high temperatures on germination of Cistus laurifolius and Cistus ladanifer seeds was analyzed. Seeds were subjected to different temperatures for different times, afterwards they were sowed in plastic petri dishes and monitored for germinated seeds over two months.The germination rate observed in Cistus ldanifer was greater than in Cistus laurifolius. In both species, heat increased germination percentages. For Cistus laurifolius higher temperatures or longer exposure times were needed. Germination percentages of Cistus ladanifer were lower when heat exposure time was 15 minutes.It must be emphasized that germination occurred when seeds were not treated, while seeds exposed to 150�C for 5 minutes or more did not germinate.

The effects of ultra-high diluted gibberellic acid on in vitro lettuce seed germination.

2021 ◽  
Vol 15 (4) ◽  
pp. 50-54
Author(s):  
Carolina Santos Barreto ◽  
Fortune Homsani ◽  
Nina C Barboza Da Silva ◽  
Carla Holandino
Keyword(s):  
Gibberellic Acid ◽  
Lactuca Sativa ◽  
Germination Rate ◽  
Petri Dish ◽  
New Drugs ◽  
Lettuce Seed ◽  
Lettuce Seeds ◽  
Lactuca Sativa L ◽  
Petri Dishes

Lettuce seeds bioassays have been used in many different tests such as: alellopathyc models; developing of new drugs; ecotoxicity tests. In most cases, lettuce (Lactuca sativa L., Asteraceae) has been used because of its sensitivity, simultaneous and rapid germination, reliability of germination percentage and homogeneity of seeds. The main goal was to evaluate the effects of ultra-high diluted gibberellic acid (GA3) on lettuce seeds germination and seedling growth. Experiment was performed using Petri dishes containing one disk of Whatman nº01 paper watered with 1ml of water. In each Petri dish 10 lettuce seeds(Lactuca sativa L.) cv Regina 500 were placed and 2ml of the different treatment solutions were add: GA33µmol, GA3 3CH (10-6), GA3 12CH (10-24), water 12CH and water (no dilution and succussion). One milliliter solutions were added every 2 days of experiment. The experiment was repeated twice and each one consisted in 5 Petri dishes per treatment (n=100). All seeds were maintained in germination incubator under controlled temperature (25°C) and photoperiod (16L/8D). The tested substances were prepared according to Brazilian Homeopathic Pharmacopoeia (Brazil, 2011). The experiment was blinded all the time. All seeds germinated at same time (2 days) and after 7 days the germination rate was the same in all treatments. Root was affected just by Water 12 CH, in which shown the longest length (4.59 cm) when compared with others treatments. Shoot length was higher where gibberellin was added in concentration upper then Avogrado’s number.

scholarly journals 871 PB 223 IMPROVED GERMINATION OF PANSY SEED AT HIGH TEMPERATURES BY PRIMING WITH SALT SOLUTIONS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 558e-558
Author(s):  
Beyoung-han Yoon ◽  
Harvey J. Lane ◽  
B. Greg Cobb
Keyword(s):  
Polyethylene Glycol ◽  
Seed Germination ◽  
High Temperatures ◽  
Salt Solution ◽  
Salt Solutions ◽  
All Solutions ◽  
Germination Temperature ◽  
Percent Germination ◽  
Priming Process ◽  
Total Seed

Pansy (Viola × wiffrockiana cv. Majestic Giant Blue Shades and Crystal Bowl Sky Blue) seeds were primed in various salt sololions at -1.0 MPa for 3, 6 or 9 days at 23C to determine if priming could overcome thermoinhihition at high temperatures (30C and above). Salt solutions tested were KNO3, KCl, NaCl, MgCl2, Na2SO4, Na2HPO4, K2HPO4 and CaCl2, with polyethylene glycol (PEG) serving as a comparison non-salt solution. Total percent germination (G) of non-primed seeds decreased significantly for both cultivars as germination temperature increased from 25C to 35C. Total seed germination and time to 50% germination (TS,) varied widely among the different priming solutions, with all solutions decreasing Tso as compared to non-primed seeds. Seeds primed with PEG for 6 and 9 days, however, germinated during the priming process and were not further examined. Priming did not significantly improve total percent germination versus non-primed seed at 25C. Seeds that had the best G and T50 at temperatures at or above 30C were those primed for 3 days with CaCl2 (for `Crystal Bowl' there was a 40% increase in G at 35C), and MgCl2 (for `Majestic Giant' there was a 15% increase in G at 35C).

scholarly journals Effects of Salinity, Temperature, and pH on Germination of Echinacea angustifolia Seeds

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 869F-869
Author(s):  
Kyu-Min Lee ◽  
Qudsia Hussaini ◽  
Shanqiang Ke ◽  
Chiwon W. Lee
Keyword(s):  
Seed Germination ◽  
Incubation Temperature ◽  
Echinacea Angustifolia ◽  
Nacl Concentration ◽  
Percent Germination ◽  
Petri Dishes ◽  
Ph Range

The influences of NaCl concentration, incubation temperature, and pH on the germination of Echinacea angustifolia seeds were investigated. Dehulled, surface-disinfected seeds were germinated in petri dishes containing 0, 0.5, 1, 1.5, 2.0, 2.5, 3.0, 3.5, or 4.0 g–liter–1 NaCl at 12, 17, 22, or 27C for 10 days. Percent seed germination was the highest at 0 ppm NaCl and was progressively reduced as NaCI concentrations increased to 4 g–liter–1 at all temperatures. The NaCI suppression of germination was most severe when seeds were incubated at 27C. No germination occurred at 12C. When seeds were germinated over a pH range from 4 to 11, the highest percent germination occurred at pHs between 6 and 8 at 25C.

scholarly journals Distinct Metabolome Changes during Seed Germination of Lettuce (Lactuca sativa L.) in Response to Thermal Stress as Revealed by Untargeted Metabolomics Analysis

2020 ◽  
Vol 21 (4) ◽  
pp. 1481 ◽  
Author(s):  
Shiwei Wei ◽  
Xiao Yang ◽  
Guotao Huo ◽  
Guojun Ge ◽  
Hongyan Liu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Thermal Stress ◽  
Seed Germination ◽  
Organic Acids ◽  
Lactuca Sativa ◽  
Sesquiterpene Lactones ◽  
Germination Percentage ◽  
Untargeted Metabolomics ◽  
Lettuce Seed ◽  
Lactuca Sativa L

Temperature strongly influences lettuce (Lactuca sativa L.) seed germination. Different lettuce genotypes respond differently to higher temperatures or thermal stress. In this study, we evaluated the germination performance of 304 lettuce accessions incubated at three temperature settings, 21 °C, 28 °C and 35 °C, respectively, for 40 h. At 21 °C, seeds of all 304 accessions germinated with very well an average germination percentage of 87.72%; at 28 °C, the average germination percentage dropped to 42.84% and at 35 °C, the germination decreased to 1.01%. Then, we investigated changes in metabolic profiles of lettuce seed response to thermal stress using an untargeted metabolomics approach. Results suggested that seeds of thermal-sensitive and thermal-tolerant cultivars employed different metabolic strategies in response to thermal stress during germination. Thermal-sensitive buds accumulated more significant amounts of organic acids, amino acids, sugars, sterols, phenolic compounds and terpenoids compared to thermal-tolerant buds at 21 °C. Thermal-tolerant lettuce cultivar accumulated higher concentrations of amino acids, organic acids, sugars, sesquiterpene lactones, sterols, and fatty acids derivatives during the germination at 35 °C compared to germinated at 21 °C. This investigation paves the way to link the metabolomics to other external and internal factors affecting lettuce seed germination under thermal stress.

Effects of wetting and drying on seed germination and seedling emergence of bull thistle, Cirsium vulgare (Savi) Ten.

2000 ◽  
Vol 78 (12) ◽  
pp. 1545-1551 ◽  
Author(s):  
Michael P Downs ◽  
Paul B Cavers
Keyword(s):  
Seed Germination ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Light Availability ◽  
Constant Darkness ◽  
Wetting And Drying ◽  
Cirsium Vulgare ◽  
Percent Germination ◽  
Petri Dishes ◽  
Bull Thistle

Seeds of bull thistle, Cirsium vulgare (Savi) Ten., were exposed to varying numbers of cycles of wetting and drying, in both Petri dishes and pots of soil, to investigate the effects of exposure to such cycles on subsequent germination of the seeds or emergence of the seedlings. Following exposure to the cycles, seeds in Petri dishes were set to germinate in one of four diurnal environments: 20:10°C alternating light and darkness, 20:10°C constant darkness, 30:15°C alternating light and darkness, or 30:15°C constant darkness. Total percent germination was reduced after exposure to eight cycles of wetting and drying, and germination rate was reduced after exposure to two or more cycles. Percent germination was reduced at the higher temperature but light availability had little effect. Reduction in seedling emergence in pots of soil after exposure to an intermediate number of cycles was greater than in Petri dishes but not as great with exposure to eight cycles. Seedling emergence patterns in pots that experienced any wetting-drying treatment were bimodal, with a second pulse of emergence several weeks after the termination of the cycles. This suggests that some seeds were induced into a dormant state through exposure to the cycles of wetting and drying. Such induced dormancy may serve to prevent seed germination in the autumn, promoting an attenuated and intermittent pattern of germination.Key words: Cirsium vulgare, bull thistle, wetting and drying, seed germination, induced dormancy, intermittent germination.

Endo-β-mannanase Activity and Seed Germination of Thermosensitive Lettuce Genotype in Response to Temperature and Seed Priming

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 543a-543 ◽  
Author(s):  
Warley M. Nascimento ◽  
Daniel J. Cantliffe ◽  
Donald J. Huber
Keyword(s):  
Seed Germination ◽  
High Temperatures ◽  
Seed Priming ◽  
Inhibitory Effect ◽  
Lettuce Seed ◽  
Lettuce Seeds ◽  
Radicle Protrusion ◽  
Mannanase Activity ◽  
Dark Green ◽  
Response To Temperature

Under high temperatures (above 30 °C) in the greenhouse (transplant industry) or field, lettuce germination can be erratic or completely inhibited. Seed priming circumvents thermodormancy of lettuce seeds and allows germination at higher temperatures. Weakening of the endosperm layer of lettuce seeds is a prerequisite to radicle protrusion at high temperatures. Enzyme-mediated degradation of endosperm cell walls may be a crucial factor for lettuce seed germination at high temperatures. Softening of the endosperm could occur during seed priming and result in improved germination. A single-seed assay for endo-β-mannanase was used to follow the activity of this enzyme during priming in lettuce seeds. We also investigated the effects of seed priming on seed germination and mannanase activity at both inhibitory and non-inhibitory temperatures for seed germination in a thermosensitive lettuce cultivar Dark Green Boston. Seeds were primed for 3 days at 15 °C with constant light in aerated solutions of polyethylene glycol (PEG) at an osmotic potential of –1.2 MPa. Afterward, seeds were rinsed and redried at 10 °C and 45% RH for 3 days. Primed and nonprimed seeds germinated 100% at 20 °C. At 35 °C, primed seeds germinated 100%, whereas nonprimed seeds did not germinate. During priming, endo-β-mannanase activity increased between 24 and 72 h after the beginning of osmotic imbibition. Mannanase activity persisted in primed seeds, even following seed drying. Radicle protrusion did not occur under the priming conditions used in this study. Higher enzyme activity was observed in primed seeds compared with nonprimed seeds. The results suggest that priming overcomes the inhibitory effect of high temperature in thermosensitive lettuce seeds by weakening of endosperm due to increased endo-β-mannanase activity.

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