Fluctuating temperature and light influence seed germination of goosegrass (Eleusine indica)

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 426-429 ◽  
Author(s):  
Roy K. Nishimoto ◽  
Lambert B. McCarty
Keyword(s):  
Seed Germination ◽  
Temperature Regime ◽  
Fluctuating Temperature ◽  
Eleusine Indica ◽  
Temperature Cycles ◽  
Temperature Regimes ◽  
Moist Environment

This research examined the effect of duration of the warm cycle and number of fluctuating temperature/light cycles on goosegrass seed germination. Less than 10% goosegrass seed germination occurred at constant temperatures of 20, 25, and 35 C, while 99% germinated at daily fluctuating temperature regimes of 20 C for 16 h and 35 C for 8 h with light. Increasing the number of fluctuating temperature cycles increased goosegrass seed germination. Fluctuating temperature cycles with 22 h at 20 C and 2 h at 35 C with light strongly stimulated germination, but not as much as the cycle with 8 h at 35 C. Goosegrass seed germination ceased once the fluctuating temperature regime was discontinued, and constant 20 C with 8 h light daily was reimposed. Germination occurred only on resumption of fluctuating temperature cycles. Seed incubated for several weeks in a moist environment at constant 20 C had 81 to 91% germination with two cycles of 20 C for 16 h and 35 C for 8 h, compared to 14% for fresh seeds.

Can alternating temperature, moist chilling, and gibberellin interchangeably promote the completion of germination in Clematis vitalba seeds?

Botany ◽  
2017 ◽  
Vol 95 (8) ◽  
pp. 847-852 ◽  
Author(s):  
Rosangela Picciau ◽  
Marco Porceddu ◽  
Gianluigi Bacchetta
Keyword(s):  
Seed Germination ◽  
Gibberellic Acid ◽  
Plant Species ◽  
Temperature Regime ◽  
Fluctuating Temperature ◽  
Temperature Regimes ◽  
Moist Chilling ◽  
Clematis Vitalba ◽  
Alternating Temperature ◽  
Positive Effect

Each plant species has particular requirements for seed germination, and some of them respond differently to constant or alternating temperature regimes. In this study, the interchangeable effects of different treatments and temperatures on the completion of seed germination of Clematis vitalba L. were investigated. The seeds were tested with a constant (from 5 °C to 25 °C) or a fluctuating (25/10 °C) temperature regime, and the effect of gibberellic acid (GA3), incubation at warm (W) or cold (C) temperatures while being imbibed, and drying after ripening (DAR) were evaluated. The final germination percentages and the time in days required to reach 50% of germination (T50) were calculated. GA3 and C significantly enhanced completion of seed germination at all of the temperatures tested. A strong positive effect of alternating temperature was observed, which triggered completion of seed germination regardless of treatment. Under the fluctuating temperature, the chilled seeds had the most rapid germination. Low germination rates were observed for both control and DAR treatments. Seeds of C. vitalba display a certain degree of dormancy, which can be broken by moist chilling and GA3 treatments. Moreover, alternating temperature stimulates the completion of seed germination by satisfying certain physiological requirements for germination under constant temperatures.

scholarly journals Assessing the role of two populations of Aedes japonicus japonicus for Zika virus transmission under a constant and a fluctuating temperature regime

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Uros Glavinic ◽  
Jasmin Varga ◽  
Anca Ioana Paslaru ◽  
Jeannine Hauri ◽  
Paul Torgerson ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Temperature Regime ◽  
Zika Virus ◽  
Incubation Temperature ◽  
Transmission Rate ◽  
Control Measures ◽  
Fluctuating Temperature ◽  
Laboratory Conditions ◽  
Temperature Regimes ◽  
Two Populations

Abstract Background Since the huge epidemic of Zika virus (ZIKV) in Brazil in 2015, questions were raised to understand which mosquito species could transmit the virus. Aedes aegypti has been described as the main vector. However, other Aedes species (e.g. Ae. albopictus and Ae. japonicus) proven to be competent for other flaviviruses (e.g. West Nile, dengue and yellow fever), have been described as potential vectors for ZIKV under laboratory conditions. One of these, the Asian bush mosquito, Ae. japonicus, is widely distributed with high abundances in central-western Europe. In the present study, infection, dissemination and transmission rates of ZIKV (Dak84 strain) in two populations of Ae. japonicus from Switzerland (Zürich) and France (Steinbach, Haut-Rhin) were investigated under constant (27 °C) and fluctuating (14–27 °C, mean 23 °C) temperature regimes. Results The two populations were each able to transmit ZIKV under both temperature regimes. Infectious virus particles were detected in the saliva of females from both populations, regardless of the incubation temperature regime, from 7 days post-exposure to infectious rabbit blood. The highest amount of plaque forming units (PFU) (400/ml) were recorded 14 days post-oral infection in the Swiss population incubated at a constant temperature. No difference in terms of infection, dissemination and transmission rate were found between mosquito populations. Temperature had no effect on infection rate but the fluctuating temperature regime resulted in higher dissemination rates compared to constant temperature, regardless of the population. Finally, transmission efficiency ranged between 7–23% and 7–10% for the constant temperature and 0–10% and 3–27% under fluctuating temperatures for the Swiss and the French populations, respectively. Conclusions To the best of our knowledge, this is the first study confirming vector competence for ZIKV of Ae. japonicus originating from Switzerland and France at realistic summer temperatures under laboratory conditions. Considering the continuous spread of this species in the northern part of Europe and its adaptation at cooler temperatures, preventative control measures should be adopted to prevent possible ZIKV epidemics.

Effect of light, salinity, and temperature on seed germination of Limonium stocksii

2004 ◽  
Vol 82 (2) ◽  
pp. 151-157 ◽  
Author(s):  
Sabahat Zia ◽  
M Ajmal Khan
Keyword(s):  
Seed Germination ◽  
Temperature Regime ◽  
Germination Rate ◽  
Gradual Decrease ◽  
Salinity Treatment ◽  
Optimal Temperature ◽  
Complete Darkness ◽  
Temperature Regimes ◽  
Effect Of Light ◽  
Recovery Temperature

Limonium stocksii (Boiss.) Kuntze (Plumbaginaceae) is a perennial, woody shrub distributed at Hawks Bay, Karachi, Pakistan. Experiments were carried out to investigate seed germination responses of L. stocksii at different salinities (0, 100, 200, 300, 400, and 500 mmol/L NaCl) and under different temperature regimes (10:20, 15:25, 20:30, and 25:35 °C), both in a 12 h dark : 12 h light photoperiod and in complete darkness. The highest percentage of germination (about 100%) was obtained at 0, 100, and 200 mmol/L NaCl at 20:30 °C, and a further increase in salinity resulted in a gradual decrease in germination. Less than 5% of seeds germinated at 500 mmol/L NaCl. Germination under salinity treatment at 15:25 °C was slightly more inhibitory than the optimal temperature regime, whereas under both 10:20 and 25:35 °C temperature regimes, seed germination was substantially reduced and few seeds germinated at concentrations higher than 200 mmol/L NaCl. Germination rate was fastest at 20:30 °C and slowest at 10:20 °C. Relatively low seed germination was obtained in the dark in comparison to seeds germinated in a 12-h photoperiod under saline conditions. Recovery experiments showed that exposure of seeds to various salinity and temperature regimes had little effect on viability of seeds.Key words: germination, light, Limonium stocksii, NaCl, recovery, temperature.

scholarly journals Assessing the role of two populations of Aedes japonicus japonicus for Zika virus transmission under a constant and a fluctuating temperature regime.

2020 ◽  
Author(s):  
Uros Glavinic ◽  
Jasmin Varga ◽  
Anca Iona Paslaru ◽  
Jeannine Hauri ◽  
Paul Torgerson ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Temperature Regime ◽  
Zika Virus ◽  
Incubation Temperature ◽  
Transmission Rate ◽  
Control Measures ◽  
Fluctuating Temperature ◽  
Laboratory Conditions ◽  
Temperature Regimes ◽  
Two Populations

Abstract Background Since the huge epidemic of Zika virus (ZIKV) in Brazil in 2015, questions were raised to understand which mosquito species could transmit the virus. Aedes aegypti has been described as the main vector. However, other Aedes species (e.g. Ae. albopictus and Ae. japonicus) proven to be competent for other Flaviviruses (e.g.West Nile, dengue and yellow fever), have been described as potential vector for ZIKV under laboratory conditions. To name one, the Asian bush mosquito Ae. japonicus which is widely distributed with high abundances in Central-Western Europe. In the present study, infection, dissemination and transmission rates of ZIKV (Dak84 strain) in two populations of Ae. japonicus from Switzerland (Zürich) and France (Steinbach, Haut-Rhin) were investigated under constant (27 °C) and fluctuating (14-27 °C, mean 23 °C) temperature regimes.Results The two populations were each able to transmit ZIKV under both temperature regimes. Infectious virus particles were detected in the saliva of females from both populations, regardless of the incubation temperature regime, from 7 days post exposure to infectious rabbit blood. The highest amount of Plaque Forming Unit (PFU) (400/ml) were recorded 14 days post oral infection in the Swiss population incubated at constant temperature. No difference in term of infection, dissemination and transmission rate were found between mosquito populations.Temperature had no effect on infection rate but the fluctuating temperature regime resulted in higher dissemination rates comparing to constant temperature, regardless of the population. Finally, transmission efficiency ranged between 7-23% and 7-10% for the constant temperature and 0-10% and 3-27% under fluctuating temperatures for the Swiss and the French populations, respectively.Conclusions This is the first work confirming vector competence for ZIKV of Ae. japonicus originating from Switzerland and France at realistic summer temperatures under laboratory conditions. Considering the continuous spread of this species in the northern part of Europe and its adaptation at cooler temperatures, preventative control measures should be adopted to prevent possible ZIKV epidemics.

scholarly journals Seed Germination of Annual Vinca Responds to Irradiation and Temperature

HortScience ◽  
1995 ◽  
Vol 30 (2) ◽  
pp. 357-359 ◽  
Author(s):  
Frank A. Blazich ◽  
Paul H. Henry ◽  
Farrell C. Wise
Keyword(s):  
Seed Germination ◽  
Catharanthus Roseus ◽  
Strong Interaction ◽  
Temperature Regime ◽  
Heat Input ◽  
Controlling Factor ◽  
The Other ◽  
Constant Darkness ◽  
Irradiation Regime ◽  
Temperature Cycles

Seeds of `Dawn Carpet' and `Little Bright Eye' annual vinca [Catharanthus roseus (L.) G. Don] were subjected to 32 treatments, arranged as a four × four × two factorial. For each cultivar, seeds were exposed to one of four temperatures (15, 20, 25, or 30C) during the 8-hour (day) and 16-hour (night) portions of the cycle. Within each temperature regime, half the seeds of each cultivar were irradiated for 1 hour daily, and the other half remained in constant darkness. Final germination percentages were suppressed at 15C day or night temperatures; at temperatures ≥20C, there were no significant differences between treatments. Heat input (daily degree hours) was a controlling factor in germination; different temperature cycles with equivalent numbers of daily degree hours had similar effects on germination response. There was a strong interaction between temperature and irradiation regime for both cultivars. Irradiating seeds for 1 hour/day reduced final germination percentages under cool (15C) conditions; response was not adversely affected when seeds at 15C were germinated in darkness. In a second experiment, seeds at 25C were exposed to daily photoperiods of 0, 1, 2, 4, 8, 12, or 24 hours. Germination percentages obtained in darkness and at photoperiods ≤12 hours were equivalent. Twenty-four-hour photoperiods suppressed germination compared to all other irradiation treatments.

A comparative study of the seed germination biology of a narrow endemic and two geographically-widespread species ofSolidago(Asteraceae). 2. Germination responses of buried seeds in relation to seasonal temperature cycles

1997 ◽  
Vol 7 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Jeffrey L. Walck ◽  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seed Germination ◽  
Comparative Study ◽  
Seasonal Temperature ◽  
Widespread Species ◽  
Temperature Cycles ◽  
Narrow Endemic ◽  
Temperature Regimes ◽  
Buried Seeds ◽  
Temperature Controlled ◽  
Cyclic Changes

AbstractSeeds of the narrow-endemicSolidago shortiiand of the geographically-widespreadS. altissimaandS. nemoraliscollected and buried in 1992 and 1993 were incubated in light and in darkness at 15/6°, 20/10°, 25/15°, 30/15° or 35/20°C following various periods of burial in soil in a non-temperature-controlled glasshouse. At maturity in November, seeds of the three species germinated to 0–1% in light at 15/6°C and to 10–77% at 20/10°, 25/15°, 30/15° and 35/20°C. Seeds exhumed each April from 1993 to 1996 and incubated in light at 15/6° and 20/10°C germinated to ≥83% and ≥90%, respectively, whereas those exhumed each September of 1993–96 germinated to ≤2%and ≤40%, respectively. At 25/15°, 30/15° and 35/20°C in light, seeds of S.altissimaandS. shortiigerminated to ≥52% and those of S.nemoralisto ≥19/, regardless of when they were exhumed. Timson's index, which integrates percentages, rates and times for onset of germination, was higher at all temperature regimes for seeds exhumed in April 1995 than for those exhumed in September 1995. Freshly-matured seeds of the three species germinated to 0–11% in darkness. Furthermore, regardless of when they were exhumed, seeds ofS. altissimaandS. nemoralisincubated in darkness germinated mostly to only 0–9% over the range of temperature regimes. In contrast, ≤88% and ≤6% of the seeds ofS. shortiiexhumed and incubated in darkness each April and September of 1993–96, respectively, germinated, ≤1% of them germinating while buried in soil. Thus, although buried seeds of all three species exhibited an annual conditional dormancy/non-dormancy cycle, only those ofS. shortiiexhibited cyclic changes in their germination response in darkness.

scholarly journals Effect of Temperature Regimes on Seed Germination Asafoetida (Ferula Assafoetida L.)

2014 ◽  
Vol 69 (1) ◽  
pp. 59-67
Author(s):  
M. Zangoie ◽  
S. Parsa ◽  
M. Mahmoodi ◽  
M. Jami Al-Ahmadi ◽  
G. Sanjari
Keyword(s):  
Seed Germination ◽  
Agricultural Development ◽  
Effect Of Temperature ◽  
Development Programs ◽  
Natural Habitats ◽  
Fluctuating Temperature ◽  
Randomized Design ◽  
Temperature Regimes ◽  
Two Factors ◽  
Ferula Assafoetida

ABSTRACT Asafoetida is a medicinal plant belonging to the Apiaceae family. Gum obtained from the lower part of the stem and roots of this plant has many industrial and pharmaceutical applications. This plant is subject to extinction in its natural habitats due to over-utilization. Understanding the biology of seed germination can help to restore such degradation by implementing agricultural development programs. The present study is an attempt to determine the germination responses to two temperature regimes (constant and fluctuating) during the course of the study. The experiment was planned based on a factorial-completely randomized design with two factors (constant and fluctuating temperature regimes) at 3 levels each (15, 20 and 25°C) with 4 replications. The results showed that the characteristics of germination in asafoetida were significantly improved under the fluctuating temperature as compared with the constant regime. It showed a mean germination time of 1.88 days for the fluctuating regime, while it was 4.88 days for the constant regime. The same results were found on germination rates in favor of fluctuating (0.62 per day) in comparison with constant regime (0.33 per day). Under the fluctuating regime, the lowest level of imposed temperature (daily application of 10 and 20 degree during the first and the second 12 hours, respectively) was the best for seed germination in this experiment.

scholarly journals Seed germination characteristics of Halogeton glomeratus

2001 ◽  
Vol 79 (10) ◽  
pp. 1189-1194 ◽  
Author(s):  
M Ajmal Khan ◽  
Bilquees Gul ◽  
Darrell J Weber
Keyword(s):  
Seed Germination ◽  
Great Basin ◽  
Temperature Regime ◽  
Germination Rate ◽  
Distilled Water ◽  
Salinity Treatment ◽  
Temperature Regimes ◽  
Germination Characteristics ◽  
Nacl Concentration ◽  
Halogeton Glomeratus

Halogeton glomeratus (Bieb.) C.A. Mey, an annual forb in the family Chenopodiaceae, is widely distributed in the inland salt deserts of western North America. Experiments were conducted to determine the effects of NaCl and temperature on seed germination and the recovery of germination responses after transfer to distilled water. Seeds of H. glomeratus were germinated at various temperature regimes (5–15°C, 10–20°C, 10–30°C, 15–25°C, 20–30°C, and 25–35°C), and salinities (0, 200, 400, 600, 800, and 1000 mM NaCl) in a 12 h dark : 12 h light photoperiod. Increases in NaCl concentration progressively inhibited seed germination, and this inhibition was more substantial in the dark than in the photoperiod treatment. Seed germination at concentrations higher than 800 mM NaCl was low (10%). Cooler temperatures significantly inhibited germination in all treatments. A temperature regime of high night (25°C) and high day (35°C) temperatures led to higher germination. Rate of germination decreased with an increase in salinity and was highest at 25–35°C and lowest at 5–15°C temperature regimes. Seeds were transferred from salt solution to distilled water after 20 days, and those from high salinities recovered quickly at all temperature regimes. Recovery germination percentages from the highest salinity treatment varied from 51 to 100% at various temperature regimes.Key words: Great Basin desert, Halogeton glomeratus, halophyte, recovery of seed germination, salt deserts, temperature regime.

scholarly journals Assessing the role of two populations of Aedes japonicus japonicus for Zika virus transmission under a constant and a fluctuating temperature regime.

2020 ◽  
Author(s):  
Uros Glavinic ◽  
Jasmin Varga ◽  
Anca Iona Paslaru ◽  
Jeannine Hauri ◽  
Paul Torgerson ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Temperature Regime ◽  
Zika Virus ◽  
Incubation Temperature ◽  
Transmission Rate ◽  
Control Measures ◽  
Fluctuating Temperature ◽  
Laboratory Conditions ◽  
Temperature Regimes ◽  
Two Populations

Abstract Background Since the huge epidemic of Zika virus (ZIKV) in Brazil in 2015, questions were raised to understand which mosquito species could transmit the virus. Aedes aegypti has been described as the main vector. However, other Aedes species (e.g. Ae. albopictus and Ae. japonicus) proven to be competent for other Flaviviruses (e.g.West Nile, dengue and yellow fever), have been described as potential vector for ZIKV under laboratory conditions. One of these, the Asian bush mosquito Ae. japonicus is widely distributed with high abundances in Central-Western Europe. In the present study, infection, dissemination and transmission rates of ZIKV (Dak84 strain) in two populations of Ae. japonicus from Switzerland (Zürich) and France (Steinbach, Haut-Rhin) were investigated under constant (27 °C) and fluctuating (14-27 °C, mean 23 °C) temperature regimes.Results The two populations were each able to transmit ZIKV under both temperature regimes. Infectious virus particles were detected in the saliva of females from both populations, regardless of the incubation temperature regime, from 7 days post exposure to infectious rabbit blood. The highest amount of Plaque Forming Unit (PFU) (400/ml) were recorded 14 days post oral infection in the Swiss population incubated at constant temperature. No difference in terms of infection, dissemination and transmission rate were found between mosquito populations.Temperature had no effect on infection rate but the fluctuating temperature regime resulted in higher dissemination rates compared to constant temperature, regardless of the population. Finally, transmission efficiency ranged between 7-23% and 7-10% for the constant temperature and 0-10% and 3-27% under fluctuating temperatures for the Swiss and the French populations, respectively.Conclusions This is the first work confirming vector competence for ZIKV of Ae. japonicus originating from Switzerland and France at realistic summer temperatures under laboratory conditions. Considering the continuous spread of this species in the northern part of Europe and its adaptation at cooler temperatures, preventative control measures should be adopted to prevent possible ZIKV epidemics.

scholarly journals Assessing the role of two populations of Aedes japonicus japonicus for Zika virus transmission under a constant and a fluctuating temperature regime.

2020 ◽  
Author(s):  
Uros Glavinic ◽  
Jasmin Varga ◽  
Anca Ioana Paslaru ◽  
Jeannine Hauri ◽  
Paul Torgerson ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Temperature Regime ◽  
Zika Virus ◽  
Incubation Temperature ◽  
Transmission Rate ◽  
Control Measures ◽  
Fluctuating Temperature ◽  
Laboratory Conditions ◽  
Temperature Regimes ◽  
Two Populations

Abstract Background: Since the huge epidemic of Zika virus (ZIKV) in Brazil in 2015, questions were raised to understand which mosquito species could transmit the virus. Aedes aegypti has been described as the main vector. However, other Aedes species (e.g. Ae. albopictus and Ae. japonicus) proven to be competent for other flaviviruses (e.g. West Nile, dengue and yellow fever), have been described as potential vectors for ZIKV under laboratory conditions. One of these, the Asian bush mosquito, Ae. japonicus, is widely distributed with high abundances in central-western Europe. In the present study, infection, dissemination and transmission rates of ZIKV (Dak84 strain) in two populations of Ae. japonicus from Switzerland (Zürich) and France (Steinbach, Haut-Rhin) were investigated under constant (27 °C) and fluctuating (14–27 °C, mean 23 °C) temperature regimes.Results: The two populations were each able to transmit ZIKV under both temperature regimes. Infectious virus particles were detected in the saliva of females from both populations, regardless of the incubation temperature regime, from 7 days post-exposure to infectious rabbit blood. The highest amount of plaque forming units (PFU) (400/ml) were recorded 14 days post-oral infection in the Swiss population incubated at a constant temperature. No difference in terms of infection, dissemination and transmission rate were found between mosquito populations.Temperature had no effect on infection rate but the fluctuating temperature regime resulted in higher dissemination rates compared to constant temperature, regardless of the population. Finally, transmission efficiency ranged between 7–23% and 7–10% for the constant temperature and 0–10% and 3–27% under fluctuating temperatures for the Swiss and the French populations, respectively.Conclusions: To the best of our knowledge, this is the first study confirming vector competence for ZIKV of Ae. japonicus originating from Switzerland and France at realistic summer temperatures under laboratory conditions. Considering the continuous spread of this species in the northern part of Europe and its adaptation at cooler temperatures, preventative control measures should be adopted to prevent possible ZIKV epidemics.

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