scholarly journals Light Governs the Germination of Impatiens wallerana Hook. f. Seed

HortScience ◽  
1994 ◽  
Vol 29 (8) ◽  
pp. 854-857
Author(s):  
William J. Carpenter ◽  
Eric R. Ostmark ◽  
John A. Cornell
Keyword(s):  
Seed Germination ◽  
Light Exposure ◽  
Germination Percentage ◽  
Regression Equations ◽  
Germination Period ◽  
Radicle Emergence ◽  
Light Darkness ◽  
Role Of Light ◽  
Impatiens Wallerana

The role of light on impatiens seed germination and radicle emergence was studied. Seeds having a photodormancy require light for only part of the germination period. Germination ≥85% was achieved after 3, 2, or 1 day of irradiance at 1.5, 15, or 75 μmol·s-1·m-2, respectively. Keeping imbibed seeds in darkness for ≥2 days before light exposure caused reduced total germination percentages (G), delayed achieving 50% of the final germination percentage (T50), and increased the days between 10% and 90% germination (T90-T10). Light for 6 hours daily at 1.5, 15, or 150 μmol·s-1·m-2 promoted high G and rapid and uniform germination, but daily 12 to 24 hours of irradiance decreased G and increased T50 and T90-T10. Estimated rates of decline (increase) in G, T50, or T90-T10 with each added day of light (darkness) or increasing daily hours of light were measured by fitting regression equations. Impatiens seed germination was promoted by the initial 1 to 3 days of light, but light inhibited radicle extension in the latter germination stages.

scholarly journals The Role of Light during Phlox drummondii Hook. Seed Germination

HortScience ◽  
1993 ◽  
Vol 28 (8) ◽  
pp. 786-788
Author(s):  
William J. Carpenter ◽  
Eric R. Ostmark ◽  
John A. Cornell
Keyword(s):  
Seed Germination ◽  
Light Level ◽  
Total Darkness ◽  
Regression Equations ◽  
Continuous Darkness ◽  
Light Duration ◽  
Radicle Emergence ◽  
Phlox Drummondii ◽  
Role Of Light

The role of light on phlox germination and radicle emergence was studied. Neither light level nor duration affected total germination (G) percentages, which ranged from 93%. to 98%. Increasing light level and lengthening light duration delayed achieving 50% of final germination (T50) and increased the span in days between 10% and 90% germination (T90 - T10). Increasing light duration from 0 to 24 hours during germination at 0.15 μmol·s-1·m-2 progressively increased T50 from 3.5 to 7.1 days and T90 - T10 from 2.6 to 13.1 days. Similarly, lengthening light duration from 0 to 24 hours at 1.5 μmol·s-1·m-2 light increased T50 from 3.7 to 10.8 days and T90 - T10 from 2.8 to 13.4 days, whereas 15 μmol·s -1·m-2 increased T50 from 3.9 to 21.9 days and T90 - T10 from 2.9 to 29.2 days. Increasing the number of days in darkness from 0 to 6 decreased T50 from 14.8 to 4.3 days and T90 - T10 from 20.2 to 3.5 days. Increasing the number of days in light from O to 6 increased T50 from 4.0 to 8.9 days and T90 - T10 from 3.8 to 8.2 days. Estimated rates of decline or increase in T50 and T90 - T10 with each added day in darkness or light were measured by fitting regression equations. Seeds germinated in continuous darkness or in 24 or 48 hours of light followed by total darkness had similar G, T50, and T90 - T10. The results indicate that initial phlox seed germination was not affected by light, but that light inhibited radicle extension in later germination stages.

The Role of Nurse Plants in Facilitating the Germination of Dandelion (Taraxacum officinale) Seeds

Weed Science ◽  
2014 ◽  
Vol 62 (3) ◽  
pp. 474-482
Author(s):  
Zdenka Martinkova ◽  
Alois Honek ◽  
Stano Pekár
Keyword(s):  
Seed Germination ◽  
Taraxacum Officinale ◽  
Germination Percentage ◽  
Herbaceous Plants ◽  
Tree Cover ◽  
Nurse Plant ◽  
Bare Ground ◽  
Manipulative Experiment ◽  
Nurse Plants

At germination, seedlings may be encouraged by the surrounding vegetation. This facilitation was studied in dandelions in a manipulative experiment to determine whether a nurse plant, either maple trees or alfalfa, assisted in the germination of dandelion seeds and whether there was a difference in germination when additional moisture (irrigation) was provided on top of rainfall. Seeds were sown into 33-cm2 “arenas” and surrounded by plastic collars, which prevented the seed from being eaten by predators. Germination was recorded at 1- to 2-d intervals, and the percentage of the seeds that germinated and their time to 50% germination (T50) was calculated. The nurse plant was consistently associated with seed germination. Compared with bare ground, the germination percentage was lower under tree cover, whereas T50 was shorter under the cover of herbaceous plants (alfalfa). The values for the germination percentage and T50 were similar under tree and herb nurse plants when the soil was irrigated. Nurse plants facilitated germination via their effects on understory humidity. Facilitating the germination of dandelions through the presence of nurse plants contributes to their propagation in crops.

Germination strategies of 20 alpine species with varying seed mass and light availability

2013 ◽  
Vol 61 (5) ◽  
pp. 404 ◽  
Author(s):  
Gao-Lin Wu ◽  
Guo-Zhen Du ◽  
Zhi-Hua Shi
Keyword(s):  
Seed Germination ◽  
Light Availability ◽  
Seed Mass ◽  
Significant Negative Correlation ◽  
Germination Percentage ◽  
Central Component ◽  
Grassland Community ◽  
Germination Characteristics ◽  
Germination Strategy

Seed germination is a central component of plant life history. To investigate the proposed role of seed size on germination strategy in plant communities, a semifield experiment was conducted in alpine meadow of the Qinghai–Tibetan Plateau, China. Interspecies relationships of seed mass and seed germination characteristics were studied under semifield conditions with different light availability. Light availability and seed mass had significant effects on final germination percentage and time to germination for studied species. There was a significant negative correlation between the strength of light required for germination and seed mass. Fifteen study species (e.g. Ligularia przewalskii, Artemisia sieversiana Willd, Tripolium vulgare Ness. and Saussurea morifolia Chen) exhibited a synchronous germination strategy. Seeds from large-seeded species, such as Dracocephalum ruyschiana, Laniophlomis rotate (Benth.) and Salvia przewalskii Maxim., were less likely to require light for germination than those of small-seeded species, such as A. sieversiana Willd, Senecio diversipinnus Ling and Saussurea mongolica (Franch.). We propose that germination strategies of small-seeded species are well suited to unpredictable environmental variation in this alpine grassland community.

scholarly journals Temperature and Light Effects on Germination Behaviour of African Eggplant (Solanum aethiopicum L.) Seeds

2021 ◽  
Author(s):  
H.M. Botey ◽  
J.O. Ochuodho ◽  
L. Ngode ◽  
H. Dwamena ◽  
I. Osei-Tutu
Keyword(s):  
Seed Germination ◽  
Seed Quality ◽  
Light Exposure ◽  
Germination Percentage ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Percentage Germination ◽  
Ambient Conditions ◽  
Solanum Aethiopicum ◽  
Germination Behaviour

Background: A preliminary study of the African eggplant seeds obtained from farmers sources recorded a wide variation in percentage germination under ambient conditions (25±2°C). The germination percentage ranged from 0% to 25%, while fresh seeds ranged between 53% and 87%. As temperature and light are important factors of seed germination, the current study investigated the effect of temperature on the germination pattern and the influence of light interaction with temperature on seed germination of African eggplant (Solanum aethiopicum L.) under controlled conditions. Methods: Seeds of two cultivars of African eggplant were subjected to constant and alternating temperatures and under three light exposure regimes. Seed quality was accessed by per cent germination, mean germination time, time to reach 50% germination, germination index and mean daily germination. Result: The highest percentage germination under constant temperatures was recorded at 25°C (76%) and 20°C (74%). The maximum temperature and light conditions required for maximum seed germination quality (76-95%) at the shortest time (4-5 days) was 30/20°C under alternating 8/16 hours light and dark.

scholarly journals Light exposure mediates circadian rhythms of rhizosphere microbial communities

2021 ◽  
Author(s):  
Kankan Zhao ◽  
Bin Ma ◽  
Yan Xu ◽  
Erinne Stirling ◽  
Jianming Xu
Keyword(s):  
Circadian Rhythms ◽  
Microbial Communities ◽  
Light Exposure ◽  
Circadian Clocks ◽  
Ecological Niches ◽  
Host Health ◽  
Regulation Mechanisms ◽  
Role Of Light ◽  
Constant Dark

AbstractMicrobial community circadian rhythms have a broad influence on host health and even though light-induced environmental fluctuations could regulate microbial communities, the contribution of light to the circadian rhythms of rhizosphere microbial communities has received little attention. To address this gap, we monitored diel changes in the microbial communities in rice (Oryza sativa L.) rhizosphere soil under light–dark and constant dark regimes, identifying microbes with circadian rhythms caused by light exposure and microbial circadian clocks, respectively. While rhizosphere microbial communities displayed circadian rhythms under light–dark and constant dark regimes, taxa possessing circadian rhythms under the two conditions were dissimilar. Light exposure concealed microbial circadian clocks as a regulatory driver, leading to fewer ecological niches in light versus dark communities. These findings disentangle regulation mechanisms for circadian rhythms in the rice rhizosphere microbial communities and highlight the role of light-induced regulation of rhizosphere microbial communities.

scholarly journals Comparing between Germination Percentage in Moringa peregrina and Moringa oleifera under Laboratory Conditions

2019 ◽  
pp. 1-9
Author(s):  
Karima M. A. El-Absy ◽  
Nouf A. Khazen ◽  
Manal M. Al-Rashidi ◽  
Bayan B. Al Anezi ◽  
Fareh H. Al Anezi ◽  
...  
Keyword(s):  
Seed Germination ◽  
Moringa Oleifera ◽  
Germination Percentage ◽  
Germination Period ◽  
Laboratory Conditions ◽  
Vigor Index ◽  
Moringa Peregrina ◽  
Germinated Seeds ◽  
Radical Length

This study was carried out in February 2019 at the laboratory; Department of Biology, College of Taymaa, Tabuk University. The numbers of germinated seeds were recorded daily after Soaking for two days during 10th, 15th, 20th, 25th and 30th days and final percentage calculated at the end of germination period. Germination percentage, radical length and vigor index values were calculated for the two studied species. The two species (S) under study, days of germination (D) and interaction between them showed highly significant (P < 0.01) for seed germination. Despite germination percentages being slightly higher at the 10th day and 15th day for M. oleifera than M. peregrina, the germination percentages recorded higher values at the 20th, 25th and 30th days for M. peregrina than M. oleifera. The highest seed germinated number recorded at 20th day and 15th day for M. peregrina and M. oleifera, respectively with significant differences between the numbers of germinated seed in two species. Generally, germination %, radical length and vigor index of M. peregrina recorded a higher value compared to M. oleifera. A total value of germination percentage (80.33% and 65.33%) was recorded for M. peregrina and M. oleifera seed after 20 days from germinating time, respectively.

The role of mucilage in the germination of Leptocereus scopulophilus (Cactaceae) seeds from Pan de Matanzas, Cuba

Botany ◽  
2015 ◽  
Vol 93 (4) ◽  
pp. 251-255 ◽  
Author(s):  
Duniel Barrios ◽  
Joel Flores ◽  
Luis R. González-Torres ◽  
Alejandro Palmarola
Keyword(s):  
Seed Germination ◽  
Light Exposure ◽  
Germination Rate ◽  
Environmental Context ◽  
Light Conditions ◽  
Combined Treatments ◽  
Minimal Time ◽  
Number Of Species ◽  
Seed Mucilage

Studies of seed mucilage in a number of species suggest that it has multiple ecological roles dependent on species and their environmental context. We evaluate whether mucilage facilitates seed germination for Leptocereus scopulophilus Areces, as well as whether light conditions influence the effect of the mucilage. Three combined treatments of light conditions: (1) shade (10% of sunlight), (2) semi-shade (30% of sunlight), and (3) full light exposure (100% of sunlight), and two seed types (with mucilage and washed) were used. Germinability was affected by light conditions but no effect of mucilage was found; higher germination occurred in shade than in semi-shade conditions. There was no germination in full light conditions. Germination rate (T50) was not affected by light conditions or by the mucilage, or the interaction of both factors. Minimal time to germination (Tmin) was affected by mucilage; seeds with mucilage germinated 2 days later than washed seeds. Thus, facilitation for imbibition of water does not occur in L. scopulophilus seeds. Perhaps the presence of mucilage in seeds of this species serves other purposes such as seed adhesion to soil or to deter predators.

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