Effects of light and temperature on germination of heteromorphic achenes of Bidens odorata (Asteraceae)

1991 ◽  
Vol 69 (3) ◽  
pp. 574-579 ◽  
Author(s):  
Lea Corkidi ◽  
Emmanuel Rincon ◽  
Carlos Vazquez-Yanes
Keyword(s):  
Key Words ◽  
White Light ◽  
Laboratory Experiments ◽  
Red Light ◽  
Germination Percentage ◽  
Light Conditions ◽  
Light Requirement ◽  
Physiological Basis ◽  
Dry Storage ◽  
Percent Germination

Bidens odorata Cav. (Asteraceae) is an annual weed with heteromorphic achenes that differ in size, weight, and shape within each capitulum. To investigate if the variability of the achene size was correlated with differences in the germination response, achenes were classified in three categories based on size (4, 5–6, and 7 mm), and laboratory experiments were conducted with freshly harvested and dry-stored seeds under several light and temperature conditions. For all conditions tested with fresh seeds, 7-mm achenes germinated faster and with a higher final germination percentage than 4-mm achenes. Germination was inhibited by darkness and far-red light conditions. Experiments conducted with different times of exposure to white light (1 min, 10 min, and 12 h) showed that 4-mm achenes required longer time of exposure to light to maximize their percent germination. However, 7-mm achenes reached similar total percent germination without regard to the period of illumination. Dry storage increased the percent germination significantly in the shorter achenes and altered the light requirement for germination differentially among the morphs. The results suggest a physiological basis of achene heteromorphism that might be related to colonization of different microenvironments. Key words: Bidens odorata, germination, heteromorphism, light, temperature.

scholarly journals Far-Red Light Acclimation for Improved Mass Cultivation of Cyanobacteria

Metabolites ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 170 ◽  
Author(s):  
Alla Silkina ◽  
Bethan Kultschar ◽  
Carole A. Llewellyn
Keyword(s):  
Biomass Production ◽  
White Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Industrial Biotechnology ◽  
Light Conditions ◽  
Light Emitting ◽  
Mass Cultivation ◽  
Chlorogloeopsis Fritschii ◽  
Bioactive Product

Improving mass cultivation of cyanobacteria is a goal for industrial biotechnology. In this study, the mass cultivation of the thermophilic cyanobacterium Chlorogloeopsis fritschii was assessed for biomass production under light-emitting diode white light (LEDWL), far-red light (FRL), and combined white light and far-red light (WLFRL) adaptation. The induction of chl f was confirmed at 24 h after the transfer of culture from LEDWL to FRL. Using combined light (WLFRL), chl f, a, and d, maintained the same level of concentration in comparison to FRL conditions. However, phycocyanin and xanthophylls (echinone, caloxanthin, myxoxanthin, nostoxanthin) concentration increased 2.7–4.7 times compared to LEDWL conditions. The productivity of culture was double under WLFRL compared with LEDWL conditions. No significant changes in lipid, protein, and carbohydrate concentrations were found in the two different light conditions. The results are important for informing on optimum biomass cultivation of this species for biomass production and bioactive product development.

scholarly journals Green and Red Light Reduces the Disease Severity by Pseudomonas cichorii JBC1 in Tomato Plants via Upregulation of Defense-Related Gene Expression

2015 ◽  
Vol 105 (4) ◽  
pp. 412-418 ◽  
Author(s):  
Rajalingam Nagendran ◽  
Yong Hoon Lee
Keyword(s):  
Disease Severity ◽  
White Light ◽  
Disease Incidence ◽  
Red Light ◽  
Light Conditions ◽  
Pseudomonas Cichorii ◽  
Tomato Plants ◽  
Tomato Seedlings ◽  
Pathogenesis Related Protein ◽  
Dark Conditions

Light influences many physiological processes in most organisms. To investigate the influence of light on plant and pathogen interaction, we challenged tomato seedlings with Pseudomonas cichorii JBC1 by flood inoculation and incubated the seedlings under different light conditions. Tomato seedlings exposed to green or red light showed a significant reduction in disease incidence compared with those grown under white light or dark conditions. To understand the underlying mechanisms, we investigated the effects of each light wavelength on P. cichorii JBC1 and tomato plants. Treatment with various light wavelengths at 120 µmol m–2s–1 revealed no significant difference in growth, swarming motility, or biofilm formation of the pathogen. In addition, when we vacuum-infiltrated P. cichorii JBC1 into tomato plants, green and red light also suppressed disease incidence which indicated that the reduced disease severity was not from direct influence of light on the pathogen. Significant upregulation of the defense-related genes, phenylalanine ammonia-lyase (PAL) and pathogenesis-related protein 1a (PR-1a) was observed in P. cichorii JBC1-infected tomato seedlings grown under green or red light compared with seedlings grown under white light or dark conditions. The results of this study indicate that light conditions can influence plant defense mechanisms. In particular, green and red light increase the resistance of tomato plants to infection by P. cichorii.

scholarly journals Ecophysiology of seed germination in Mediterranean geophytes. 1. Muscari spp

2002 ◽  
Vol 12 (3) ◽  
pp. 193-201 ◽  
Author(s):  
Maria A. Doussi ◽  
Costas A. Thanos
Keyword(s):  
Seed Germination ◽  
White Light ◽  
Mediterranean Climate ◽  
Germination Rate ◽  
Red Light ◽  
Rainfall Regime ◽  
Light Conditions ◽  
Rainy Period ◽  
Germination Characteristics ◽  
The Mediterranean

Ecophysiological aspects of seed germination were investigated in four Mediterranean geophytes of the genus Muscari (Liliaceae): M. comosum (tassel hyacinth), M. neglectum (common grape hyacinth), M. commutatum and M. weissii. Experiments were performed at constant temperatures in the dark and under temperature and light conditions simulating those prevailing in nature during November–January, i.e. well into the rainy season of the Mediterranean climate. In all species, no primary dormancy was revealed, and germination occurred in a rather narrow range of cool temperatures (optimum at 10 or 15°C) and at a remarkably slow rate; both germination characteristics seem to be associated with autumn/winter seed germination and seedling establishment. Such a postulated strategy is ecologically advantageous within an unpredictable rainfall regime, known to prevail during the start of the rainy period of the Mediterranean climate. This strategy may also explain the spread of germination of M. comosum seeds over two consecutive years, observed by Theophrastus. Far-red light, simulating light conditions under a dense canopy, resulted in only a slight delay of germination compared to dark controls. Diurnal white light, qualitatively simulating natural daylight, caused a significant decrease of the germination rate in all four species studied. Moreover, white light was found to suppress considerably final seed germination (photoinhibition) in M. weissii and M. neglectum; in the latter species, prolonged imbibition under white light also led to the induction of secondary dormancy.

scholarly journals GERMINATION OF VERBENA SEED IN RESPONSE TO PLANT GROWTH REGULATORS

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1156c-1156
Author(s):  
Gamil A. Kabbabe ◽  
William J. Carpenter
Keyword(s):  
Polyethylene Glycol ◽  
Gibberellic Acid ◽  
Growth Regulators ◽  
Traditional Method ◽  
Germination Percentage ◽  
Dry Storage ◽  
Gradual Loss ◽  
Acetone Treatment ◽  
Percent Germination ◽  
Peg 8000

Verbena seed when harvested, has a natural dormancy that gradually dissipates during a 5 to 8 month period of dry storage. In this study, the gradual loss of the dormancy causing factor was correlated with germination percentage. Acetone treatment of verbena seeds was found to cause a slight, but non-significant, reduction in total germination. However, the infusion of gibberellic acid (GA4/7) and kinetin (KIN) with the acetone at various concentrations improved germination. The traditional method of seed osmoconditioning using Polyethylene Glycol (PEG 8000) at -1.0 MPa caused a non-significant reduction in percent germination, similar to that with acetone. When growth regulators were mixed with the osmoconditioning solution, at the concentrations used with acetone, a definite and significant improvement in terms of rate and percent of germination was observed.

Factors controlling seed dormancy and germination response of Brachypodium hybridum growing in the hot arid mountains of the Arabian Desert

Botany ◽  
2019 ◽  
Vol 97 (7) ◽  
pp. 371-379 ◽  
Author(s):  
Masarra Elgabra ◽  
Ali El-Keblawy ◽  
Kareem A. Mosa ◽  
Sameh Soliman
Keyword(s):  
Seed Dormancy ◽  
Light Quality ◽  
Genetic Model ◽  
Germination Rate ◽  
Red Light ◽  
Germination Percentage ◽  
Light Conditions ◽  
One Year ◽  
Native And Introduced Ranges ◽  
Seed Dormancy And Germination

Seed dormancy and germination have been studied in the genetic model Brachypodium species complex in cooler, moist higher latitudes. Studying environmental factors in arid mountains affecting dormancy and germination in Brachypodium complex could determine the factors controlling these processes. This study assesses the impacts of temperature during seed maturation, seed after-ripening, drought, photoperiod, and thermoperiod on final germination and germination rate index of B. hybridum in the Arabian Desert. Seeds were germinated under dark or light conditions and under different ratios of red:far-red light, with three diurnal thermoperiods. The final germination percentage was significantly greater at 15/25 °C and 20/30 °C than at 25/35 °C and in light rather than in darkness. Seeds that reached maturity at 15/25 °C attained greater germination rates and faster germination than those that reached maturity at 20/30 °C. One-year after-ripening enhanced the final germination percentage and reduced photoperiod requirements. Light quality did not affect final germination percentage. The seeds tolerated drought of up to –0.8 MPa polyethylene glycol. The tolerance of B. hybridum seeds produced at higher thermoperiods to moderate levels of osmotic stress and their higher dormancy indicate that this species has the potential to survive the projected global warming in its native and introduced ranges.

scholarly journals Light and Phytochrome Involvement in Rosa multiflora Seed Germination

1995 ◽  
Vol 120 (6) ◽  
pp. 953-955 ◽  
Author(s):  
Yoshiko Yambe ◽  
Kiyotoshi Takeno ◽  
Takashi Saito
Keyword(s):  
Seed Germination ◽  
White Light ◽  
Red Light ◽  
Germination Percentage ◽  
Rosa Multiflora ◽  
Light Effect ◽  
Complete Darkness ◽  
Subsequent Exposure ◽  
Multiflora Rose

Seed germination percentage of multiflora rose (Rosa multiflora Thunh.) was much higher under continuous white light than in complete darkness. Red light was the most effective in inducing germination, and far-red light was ineffective. Exposure to red light for 1 min increased germination; this effect was saturated at an exposure of2 min. The red-light effect was reversed by subsequent exposure to far-red light. The results indicate that rose seeds are positively photoblastic, and that the photoreceptor involved is most likely phytochrome.

Ultrastructure of Differently Pigmented Synechococcus Cells

1981 ◽  
Vol 36 (9-10) ◽  
pp. 907-909
Author(s):  
Günter Döhler ◽  
Ralf Barckhausen ◽  
Manfred Ruppel
Keyword(s):  
White Light ◽  
Red Light ◽  
Culture Conditions ◽  
Anacystis Nidulans ◽  
Light Conditions ◽  
Pigment Composition ◽  
Pigment Ratios ◽  
Polyhedral Bodies ◽  
Storage Carbohydrates

Abstract Synechococcus (Anacystis nidulans, strain L 1402-1) were grown at + 37 °C in an atmosphere of 0.04 vol.% CO2 using different light conditions. Changing the culture conditions caused alterations in pigment ratios and ultrastructure of Synechococcus. In comparison to the low white and red light grown cells under strong white light the number of thylakoids decreased and an accumulation of storage carbohydrates could be observed. The number of the polyhedral bodies also varied with culture conditions. The results are discussed with reference to the pigment composition and the function of the polyhedral bodies.

The Effect of Light Quality on the Germination of Eight Species From Sandy Habitats in Western Australia.

1993 ◽  
Vol 41 (3) ◽  
pp. 321 ◽  
Author(s):  
DT Bell
Keyword(s):  
Western Australia ◽  
Light Quality ◽  
Red Light ◽  
Monochromatic Light ◽  
Coastal Dunes ◽  
High Energy ◽  
Germination Percentage ◽  
Light Conditions ◽  
Light Inhibition ◽  
Effect Of Light

The impacts of darkness and a range of monochromatic light conditions on germination was documented for eight native and naturalized species growing in sandy habitats in Western Australia. Four lake-margin species, Juncus articulatus, J. microcephalus, J. pallidus and Isolepis prolifera, germinated under red (c. 520-640 nm) light, but remained dormant in the dark or when illuminated with far-red (720 nm) or blue (430-490 nm) light. Sunlight-stimulated germination could be beneficial to these very small seeded species, which may not have sufficient reserves for seedlings to establish following deep burial. Oenothera stricta, a short-lived ruderal species, was also stimulated by red light, a response possibly related to germination following disturbance of overlying vegetation. Trachyandra divaricata, a dune inhabiting species, was inhibited by red light. Inhibition by the wavelengths of light dominant in full sunlight was thought to be a response beneficial to species of blowing sand habitats where germination on the dry surface could prove detrimental. Oenothera drummorndii , also a species of coastal dunes was inhibited under high energy light (430-490 nm) but showed no percentage gemination differences in light of wavelengths between 520 and 720 nm and under dark conditions. Asphodelus fistulosus, a species of similar life-fonn characteristics to Trachyarndra divaricata, showed no effect on germination percentage of varying light quality.

scholarly journals The Preferences of Different Cultivars of Lettuce Seedlings (Lactuca sativa L.) for the Spectral Composition of Light

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1211
Author(s):  
Barbara Frąszczak ◽  
Monika Kula-Maximenko
Keyword(s):  
Chlorophyll Content ◽  
Blue Light ◽  
White Light ◽  
Leaf Shape ◽  
Red Light ◽  
Spectral Composition ◽  
Fresh Weight ◽  
Light Spectrum ◽  
Dark Green ◽  
Relative Chlorophyll Content

The spectrum of light significantly influences the growth of plants cultivated in closed systems. Five lettuce cultivars with different leaf colours were grown under white light (W, 170 μmol m−2 s−1) and under white light with the addition of red (W + R) or blue light (W + B) (230 μmol m−2 s−1). The plants were grown until they reached the seedling phase (30 days). Each cultivar reacted differently to the light spectrum applied. The red-leaved cultivar exhibited the strongest plasticity in response to the spectrum. The blue light stimulated the growth of the leaf surface in all the plants. The red light negatively influenced the length of leaves in the cultivars, but it positively affected their number in red and dark-green lettuce. It also increased the relative chlorophyll content and fresh weight gain in the cultivars containing anthocyanins. When the cultivars were grown under white light, they had longer leaves and higher value of the leaf shape index. The light-green cultivars had a greater fresh weight. Both the addition of blue and red light significantly increased the relative chlorophyll content in the dark-green cultivar. The spectrum enhanced with blue light had positive influence on most of the parameters under analysis in butter lettuce cultivars. These cultivars were also characterised by the highest absorbance of blue light.

Effects of electron-withdrawing groups in imidazole-phenanthroline ligands and their influence on the photophysical properties of EuIII complexes for white light-emitting diodes

2017 ◽  
Vol 41 (18) ◽  
pp. 9826-9839 ◽  
Author(s):  
Boddula Rajamouli ◽  
Rachna Devi ◽  
Abhijeet Mohanty ◽  
Venkata Krishnan ◽  
Sivakumar Vaidyanathan
Keyword(s):  
Thin Film ◽  
Quantum Yield ◽  
White Light ◽  
Light Emitting Diode ◽  
Photophysical Properties ◽  
Red Light ◽  
Europium Complexes ◽  
Light Emitting ◽  
White Light Emitting Diodes ◽  
Phenanthroline Ligands

The red light emitting diode (LED) was fabricated by using europium complexes with InGaN LED (395 nm) and shown digital images, corresponding CIE color coordinates (red region) as well as obtained highest quantum yield of the thin film (78.7%).

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