Growth Characteristics of Common Milkweed

Weed Science ◽  
1971 ◽  
Vol 19 (3) ◽  
pp. 193-196 ◽  
Author(s):  
Larry S. Jeffery ◽  
Laren R. Robison
Keyword(s):  
Low Temperature ◽  
Seed Dormancy ◽  
Seedling Emergence ◽  
Multiple Shoots ◽  
Growth Characteristics ◽  
Temperature Dependent ◽  
Asclepias Syriaca ◽  
Leaf Pair

Seed dormancy of common milkweed (Asclepias syriaca L.) is broken by a few days of moist low-temperature after-ripening. The duration of low-temperature after-ripening of the seeds is temperature dependent. Seedling emergence is best when the seeds are planted 1 to 2 cm deep and extremely limited when planted 6 cm deep. Seedlings have the capacity to produce new shoots if clipped in the 1 to 1¾-leaf pair stage and multiple shoots if clipped in the 2 to 2½-leaf pair stage. All seedlings reaching the 4 to 4½-leaf pair stage before clipping produced new shoots.

In Situ Analysis of Surface Contaminant Desorption during Low-Temperature Silicon Substrate Cleaning using Reflection Electron Energy Loss Spectrometry

1992 ◽  
Vol 259 ◽  
Author(s):  
Selmer S. Wong ◽  
Shouleh Nikzad ◽  
Channing C. Ahn ◽  
Aimee L. Smith ◽  
Harry A. Atwater
Keyword(s):  
Low Temperature ◽  
Energy Loss ◽  
Electron Energy ◽  
Core Loss ◽  
Temperature Dependent ◽  
Electron Energy Loss Spectrometry ◽  
Analysis Technique ◽  
Chemical Analysis Technique ◽  
Electron Energy Loss

ABSTRACTWe have employed reflection electron energy loss spectrometry (REELS), a surface chemical analysis technique, in order to analyze contaminant coverages at the submonolayer level during low-temperature in situ cleaning of hydrogen-terminated Si(100). The chemical composition of the surface was analyzed by measurements of the C K, O K and Si L2,3 core loss intensities at various stages of the cleaning. These results were quantified using SiC(100) and SiO2 as reference standards for C and O coverage. Room temperature REELS core loss intensity analysis after sample insertion reveals carbon at fractional monolayer coverage. We have established the REELS detection limit for carbon coverage to be 5±2% of a monolayer. A study of temperature-dependent hydrocarbon desorption from hydrogen-terminated Si(100) reveals the absence of carbon on the surface at temperatures greater than 200°C. This indicates the feasibility of epitaxial growth following an in situ low-temperature cleaning and also indicates the power of REELS as an in situ technique for assessment of surface cleanliness.

Morphophysiological dormancy and germination ecology in diaspores of the subtropical palm Phoenix canariensis Chabaud

Botany ◽  
2021 ◽  
Author(s):  
Lanlan He ◽  
Ganesh K. Jaganathan ◽  
Baolin Liu
Keyword(s):  
Seed Dormancy ◽  
Seedling Emergence ◽  
Primary Root ◽  
Germination Percentage ◽  
Early Summer ◽  
Germination Ecology ◽  
Phoenix Canariensis ◽  
Morphophysiological Dormancy ◽  
Cotyledonary Petiole ◽  
Seed Dormancy And Germination

The timing of germination is a crucial event in a plant’s life cycle. Seed dormancy and germination mechanisms are important factors regulating seedling emergence. Since detailed experimental evidence for germination pattern of Phoenix canariensis colonizing sub-tropical climate is scarce, we investigated seed dormancy and germination ecology of P. canariensis. We found that the embryo is underdeveloped at the time of dispersal and doubles in size before the cotyledonary petiole (CP) protrudes through the operculum. The primary root and plumule emerge from the elongated CP outside the seed. In light/dark at 30/25°C, the CP emerged from 8% of the diaspores within 30 days and from 76% within 14 weeks. Thus, 8% of the diaspores have MD and the others MPD. Removal of the pericarp and operculum resulted in 100% germination within 5 days in light/dark at 30/25°C. Cold and warm stratification as well as treatment with GA3 significantly increased the germination speed, but the final germination percentage was not significantly increased. Seed germination was synchronized in early summer when seed dormancy was released by cold stratification in the soil over winter. A remote-tubular germination type and intricate root system provide an ecological advantage to the seedling establishment.

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.

Seed dormancy and periodicity of seedling emergence in Veronica hederifolia L.

Weed Research ◽  
1978 ◽  
Vol 18 (1) ◽  
pp. 41-48 ◽  
Author(s):  
H.A. ROBERTS ◽  
PATRICIA M. LOCKETT
Keyword(s):  
Seed Dormancy ◽  
Seedling Emergence

DYNAMICS OF THE LOW TEMPERATURE GLASS-LIKE PHASE IN MANGANITES

2003 ◽  
Vol 17 (04n06) ◽  
pp. 842-847
Author(s):  
C. CASTELLANO ◽  
F. CORDERO ◽  
R. CANTELLI ◽  
M. FERRETTI
Keyword(s):  
Distribution Function ◽  
Phase Transitions ◽  
Quantitative Analysis ◽  
Low Temperature ◽  
Imaginary Part ◽  
Lattice Relaxation ◽  
Relaxation Processes ◽  
Temperature Dependent ◽  
Energy Barriers ◽  
Nanostructured State

We report anelastic spectroscopy measurements of La 1-x Ca x MnO 3 performed in order to better characterize the nature of the phase transitions and microscopic lattice relaxation processes present in these materials. A peak in the imaginary part of the elastic susceptibility presents a behaviour typical of inhomogeneous and glass-like systems. We have performed a quantitative analysis calculating the temperature dependent distribution function of the energy barriers of the fluctuations characterizing this nanostructured state.

Morphological and physiological dormancy in seeds of Aegopodium podagraria (Apiaceae) broken successively during cold stratification

2009 ◽  
Vol 19 (2) ◽  
pp. 115-123 ◽  
Author(s):  
Filip Vandelook ◽  
Nele Bolle ◽  
Jozef A. Van Assche
Keyword(s):  
Low Temperature ◽  
Seedling Emergence ◽  
Early Spring ◽  
Temperate Climate ◽  
Cold Stratification ◽  
Dormancy Breaking ◽  
Morphophysiological Dormancy ◽  
Temperature Requirement ◽  
Physiological Dormancy ◽  
Chilling Period

AbstractA low-temperature requirement for dormancy break has been observed frequently in temperate-climate Apiaceae species, resulting in spring emergence of seedlings. A series of experiments was performed to identify dormancy-breaking requirements of Aegopodium podagraria, a nitrophilous perennial growing mainly in mildly shaded places. In natural conditions, the embryos in seeds of A. podagraria grow in early winter. Seedlings were first observed in early spring and seedling emergence peaked in March and April. Experiments using temperature-controlled incubators revealed that embryos in seeds of A. podagraria grow only at low temperatures (5°C), irrespective of a pretreatment at higher temperatures. Seeds did not germinate immediately after embryo growth was completed, instead an additional cold stratification period was required to break dormancy completely. Once dormancy was broken, seeds germinated at a range of temperatures. Addition of gibberellic acid (GA3) had a positive effect on embryo growth in seeds incubated at 10°C and at 23°C, but it did not promote germination. Since seeds of A. podagraria have a low-temperature requirement for embryo growth and require an additional chilling period after completion of embryo growth, they exhibit characteristics of deep complex morphophysiological dormancy.

The effect of low temperature coating and annealing on structural and optical properties of CdSe/CdS core/shell QDs

2016 ◽  
Vol 55 (4) ◽  
Author(s):  
Maya Isarov ◽  
N. Grumbach ◽  
Georgy I. Maikov ◽  
Jenya Tilchin ◽  
Youngjin Jang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Interface Layer ◽  
Longitudinal Optical ◽  
Band Gap Energy ◽  
Longitudinal Optical Phonon ◽  
Core Shell ◽  
Temperature Dependent ◽  
Structural And Optical Properties ◽  
Wide Range ◽  
Temperature Dependent Properties

This paper presents the optical temperature dependent properties, over a wide range of temperatures from 4 to 300 K, of new CdSe/CdS core/shell colloidal quantum dots (QDs) with varying shell thickness coated and annealed at low temperature. It was demonstrated that low temperature coating and annealing processes enhanced the photoluminescence (PL) quantum yield accompanied by variation in the QDs structure, formation of an alloyed interface layer, suppression of the number of defects at the CdSe/CdS interface, band gap energy red-shift, narrowing of CdS longitudinal optical phonon band, and decrease of the PL inhomogeneous broadening parameter.

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