scholarly journals Comportamiento germinativo y potencial forrajero de Setaria magna (Poaceae) Germinative behavior and forage potential of Setaria magna (Poaceae)

1970 ◽  
Vol 48 (2) ◽  
pp. 261-270 ◽  
Author(s):  
Lorena del R. Marinoni ◽  
Juan M. Zabala ◽  
Eliana de L. Exner ◽  
José F. Pensiero
Keyword(s):  
Salt Water ◽  
Vegetative State ◽  
Natural Habitat ◽  
First Year ◽  
Annual Grass ◽  
Temperature Regimes ◽  
Germination Ability ◽  
Cultivated Species ◽  
Productive Traits ◽  
Alternating Temperature

Summary: Germinative behavior and forage potential of Setaria magna (Poaceae). Setaria magna Griseb. is an American species that grows well in damp, swampy environments either in fresh or salt water. It is an annual, grass with vigorous plants in their natural habitat. In this study the germinative behavior as well as the forage potential of this species were evaluated. Caryopses viability and their germination ability at different temperature regimes were analyzed, by means of different scarification treatments and temperatures from diverse environments and harvest times. Morphological and productive traits in genotypes of a population in vegetative and reproductive states were evaluated in field. Results showed that caryopses viability remained the same during the first year after harvest and then decreased. Covered caryopses did not germinate at any of the temperatures tested, which suggests dormancy, whereas in naked caryopses alternating temperature allowed a greater percentage and velocity of germination. Some morphological traits differed significantly among genotypes on the vegetative state, while no differences were found regarding reproductive state. Biomass quality varied between genotypes and states and proved to be similar to that cited for other widely cultivated species of the same cycle. The results obtained suggest the possibility of domestication of this species.Key words: Forage potential, germination, dormancy, productivity, selection, domestication.Resumen: Setaria magna Griseb. es una especie americana que crece en ambientes húmedos y pantanosos de agua dulce o salada. Es una gramínea anual y de ciclo estival, con plantas vigorosas en su ambiente natural. En el presente trabajo se evaluó su comportamiento germinativo y potencial forrajero. Se analizó la viabilidad de las cariopsis y su germinación con diferentes tratamientos de escarificación y temperaturas provenientes de diversos ambientes y años de cosecha. Se caracterizaron morfológica y productivamente a campo, al estado vegetativo y reproductivo. Los resultados mostraron que la viabilidad de las cariopsis se mantiene durante el primer año para luego decrecer. Las cariopsis cubiertas no germinaron a ninguna de las temperaturas ensayadas, sugiriendo la presencia de dormición, mientras que en cariopsis desnudas la alternancia de temperatura permitió aumentar el porcentaje y la tasa de germinación. Algunos caracteres morfológicos difirieron significativamente entre genotipos al estado vegetativo, mientras que ninguna diferencia fue hallada al estado reproductivo. La calidad de la biomasa difirió entre genotipos y estados fenológicos y resultó ser semejante a la citada para especies ampliamente cultivadas de igual ciclo. Los resultados obtenidos sugieren la posibilidad de domesticación de la especie.Palabras clave: Potencial forrajero, germinación, dormición, productividad, selección, domesticación.

Dormancy break and germination requirements in acorns of two bottomland Quercus species (Sect. Lobatae) of the eastern United States with references to ecology and phylogeny

2020 ◽  
Vol 30 (3) ◽  
pp. 199-205
Author(s):  
Tracy S. Hawkins
Keyword(s):  
United States ◽  
Cold Stratification ◽  
Eastern United States ◽  
Closely Related Species ◽  
Temperature Regimes ◽  
Quercus Species ◽  
Physiological Dormancy ◽  
Alternating Temperature ◽  
Incubation Temperatures ◽  
Germination Requirements

AbstractQuercus species are ecologically and economically important components of deciduous forests of the eastern United States. However, knowledge pertinent to a thorough understanding of acorn germination dynamics for these species is lacking. The objectives of this research were to determine dormancy break and germination requirements for acorns of two eastern United States bottomland species, Quercus nigra and Quercus phellos (Section Lobatae), and to present results within ecological and phylogenetic contexts. Three replicates of 50 acorns of each species received 0 (control), 6, 12 or 18 weeks of cold stratification, followed by incubation in alternating temperature regimes of 15/6, 20/10, 25/15 and 30/20°C. Eighteen weeks of cold stratification were not sufficient for dormancy break in Q. nigra acorns. Cumulative germination percentages at 4 weeks of incubation were ≥77%, but only in incubation temperatures of 25/15 and 30/20°C. Dormancy break in Q. phellos acorns was achieved with 18 weeks of cold stratification, and cumulative germination percentages were ≥87% at 4 weeks of incubation in all test temperature regimes. Gibberellic acid solutions were not an effective substitute for cold stratification in either species. Phylogenetically, Q. nigra and Q. phellos are closely related species and, ecologically, both grow in the same habitat. Acorns of both species possess deep physiological dormancy (PD), but dormancy break and germination requirements differ in acorns of these two Quercus species.

scholarly journals Effects of Environmental Factors on Seed Germination and Emergence of Velvetleaf (Abutilon theophrasti)

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
RC. XIONG ◽  
Y. MA ◽  
HW. WU ◽  
WL. JIANG ◽  
XY. MA
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Field Experiments ◽  
Cropping Systems ◽  
Control Strategies ◽  
Seedling Emergence ◽  
Central China ◽  
Burial Depth ◽  
Temperature Regimes ◽  
Alternating Temperature

ABSTRACT: Velvetleaf, an annual broadleaf weed, is a common and troublesome weed of cropping systems worldwide. Laboratory and field experiments were conducted to determine the effects of environmental factors on germination and emergence of velvetleaf. Seeds germinated over a range of constant temperatures from 10 to 40 oC regardless of light conditions, but no germination occurred at temperature below 5 oC and beyond 50 oC. Seeds germinated at alternating temperature regimes of 15/5 to 40/30 oC, with maximum germination (>90%) at alternating temperatures of 40/30 oC. Germination was sensitive to water stress, and only 0.4% of the seeds germinated at the osmotic potential of -0.4 MPa. There was no germination at ? 0.6 MPa. Moreover, germination was reduced by saline and alkaline stresses and no germination occurred at ³ 150 mM NaCl or ³ 200 mM NaHCO3 concentrations. However, pH values from 5 to 9 had no effect on seed germination. Seedling emergence was significantly affected by burial depth and maximum emergence (78.1-85.6%) occurred at the 1-4 cm depth. The results of this study have contributed to our understanding of the germination and emergence of velvetleaf and should enhance our ability to improve control strategies in cropping systems in central China.

Germination of Seeds of Perennial Pepperweed (Lepidium latifolium)

Weed Science ◽  
1986 ◽  
Vol 34 (2) ◽  
pp. 252-255 ◽  
Author(s):  
Gerald K. Miller ◽  
James A. Young ◽  
Raymond A. Evans
Keyword(s):  
United States ◽  
Constant Temperature ◽  
Western United States ◽  
Lepidium Latifolium ◽  
Temperature Regimes ◽  
Riparian Habitats ◽  
Alternating Temperature

Perennial pepperweed (Lepidium latifoliumL. # LEPLA) is a serious weed of meadows and riparian habitats in the intermountain area of the western United States. Germination of seeds of this species was tested at 55 constant- and alternating-temperature regimes. No significant differences were found in mean germination at a range of temperatures varying from 0 to 40 C for seedlots collected at the same site in different years or at different locations in the same year. Optimum germination not significantly (P = 0.01) lower than the maximum observed occurred most frequently at 5/40 C (5 C for 16 h and 40 C for 8 h), and 10/40 and 15/40 C. Germination was enhanced by alternating regimes with low night temperatures (0, 2, or 5 C) and high day temperatures (35 and 40 C), in comparison with more moderate constant-temperature regimes.

Germination of Cenchrus ciliaris, Pennisetum divisum, and Panicum turgidum is seasonally dependent

Botany ◽  
2020 ◽  
Vol 98 (8) ◽  
pp. 449-458
Author(s):  
Arvind Bhatt ◽  
Willian Batista-Silva ◽  
David J. Gallacher ◽  
Marcelo F. Pompelli
Keyword(s):  
Grass Species ◽  
Harvest Time ◽  
Lower Mass ◽  
Temperature Regimes ◽  
Fodder Production ◽  
Germination Ability ◽  
Light Requirements ◽  
Germination Temperature ◽  
C 30 ◽  
Temperature Interactions

Knowledge of optimal conditions for germination facilitates more efficient practices, such as fodder production and restoration. We assessed seeds of three grass species harvested in winter and summer 2018. Germination ability was assessed under two night/day temperature regimes (15 °C/20 °C, 20 °C/30 °C) and two photoperiod regimes (0, 12 h light per day). Winter-maturing seeds had a slightly lower mass and reduced germination. Temperature and light requirements for optimal germination were dependent on species and harvest-time. Summer-maturing seeds of all three species had higher germination rates regardless of germination temperature. Interactions among treatment temperatures and species were 0.7- to 5.4-times higher than the control, as shown by heatmaps. Therefore, attention to these factors will improve the efficiency of seedling establishment for rehabilitation work.

Dispersal and establishment of slender thistle, Carduus pycnocephalus L. as affected by ground cover

1985 ◽  
Vol 36 (6) ◽  
pp. 791 ◽  
Author(s):  
AR Harradine
Keyword(s):  
Seed Dispersal ◽  
Seedling Establishment ◽  
Ground Cover ◽  
The Other ◽  
Grass Species ◽  
First Year ◽  
Parent Plant ◽  
Annual Grass

After 3 years of spread from sown infestations, slender thistle density in spring was 0.12 and 4.67 plants m-2 for plots in which the ground cover was dominated by cocksfoot and annual grass species, respectively. On plots maintained free of plants other than slender thistle ('bare plots'), the corresponding density was 47.31 plants m-2. Slender thistle seed was dispersed at least 10 m from the parent plant in the first year of seeding and plants were evenly spread over the bare plots after 2 years. After 3 years, slender thistle ingress was still occurring on the other plots. The results indicate the importance of ground cover, either of living plants or of litter, in reducing seedling establishment and seed dispersal of slender thistle.

Changes in the Transcriptome of Dry Leafy Spurge (Euphorbia esula) Seeds Imbibed at a Constant and Alternating Temperature

Weed Science ◽  
2012 ◽  
Vol 60 (1) ◽  
pp. 48-56 ◽  
Author(s):  
Michael E. Foley ◽  
Wun S. Chao ◽  
Münevver Doğramaci ◽  
David P. Horvath ◽  
James V. Anderson
Keyword(s):  
Stress Responses ◽  
Anaerobic Respiration ◽  
Reducing Power ◽  
Principal Component ◽  
Leafy Spurge ◽  
Specific Effects ◽  
Temperature Regimes ◽  
Stress Related Genes ◽  
Alternating Temperature ◽  
Species Specific

Leafy spurge seeds are responsive to alternating temperature rather than constant temperature for germination. Transcriptome changes of dry leafy spurge seeds and seeds imbibed for 1 and 3 d at 20 C constant (C) and 20 : 30 C alternating (A) temperature were determined by microarray analysis to examine temperature responsiveness. Principal component analysis revealed differences in the transcriptome of imbibed seeds based on the temperature regime. Computational methods in bioinformatics parsed the data into overrepresented AraCyc pathways and gene regulation subnetworks providing biological context to temperature responses. After 1 d of imbibition, the degradation of starch and sucrose leading to anaerobic respiration were common pathways at both temperature regimes. Several overrepresented pathways unique to 1 d A were associated with generation of energy, reducing power, and carbon substrates; several of these pathways remained overrepresented and up-regulated at 3 d A. At 1 d C, pathways for the phytohormones jasmonic acid and brassinosteroids were uniquely overrepresented. There was little similarity in overrepresented pathways at 1 d C between leafy spurge and arabidopsis seeds, indicating species-specific effects upon imbibition of dry seeds. Overrepresented gene subnetworks at 1 d and 3 d at both temperature regimes related to signaling processes and stress responses. A major overrepresented subnetwork unique to 1 d C related to photomorphogenesis via the E3 ubiquitin ligase COP1. At 1 d A, major overrepresented subnetworks involved circadian rhythm via LHY and TOC1 proteins and expression of stress-related genes such as DREB1A, which is subject to circadian regulation. Collectively, substantial differences were observed in the transcriptome of leafy spurge seeds imbibed under conditions that affect the capacity to germinate.

scholarly journals Torpor duration, more than temperature, is key to hummingbird nighttime energy savings

2018 ◽  
Author(s):  
A Shankar ◽  
RJ Schroeder ◽  
SM Wethington ◽  
CH Graham ◽  
DR Powers
Keyword(s):  
Energy Management ◽  
Energy Savings ◽  
Natural Habitat ◽  
Natural Environments ◽  
List Type ◽  
Laboratory Studies ◽  
Ambient Temperatures ◽  
Torpor Bout ◽  
Bout Duration ◽  
Temperature Regimes

ABSTRACTTorpor is an important energy saving strategy in small endotherms, but it has been insufficiently studied in natural field conditions. Building on what we know from laboratory studies, we compared torpor use across hummingbird species and different natural temperature regimes to explore predominant hypotheses about torpor use and evaluate the possible effects of environmental variation on energy management.We found that the probability of an individual entering torpor was correlated with mass and unrelated to nighttime temperature, and that hummingbirds at both warm tropical and cooler temperate sites used torpor.Energy savings in torpor were maximized as ambient temperatures approached a species’ minimum body temperature consistent with laboratory studies; energy savings ranged between 65-92% of energy per hour in torpor compared to normothermy.However, variation in total nighttime energy expenditure was more significantly influenced by torpor bout duration than by the variation in energy savings in torpor.Our results show that a small endotherm’s nighttime energy management in its natural habitat is more affected by torpor bout duration, which is linked to photoperiod, than by temperature. This result suggests that in their natural environments, hummingbirds are able to save energy in torpor across a range nighttime temperature, indicating that they may have sufficient physiological flexibility to tolerate climatic variation.

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