Dormancy in sunflower line A-3: the role of the pericarp

Botany ◽  
2017 ◽  
Vol 95 (8) ◽  
pp. 853-858
Author(s):  
Ana E. Vigliocco ◽  
Andrea M. Andrade ◽  
Lilia I. Lindström ◽  
Sergio G. Alemano
Keyword(s):  
Seed Dormancy ◽  
Cross Sections ◽  
Morphological Characteristics ◽  
Germination Percentage ◽  
Physical Dormancy ◽  
Relative Contribution ◽  
Sunflower Line ◽  
Whole Seed ◽  
Final Degree

Sunflower (Helianthus annuus L.) can often display seed dormancy, which causes a delay for immediate sowing. The final degree of “whole seed” dormancy is determined by the contributions of the tissues that comprise it, such as, embryo, seed coat, and (or) pericarp. The sunflower dormancy can be reduced during after-ripening and by removing seed constraints. Our objective was to study how the conditions of storage and removal of the pericarp affect the level of dormancy in line A-3. Also we provide insight on the basis of the morphological characteristics of A-3 pericarp-imposed dormancy. A germination test was conducted on dry cypselas with and without pericarp, at 30 and 70 days after harvest. For histological analysis, permanent slides of pericarp cross-sections were obtained. The germination percentage showed significant differences between cypselas with intact pericarp (30 days after harvest = 26%; 70 days after harvest = 77%), and cypselas without pericarp (30 days after harvest = 65%; 70 days after harvest = 96%). This indicates that the pericarp plays an important role in regulating physical dormancy in the seed of sunflower line A-3, and that its relative contribution to the dormancy level is modified during after-ripening.

A critical update on seed dormancy. I. Primary dormancy

1995 ◽  
Vol 5 (2) ◽  
pp. 61-73 ◽  
Author(s):  
Henk W. M. Hilhorst
Keyword(s):  
Cell Wall ◽  
Abscisic Acid ◽  
Seed Dormancy ◽  
Decisive Role ◽  
Morphological Development ◽  
Primary Dormancy ◽  
Whole Seed ◽  
Aba Content ◽  
Cell Wall Properties

AbstractThe emphasis of modern dormancy research is almost entirely on the form of dormancy that is acquired during seed development, primary dormancy. Abscisic acid (ABA) appears to be intimately involved in its regulation. The action of abscisic acid has also been implied in many other developmental processes. The coincidence of developmental events, such as dehydration and completion of maturation, with the acquisition of primary dormancy suggests that dormancy is influenced by these processes. Germinability, both during development and after maturation, is sometimes directly correlated with ABA content. The lack of such a correlation may be explained by assuming a decisive role for the responsiveness to ABA or other overriding factors. ABA has been detected in all seed components. The different seed tissues may all contribute, to various extents, to the degree of whole seed dormancy. It is concluded that ABA action in dormancy regulation is not restricted to the embryo but is also located in endospermic tissue. In addition, a role of ABA in the morphological development of germination modifying seed tissues is proposed. The mechanism for ABA action appears to be associated with cell wall properties.

Dormancy breakage in Cercis chinensis seeds

2020 ◽  
Vol 100 (6) ◽  
pp. 666-673
Author(s):  
Yunpeng Gao ◽  
Mingwei Zhu ◽  
Qiuyue Ma ◽  
Shuxian Li
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Seed Coat ◽  
Germination Percentage ◽  
Physical Dormancy ◽  
Optimal Method ◽  
Hard Seed ◽  
Positive Effects ◽  
Physiological Dormancy ◽  
Hard Seed Coat

The seeds of Cercis chinensis Bunge are important for reproduction and propagation, but strong dormancy controls their germination. To elucidate the causes of seed dormancy in C. chinensis, we investigated the permeability of the hard seed coat and the contribution of the endosperm to physical dormancy, and we examined the effect of extracts from the seed coat and endosperm. In addition, the effectiveness of scarification methods to break seed dormancy was compared. Cercis chinensis seeds exhibited physical and physiological dormancy. The hard seed coat played an important role in limiting water uptake, and the endosperm acted as a physical barrier that restricted embryo development in imbibed seeds. Germination percentage of Chinese cabbage [Brassica rapa subsp. chinensis (L.) Hanelt] seeds was reduced from 98% (control) to 28.3% and 56.7% with a seed-coat extract and an endosperm extract, respectively. This demonstrated that both the seed coat and endosperm contained endogenous inhibitors, but the seed-coat extract resulted in stronger inhibition. Mechanical scarification, thermal scarification, and chemical scarification had positive effects on C. chinensis seed germination. Soaking non-scarified seeds in gibberellic acid (GA3) solution did not promote germination; however, treatment with exogenous GA3 following scarification significantly improved germination. The optimal method for promoting C. chinensis seed germination was soaking scarified seeds in 500 mg·L−1 GA3 for 24 h followed by cold stratification at 5 °C for 2 mo.

scholarly journals THE POMERON AND ODDERON IN ELASTIC, INELASTIC AND TOTAL CROSS-SECTIONS AT THE LHC

2011 ◽  
Vol 26 (27n28) ◽  
pp. 4755-4771 ◽  
Author(s):  
L. L. JENKOVSZKY ◽  
A. I. LENGYEL ◽  
D. I. LONTKOVSKYI
Keyword(s):  
Simple Model ◽  
Cross Section ◽  
Cross Sections ◽  
Energy Region ◽  
Scattering Amplitude ◽  
Total Cross Sections ◽  
Regge Trajectories ◽  
Relative Contribution ◽  
Main Emphasis

A simple model for elastic diffractive hadron scattering, reproducing the dip-bump structure is used to analyze pp and [Formula: see text] scattering. The main emphasis is on the delicate and nontrivial dynamics in the dip-bump region, near t = -1 GeV 2. The simplicity of the model and the expected smallness of the absorption corrections enables one the control of various contributions to the scattering amplitude, in particular the interplay between the C-even and C-odd components of the amplitude, as well as their relative contribution, changing with s and t. The role of the nonlinearity of the Regge trajectories is scrutinized. The ratio of the real to imaginary parts of the forward amplitude, the ratio of elastic to total cross-sections and the inelastic cross-section are calculated. Predictions for the LHC energy region, where most of the existing models will be either confirmed or ruled out, are presented.

Characterisation of seed dormancy of 12 Chilean species of Nolana (Solanaceae) from the coastal Atacama Desert

2020 ◽  
pp. 1-10
Author(s):  
Josefina Hepp ◽  
Miguel Gómez ◽  
Pedro León-Lobos ◽  
Gloria Montenegro ◽  
Luis Vilalobos ◽  
...  
Keyword(s):  
Seed Dormancy ◽  
Atacama Desert ◽  
Distilled Water ◽  
Latitudinal Distribution ◽  
Physical Dormancy ◽  
Physiological Dormancy ◽  
Arid Habitat ◽  
The Relationship ◽  
Germination Requirements

Abstract The genus Nolana (Solanaceae) comprises numerous species endemic to the coastal Atacama Desert of Chile and Peru of high ornamental potential and conservation value. The environments in which these species have evolved and are present today correspond to particular conditions in the midst of a hyper-arid habitat, so the study of their germination requirements and characterisation of seed dormancy becomes important in terms of conservation but also for ecological and evolutionary purposes. Different treatments were performed on mericarps of 12 species of Nolana: control (intact seeds imbibed in distilled water), scarification in funicular plug and distilled water and scarification in funicular plug and addition of GA3 (500 ppm); their permeability to water was also tested. It was determined that the species did not present physical dormancy, as had been previously reported, but rather physiological dormancy (PD). Germination results after treatments were not homogeneous among all 12 species, indicating differences in their dormancy levels. Also, the important role of the endosperm in the prevention of germination for the studied Nolana species was highlighted. Regarding the relationship between the level of PD (expressed as the percentage of germination for the most successful treatment) and the latitudinal distribution of the species or their phylogenetic closeness, it was determined that, for the studied species, their proximity in terms of clades was more relevant than their latitudinal distribution.

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

An Study of Influence of Imperfections on the Delamination of Diamond-Like Carbon Films

2002 ◽  
Vol 719 ◽  
Author(s):  
Myoung-Woon Moon ◽  
Kyang-Ryel Lee ◽  
Jin-Won Chung ◽  
Kyu Hwan Oh
Keyword(s):  
Cross Sections ◽  
Focused Ion Beam ◽  
Imaging System ◽  
Ion Beam ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Glass Substrates ◽  
Atomic Force ◽  
Initiation And Propagation

AbstractThe role of imperfections on the initiation and propagation of interface delaminations in compressed thin films has been analyzed using experiments with diamond-like carbon (DLC) films deposited onto glass substrates. The surface topologies and interface separations have been characterized by using the Atomic Force Microscope (AFM) and the Focused Ion Beam (FIB) imaging system. The lengths and amplitudes of numerous imperfections have been measured by AFM and the interface separations characterized on cross sections made with the FIB. Chemical analysis of several sites, performed using Auger Electron Spectroscopy (AES), has revealed the origin of the imperfections. The incidence of buckles has been correlated with the imperfection length.

A Developmental Perspective on the Genetic Basis of Alcohol Use Disorder

2018 ◽  
Author(s):  
Elisa M. Trucco ◽  
Gabriel L. Schlomer ◽  
Brian M. Hicks
Keyword(s):  
Alcohol Use ◽  
Alcohol Use Disorder ◽  
Developmental Perspective ◽  
Relative Contribution ◽  
Intermediate Phenotypes ◽  
Problematic Alcohol ◽  
Age Related ◽  
Genetic And Environmental Factors ◽  
Problematic Alcohol Use

Approximately 48–66% of the variation in alcohol use disorders is heritable. This chapter provides an overview of the genetic influences that contribute to alcohol use disorder within a developmental perspective. Namely, risk for problematic alcohol use is framed as a function of age-related changes in the relative contribution of genetic and environmental factors and an end state of developmental processes. This chapter discusses the role of development in the association between genes and the environment on risk for alcohol use disorder. Designs used to identify genetic factors relevant to problematic alcohol use are discussed. Studies examining developmental pathways to alcohol use disorder with a focus on endophenotypes and intermediate phenotypes are reviewed. Finally, areas for further investigation are offered.

scholarly journals Role of α-Cluster Transfer in the Formation of 20Ne + 16O Cross-Sections at Backward Angles

2021 ◽  
Vol 51 (3) ◽  
pp. 780-787
Author(s):  
Sh. Hamada ◽  
Nourhan M. Elmedalaa ◽  
I. Bondouk ◽  
N. Darwish ◽  
Awad A. Ibraheem
Keyword(s):  
Cross Sections ◽  
Cluster Transfer

scholarly journals Few Body Effects in the Electron and Positron Impact Ionization of Atoms

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 33
Author(s):  
R.I. Campeanu ◽  
Colm T. Whelan
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Differential Cross ◽  
Impact Ionization ◽  
Inert Gas ◽  
Interference Effects ◽  
Positron Impact ◽  
Competing Interactions ◽  
Energy Sharing

Triple differential cross sections (TDCS) are presented for the electron and positron impact ionization of inert gas atoms in a range of energy sharing geometries where a number of significant few body effects compete to define the shape of the TDCS. Using both positrons and electrons as projectiles has opened up the possibility of performing complementary studies which could effectively isolate competing interactions that cannot be separately detected in an experiment with a single projectile. Results will be presented in kinematics where the electron impact ionization appears to be well understood and using the same kinematics positron cross sections will be presented. The kinematics are then varied in order to focus on the role of distortion, post collision interaction (pci), and interference effects.

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