Optical Properties of Hairs During the Early Stages of Leaf Development in Platanus orientalis

1996 ◽  
Vol 23 (4) ◽  
pp. 535 ◽  
Author(s):  
M Ntefidou ◽  
Y Manetas
Keyword(s):  
Optical Properties ◽  
Leaf Development ◽  
Visible Radiation ◽  
Leaf Hairs ◽  
Early Stages ◽  
Platanus Orientalis ◽  
Young Leaves ◽  
Excess Light ◽  
Dense Hair ◽  
High Reflectance

Young, developing leaves of plane (Platanus orientalis L.) possess a dense hair cover on both surfaces but, as the leaf matures, the hairs of the upper surface abscise, leading to a glabrous epidermis. Leaf hairs strongly attenuate visible radiation, partly due to high reflectance of the trichome layer and partly to the presence of an absorbing pigment, tentatively identified as the anthocyanidin peonidin, which was present in the hairs of exposed young leaves but was absent on leaves harvested from the interior of the canopy. It is suggested that leaf hairs, apart from other functions, may protect developing leaves against the photoinhibitory effect of excess light.

The rotated-lamina syndrome. V. Partial lamina rotation and related features in Hamamelidaceae

1994 ◽  
Vol 72 (5) ◽  
pp. 626-634 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Key Words ◽  
Shoot Apex ◽  
Leaf Development ◽  
Early Stage ◽  
Leaf Primordia ◽  
Leaf Base ◽  
Early Stages ◽  
Young Leaves

Shoots of Hamamelidaceae have been examined for the presence of the rotated-lamina syndrome, a condition in which young leaves in bud face towards one side of the shoot (normally the upper) rather than towards their own shoot apex. Early leaf development and bud organisation have been examined in representatives of eight genera with dorsiventral shoots and distichous phyllotaxis, and of four genera with radially symmetrical shoots and spiral or decussate phyllotaxis. Radially symmetrical shoots do not show any evidence of the syndrome. The distichous Corylopsis and Hamamelis species studied have leaf primordia that are asymmetrical from an early stage and show partial lamina rotation, the lamina facing obliquely towards the upper side of the bud. Mature laminae are usually asymmetrical. In Corylopsis rotation arises by torsion in the petiole region, and in Hamamelis by asymmetrical growth of the leaf base. Distichous examples without lamina rotation also have asymmetrical primordia in most cases, often have asymmetrical leaves, and all show the same asymmetrical development of the leaf base as found in Hamamelis. It is suggested that these features represent either (i) relics of rotated-lamina syndrome that was present in these cases but has been suppressed or (ii) early stages in evolution of rotated-lamina syndrome. It is suggested that suppression is the more likely interpretation. Corylopsis and Hamamelis may also be in the process of suppressing the syndrome. Key words: Hamamelidaceae, leaf, development, dorsiventrality, lamina rotation.

scholarly journals Evaluating model parameterizations of submicron aerosol scattering and absorption with in situ data from ARCTAS 2008

2016 ◽  
Vol 16 (14) ◽  
pp. 9435-9455 ◽  
Author(s):  
Matthew J. Alvarado ◽  
Chantelle R. Lonsdale ◽  
Helen L. Macintyre ◽  
Huisheng Bian ◽  
Mian Chin ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Aerosol Size Distribution ◽  
Visible Radiation ◽  
Submicron Aerosol ◽  
In Situ Data ◽  
Aerosol Absorption ◽  
Aerosol Scattering ◽  
The Impact

Abstract. Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution are used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10–23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding a variable size distribution, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction throughout the aerosol size distribution. Using a core-shell mixing rule in ASP overestimates aerosol absorption, especially for the fresh biomass burning aerosol measured in ARCTAS-B, suggesting the need for modeling the time-varying mixing states of aerosols in future versions of ASP.

Diaporthe manihotis. [Descriptions of Fungi and Bacteria].

1982 ◽  
Author(s):  
E. Punithalingam
Keyword(s):  
South America ◽  
Central America ◽  
Geographical Distribution ◽  
Leaf Spot ◽  
Manihot Esculenta ◽  
West Indies ◽  
Severe Attack ◽  
Early Stages ◽  
Young Leaves ◽  
Pale Green

Abstract A description is provided for Diaporthe manihotis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOST: Manihot esculenta. DISEASE: Leaf spot of cassava (46, 64) or sometimes referred to as Phomopsis blight of tapioca (54, 2588). In the early stages of infection the visible symptoms are pale green, watersoaked, small round spots on young leaves and petioles which rapidly enlarge and turn brown. Severe attack leads to defoliation and infection spreading to the stem. Affected areas become shrivelled with numerous pycnidia embedded in the tissue. On severely infected stems the bark starts to peel off gradually leading to partial or total girdling. GEOGRAPHICAL DISTRIBUTION: Africa (Ethiopia, Nigeria); Asia (India); Central America and West Indies (S.E. Dominica); South America (Colombia). TRANSMISSION: Probably by watersplash-dispersed conidia.

scholarly journals Evaluating Model Parameterizations of Submicron Aerosol Scattering and Absorption with In Situ Data from ARCTAS 2008

2016 ◽  
Author(s):  
M. J. Alvarado ◽  
C. R. Lonsdale ◽  
H. L. Macintyre ◽  
H. Bian ◽  
M. Chin ◽  
...  
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Aerosol Size Distribution ◽  
Visible Radiation ◽  
Submicron Aerosol ◽  
In Situ Data ◽  
Aerosol Absorption ◽  
Aerosol Scattering ◽  
The Impact

Abstract. Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution is used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10–23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding in situ size distribution information, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction through out the aerosol size distribution. Using a core-shell mixing state in ASP overestimates aerosol absorption, especially for the fresh biomass burning aerosol measured in ARCTAS-B, suggesting the need for time-varying mixing states in future versions of ASP.

Development of bundle sheath chloroplasts in rice seedlings

1976 ◽  
Vol 54 (7) ◽  
pp. 556-565 ◽  
Author(s):  
Hiroshi Miyake ◽  
Eizo Maeda
Keyword(s):  
Leaf Development ◽  
Chloroplast Development ◽  
Developmental Process ◽  
Bundle Sheath ◽  
Rice Seedlings ◽  
Early Stages ◽  
Late Stages ◽  
Storage Starch

A developmental process of bundle sheath chloroplasts in rice seedlings is examined and compared with that of mesophyll chloroplasts. Chloroplast development is accompanied with the leaf development. Both types of chloroplasts accumulate starch derived from endosperm in the early stages of the leaf development, and the accumulated starch is dissipated during the leaf development. In contrast with mesophyll chloroplasts, bundle sheath chloroplasts accumulate large amounts of starch, appear as spherical, amyloplast-like structures, and preserve the starch up to the late stages of the leaf development. It is suggested that bundle sheath chloroplasts of rice seedlings are specialized in the accumulation and supply of storage starch, which is presumed to be consumed for the leaf development.

The transiently pubescent young leaves of plane (Platanus orientalis) are deficient in photodissipative capacity

1997 ◽  
Vol 101 (2) ◽  
pp. 373-378 ◽  
Author(s):  
Aspasia Bisba ◽  
Yiola Petropoulou ◽  
Yiannis Manetas
Keyword(s):  
Platanus Orientalis ◽  
Young Leaves

Relations between optical properties, dinoflagellates and zooplanktonic crustaceans in Antofagasta Bay (23°S, Chile)

Crustaceana ◽  
2020 ◽  
Vol 93 (1) ◽  
pp. 41-49
Author(s):  
Patricio De los Ríos ◽  
Angel Contreras ◽  
Gladys Lara ◽  
Mirtha Latsague ◽  
Carlos Esse
Keyword(s):  
Optical Properties ◽  
Primary Productivity ◽  
Coastal Waters ◽  
Climate Changes ◽  
Global Climate ◽  
High Abundance ◽  
Global Climate Changes ◽  
High Diversity ◽  
High Reflectance ◽  
Chlorophyll Concentrations

Abstract Antofagasta Bay is characterized by a high primary productivity due to the presence of the cold Humboldt Stream that is associated with a high diversity in flora and fauna in the benthic and pelagial environments of the Chilean west coast. Nevertheless, due to the global climate changes, the existing biodiversity patterns change as well. The aim of the present study was to analyse Antofagasta Bay for determining the existence of patterns between optical properties of the water, and the phytoplankton and zooplankton. The results show that one site had high chlorophyll concentrations, high reflectance, a high abundance of the dinoflagellate genus Dinophysis, and a high abundance of copepodites, whereas five sites had low chlorophyll concentrations, a low reflectance value, low copepodite abundances, and high abundances of dinoflagellates of the genera Ceratium, Gymnodinium and Prorocentrum. These results are similar to earlier observations for the coastal waters along northern Chile.

Sign in / Sign up

Export Citation Format

Share Document