scholarly journals Comparative morphological screening of some species of Cenchrus L. (Poaceae) from Thar Desert of Rajasthan, India.

2018 ◽  
Vol 7 (4) ◽  
pp. 2175
Author(s):  
Ganesh Kumar ◽  
Arora Sunita
Keyword(s):  
Soil Moisture ◽  
Wild Species ◽  
Full Potential ◽  
Thar Desert ◽  
Perennial Species ◽  
Minimal Level ◽  
C4 Grass ◽  
Exact Identification

In present study an attempt has been made to describe widely confused species of Cenchrus (Poaceae). The exact identification has been critically assessed. The name Cenchrus comes from the Greek word “Kenchrous” meaning millet. Cenchrus is an extremely variable genus having both annual and perennial species. Morphologically Cenchrus is very similar to Pennisetum. All species of Cenchrus are very much similar in their morphology except few micromorphological distinctions.  It is a xerophytic C4 grass, which grows in bunches and more often with creeping rhizomes. These grasses can exist under minimal level of precipitation ranging from as low as 95 mm to 1000 mm. Cenchrus is very efficient in water usages as its root draws soil moisture rapidly as compared to other plants. Various traits are known to wild species of genus Cenchrus but due to lack of enough studies their full potential has not been exercised.  An attempt has been need to study morphology of three species common in our region so that these details can further be utilized to exploit these species for their full potential.

Genetic diversity, population structure and gene flow pattern among populations of Lasiurus sindicus Henr. - an endemic, C4 grass of Indian Thar desert

Plant Gene ◽  
2020 ◽  
Vol 21 ◽  
pp. 100206 ◽  
Author(s):  
Bhuwnesh Goswami ◽  
Rekha Rankawat ◽  
Wahlang Daniel Regie ◽  
Bhana Ram Gadi ◽  
Satyawada Rama Rao
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Flow Pattern ◽  
Thar Desert ◽  
C4 Grass

scholarly journals Assimilation of passive microwave vegetation optical depth in LDAS-Monde: a case study over the continental US

2021 ◽  
Author(s):  
Anthony Mucia ◽  
Bertrand Bonan ◽  
Clément Albergel ◽  
Yongjun Zheng ◽  
Jean-Christophe Calvet
Keyword(s):  
Soil Moisture ◽  
Optical Depth ◽  
Land Surface ◽  
Positive Impact ◽  
Gross Primary Production ◽  
Soil Surface ◽  
Passive Microwave ◽  
Surface Model ◽  
Full Potential ◽  
Area Index

Abstract. The land data assimilation system, LDAS-Monde, developed by the Research Department of the French Meteorological service (Centre National de Recherches Météorologiques – CNRM) is capable of well representing Land Surface Variables (LSVs) from regional to global scales. It jointly assimilates satellite-derived observations of leaf area index (LAI) and surface soil moisture (SSM) into the Interactions between Soil Biosphere and Atmosphere (ISBA) land surface model (LSM), increasing the accuracy of the model simulations and forecasts of the LSVs. The assimilation of vegetation variables directly impacts RZSM through seven control variables consisting in soil moisture of seven soil layers from the soil surface to 1 m depth. This capability is particularly useful in dry conditions, where SSM and RZSM are decoupled to a large extent. However, this positive impact does not reach its full potential due to the low temporal availability of optical-based LAI observations, at best, every ten days, and can suffer from months of no data over regions and seasons with heavy cloud cover such as winter or monsoon conditions. In that context, this study investigates the assimilation of low frequency passive microwave vegetation optical depth (VOD), available in almost all weather conditions, as a proxy of LAI. The Vegetation Optical Depth Climate Archive (VODCA) dataset provides near-daily observations of vegetation conditions, far more frequently than optical based product such as LAI. This study's goal is to convert the more frequent X-band VOD observations into proxy-LAI observations through linear re-scaling and to assimilate them in place of direct LAI observations. Seven assimilation experiments were run from 2003 to 2018 over the contiguous United States (CONUS), with 1) no assimilation, the assimilation of 2) SSM, 3) LAI, 4) re-scaled VODX, 5) re-scaled VODX only when LAI observations available, 6) LAI + SSM, and 7) re-scaled VODX + SSM. This study analyzes these assimilation experiments by comparing to satellite derived observations and in situ measurements and is focused on the variables of LAI, SSM, gross primary production (GPP), and evapotranspiration (ET). Each experiment is driven by atmospheric forcing reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5. Results showed improved representation of GPP and ET by assimilating re-scaled VOD in place of LAI. Additionally, the joint assimilation of vegetation related variables (i.e. LAI or re-scaled VOD) and SSM demonstrates a small improvement in the representation of soil moisture over the assimilation of any dataset by itself.

Analysis of chromosomal structural polymorphisms in the St, P, and Y genomes of Triticeae (Poaceae)

Genome ◽  
2010 ◽  
Vol 53 (3) ◽  
pp. 241-249 ◽  
Author(s):  
Qiuxia Wang ◽  
Jishan Xiang ◽  
Ainong Gao ◽  
Xinming Yang ◽  
Weihua Liu ◽  
...  
Keyword(s):  
Wild Species ◽  
Centromeric Region ◽  
Perennial Species ◽  
Origin And Evolution ◽  
Fish Method ◽  
The Individual ◽  
Evolution Of Genomes ◽  
Tribe Triticeae

The St, P, and Y genomes are three important genomes in the tribe Triticeae, which includes many perennial species. To study polymorphisms within the chromosomes of the St, P, and Y genomes, a GISH–FISH method was developed that allowed them to be clearly distinguished. The karyotypes of five individuals from population Z1925 of Kengyilia grandiglumis (Keng) J.L. Yang et al. (2n = 6x = 42, StStPPYY) were analyzed. The results showed that there were structural polymorphisms in all of the chromosomes from the three individual genomes. The polymorphisms were found mainly in the terminal regions of chromosomes and infrequently near the centromeric region. Of all the chromosomes, 1P, 1St, 1Y, 2Y, 3St, and 3Y showed the most polymorphisms. The polymorphisms within the individual chromosomes suggested that more extensive and scientific conclusions regarding the origin and evolution of genomes in wild species of Triticeae would be achieved by studying a population as a sampling and analysis unit.

Peat Wedges Aid Seedling Establishment on Shallow Soil

1976 ◽  
Vol 52 (2) ◽  
pp. 47-52
Author(s):  
George Stroempl
Keyword(s):  
Soil Moisture ◽  
Seedling Establishment ◽  
Tree Planting ◽  
Severe Drought ◽  
Full Potential ◽  
Stages Of Growth ◽  
Growing Seasons ◽  
Shallow Soil ◽  
Drought Conditions ◽  
Limestone Bedrock

Tree planting experiments were established in south-eastern Ontario on old pastures with shallow soil over limestone bedrock known to have frequent moisture deficits during the growing seasons. Wedge-shaped pieces of solid peat, saturated with water, were placed at the bottom of a planting hole to supply water to the roots during the early stages of growth and prevent dessiccation during severe drought conditions. The survival of trees planted with peat wedges was higher than those planted without, particularly in the year when soil moisture was most frequently within the wilting range. Additional experience is needed to realize the full potential of this method.

scholarly journals Future forage plants for hill country systems

2016 ◽  
Vol 16 ◽  
pp. 233-242
Author(s):  
S.N. Nichols ◽  
J.R. Crush ◽  
C.C. Eady ◽  
M.J. Faville ◽  
K. Ghamkhar ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Interspecific Crosses ◽  
Full Potential ◽  
Root Characteristics ◽  
Pasture Management ◽  
Great Opportunity ◽  
Hill Country ◽  
Forage Plants ◽  
Wide Range ◽  
Breeding Programmes

The issues currently limiting the performance of forage plants in hill country are largely unchanged from preceding decades. Low soil pH/high aluminium, low soil phosphate and low soil moisture or summer dry conditions are all ongoing problems. Furthermore, predicted climatic changes in many regions will only intensify soil moisture stress. Forage breeding programmes in the 1970s and 1980s delivered a range of cultivars that improved hill country productivity, but small market size for seed has not been conducive to widespread success of these cultivars or to provision of dedicated plant breeding programmes for these farming systems. Intensification is however driving renewed interest in forages for hill country. A wide range of genetic resources is now available to breeders for better adaptation to these conditions. These include large germplasm collections within existing species, germplasm for interspecific crosses, and potential "new" species which have evolved appropriate adaptations at their point of origin. Advances in genomic technologies offer potential to provide accelerated, more targeted selection of germplasm. This would be particularly valuable for traits that are under complex genetic control, or are more difficult to visually assess, such as physiological and root characteristics. Adjustments in pasture management will be necessary to capture the full potential of new germplasm, while tools to improve pasture establishment and renewal (e.g. new herbicide tolerant brassicas) are also needed to enable its successful introduction. The amalgamation of seed companies into large international enterprises adds potential scale to what has traditionally been a localised issue, making the commercial proposition of developing and marketing such specialised products more attractive. These developments, combined with improved seed distribution technologies, should provide a great opportunity for future hill country farming. Keywords: germplasm, phosphorus, aluminium, drought, genomic selection, cultivars

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

“High Resolution High Voltage Electron Microscopy”

1968 ◽  
Vol 26 ◽  
pp. 326-327
Author(s):  
Benjamin M. Siegel
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Voltage ◽  
Full Potential ◽  
Contrast Imaging ◽  
High Voltage Electron Microscopy ◽  
Low Contrast ◽  
Voltage Electron ◽  
Critical Areas ◽  
High Voltage Electron

The potential advantages of high voltage electron microscopy for extending the limits of resolution and contrast in imaging low contrast objects, such as biomolecular specimens, is very great. The results of computations will be presented showing that at accelerating voltages of 500-1000 kV it should be possible to achieve spacial resolutions of 1 to 1.5 Å and using phase contrast imaging achieve adequate image contrast to observe single atoms of low atomic number.The practical problems associated with the design and utilization of the high voltage instrument are, optimistically, within the range of competence of the state of the art. However, there are some extremely important and critical areas to be systematically investigated before we have achieved this competence. The basic electron optics of the column required is well understood, but before the full potential of an instrument capable of resolutions of better than 1.5 Å are realized some very careful development work will be required. Of great importance for the actual achievement of high resolution with a high voltage electron microscope is the fundamental limitation set by the characteristics of the high voltage electron beam that can be obtained from the accelerator column.

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