58 research outputs found
Sugarbeet Yields Unaffected by Afternoon Wilting
Sugarbeet irrigation has been studied extensively in the western
United States. The present "state of the art" has been reviewed
by Loomis and Haddock (2) 8. Most field experiments
have been run at three or more levels of soil moisture—wet,
medium and dry. Differences in root and sugar yields under
these moisture regimes have not been strikingly different so long
as the "dry" treatment did not cause prolonged wilting, and so
long as the "wet" treatment did not cause leaching of nutrients
Row Cropping Sandy Soils Under Sprinklers Using a Winter Grain Cover to Control Wind Erosion
One of the most effective ways to prevent the wind erosion
of sandy soils is to maintain a continuous crop cover. Summer
row cropping following a winter grain cover offers several
attractive features, although it does present management
problems. The grain cover must be established in the fall
after harvesting the row crop, and the transition back to a
row crop in the spring must be made without leaving the
soil surface unprotected from the wind.
This report summarizes 4 years of observations and
exploratory studies in which a variety of cover-row cropping
management systems were tested with emphasis on methods
for establishing row crops directly in the winter cover.
Pertinent literature and observations of other field trials
are also discussed
Co-variation in soil biodiversity and biogeochemistry in northern and southern Victoria Land, Antarctica
Social capital and soil conservation: Evidence from the Philippines
The formation of social capital is hypothesised to enhance collective efforts for soil conservation. The Landcare Program in the Southern Philippines promotes simple conservation practices in upland environments by supporting community landcare groups and municipal landcare associations, thus augmenting social capital. A study was conducted in 2002 to evaluate the Landcare Program, using a mix of quantitative and qualitative techniques. In this paper the relationship between social capital formation and adoption of soil conservation is investigated. It is concluded that, although membership in a local landcare group was not a major factor in adoption, the Landcare Program as a whole created a valuable stock of bridging social capital, with significant benefits for long-term natural resource management
Measurement of atmospheric elemental carbon: Real-time data for Los Angeles during summer 1987
Two fundamentally different techniques for measuring atmospheric elemental carbon (EC) aerosol were compared to validate the methods. One technique, photoacoustic spectroscopy, was used to measure the optical absorption ([lambda] = 514.5 nm) of in situ atmospheric aerosol in real time. This optical absorption can be converted to EC concentration using the appropriate value of the absorption cross-section for C, so that a comparison could be made with the second technique, thermal-optical analysis of filter-collected samples, which measures the collected EC by combustion. Solvent extraction of the filter samples prior to the thermal analysis procedure was required to minimize errors due to pyrolysis of organic carbon. Excellent 1:1 correlation of atmospheric EC concentrations resulted for measurements by the photoacoustic method vs the thermal method over coincident sampling times. The linear regression gave y = 1.006 (+/-0.056) x+0.27 (+/-0.56) with R = 0.945 (n = 41), where y is the photoacoustic EC concentration and x is the thermal elemental carbon concentration, both in [mu]g m-3. This data set was collected in Los Angeles as part of the Southern California Air Quality Study (SCAQS) during the summer 1987, and supplements the results of an earlier, more limited data set taken in Dearborn, MI. The diurnal variability of EC aerosol in Los Angeles during SCAQS, as determined by photoacoustic spectroscopy, is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28903/1/0000740.pd
Secondary metabolite profiling, growth profiles and other tools for species recognition and important Aspergillus mycotoxins
Species in the genus Aspergillus have been classified primarily
based on morphological features. Sequencing of house-hold genes has also been
used in Aspergillus taxonomy and phylogeny, while extrolites and
physiological features have been used less frequently. Three independent ways
of classifying and identifying aspergilli appear to be applicable: Morphology
combined with physiology and nutritional features, secondary metabolite
profiling and DNA sequencing. These three ways of identifying
Aspergillus species often point to the same species. This consensus
approach can be used initially, but if consensus is achieved it is recommended
to combine at least two of these independent ways of characterising aspergilli
in a polyphasic taxonomy. The chemical combination of secondary metabolites
and DNA sequence features has not been explored in taxonomy yet, however.
Examples of these different taxonomic approaches will be given for
Aspergillus section Nigri
Two new aflatoxin producing species, and an overview of Aspergillus section Flavi
Aspergillus subgenus Circumdati section Flavi includes species with usually biseriate conidial heads, in shades of yellow-green to brown, and dark sclerotia. Several species assigned to this section are either important mycotoxin producers including aflatoxins, cyclopiazonic acid, ochratoxins and kojic acid, or are used in oriental food fermentation processes and as hosts for heterologous gene expression. A polyphasic approach was applied using morphological characters, extrolite data and partial calmodulin, β-tubulin and ITS sequences to examine the evolutionary relationships within this section. The data indicate that Aspergillus section Flavi involves 22 species, which can be grouped into seven clades. Two new species, A. pseudocaelatus sp. nov. and A. pseudonomius sp. nov. have been discovered, and can be distinguished from other species in this section based on sequence data and extrolite profiles. Aspergillus pseudocaelatus is represented by a single isolate collected from Arachis burkartii leaf in Argentina, is closely related to the non-aflatoxin producing A. caelatus, and produces aflatoxins B & G, cyclopiazonic acid and kojic acid, while A. pseudonomius was isolated from insects and soil in the USA. This species is related to A. nomius, and produces aflatoxin B1 (but not G-type aflatoxins), chrysogine and kojic acid. In order to prove the aflatoxin producing abilities of the isolates, phylogenetic analysis of three genes taking part in aflatoxin biosynthesis, including the transcriptional regulator aflR, norsolonic acid reductase and O-methyltransferase were also carried out. A detailed overview of the species accepted in Aspergillus section Flavi is presented
Biomass allocation and nutrients balance related to the concentration of Nitrogen and Phosphorus in Salvinia auriculata (Salviniaceae)
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