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121.
Kamal Fouad Abdellatif Yehia Abdallah Khidr Yasser Mohammad El-Mansy Mohammad Mohammad El-Lawendey Yasser Abdelraouf Soliman 《Journal of Crop Science and Biotechnology》2012,15(2):93-99
Twenty-eight Egyptian cotton (Gossypium barbadense L.) genotypes (varieties and hybrids) were used for analysis of genetic diversity using DNA based markers (ISSR, SSR, and
EST) and to study varietal development of cotton. The ISSR markers gave the highest percentage of polymorphic bands as well
as polymorphic information content compared with the other molecular markers (i.e. EST and SSR markers). Using clustering
analysis, no general clustering according to the pedigree history of the genotypes was observed. Using principal coordinate
analysis (PCOORDA), cotton genotypes were separated by the first three principal coordinates (PC1, PC2, and PC3) accounting
for 11.5, 8.6, and 7.2% of the total genetic variance, respectively. The cotton genotypes were distributed into three parts
based on the first PC, each part containing a group of varieties having a common ancestor. ‘Giza 12’ variety was the common
ancestor for the varieties included in the first part and ‘Ashmouni’ variety was the common ancestor for the varieties included
in the second part, while both ‘Sakha 3’ and ‘Sakha 4’ varieties were common ancestors for the varieties included in the third
part. The results of the PCOORDA also showed better resolution of the genetic diversity than cluster analysis especially in
the illustration of the varietal development of cotton. That means that principal coordinate analysis can be strongly used
either alone or in combination with cluster analysis to discuss both genetic diversity and varietal development in the cotton
genotypes. 相似文献
122.
123.
Shima Bagherabadi Doustmorad Zafari Yousef Moradi Amirabad Joyce H. C. Woudenberg 《Journal of General Plant Pathology》2017,83(6):398-401
Drimia maritima (squill) is a historically important medicinal plant. During the spring of 2016, small, yellow leaf spots, which became brown and finally necrotic, were observed on squill plants in Kohgiluyeh and Boyer-Ahmad Provinces in Iran. A fungus was consistently isolated from infected leaves and identified as Alternaria alternata based on morphological and phylogenetic analyses. Pathogenicity tests confirmed A. alternata to be the causal agent of the newly observed leaf spot disease. This is the first report of leaf spot on D. maritima caused by A. alternata in the world. 相似文献
124.
A systematic and quantitative approach to improve water use efficiency in agriculture 总被引:4,自引:2,他引:4
As the competition for the finite water resources on earth increases due to growth in population and affluence, agriculture
is faced with intensifying pressure to improve the efficiency of water used for food production. The causes for the relatively
low water use efficiency in agriculture are numerous and complex, including environmental, biological, engineering, management,
social, and economic facets. The complexity of the problem, with its myriads of local variations, requires a comprehensive
conceptual framework of the underlying physical and biological processes as the basis to analyze the existing situation and
quantify the efficiencies, and to plan and execute improvements. This paper proposes such a framework, based on the simple
fact that the overall efficiency of any process consisting of a chain of sequential step is the product of the efficiency
(i.e., output/input ratio) of its individual component steps. In most cases of water use, a number of process chains, both
branching and merging, are involved. Means to integrate the diverging and converging chains are developed and presented as
equations. Upscaling from fields to regions and beyond are discussed. This chain of efficiencies approach is general and can
be applied to any process composed of chains of sequential steps. Here the framework is used to analyze the systems of irrigated
and dryland crop production, and animal production on rangeland. Range of plausible efficiencies of each step is presented
as tables, with values separately for the poor and for the good situation of circumstances, management and technology. Causes
of the differences in efficiency of each step, going from water delivery to soil water extraction, transpiration, photosynthesis,
and conversion to crop biomass and yield, and to animal product are briefly discussed. Sample calculations are made to demonstrate
how modest differences in the efficiencies of the component steps are manifested as large to huge differences in the overall
efficiency. Based on an equation quantifying the impact of changes in efficiency of component steps on the overall efficiency,
it is concluded that generally, it is more effective to made modest improvements in several or more steps than to concentrate
efforts to improve one or two steps. Hence, improvement efforts should be systematic and not overly concentrated on one or
two components. The potential use of the same equation as the point of departure to optimize the allocation of economic resource
among the component steps to maximize the improvement in the overall water use efficiency is elaborated on. The chain of efficiencies
framework provides the means to examine the current levels of efficiency along the pathways of agricultural water use, to
analyze where inefficiencies lie by comparing with the range of known efficiency values in the tables presented, to assess
the potential improvements that may be achieved in various parts and their impact on the overall efficiency, and to aid in
the optimal allocation of resources for improvements.
相似文献
Theodore C. HsiaoEmail: |
125.
Ricardo Rocha Milou Groenenberg Paulo E. D. Bobrowiec Mar Cabeza Jorge M. Palmeirim Christoph F. J. Meyer 《Landscape Ecology》2017,32(1):31-45
Context
Habitat loss, fragmentation and degradation are widespread drivers of biodiversity decline. Understanding how habitat quality interacts with landscape context, and how they jointly affect species in human-modified landscapes, is of great importance for informing conservation and management.Objectives
We used a whole-ecosystem manipulation experiment in the Brazilian Amazon to investigate the relative roles of local and landscape attributes in affecting bat assemblages at an interior-edge-matrix disturbance gradient.Methods
We surveyed bats in 39 sites, comprising continuous forest (CF), fragments, forest edges and intervening secondary regrowth. For each site, we assessed vegetation structure (local-scale variable) and, for five focal scales, quantified habitat amount and four landscape configuration metrics.Results
Smaller fragments, edges and regrowth sites had fewer species and higher levels of dominance than CF. Regardless of the landscape scale analysed, species richness and evenness were mostly related to the amount of forest cover. Vegetation structure and configurational metrics were important predictors of abundance, whereby the magnitude and direction of response to configurational metrics were scale-dependent. Responses were ensemble-specific with local-scale vegetation structure being more important for frugivorous than for gleaning animalivorous bats.Conclusions
Our study indicates that scale-sensitive measures of landscape structure are needed for a more comprehensive understanding of the effects of fragmentation on tropical biota. Although forest fragments and regrowth habitats can be of conservation significance for tropical bats our results further emphasize that primary forest is of irreplaceable value, underlining that their conservation can only be achieved by the preservation of large expanses of pristine habitat.126.
127.
Stacy N. Galleher Matthew R. Gilg Kelly J. Smith 《Fish physiology and biochemistry》2010,36(3):731-740
Fundulus heteroclitus and F. grandis are resident salt marsh fishes that overlap in distribution over a narrow range in northeastern Florida. The objective of
the present study was to examine whether the limits of the species’ ranges could be explained by differences in thermal tolerance.
Two populations of each species were collected and then spawned in the laboratory, and 9-day-old larvae were used for critical
thermal maxima trials. Mean LOE temperatures of larvae ranged from 43.04 to 43.65°C and showed little difference between species.
Therefore, differences in high temperatures experienced cannot account for the differences of the distributions of the two
species. Condition-specific competition may play a greater role in determining the observed range of the two species. 相似文献
128.
129.
Salvador Becerra-Rodríguez Víctor Manuel Medina-Urrutia Marciano Manuel Robles-González Timothy Williams 《Euphytica》2008,164(1):27-36
Grapefruit growers in the tropics require information about existing and new citrus cultivars with high productivity potential.
The objective of this study was to determine the growth, yield, and fruit quality performance of seven pigmented and four
white grapefruit cultivars under the dry tropic conditions of Colima, Mexico. The trees were budded on sour orange (Citrus aurantium L.) rootstock and planted at a distance of 8 × 4 m. ‘Oroblanco’ and ‘Marsh Gardner’ white-fleshed grapefruit cultivars and
‘Chandler’, a pink-fleshed pummelo, were the largest trees with the greatest height (5.0–5.6 m), canopy diameter (6.2–6.3 m),
trunk diameter (21.9–23.3 cm), and canopy volume (109–123 m3). Lower height (4.3–4.8 m) and canopy volume (73–96 m3), but with similar canopy diameter to the previously mentioned cultivars, were recorded for the remaining pigmented cultivars.
‘Chandler’ pummelo and four pigmented grapefruit cultivars (‘Shambar’, ‘Río Red’, ‘Ray Ruby’, and ‘Redblush #3’) had yearly
productions of 34.8, 34.9, 34.1, 32.7, and 30.6 ton ha−1, respectively. The most productive white grapefruit cultivar was ‘Marsh Gardner’ (30.5 ton ha−1). Grapefruit cultivars having the largest fruit size showed a higher inverse relationship between fruit weight and yield
than those with small fruit. Most genotypes had higher values of fruit weight, juice content, and maturity index than those
required by the local market. The most promising grapefruit cultivars based on their acceptable growth, yield superior to
30 ton ha−1, and acceptable fruit color were ‘Río Red’, ‘Shambar’, ‘Ray Ruby’, and ‘Redblush #3’. 相似文献
130.
Nagamine MK Sanches DS Pinello KC Torres LN Mennecier G Latorre AO Fukumasu H Dagli ML 《Veterinary research communications》2011,35(6):391-399
Mast cell tumor (MCT) is one of the most prevalent neoplasms that affect skin and soft tissue in dogs. Because mast cell tumors
present a great variety of clinical appearance and behavior, their treatment becomes a challenge. Trichostatin A (TSA), an
antifungal antibiotic, has shown inhibitory effects on the proliferation and induction of apoptosis in various types of cancer
cells. In order to evaluate the potential of trichostatin A as a therapeutic drug, cells of grade 3 MCT were cultured and
treated with concentrations of 1 nM to 400 nM of TSA. MTT assay and trypan blue exclusion assays were performed to estimate
cell growth and cell viability, and cell cycle analysis was evaluated. TSA treatment showed a reduction in numbers of viable
cells and an increase of cell death by apoptosis. The cell cycle analysis showed an increase of hypodiploid cells and a reduction
of G0/G1 and G2/M –phases. According to these results, trichostatin A may be an interesting potential chemotherapeutic agent
for the treatment of canine MCT. 相似文献