排序方式： 共有49条查询结果，搜索用时 15 毫秒
1.
Sandeep?KumarEmail author Ranjith?P.?Udawatta Stephen?H.?Anderson Ashish?Mudgal 《Agroforestry Systems》2011,83(1):51-62
Buffers have been found to reduce non-point source pollution (NPSP) from watersheds. Hydrologic simulation models assist in
predicting the effects of buffers on runoff and sediment losses from small watersheds. The objective of this study was to
calibrate, validate and simulate runoff and sediment losses and compare buffer effects on NPSP losses relative to control
watersheds (no buffer) for seven years. The experimental design consists of four watersheds under pasture management which
were monitored from 2002 through 2008; two with agroforestry buffers (AgB 100 and AgB 300) and two control watersheds (CW
400 and CW 600). Pasture areas included red clover (Trifolium pretense L.) and lespedeza (Kummerowia stipulacea Maxim.) planted into fescue (Festuca arundinacea Schreb.) while the agroforestry buffer area included Eastern cottonwood trees (Populus deltoids Bortr. ex Marsh.) planted into fescue. The APEX model was calibrated from 2002 to 2005 and was validated from 2006 to 2008.
The r
2
and NSE values for the calibration and validation periods of the runoff varied from 0.52 to 0.78 and 0.50 to 0.74, respectively.
The model did not predict sediment loss very well probably due to insufficient number of measured events and low measured
sediment loss. The measured runoff was 57% higher for CW watersheds compared to AgB watersheds. The measured sediment loss
was 95% higher for CW watersheds compared to AgB watersheds. After calibrating and validating the model, it was run for long-term
scenario analyses for 10 years from 1999 to 2008. Simulated buffer width had a significant influence on runoff. Simulated
runoff decreased by 24% when the buffer width was doubled compared to losses associated with the measured buffer width. Simulated
runoff from the CW watersheds was 11% higher with double stocking density (relative to measured density) compared to AgB watersheds
with double stocking density. With half stocking density (relative to measured density), the AgB watershed had 18% lower runoff
compared to CW. Results from this study imply that establishment of agroforestry buffers on grazed pasture watersheds reduce
runoff and sediment losses compared to control watersheds without buffers. 相似文献
2.
Gyrinops walla Gaertn. is the only species growing in Sri Lanka that belongs to the agarwood family,Thymelaeaceae. Although agarwood resin induction and extraction from Aquilaria species of the same family have been practised for many decades in Southeast Asian region,the ability of producing agarwood resins in G. walla was discovered recently. Since previous studies were on agarwood resins formed due to natural causes, the present study was conducted to identify the potential fungal species that are capable of artificially inducing agarwood resin formation in G. walla. Since this is the first ever study conducted on artificial inducement of agarwood resin formation in G.walla, Aspergillus niger and Fusarium solani were selected owing to their high abundance in the naturally formed agarwood resinous tissues collected from 25 G. walla trees.Both fungal species were separately grown in yeast extract glucose agar and used to inoculate healthy G. walla trees under aseptic conditions. Three holes were made for each tree and 2 g of fungal culture including the medium were placed in each hole. Tissue discoloration, characteristic aroma, resin content and resin constituents were checked at10 cm intervals above and below the inoculation points for a period of 1 year. Results revealed that tissue discoloration and resin content were higher in the trees inoculated with A. niger. Other than at 10 cm above and below the inoculation points, samples collected at all locations had significantly higher resin contents when inoculated with A. niger compared to F. solani. Sixteen agarwood resin constituents, which were also recorded in Aquilaria species, were identified from the discolored tissues using GC–MS analysis. Jinkohol, agarospirol and 2(2-phenyl)chromone derivatives were found in all discolored tissues collected at 10-cm intervals of the trees inoculated with both fungi. b-Seline, c-eudesmol and valerenal were found in nine of 10 sample points on the stem. c-Elemene was recorded only in one sample. The characteristic aroma during burning was stronger for dark-colored tissues than the light-colored ones. The present study confirmed the potential use of certain fungal species to induce agarwood resin in G. walla and that A. niger is more effective than F.solani. 相似文献
3.
4.
Jamseel Moopantakath Madangchanok Imchen Ranjith Kumavath Rosa María Martínez-Espinosa 《Marine drugs》2021,19(8)
This study presents a comparative analysis of halophiles from the global open sea and coastal biosystems through shotgun metagenomes (n = 209) retrieved from public repositories. The open sea was significantly enriched with Prochlorococcus and Candidatus pelagibacter. Meanwhile, coastal biosystems were dominated by Marinobacter and Alcanivorax. Halophilic archaea Haloarcula and Haloquandratum, predominant in the coastal biosystem, were significantly (p < 0.05) enriched in coastal biosystems compared to the open sea. Analysis of whole genomes (n = 23,540), retrieved from EzBioCloud, detected crtI in 64.66% of genomes, while cruF was observed in 1.69% Bacteria and 40.75% Archaea. We further confirmed the viability and carotenoid pigment production by pure culture isolation (n = 1351) of extreme halophiles from sediments (n = 410 × 3) sampling at the Arabian coastline of India. All red-pigmented isolates were represented exclusively by Haloferax, resistant to saturated NaCl (6 M), and had >60% G + C content. Multidrug resistance to tetracycline, gentamicin, ampicillin, and chloramphenicol were also observed. Our study showed that coastal biosystems could be more suited for bioprospection of halophiles rather than the open sea. 相似文献
5.
Bei Chu Keith W. Goyne Stephen H. Anderson Chung-Ho Lin Ranjith P. Udawatta 《Agroforestry Systems》2010,79(1):67-80
The potential of veterinary antibiotics (VAs) to impact human and environmental health requires the development and evaluation
of land management practices that mitigate VA loss from manure-treated agroecosystems. Vegetative buffer strips (VBS) are
postulated to be one management tool that can reduce VA transport to surface water resources. The objectives of this study
were to (1) investigate oxytetracycline (OTC) and sulfadimethoxine (SDT) sorption to agroforestry buffer, grass buffer, and
cropland soils, (2) evaluate differences in VA sorption to soils collected from different vegetative management and soil series,
and (3) elucidate relationships between soil properties and VA sorption. Sorption/extraction isotherms for OTC were well-fitted
by the Freundlich isotherm model (r
2 > 0.86). OTC was strongly adsorbed by all soils and the VA was not readily extractable. OTC and SDT solid to solution partition
coefficients (K
d) values are significantly greater for soils planted to VBS relative to grain crops. Significant differences in OTC and SDT
K
d values were also noted among the soil series studied. Linear regression analyses indicate that clay content and pH were the
most important soil properties controlling OTC and SDT adsorption, respectively. Results from this study suggest that agroforestry
and grass buffer strips may effectively mitigate antibiotic loss from agroecosystems, in part, due to enhanced antibiotic
sorption properties. 相似文献
6.
Brummell DA Watson LM Pathirana R Joyce NI West PJ Hunter DA McKenzie MJ 《Journal of agricultural and food chemistry》2011,59(20):10987-10994
Methylselenocysteine (MeSeCys) is an amino acid derivative that possesses potent anticancer activity in animals. Plants that can tolerate growth on soils with high Se content, known as Se hyperaccumulators, do so by converting inorganic Se to MeSeCys by the enzyme selenocysteine methyltransferase (SMT). A cDNA encoding the SMT from a Se hyperaccumulator was overexpressed in tomato (Solanum lycopersicum). Transgenic plants were provided with selenite or selenate to the roots during fruit development, and liquid chromatography-mass spectrometry was used to show that MeSeCys accumulated in the fruit but not in the leaves. Depending on the transgenic line and Se treatment, up to 16% of the total Se in the fruit was present as MeSeCys. MeSeCys was produced more effectively from selenite on a percentage conversion basis, but greater accumulation of MeSeCys could be achieved from selenate due to its better translocation from the roots. MeSeCys was heat stable and survived processing of the fruit to tomato juice. 相似文献
7.
8.
Ranjith Jayaweera Richard Petersen Pavel Smejtek 《Pesticide biochemistry and physiology》1982,18(2):197-204
Pentachlorophenol (PCP) decreases the rate of carbon assimilation in the alga Selenastrum capricornutum. In parallel with the reduction of carbon assimilation in this alga there is a decrease of electrical resistance of lipid membranes and development of negative membrane surface charge. The experimental results suggest that PCP toxicity to algae is due to adsorption of negatively charged PCP ions at the membrane surface that act as carriers of hydrogen ion across the membrane. This protonophoretic action of PCP causes the decrease of membrane electrical resistance and the dissipation of hydrogen ion electrochemical potential gradients across cellular and subcellular membranes, which reduces the ability of algae to assimilate carbon. 相似文献
9.
Raja A Vignesh AR Mary BA Tirumurugaan KG Raj GD Kataria R Mishra BP Kumanan K 《Veterinary immunology and immunopathology》2011,140(3-4):252-258
This study involved cloning and sequencing of the coding regions of all 10 Toll-like receptor (TLR) genes of goat. Goat TLR 1-10 gene sequences revealed a high degree of nucleotide identity with sheep and cattle sequences (>90%) and 75-85% with pig, mouse and human sequences. At the amino acid level, 85-99% similarity was observed with sheep and cattle and 60-85% with pig, mouse and human. TLR9c DNA of goat showed the highest amino acid identity to that of sheep (99%) while TLR8 cDNA showed the lowest identity of 88.7% to that of sheep. Variations were seen in the number of leucine rich repeats (LRRs) of goat TLRs as compared to other ruminant species with maximum differences in the TLR3 gene. Phylogenetic analysis through molecular evolution and genetic analysis (MEGA) software and multi dimensional scaling revealed a high degree of conservation of goat TLRs with those from other species. However when the TIR domain of all the TLRs were compared, goat TLR7 TIR alone showed a high divergence of 19.3 as compared to sheep sequences. This is the first report of the full-length cDNA sequences of all the 10 TLR genes of goats which would be a useful tool for the study of evolutionary lineages and for phylogenetic analysis. 相似文献
10.
Koratigere Parameshanayka Devaraja Ranjith Kumar Ellur Pankaj Ashok K. Singh Anumanahalli Puttasawamy Abhishek Gowda Anil Sirohi 《Plant pathology》2023,72(1):179-194
The rice root-knot nematode (RRKN), Meloidogyne graminicola, is one of the major pests of the rice–wheat cropping system. Resistance against M. graminicola in rice could be most valuable in alleviating this problem. The host response of 75 Oryza genotypes was examined at three day/night temperature regimes, 29/26°C, 34/31°C and 38/35°C, in Pluronic gel as well as in soil. Out of the 75 selected rice genotypes, only Zhenshan 97 B exhibited high resistance to this set of temperature regimes, with the least number of galls/root system. At 34/31°C, more second-stage juveniles (J2s) were hatched and J2 population densities in roots of the susceptible rice genotypes increased significantly compared with those of plants grown at the 29/26°C. In resistant genotypes, only a few J2s penetrated roots and developed into mature females. The histopathological studies revealed that in susceptible rice genotypes at high-temperature regimes, the multinucleate giant cells were well developed. The results presented in this study revealed that an increase in temperature had a significant effect on the resistance of rice genotypes and resistance appeared more pronounced in genotype Zhenshan 97 B. This resistant genotype can be used in marker-assisted selection to develop resistant elite cultivars. 相似文献