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951.
Harman-Fetcho JA Hapeman CJ McConnell LL Potter TL Rice CP Sadeghi AM Smith RD Bialek K Sefton KA Schaffer BA Curry R 《Journal of agricultural and food chemistry》2005,53(15):6040-6048
Climate and soil conditions in South Florida along with an extensive canal system facilitate movement of agricultural pesticides into surface waters. In a two-year study (2002-2004) of the currently used pesticides in South Florida, atrazine, endosulfan, metolachlor, chlorpyrifos, and chlorothalonil were the most frequently detected in the canals and in Biscayne Bay, with average concentrations of 16, 11, 9.0, 2.6, and 6.0 ng/L, respectively. Concentrations of atrazine and chlorpyrifos were highest near corn production. Chlorothalonil and endosulfan concentrations were highest near vegetable production, with no clear trend for metolachlor, which is used on multiple crops. Concentration data were used to calculate an aquatic life hazard potential for the planting period (November) versus the harvest period (March). This analysis indicated that a higher hazard potential occurs during harvest, primarily from the use of endosulfan. These data will also serve to document canal conditions prior to implementation of the Comprehensive Everglades Restoration Plan (CERP). 相似文献
952.
953.
Effect of cropping systems on phosphatases in soils 总被引:2,自引:0,他引:2
Phosphatases are widely distributed in nature and play a major role in phosphorus nutrition of plants. The effects of crop rotations and nitrogen fertilization on the activities of phosphatases (acid phosphatase, alkaline phosphatase, and phosphodiesterase) were studied in soils from two long‐term cropping systems at the Northeast Research Center (NERC) in Nashua and the Clarion Webster Research Center (CWRC) in Kanawha, Iowa, USA. Surface soils (0—15 cm) were taken in 1996 and 1997 from replicated field plots in corn, soybeans, oats, or meadow (alfalfa) that received 0 or 180 kg N ha—1 before corn. Because of differences in organic C contents among soils of the two sites, the soils from the CWRC sites contained greater enzyme activity values than those from the NERC site. Plots under oats or meadow showed the greatest activity values, whereas those under continuous corn at the CWRC site and soybean at the NERC site showed the least activities. Analysis of variance indicated that the activities of the phosphatases were significantly affected by crop rotation (P < 0.001) in both years at the NERC site but not at the CWRC site. Nitrogen fertilization affected the activity of acid phosphatase in soils from the CWRC site in both years and alkaline phosphatase only in 1997; but it did not affect the activities of the phosphatases in the soils from the NERC site. With the exception of alkaline phosphatase (CWRC) and phosphodiesterase (NERC) in soils sampled in 1997, activities of alkaline phosphatase and phosphodiesterase were significantly correlated with microbial biomass C (C mic) in soils from both sites and years, with r values ranging from 0.366* to 0.599***. Cropping systems and N fertilization affected the specific activities of phosphomonoesterases, especially acid phosphatase, but not of phosphodiesterase. Regression analysis showed that activities of phosphatases were significantly correlated with organic C contents of soils from the NERC site but not from the CWRC site. 相似文献
954.
Chris Johansen Abu M. Musa J. V. D. K. Kumar Rao David Harris M. Yusuf Ali A. K. M. Shahidullah Julie G. Lauren 《植物养料与土壤学杂志》2007,170(6):752-761
A major limitation to chickpea grown on residual soil moisture after the harvest of rice in the High Barind Tract (HBT) of Bangladesh is acidic surface soil. A diagnostic trial conducted in the 2001/02 season showed that Mo was limiting growth and yield of chickpea. Multilocational on‐farm trials in the 2002/03 season established that Mo applied to the soil at 500 g ha–1 improved nodulation and plant growth and resulted in grain‐yield responses of 58%–173%. In addition, we tested an application method suitable for resource‐poor farmers where Mo and Rhizobium were added in the seed‐priming process. Multilocational trials in farmers' fields in 2003/04 confirmed that this was as effective as soil application of Mo, giving yield responses of 37%–90%. In each of 2004/05 and 2005/06 seasons, 50 farmers implemented on‐farm evaluations of adding Mo + Rhizobium in the priming solution in operational scale plots (666 m2) across the HBT. Mean responses of up to 50%, compared to priming in water only, were obtained. These results suggest that the severe N deficiency of chickpea commonly observed in the HBT can be effectively alleviated by applying Mo and Rhizobium inoculum through a simple low‐cost technology within the scope of resource‐poor farmers. 相似文献
955.
The yield response of a wheat (Kirik) and a barley (Tokak 157/37) cultivar to inoculation with Azospirillum brasilense Sp246 and Bacillus sp. OSU‐142 was studied in relation to three levels of N fertilization (0, 40, and 80 kg ha–1) under field conditions in Erzurum, Turkey, in 1999 and 2000. Seed inoculation with A. brasilense Sp246 significantly affected yield and yield components, both in wheat and barley. On average of years and N doses, inoculation with A. brasilense Sp246 increased spike number per m2, grain number per spike, grain yield, and crude protein content by 7.2, 5.9, 14.7, and 4.1 % in wheat and by 6.6, 8.1, 17.5, and 5.1 % in barley, respectively, as compared to control. Inoculation with Bacillus sp. OSU‐142 significantly increased kernel number per spike in wheat, but no significant effect was determined in the other characteristics. Grain yields and yield components were also higher at all levels of nitrogen fertilizer in the inoculated plots as compared to the control. However, these increases diminished at high fertilizer levels. These results suggest that application of the growth promoting bacteria A. brasilense Sp246 may have the potential to be used as a biofertilizer for spring wheat and barley cultivation in organic and low‐N input agriculture. 相似文献
956.
Effect of acetylene and ethylene gases released from encapsulated calcium carbide on growth and yield of wheat and cotton 总被引:4,自引:1,他引:4
Calcium carbide (CaC2) is a rich source of the nitrification inhibitor acetylene (C2H2) and plant hormone ethylene (C2H4). C2H4 formed from biotic reduction of C2H2 released from CaC2 may accumulate in soil at physiologically active concentrations. Laboratory studies were conducted to evaluate the potential of encapsulated CaC2 for gradually releasing C2H2 and its product C2H4 in soil. The GC-FID analysis revealed that encapsulated CaC2 released a copious amount of C2H2 (up to 23700 nmol kg−1 soil), which was gradually reduced to C2H4 over a period of time via a strictly biotic reaction as no C2H4 was detected in CaC2-amended sterilized soil. Ammonium oxidation was suppressed by the encapsulated CaC2 indicating that C2H2 acted as a nitrification inhibitor. Results of pot trials conducted in the net house indicated that encapsulated CaC2 applied at 30 mg kg−1 soil significantly increased the number of tillers (up to 45.5%), root weight (up to 14.9%), straw (up to 32.8%) and grain yield (up to 37.3%) of wheat over the fertilizer application alone. In the case of cotton, the number of bolls, root, shoot and seed weight were also significantly increased in response to the application of encapsulated CaC2. Moreover, application of encapsulated CaC2 resulted in greater N-use efficiency (NUE) (up to 61.1%) by both wheat and cotton crops than that observed at the same rates of N fertilizer alone. These findings imply that CaC2 affects plant growth through hormonal action of C2H4 as well as improved NUE; however, the latter factor might be a relatively more contributing. It is desirable that CaC2 is formulated for gradually slow release of C2H2 and C2H4 in soil air. 相似文献
957.
Mohammad Arshad Muhammad Ashraf Niala Arif 《Genetic Resources and Crop Evolution》2006,53(8):1589-1596
Sixty-two accessions of Prosopis cineraria, collected from different areas of the Cholistan desert and from the vicinity of Islamia University, Bahawalpur during June,
2002 were evaluated for agro-morphological diversity. Data collected revealed considerable variation for pod length, pod thickness,
number of seeds per pod, pod weight, 100-seed weight, seed size, number of pinnules, length of pinnae, length of the pinnulae,
and breadth of the pinnulae. Accessions GD-1 and GD-2, collected from Gadhen Wala Toba, KWT-1, KWT-3, KWT-4, KWT-6, from Khokhran
Wala Toba, TWT-2, TWT-7, TWT-8, from Taraway Wala Toba, CSW-2, CSW-7, CSW-8, from Chah Sulleh Wala, and IUB-5, IUB-9, from
Islamia University, Bahawalpur, showed very high variation. Overall, accessions KWT-6 from Khokhran Wala Toba, and TWT-7,
from Taraway Wala Toba, (both from Cholistan desert), appeared as best genotypes based on their morphological variation detected
in this study. 相似文献
958.
Van Den Hauwe O Schneider M Sahin A Van Peteghem CH Naegeli H 《Journal of agricultural and food chemistry》2003,51(1):326-330
A field study was performed to assess the drug residue level in edible tissues after a therapeutic application of the synthetic glucocorticoids dexamethasone and flumethasone. Three diseased calves were injected intramuscularly with a commercial batch of dexamethasone esters and slaughtered 72 h after treatment. Another three calves were injected intramuscularly with an aqueous flumethasone preparation and slaughtered 24 h later. Residues of synthetic glucocorticoids in liver, muscle, kidney, and urine were assessed by competitive enzyme immunoassay. All dexamethasone concentrations exceeded the maximal residue level of 0.75 microg/kg in muscle and kidney and 2 microg/kg in the liver. The presence of both dexamethasone and flumethasone in the liver was confirmed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). These results indicate that liver tissue provides a suitable matrix to monitor the presence of illegal residues of synthetic glucocorticoids in slaughtered animals. 相似文献
959.
Most available remediation technologies for treatment of heavymetal contaminated soils are very expensive and result in residues requiring further treatment. Stabilization/solidification (immobilization) techniques however, which aredesigned to decrease leaching potential of heavy metals from soil by addition of chemical additives, provide very cost-effective solutions for heavy metal contaminated soils. Thisstudy investigates the most efficient additive for immobilization of lead. To achieve this goal, several leachingexperiments were conducted for mixtures of different additives(lime, activated carbon, clay, zeolite, sand and cement) withartificially Pb contaminated (spiked) soil samples in accordancewith the Toxicity Characterization Leaching Procedure (TCLP) developed by U.S. EPA. Results showed that among the additivestried, activated carbon, clay, zeolite and sand are not very efficient for Pb immobilization. On the other hand, lime andcement are significantly effective in Pb immobilization with 88% efficiency at 1:21 lime:soil ratio and 99% efficiency at1:15 cement:soil ratio, respectively. 相似文献
960.
Mehmet Ali Sudupak 《Euphytica》2004,135(2):229-238
Intra and inter-species ISSR variation and use of ISSR markers in determination of genetic relationship were investigated
in an accession collection representing twoperennial and six annual Cicerspecies. Screening of Ciceraccessions with SSR primers revealed highly reproducible amplicon profiles with relatively high multiplex ratios. Many of
the primers generated amplicon profiles with which not only the differences among species can readily be identified, but also
polymorphisms within species could be detected more efficiently. PCR products at 150 gel positions detected using six SSR
primers in Cicer accessions were treated as dominant DNA markers and utilized to compute the distances among accessions and species. Cluster
analysis of accessions and species revealed groupings that corroborate our previous studies of relationships based on allozyme
and AFLP analysis. Consistent with the AFLP analysis carried out in the same accession collection, ISSR-based groupings indicated
that perennial C. incisumis genetically close to the annuals of the second crossability group (C. pinnatifidum,C. bijugum, C. judaicum) while C. reticulatum is the closest wild species to the cultivated chickpea. ISSR-based variation estimates were relatively higher when compared
to previous estimates computed from RAPD and AFLP data. Technically, ISSR analysis combines the PCR-based targeting of microsatellite-associated
polymorphisms with no prior sequence requirement and stringent PCR conditions. Similarly, when compared to AFLP analysis,
it is less technically demanding allowing to survey polymorphic loci in the genome. Thus, ISSR-PCR technology is a reliable,
fast, and cost-effective marker system that can be used to study genetic variation and genetic relationships in the genusCicer.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献