Mercury pollution of effluent,air, and soil near a battery factory in Tanzania     

E. Semu  B. R. Singh  A. R. Selmer-Olsen 《Water, air, and soil pollution》1986,27(1-2):141-146

Effluent, air, and soil samples near a battery factory in Dar es Salaam, Tanzania, where HgCl₂ is used to prevent mold growth, were collected to explore the potential for pollution of the environment from industrial discharge of Hg. Flameless atomic absorption spectrophotometry was used for Hg determinations. The concentration of Hg in the effluent ranged from <0.2 to 5.2 mg L^?1 and the Hg concentration varied greatly within and among sampling days, showing different peaks. Air contained a mean of 4.0 μg m^?3 with little variation within and between sampling days. Soils near the factory contained high Hg levels, from 6.7 to 472 mg kg^?1 in the immediate vicinity, the highest level being associated with disposal of solid waste (defective batteries). Downwind the concentration of Hg decreased with increasing distance from the factory resulting in a soil concentration of 1.0 mg Hg kg^?1 about 2 km away. Upwind the Hg concentration decreased drastically within a distance of 100 to 200 m.  相似文献   

Nutrient immobilization and release patterns during plant decomposition in a dry tropical bamboo savanna,India   总被引：3，自引：0，他引：3  

S. K. Tripathi  K. P. Singh 《Biology and Fertility of Soils》1992,14(3):191-199

Summary Decomposition and changes in nutrient content of six litter types (leaves, sheaths, roots, twigs, and wood of bamboo, and grass shoots) were studied in nylon net bags for 2 years. The annual weight loss was (% of initial) bamboo leaves 56.5, bamboo sheaths 79.5, bamboo roots 65.8, bamboo twigs 49.6, bamboo wood 31.2, and grass shoots 74.9. Elemental mobility followed the order K>Na>C>P>Ca>N in all components except wood. Generally, an initial increase was followed by a consistent decrease in the contents of N (leaves), P (leaves, roots, wood) and Ca (leaves, roots, grass), and Na (wood). Most of the nutrients were immobilized in the rainy season. C and K contents showed a constant decrease throughout the decomposition period. Materials with a greater C:N ratio (>50) tended to accumulate more nutrients and retain them for longer, except for the bamboo twigs. The critical C:N ratio (at which a net release of N occured) for the leaf material was 25. Litter components with more initial N (sheaths) showed greater weight loss than those with less N (leaves, twigs, and wood). Overall, N and P were lost at the slowest rates while C and K were lost at faster rates. Initial lignin, lignin: N, C:N and C concentrations had a better predictive value for annual weight loss and nutrient release in bivariate relationships. A combination of the initial lignin value and the C: N ratio explained 93% of the variation in annual weight loss. A significant relationship was also observed between the annual weight loss rate and the nutrient mineralization/release rate.  相似文献   

Effects of solar treatment on germination of sclerotia (Sclerotium rolfsii Sacc.) and on other soil mycoflora     

R. K. Singh  R. P. Shukla  R. S. Dwivedi 《Biology and Fertility of Soils》1990,10(2):152-154

Summary Only 10% of sclerotia germinated in a tarpcovered plot after 45 days of treatment while 50% of sclerotia germinated in the control plot. However, complete inhibition of sclerotia germination was not achieved. The maximum temperature recorded was 53°C, after 45 days of treatment in a tarped plot at 1 cm depth. The incidence of Acrophialophora fusispora, Aspergillus spp., Spicaria sp., and Trichoderma viride increased in soil after 45 days of the solar treatment.  相似文献   

Optimisation of Design and Operational Parameters of a Pneumatic Seed Metering Device for Planting Cottonseeds   总被引：2，自引：0，他引：2  

R.C. Singh  G. Singh  D.C. Saraswat 《Biosystems Engineering》2005,92(4):3753

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Synthesis and fungicidal activity of novel 4,4'-bis(2' '-aryl-5' '-methyl/unsubstituted-4' '-oxo-thiazolidin-3' '-yl) bibenzyl     

Siddiqui IR  Singh PK  Singh J  Singh J 《Journal of agricultural and food chemistry》2003,51(24):7062-7065

Reduction followed by nitration of benzil I yielded 4,4'-dinitrobibenzyl (III) which by reduction furnished quantitatively and analytically pure 4,4'-diaminobibenzyl (IV) which on condensation with different carbonyl compounds gave 4,4'-bis (benzylideneamino) bibenzyls (Va-f). Compounds (Va-f) on cycloaddition with mercaptoacetic acid/2-mercaptopropionic acid yielded the corresponding 4-oxothiazolidin-3-yl bibenzyls (VIa-l). The compounds VIg-l have two chiral centers in each thiazolidinone moiety so two diastereomers are possible, but on crystallization and repeated chromatography, one diastereomer was obtained. The absolute configuration of the diastereomer was tentatively assigned on the basis of (1)H NMR spectra. (1)H NMR spectra of the product showed a distinct doublet at delta 1.22 for C(5)-CH(3) of thiazolidinone ring (22, 23) and a distinct quartet at delta 4.20 for the C(5)-H proton. Similarly, the C(2) proton showed an independent singlet at delta 5.95, so the diastereomers obtained were assigned trans configuration. Compounds Va-f and VIa-l were evaluated in vitro for their fungitoxicities against Fusarium oxysporium and Penicillium citrinum. All the compounds were found to be antifungal active. Some of the compounds displayed activities comparable with that of the commercial fungicide Dithane M-45. Structure-activity relationships for the screened compounds are discussed.  相似文献   

<Emphasis Type="Italic">Azolla</Emphasis> sporulation in response to application of some selected auxins and their combination with gibberellic acid     

P. Kar  S. Mishra  D. Singh 《Biology and Fertility of Soils》2002,35(5):314-319

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Modeling yield sustainability for different rotations in long-term barley trials     

Murari Singh  Michael J. Jones 《Journal of Agricultural, Biological & Environmental Statistics》2002,7(4):525-535

In crop rotation trials, the errors arising over time on the same plot are correlated. Often-used analyses assume zero or constant correlation between the errors while the actual covariance structure for the plot errors might be very different. The objective of this study was to identify the most suitable covariance structure and incorporate the error structure in assessment of the crop rotations in terms of yield productivity and yield sustainability. A set of five covariance structures were examined for barley yield data from a 14-year, two-course barley rotation trial conducted at two locations in northern Syria. Selection of the covariance structures was based on the Akaike information criterion (AIC, Akaike 1974) (a function of penalized log-likelihood) obtained from fitting the structure. Covariance structure with heterogeneous variances and with constant correlation between errors over cycles within the same plot was found to account for most variability in grain and straw yields at both locations. Modeling data with this covariance structure, the legume rotations gave higher productivity as well as higher annual increases compared with the continuous barley system. This implies that an agricultural production system based on a legume following a cereal is likely to be more sustainable for cereal production compared to cereal followed by cereals.  相似文献   

The nature of amorphous materials in alluvial soils     

T. V. Rao  Gurcharan Singh  G. S. R. Krishna Murti 《植物养料与土壤学杂志》1977,140(6):689-696

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Helminthosporium leaf blight resistance and agronomic performance of wheat genotypes across warm regions of South Asia   总被引：5，自引：0，他引：5  

R. C. Sharma    E. Duveiller    F. Ahmed    B. Arun    D. Bhandari    M. R. Bhatta    R. Chand    P. C. P. Chaurasiya    D. B. Gharti    M. H. Hossain    A. K. Joshi    B. N. Mahto    P. K. Malaker    M. A. Reza    M. Rahman    M. A. Samad    M. A. Shaheed    A. B. Siddique    A. K. Singh    K. P. Singh    R. N. Singh  S. P. Singh 《Plant Breeding》2004,123(6):520-524

Helminthosporium leaf blight (HLB) is the most important disease constraint to wheat (Triticum aestivum L.) cultivation in the eastern Gangetic Plains of South Asia. A Helminthosporium Monitoring Nursery (HMN) including potential adapted and exotic sources of HLB resistance was developed in Bangladesh, India and Nepal to assess the stability of genetic resistance across locations. The 8th, 9th and 10th HMN assessed the HLB resistance and agronomic traits of 17 wheat genotypes across 20 environments of Bangladesh, India and Nepal in the 1999‐2000, 2000‐2001 and 2001‐2002 cropping seasons, respectively. The area under the disease progress curve (AUDPC) for HLB, grain yield, thousand‐kernel weight (TKW), days to heading, days to maturity, and plant height were examined. The 17 genotypes showed a range of variability for disease and agronomic characters. Disease severity (AUDPC) differed in the 3 years and showed the highest values in 2002. The increase in AUDPC in 2002 caused the lowest grain yield, with an average 18% reduction due to HLB. A few genotypes (SW 89‐5422, Yangmai‐6 and Ning 8201) appeared to have stable HLB resistance across environments. However, most of the higher‐yielding genotypes, except BL 1883, were unstable. The results suggest that careful selection of HLB resistance with acceptable grain yield, TKW and plant height may be possible using the wheat genotypes included in the HMN.  相似文献   

Monosomic analysis of Helminthosporium leaf blight resistance genes in wheat   总被引：1，自引：0，他引：1  

M. Ragiba    K. V. Prabhu  R. B. Singh 《Plant Breeding》2004,123(5):405-409

A set of 21 monosomic (2n ‐ 1) and the disomic (2n) lines of the ‘Chinese Spring’ cultivar were crossed with ‘Chirya‐3′, the CIMMYT synthetic wheat line which has been identified as highly resistant for Helminthosporium leaf blight disease (HLB), in order to locate the genes governing disease resistance. The F₁ and segregating populations were challenged and screened against the most virulent pure mono‐conidial HLB isolate KL‐8 (Karnal, India). The F₁ progenies of the crosses were found to be susceptible because of the recessive nature of resistance. The F₂ progeny of the control cross (‘Chinese Spring’בChirya‐3’), segregated in the ratio of 1: 15 (resistant: susceptible), indicating that resistance to HLB was controlled by a pair of recessive genes. While the F₂ progeny of 19 monosomic crosses segregated in the ratio of 1: 15 (resistant: susceptible), the progeny of the remaining two crosses, 7B and 7D, deviated significantly from the ratio, revealing that 7B and 7D were the critical chromosomes for resistance genes that were located one on each chromosome. Moreover, the critical lines, 7B and 7D, confirmed the digenic complementary recessive nature of gene action by fitting well with the overall pooled F₂ segregation ratio of 13: 51 (resistant: susceptible) as expected for digenic complementary recessive resistance. The F₃ segregation ratios of the critical crosses, based on their pooled F₂ analysis, was estimated as 19: 32: 13 (non‐segregating susceptible: segregating as susceptible and resistant: non‐segregating resistant). F₃ progenies when tested with these ratios showed goodness‐of‐fit, confirming that the two pairs of recessive resistance genes were located on chromosomes 7B and 7D.  相似文献