Assessment of Brown Planthopper, (Nilaparvata lugens) [Stål], damage in rice using hyperspectral remote sensing

Hyperspectral remote sensing was used to detect stress on potted rice plants caused by the Brown Planthopper (BPH), Nilaparvata lugens (Stål). BPH damage influenced reflectance of rice plants compared to uninfested plants in the visible and near-infrared regions of the electromagnetic spectrum. Correlations between plant reflectance and BPH damage, when plotted against wavelengths, enabled us to identify four sensitive wavelengths, at 1986, 665, 1792 and 500 nm, in relation to BPH stress on rice plants. Based on rice plant reflectance corresponding to the sensitive wavelengths, three hyperspectral indices were developed. The BPH damage showed a positive association with normalized pigment chlorophyll index, and a negative relationship with normalized difference vegetation index and soil adjusted vegetation index. Using rice plant reflectance corresponding to the sensitive wavelengths, a multiple-linear regression model was developed and validated, which would facilitate assessment of BPH damage based on rice plant reflectance, thereby ensuring prompt forewarning to stakeholders.     

Biochar-based bioenergy and its environmental impact in Northwestern Ontario Canada: A review

Biochar is normally produced as a by-product of bioenergy. However, if biochar is produced as a co-product with bioenergy from sustainably managed forests and used for soil amendment, it could pro- vide a carbon neutral or even carbon negative solution for current envi- ronmental degradation problems. In this paper, we present a comprehen- sive review of biochar production as a co-product of bioenergy and its implications. We focus on biochar production with reference to biomass availability and sustainability and on bioehar utilization for its soil amendment and greenhouse gas emissions reduction properties. Past studies confirm that northwestern Ontario has a sustainable and sufficient supply of biomass feedstock that can be used to produce bioenergy, with biochar as a co-product that can replace fossil fuel consumption, increase soil productivity and sequester carbon in the long run. For the next step, we recommend that comprehensive life cycle assessment of bio- char-based bioenergy production, from raw material collection to bioehar application, with an extensive economic assessment is necessary for making this technology commercially viable in northwestern Ontario.     

Superior CMS (<Emphasis Type="Italic">Ogura</Emphasis>) lines with better combining ability improve yield and maturity in cauliflower (<Emphasis Type="Italic">Brassica oleracea</Emphasis> var. <Emphasis Type="Italic">botrytis</Emphasis>)

Three CMS lines, Ogu1A, Ogu2A and Ogu3A were selected among ten lines after BC₇ based on superior commercial, floral and seed setting traits. Introgression of sterile Ogura cytoplasm in cauliflower nuclear background reduced the flower size but did not affect commercial and seed setting traits drastically. Line × Tester analysis was done by taking these three CMS lines free from floral deformities as female parent with nine diverse lines of snowball cauliflower as tester. The parent Ogu2A exhibited highest GCA effect for curd yield (4.51) and harvest index (1.97) while Ogu1A exhibited highest GCA for earliness (−2.73). The parent, Ogu2A exhibited significant GCA for curd length (0.39) while, none of the CMS lines showed significant GCA for curd diameter and depth. Heterosis for curd yield was highest in the hybrid, Ogu2A × Kt-22 (63.5%) followed by Ogu1A × WF (36.9%) and Ogu1A × Kt-15 was the best hybrid for earliness followed by Ogu3A × Kt-22 with heterosis of −14.4% and −11.7%. However, the number of heterotic hybrids for yield and earliness was low indicating narrow genetic base of the snowball cauliflower.     

Decomposition of biodegradable packing materials jute, Biopol, BAK and their composites in soil

We investigated the effects of the biodegradable polymers jute, Biopol and BAK 2195 and their composites on the mineralisation activity and biomass of microorganisms in soil and on the fungal component of the microbial community. Two different pre-treatments of jute were used to produce the composites, treatment of the fibres with sodium hydroxide (SH-jute) and co-polymerisation with acrylonitrile (AN-jute). All products tested were highly degradable, as indicated by the increase in CO₂ evolution after amendment. The additional amount of CO₂-C evolved after polymer incorporation into the soil corresponded to between 21% and 34% of the added C after 85 days incubation at 25°C. The extra CO₂-C evolved decreased in the order BAK > jute > Biopol. Composites of AN-jute were less mineralisable than those of SH-jute. Degradation of jute is characterised by a rapid increase, then a slow decline of microbial respiratory activity. In contrast, in the Biopol treatments, and especially in the BAK treatments, maximum CO₂ evolution rates occurred considerably later, indicating that the soil microorganisms needed some time to colonise the polymer particles. All polymers and composites tested increased the soil microbial biomass in the order jute h Biopol < BAK. The net increase in microbial biomass C was 3% of the added polymer C in the jute treatment, an average of 4% in the three Biopol treatments, and 7% in the three BAK treatments. The content of ergosterol, an indicator for fungal biomass, was also increased by all amendments, but the effect on ergosterol content was much more pronounced than on microbial biomass C.     

Sources of Heavy Metals and Their Long-term Effects on Microbial C, N and P Relationships in Soil

The effects of heavy metals (Zn, Pb, and Cu) on microbial biomass C, N, and P were assessed in soils contaminated over a wide range by sewage sludge, exhaust dust deposition of a lead factory and river sediments of mining residues. Microbial biomass C, N, and P did not show any clear heavy metal effect related to soil dry weight. Also the ratios of microbial biomass C/N and biomass C/P remained unaffected by heavy metals. The ratios of microbial biomass C/soil organic C, biomass N/total N, and biomass P/total P were all negatively affected by increasing concentrations of Zn, Pb, and Cu as detected by a source-specific analysis of covariance using the different heavy metal fractions as covariate. Negative effects of Zn on the ratios microbial biomass C/soil organic C and biomass N/total N increased with increasing metal solubility in the order: (X-ray fluorescence analysis) XFA-detectable <HNO₃ <EDTA ?NH₄NO₃-extractable Zn. The Zn effects on the microbial biomass N/total N were always smaller than those on the microbial biomass C/soil organic C ratio. The same was true for all effects of the Pb and Cu fractions on these two ratios. For this reason, the deposition of highly soluble Zn and Pb by exhaust dust has the most negative effects, although sediments contained the maximum total burden of Zn and Pb. All fractions of Zn, Pb, and Cu had similar negative effects on the microbial biomass P/total P ratio, although the NH₄NO₃-extractable fraction again showed the most pronounced effects.     

InfoCrop: A dynamic simulation model for the assessment of crop yields,losses due to pests,and environmental impact of agro-ecosystems in tropical environments. I. Model description

The problems of agriculture in many tropical countries are gradually becoming more intense due to increasing food demand led by population growth, stagnation in farm productivity, mounting yield losses due to multiple pests, increasing vulnerability to global environmental changes and the need to reduce emission of greenhouse gases. Tools and techniques are needed to assist in developing strategies that can lead to higher food production, prevent crop production losses, and ensure minimal greenhouse gas emissions while maintaining soil fertility. Several dynamic models have been developed in recent past but most of these are generally strong either in soils and crops, or in greenhouse gases (GHG) emissions. Pest induced yield losses, a critical issue in the tropics, is not addressed in most models. InfoCrop, a generic dynamic crop model, has been developed to meet these specific requirements. It provides integrated assessment of the effect of weather, variety, pests, soil and management practices on crop growth and yield, as well as on soil nitrogen and organic carbon dynamics in aerobic as well as anaerobic conditions, and greenhouse gas emissions. The model considers the key processes related to crop growth, effects of water deficit, flooding, nitrogen management, temperature and frost stresses, crop–pest interactions, soil water and nitrogen balance and (soil) organic carbon dynamics. Its general structure relating to basic crop growth and yield is largely based on several earlier models, especially SUCROS series, and is written in Fortran Simulation Environment (FSE) programming language. The model has been validated for dry matter and grain yields of several annual crops, losses due to multiple diseases and pests, and emissions of carbon dioxide, methane and nitrous oxide in a variety of agro-environments. To increase the applications of model in research and development, an extremely simple menu driven version of InfoCrop has also been developed. The users of this version do not need any background in programming.     

Arbuscular mycorrhizae and phosphate solubilising bacteria of the rhizosphere of the mangrove ecosystem of Great Nicobar island, India

Mangroves form an important ecosystem of Great Nicobar, a continental island in the Bay of Bengal with luxuriant tropical rainforests. The rhizosphere of the mangrove plants of Great Nicobar was investigated for the presence of arbuscular mycorrhizal fungus (AMF) and phosphate solubilising bacteria (PSB). The soils of the Great Nicobar mangroves were silt–clays and were poor in phosphate content. Five species of AMF belonging to the genus Glomus were isolated. The %AMF colonization in the mangrove plants was between 0 and 17%, and the presence of AMF in the aerenchymatous cortex suggests that the mangrove plants may be aiding in AMF survival by providing oxygen. Two strains of phosphate solubilising Pseudomonas aeruginosa were found in the mangrove soils of Great Nicobar. Phosphate solubilisation by the two isolated strains was almost 70% under in vitro conditions. PSB may play a role in the mangrove ecosystems of Great Nicobar by mobilising insoluble phosphate. The plant roots could pick up the released phosphate directly or with the aid of AMF hyphae.     

Antimicrobial resistance in enteric pathogens isolated from Minnesota pigs from 1995 to 2004

This study investigated the occurrence and antimicrobial resistance profiles of Escherichia coli and Salmonella sp. isolated from swine samples submitted to the Minnesota Veterinary Diagnostic Laboratory (MVDL) in Saint Paul, Minnesota from 1995 to 2004. During this time period, a total of 5072 E. coli and 2793 Salmonella sp. was isolated. Most of these isolates were found to be resistant to the tetracycline and beta-lactam group of antibiotics. Resistance to spectinomycin was also frequently observed. An increasing trend in ampicillin resistance and a decreasing trend in apramycin resistance were seen in both pathogens, although ampicillin resistance was relatively higher in E. coli than in Salmonella. Aminoglycoside (amikacin) and quinolone (enrofloxacin) were the only antimicrobials to which minimum or no resistance was observed. The resistance of pig pathogens to several antibiotics indicates the need to routinely monitor the use of these antimicrobials and their associated resistance in pig populations.