Studies on a mixed bacterial culture from soil which degrades the herbicide linuron     

Steven J. Roberts  Allan Walker  Nisha R. Parekh  Sarah J. Welch  Martin J. Waddington 《Pest management science》1993,39(1):71-78

A stable mixed bacterial culture which degrades the herbicide linuron was isolated from soil by enrichment with linuron in a liquid mineral medium. Radio-respirometry studies showed that the culture mineralised linuron completely. No intermediate degradation products were detected in the medium. The culture was able to utilise linuron as a source of both nitrogen and carbon and was also able to degrade the related herbicides monolinuron and chlorbromuron and the possible intermediate degradation products of linuron: 3,4-dichlorophenyl-l-methylurea, 3,4-dichlorophenylurea and 3,4-dichloroaniline. The culture was unable to degrade the 1,1-dimethyl substituted ureas monuron, diuron or metoxuron. The culture contained Gram-negative aerobic rods, and Gram-positive aerobic non-spore-forming rods and cocco-bacilli. Of 124 isolates from the mixed culture, none degraded linuron in pure culture, indicating that a consortium of organisms is involved. Further investigation suggested that Pseudomonas spp. were important components of the population responsible for degradation.  相似文献   

Development of a CAPS marker for the badh2.7 allele in Sri Lankan fragrant rice (Oryza sativa)     

Shachinthaka Dissanayaka  Nisha Sulari Kottearachchi  Jagathpriya Weerasena  Milani Peiris 《Plant Breeding》2014,133(5):560-565

Fragrance in rice is caused by mutations in the badh2 (betaine aldehyde dehydrogenase) gene. It was previously reported that exons 1, 2, 7, 10, 13 and 14 of badh2 are hot spots for various mutations leading to fragrance in most aromatic rice. This study was carried out to sequence the 14th exon of badh2 gene of Sri Lankan aromatic rice varieties that lack the badh2.1 allele. The aims of the study were to predict the aberrant protein structure and to develop a functional DNA marker. In view of this, we sequenced the 14th exon of four traditional aromatic accessions and compared with a published sequence. Four accessions contained a nucleotide ‘G’ insertion in the 14th exon. This novel mutation can be classified as the badh2.7 allele. The predicted three‐dimensional protein structure of the mutant shows loss of part of the oligomerization and coenzyme binding domains, a change that is predicted to result in fragrance. A CAPS‐based novel marker, Bad2.7CAPS, was developed to identify varieties possessing this badh2.7 allele, and it can be utilized in rice breeding programmes.  相似文献   

Synthesis,biological activities and SAR studies of novel 1‐Ethyl‐7‐methyl‐4‐oxo‐1,4‐dihydro‐[1,8]naphthyridine‐3‐carboxylic acid based diacyl and sulfonyl acyl hydrazines     

Nisha Aggarwal  Rajesh Kumar  Chitra Srivastava  Prem Dureja  J. M. Khurana 《Pest management science》2014,70(7):1071-1082

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Impact of addition of soil amendments and microbial inoculants on nursery growth of <Emphasis Type="Italic">Populus deltoides</Emphasis> and <Emphasis Type="Italic">Toona ciliata</Emphasis>     

H. Aggarwal  D. Goyal 《Agroforestry Systems》2009,75(2):167-173

Present study evaluated growth of Populus deltoides G48 and Toona ciliata over a period of 6 months, in nursery soil amended with 10% fly ash (v/v), 5% distillery waste (v/v), 20% farmyard manure (v/v) and microbial consortium of Pseudomonas striata and Azotobacter sp. @ 30 ml/pot in different combinations leading to 12 different treatments with 16 replicates in completely randomized block design. Biometric parameters such as plant height, collar diameter and total dry biomass were analyzed which indicated that the treatment (T8) comprising of fly ash @ 10% (v/v), farmyard manure @ 20% (v/v) and microbial consortium @ 30 ml/pot promoted growth of P. deltoides. The results indicated that combined addition of fly ash, farm yard manure and microbial inoculants can be used as a good potting mixture for improving survival rates and plant growth in forestry nurseries.  相似文献   

Simulating rice stem borer, Scirpophaga incertulas Wlk., damage for developing decision support tools     

G. Reji  Subhash Chander  P.K. Aggarwal 《Crop Protection》2008,27(8):1194-1199

InfoCrop, a generic crop–pest simulation model, was used to validate yellow stem borer, Scirpophaga incertulas Wlk., damage mechanism on two rice cultivars, Pusa Basmati 1 and Ratna. Data sets consisted of three experiments, one under natural infestation of the pest and two involving artificial detillering. The simulated yields showed less than 10% variation from the observed yields, except in one treatment, where the difference was 10.5%. The simulated yield losses were also proximal to respective observed yield losses (R²=0.922, RMSE=3.825), indicating proper validation of damage mechanism of the stem borer. As the model simulated the pest damage appropriately under natural injury, as well under artificial detillering; artificial detillering seemed comparable to natural injury of the stem borer in its effect on rice growth and yield. Validated InfoCrop was used to simulate economic injury levels (EILs) of the stem borer at different rice growth stages for varied control expenditure, incurred on two and three sprays of monocrotophos and one granular application of carbofuran, and for three market prices of produce. The EIL consistently decreased with advancing crop age and it exhibited a positive relationship with control expenditure and a negative relationship with market value of the produce. The simulated EILs were observed to be comparable to empirical injury levels that were previously established. The validated model was also used to devise iso-loss curves that depicted same yield loss for different combinations of the stem borer injury and crop age. Crop simulation model-based EILs and iso-loss curves are useful in monitoring the stem borer injury and in need assessment for pesticide application, thereby avoiding unnecessary expenditure and environmental contamination. Due to their mechanistic nature, crop models can be used to formulate location-specific decision support tools and therefore, help improve decision making in pest management.  相似文献   

Feline calicivirus: a neglected cause of feline ocular surface infections?     

Gerriets W  Joy N  Huebner-Guthardt J  Eule JC 《Veterinary ophthalmology》2012,15(3):172-179

Objective To investigate the prevalence of feline calicivirus (FCV) infection in relation to ocular surface lesions in cats with upper respiratory tract diseases (URTD). Animals studied Ninety‐nine cats with ocular surface infection and symptoms or recent history of URTD were examined at various rescue shelters and hospitals. Procedure A complete general and ophthalmic examination was performed including Schirmer tear test, slit‐lamp biomicroscopy, fluorescein and lissamine green staining. Clinical and ocular symptoms were scored and recorded. Conjunctival samples were collected using a cytobrush, and nucleic acid extraction using RT‐PCR was carried out to analyze for the presence of various infectious agents. Results RT‐PCR detected either FCV, feline herpes virus type 1 (FHV‐1), Chlamydophila felis or Mycoplasma spp. in 63/99 samples. 30/63 samples were positive for FCV, 23/63 for C. felis, 21/63 for Mycoplasma spp., and 16/63 for FHV‐1. Out of the 30 FCV‐positive samples, 11 were positive only for FCV and in 19 samples FCV was seen in combination with other agents. FCV infection was highest in animals examined at the rescue centers and in the age group of 0–2 months. Erosive conjunctivitis was an important ocular finding. Oral ulcers were detected in all FCV‐infected cats. Conclusion Results indicate that FCV is highly prevalent in cats with URTD either as a sole infectious agent or in combination with other pathogens and therefore is a potential cause for ocular surface lesions during the URTD.  相似文献   

Actions for ex situ conservation of Gloriosa superba L. - an endangered ornamental cum medicinal plant     

Kuldeep Yadav  Ashok Aggarwal  Narender Singh 《Journal of Crop Science and Biotechnology》2012,15(4):297-303

Factors affecting in vitro propagation and microtuberization were evaluated for Gloriosa superba L., an endangered ornamental cum medicinal plant having limited reproductive capacity. Surface sterilization of tuber explants with 0.1% mercuric chloride (HgCl₂) for 5 min eliminated the contamination effectively with highest survival rate. Among the various combinations used, Murashige and Skoog (MS) medium with 2.0 mg L^?1 6-benzylaminopurine (BAP) + 0.5 mg L^?1 α-naphthalene acetic acid (NAA) containing 3% sucrose with 16-h photoperiod exhibited the greatest in vitro tuberization (3.2) with the highest shoot regeneration frequency (90%). The longest tuber regeneration occurred on MS media containing 4% sucrose. Transfer of in vitro-regenerated shoots to half-strength MS medium with 1.0 mg L^?1 indole-3-butyric acid (IBA) + 0.5 mg L^?1 NAA showed maximum root induction (66.6%). The in vitro-grown plantlets were successfully acclimatized and transplanted to sterilized soil and sand mixture (3:1) in the glasshouse with 70% survival. The colchicine content was determined in the tubers of ex vitro plants by HPLC using the same retention time (1.5 min) as that of the standard colchicine. This revealed that the micropropagation protocol developed by us for rapid mass production could be used as raw material for colchicine extraction and provides a basis for germplasm conservation and genetic improvement of G. superba.  相似文献   

Influence of crops, crop residues and manure on amino acid and amino sugar fractions of organic nitrogen in soil     

Praveen-Kumar  K. Tripathi  R. Aggarwal 《Biology and Fertility of Soils》2002,35(3):210-213

A field experiment was carried out to study the effect of: (1) the cultivation of a cereal (pearl millet) and two legumes (mung bean and clusterbean), and (2) incorporation of crop residues and manure in soil, on depletion or enrichment of pools of amino acid-N and amino sugar-N in soil. Both legumes enriched amino acid and amino sugar fractions but pearl millet cultivation depleted them. Enrichment of these fractions was partly attributed to the conversion of N biologically fixed during legume cultivation to these fractions and partly to the conversion of unknown and non-hydrolysable N fractions to amino acid-N and amino sugar-N. Mineralization of amino acid-N and amino sugar-N fractions along with their conversion to unknown and non-hydrolysable fractions were the plausible reasons for the decline in their concentrations after pearl millet cultivation. Application of residues or manure reversed this effect of pearl millet.  相似文献   

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

P.K. Aggarwal  B. BanerjeeM.G. Daryaei  A. BhatiaA. Bala  S. RaniS. Chander  H. PathakN. Kalra 《Agricultural Systems》2006

InfoCrop, a generic crop model, simulates the effects of weather, soils, agronomic management (planting, nitrogen, residues and irrigation) and major pests on crop growth, yield, soil carbon, nitrogen and water, and greenhouse gas emissions. This paper presents results of its evaluation in terms of its validation for rice and wheat crops in contrasting agro-environments of tropics, sensitivity to the key inputs, and also illustrates two typical applications of the model. Eleven diverse field experiments, having treatments of location, seasons, varieties, nitrogen management, organic matter, irrigation, and multiple pest incidences were used for validation. Grain yields in these experiments varied from 2.8 to 7.2 ton ha⁻¹ in rice and from 3.6 to 5.5 ton ha⁻¹ in wheat. The results indicated that the model was generally able to explain the differences in biomass, grain yield, emissions of carbon dioxide, methane and nitrous oxides, and long-term trends in soil organic carbon, in diverse agro-environments. The losses in dry matter and grain yield due to different pests and their populations were also explained satisfactorily. There were some discrepancies in the simulated emission of these gases during first few days after sowing/transplanting possibly because of the absence of tillage effects in the model. The sensitivity of the model to change in ambient temperature, crop duration and pest incidence was similar to the available field knowledge. The application of the model to quantify multiple pests damage through iso-loss curves is demonstrated. Another application illustrated is the use of InfoCrop for analyzing the trade-offs between increasing crop production, agronomic management strategies, and their global warming potential.  相似文献   

Changes in plant water status of Maize (Zea mays L.) with ontogeny     

Nirmal Sekhon  G. C. Aggarwal 《Irrigation Science》1988,9(3):227-231

Summary Irrigations scheduled on plant water status ignore the effect of ontogeny on plant water status. Leaf xylem water potential (XWP) of maize sown on three dates in a sandy loam soil was measured under the same environment for evaluating the effect of ontogeny on plant water status. Minimum XWP (measured between 13.00-14.30 h) of the youngest crop was the highest during two crop seasons and the differences in XWP of the youngest and the oldest maize plants ranged from 0.25 to 0.65 MPa during the season. Maximum XWP (measured before dawn) of the youngest crop was nearly 0.1 MPa higher than that of the oldest crop. Diurnal variation in XWP was lowest in the youngest crop. The results highlight the need of ontogeny dependent critical values of plant water status for scheduling irrigation.  相似文献