Studies on the potential use of Pasteuria penetrans as a biocontrol agent of root-knot nematodes (Meloidogyne spp.)     

E. A. TZORTZAKAKIS  A. G. DE. R. CHANNER  S. R. GOWEN  & R. AHMED 《Plant pathology》1997,46(1):44-55

Some aspects of the interaction of the bacterial parasite Pasteuria penetrans and the root-knot nematode ( Meloidogyne spp.) were investigated in laboratory and pot experiments. The variable spore attachment on juveniles exposed to water suspensions of the bacterium is probably attributed to differential susceptibility of biotypes within a heterogeneous Meloidogyne population. The relationship between spore concentration and attachment level is not linear over a range of spore dosages, indicating that even at very high spore concentrations the number of spores capable of attachment may not be present in excess and it is difficult to ensure sufficient numbers of spores to ensure infection will attach to all nematodes. Attempts to apply the bacterium in conditions such as might occur in seedbeds did not suppress nematode multiplication after transplanting in nematode-infested soil, indicating that the only effective application method is a thorough spore distribution in the planting sites. Two major constraints were revealed: high levels of spore attachment to juveniles does not always guarantee a significant reduction of egg laying and this is greatly influenced by the Meloidogyne biotype. Furthermore, the cumulative effect of the parasite in reducing Meloidogyne populations over several crop cycles was less than expected as the bacterium reduced intra-specific competition for the food supply and the less damaged root enabled many nematodes to survive.  相似文献   

Genome-wide association analysis for stripe rust resistance in spring wheat(Triticum aestivum L.) germplasm          下载免费PDF全文

Sher MUHAMMAD  Muhammad SAJJAD  Sultan Habibullah KHAN  Muhammad SHAHID  Muhammad ZUBAIR  Faisal Saeed AWAN  Azeem Iqbal KHAN  Muhammad Salman MUBARAK  Ayesha TAHIR  Muhammad Umer  Rumana KEYANI  Muhammad Inam AFZAL  Irfan MANZOOR  Javed Iqbal WATTOO  Aziz-ur REHMAN 《农业科学学报》2020,19(8):2035-2043

Stripe rust is a continuous threat to wheat crop all over the world. It causes considerable yield losses in wheat crop every year. Continuous deployment of adult plant resistance(APR) genes in newly developing wheat cultivars is the most judicious strategy to combat this disease. Herein, we dissected the genetics underpinning stripe rust resistance in Pakistani wheat germplasm. An association panel of 94 spring wheat genotypes was phenotyped for two years to score the infestation of stripe rust on each accession and was scanned with 203 polymorphic SSRs. Based on D' measure, linkage disequilibrium(LD) exhibited between loci distant up to 45 c M. Marker-trait associations(MTAs) were determined using mixed linear model(MLM). Total 31 quantitative trait loci(QTLs) were observed on all 21 wheat chromosomes. Twelve QTLs were newly discovered as well as 19 QTLs and 35 previously reported Yr genes were validated in Pakistani wheat germplasm. The major QTLs were QYr.uaf.2 AL and QYr.uaf.3 BS(PVE, 11.9%). Dissection of genes from the newly observed QTLs can provide new APR genes to improve genetic resources for APR resistance in wheat crop.  相似文献   

IMAGING DIAGNOSIS—CORPUS CAVERNOSUM, ISCHIOCAVERNOSUS, AND BULBOSPONGIOSUS MUSCLE INJURY IN A DOG     

DANIEL G. HICKS  RODNEY S. BAGLEY  PATRICK R. GAVIN  SHANNON P. HOLMES  AHMED TIBARY 《Veterinary radiology & ultrasound》2007,48(3):239-242

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Effect of a single injection of gonadotropin-releasing hormone (GnRH) and human chorionic gonadotropin (hCG) on testicular blood flow measured by color doppler ultrasonography in male Shiba goats     

Haney SAMIR  Kazuaki SASAKI  Eman AHMED  Aly KAREN  Kentaro NAGAOKA  Mohamed EL SAYED  Kazuyoshi TAYA  Gen WATANABE 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(5):549-556

Although color Doppler ultrasonography has been used to evaluate testicular blood flow in many species, very little has been done in goat. Eight male Shiba goats were exposed to a single intramuscular injection of either gonadotropin-releasing hormone (GnRH group; 1 µg/kg BW) or human chorionic gonadotropin (hCG group; 25 IU/kg BW). Plasma testosterone (T), estradiol (E2) and inhibin (INH) were measured just before (0 hr) and at different intervals post injection by radioimmunoassay. Testis volume (TV) and Doppler indices, such as resistive index (RI) and pulsatility index (PI) of the supratesticular artery, were measured by B-mode and color Doppler ultrasonography, respectively. The results indicated an increase in testicular blood flow in both groups, as RI and PI decreased significantly (P<0.05), but this increase was significant higher and earlier in hCG group (1 hr) than in the GnRH group (2 hr). A high correlation was found for RI and PI with both T (RI, r= −0.862; PI, r= −0.707) and INH in the GnRH group (RI, r=0.661; PI, r=0.701). However, a significant (P<0.05) correlation was found between E2 and both RI (r= −0.610) and PI (r= −0.763) in hCG group. In addition, TV significantly increased and was highly correlated with RI in both groups (GnRH, r= −0.718; hCG, r= −0.779). In conclusion, hCG and GnRH may improve testicular blood flow and TV in Shiba goats.  相似文献   

Dynamics of organic carbon and nitrogen in deep soil profile and crop yields under long-term fertilization in wheat-maize cropping system          下载免费PDF全文

Muhammad QASWAR  LI Dong-chu  HUANG Jing  HAN Tian-fu  Waqas AHMED  Sehrish ALI  Muhammad Numan KHAN  Zulqarnain Haider KHAN  XU Yong-mei  LI Qian  ZHANG Hui-min  WANG Bo-ren  Ahmad TAUQEER 《农业科学学报》2022,21(3):826-839

Soil organic carbon (SOC) and nitrogen (N) are two of the most important indicators for agricultural productivity. The primary objective of this study was to investigate the changes in SOC and N in the deep soil profile (up to 100 cm) and their relationships with crop productivity under the influence of long-term (since 1990) fertilization in the wheat-maize cropping system. Treatments included CK (control), NP (inorganic N and phosphorus (P) fertilizers), NPK (inorganic N, P and potassium fertilizers), NPKM (NPK plus manure), and M (manure). Crop yield and the properties of topsoil were measured yearly from 2001 to 2009. C and N contents were measured at five different depths in 2001 and 2009. The results showed that wheat and maize yields decreased between 2001 and 2009 under the inorganic fertilizer (NP and NPK) treatments. The average yield between 2001 and 2009 under the NP, NPK, NPKM, and M treatments (compared with the CK treatment) increased by 38, 115, 383, and 381%, respectively, for wheat and 348, 891, 2 738, and 1 845%, respectively, for maize. Different long-term fertilization treatments significantly changed coarse free particulate (cfPOC), fine free particulate (ffPOC), intramicroaggregate particulate (iPOC), and mineral-associated (mSOC) organic carbon fractions. In the experimental years of 2001 and 2009, soil fractions occurred in the following order for all treatments: mSOC>cfPOC>iPOC>ffPOC. All fractions were higher under the manure application treatments than under the inorganic fertilization treatments. Compared to the inorganic fertilization treatments, manure input enhanced the stocks of SOC and total N in the surface layer (0–20 cm) but decreased SOC and N in the deep soil layer (80–100 cm). This reveals the efficiency of manure in increasing yield productivity and decreasing risk of vertical loss of nutrients, especially N, compared to inorganic fertilization treatments. The findings provide opportunities for understanding deep soil C and N dynamics, which could help mitigate climate change impact on agricultural production and maintain soil health.  相似文献   

Experience of partnership models for the co-management of Bangladesh fisheries     

M. AHMED  A.D. CAPISTRANO  & M. HOSSAIN 《Fisheries Management and Ecology》1997,4(3):233-248

Failure in the past to ascertain responsible fishing practices and equitable distribution of benefits under traditional leasing systems has motivated the Bangladesh government to work in partnership with non-governmental organizations (NGOs) and fishing communities in recent times. This paper discusses the operational approaches that were used to identify fishing people and create institutions for their increasing participation in local fisheries, and in making and enforcing resource use rules under various partnership arrangements. The group-based empowerment strategies of NGOs; their role in securing for the beneficiaries the access rights to water bodies; the provision of credits and inputs for employment and income generation activities showed some practical evidence of the concept of the poor as managers of the fisheries resources. The policy issues involved in the rights of local community members to catch fish for subsistence are also discussed, as well as the challenges associated with the difficulties of reconciling differing government (GO) and nongovernment (NGO) organization priorities and points of view with regard to target group identification and levels of responsibilities.  相似文献   

DISTRIBUTION OF INOSITOL PHOSPHATES, PHOSPHOLIPIDS, AND NUCLEIC ACIDS AND MINERALIZATION OF INOSITOL PHOSPHATES IN SOME BANGLADESH SOILS   总被引：1，自引：0，他引：1  

A. ISLAM  B. AHMED 《European Journal of Soil Science》1973,24(2):193-198

Concentration of inositol phosphates, phospholipids, and RNA and its derivatives of ten Bangladesh soils varied between 17.5 and 150 ppm, 0.5 and 11.0 ppm, and 0.22 and 1.30 ppm respectively. Variation in inositol phosphates was related to total phosphate and organic phosphate contents. Variation in phospholipids was associated with total phosphate, organic phosphate, and organic matter contents whereas the variation in RNA and its derivatives was related to total phosphate contents of the soils. Maximum mineralization of inositol phosphates was obtained in the first 30 days either when incubated with lime or when submerged under water. A moderate rate was observed in the subsequent 30-day incubation periods. The mineralization was greater in soil which contained more organic matter and inositol phosphates. Mineralization also increased with pH. Liming enhanced mineralization as it induced conditions for the proliferation of phosphate transforming organisms.  相似文献   

EFFECTS OF ADSORBED CATIONS ON PHYSICAL PROPERTIES OF TROPICAL RED EARTHS AND TROPICAL BLACK EARTHS     

S. AHMED  L. D. SWINDALE  S. A. EL-SWAIFY 《European Journal of Soil Science》1969,20(2):255-268

Similar relative effects were obtained for plastic limits, percentage stable aggregates, and hydraulic conductivities when a tropical red earth, consisting predominantly of kaolin and iron oxide, and a tropical black earth consisting predominantly of montmorillonite, were saturated with Ca, Mg, K, or Na ions or combinations of these. Plastic limits were independent of the nature of the saturation cations, but were significantly dependent upon clay type. Percentage stable aggregates of artificially prepared aggregates and hydraulic conductivity were affected by the four cations in the order Ca = Mg > K Na and were also significantly affected by clay type. Combinations of the four cations generally gave intermediate effects with Ca-saturated soils more susceptible to deterioration by K or Na than Mg-saturated soils. The results confirm the generally deleterious effect of Na ions and show that K ions have effects similar to Na on the properties investigated. They suggest that heavy potash fertilization without liming may lead to structural deterioration of these soils.  相似文献   

Gas-phase Diffusive Tracer Test for the In-Situ Measurement of Tortuosity in the Vadose Zone     

Geoffrey R. Tick  Colleen M. McColl  Irfan Yolcubal  Mark L. Brusseau 《Water, air, and soil pollution》2007,184(1-4):355-362

Robust measurements of porous-medium tortuosity are one of the many components needed for accurate characterization and prediction of fluid flow and contaminant transport in the subsurface. A gas-phase diffusive tracer-test method is evaluated for the in-situ measurement of tortuosity in the vadose zone. This technique presents an alternative to employing widely-used correlations to estimate tortuosity. A small-scale field study was conducted using a single well and a non-reactive gas-phase tracer (sulfur hexafluoride; SF₆). Gas samples were collected from the injection point periodically after tracer injection into the soil matrix. An effective radius of influence of 50 cm was determined for the tests. An analytical solution was calibrated to the measured temporal concentration distribution, producing a fitted value for tortuosity. The value obtained from the tracer tests was compared to values estimated with several widely-used correlations. The value obtained from the tracer tests was generally larger than the values estimated with the correlations, which spanned a relatively wide range. The tracer-test method provides a means by which to determine in-situ measurements of tortuosity, allowing for better characterization of contaminant transport in the vadose zone.  相似文献   

Genetic and Phenotypic Analysis of Soybean mosaic virus Resistance in PI 88788 Soybean     

Gunduz I  Buss GR  Chen P  Tolin SA 《Phytopathology》2004,94(7):687-692

ABSTRACT Resistance to Soybean mosaic virus (SMV) was identified in PI 88788 soybean, a germ plasm accession from China that is used widely as a source of resistance to soybean cyst nematode. Strains SMV-G1 through -G7 infected the inoculated leaves of PI 88788 but were not detected in upper, noninoculated trifoliolate leaves. Inheritance of resistance was determined by inoculating progenies of crosses of PI 88788 with susceptible cvs. Essex and Lee 68 with SMV strains G1 and G7. Allelomorphic relationships with known genes for resistance to SMV were tested in crosses with the resistant genotypes PI 96983, L29, and V94-5152, possessing Rsv1, Rsv3, and Rsv4 genes, respectively. Data analyses showed that resistance in PI 88788 to SMV-G1 is controlled by a single, partially dominant gene; however, to SMV-G7, the same gene was completely dominant. The PI 88788 gene was independent of the Rsv1 and Rsv3 loci, but allelic to Rsv4 in V94-5152. Expression of the Rsv4 gene in PI 88788 resulted in a reduced number of infection sites and restricted short- and long-distance movement of virus, rather than hypersensitivity. A unique late susceptible phenotype was strongly associated with heterozygosity. This gene has potential value for use in gene pyramiding to achieve resistance to several SMV strains, as well as for rate-reducing resistance.  相似文献