Yield and water-production functions of two durum wheat cultivars grown under different irrigation and nitrogen regimes

Wheat (Triticum durum L.) yields in the semi-arid regions are limited by inadequate water supply late in the cropping season. Planning suitable irrigation strategy and nitrogen fertilization with the appropriate crop phenology will produce optimum grain yields. A 3-year experiment was conducted on deep, fairly drained clay soil, at Tal Amara Research Station in the central Bekaa Valley of Lebanon to investigate the response of durum wheat to supplemental irrigation (IRR) and nitrogen rate (NR). Three water supply levels (rainfed and two treatments irrigated at half and full soil water deficit) were coupled with three N fertilization rates (100, 150 and 200 kg N ha⁻¹) and two cultivars (Waha and Haurani) under the same cropping practices (sowing date, seeding rate, row space and seeding depth). Averaged across N treatments and years, rainfed treatment yielded 3.49 Mg ha⁻¹ and it was 25% and 28% less than half and full irrigation treatments, respectively, for Waha, while for Haurani the rainfed treatment yielded 3.21 Mg ha⁻¹, and it was 18% and 22% less than half and full irrigation, respectively. On the other hand, N fertilization of 150 and 200 kg N ha⁻¹ increased grain yield in Waha by 12% and 16%, respectively, in comparison with N fertilization of 100 kg N ha⁻¹, while for cultivar Haurani the increases were 24% and 38%, respectively. Regardless of cultivar, results showed that supplemental irrigation significantly increased grain number per square meter and grain weight with respect to the rainfed treatment, while nitrogen fertilization was observed to have significant effects only on grain number per square meter. Moreover, results showed that grain yield for cultivar Haurani was less affected by supplemental irrigation and more affected by nitrogen fertilization than cultivar Waha in all years. However, cultivar effects were of lower magnitude compared with those of irrigation and nitrogen. We conclude that optimum yield was produced for both cultivars at 50% of soil water deficit as supplemental irrigation and N rate of 150 kg N ha⁻¹. However, Harvest index (HI) and water use efficiency (WUE) in both cultivars were not significantly affected neither by supplemental irrigation nor by nitrogen rate. Evapotranspiration (ET) of rainfed wheat ranged from 300 to 400 mm, while irrigated wheat had seasonal ET ranging from 450 to 650 mm. On the other hand, irrigation treatments significantly affected ET after normalizing for vapor pressure deficit (ET/VPD) during the growing season. Supplemental irrigation at 50% and 100% of soil water deficit had approximately 26 and 52 mm mbar⁻¹ more ET/VPD, respectively, than those grown under rainfed conditions.     

Effect of salinity on water stress, growth, and yield of maize and sunflower

Maize and sunflower were grown in tanks filled with loam and clay, and were irrigated with water of three different levels of salinity. Predawn leaf-water potential and stomatal conductance were used as parameters for water stress. The predawn leaf-water potential of maize was higher than that of sunflower, but the effect of salinity and soil texture on the predawn leaf-water potential was the same for both crops. The stomatal conductance of sunflower was much higher and more severely affected by salinity and soil texture than the stomatal conductance of maize.

Although salinity had a more serious effect on the development of leaf area and canopy dry matter of sunflower, its effect on evapotranspiration and grain yield was the same for both crops. Soil texture had a stronger effect on the development of leaf area and canopy dry matter of sunflower, which also appeared in the evapotranspiration and grain yield, indicating that sunflower is more sensitive to drought than maize.     

Production of an Antibody Fragment (scFv) Targeting PcrV Protein of Pseudomonas aeruginosa in Fed-Batch Cultivation Mode

Background: Pseudomonas aeruginosa is one of the opportunistic pathogens causing frequent hospital-acquired life-threatening infections in mechanically ventilated patients. The most significant virulence factor of P. aeruginosa is T3SS. PcrV is an important structural protein of the T3SS. Methods:In the current investigation, a recombinant scFv mAb against the PcrV protein was expressed in EnBase® (fed-batch) cultivation mode. The pETiteTM N-His SUMO Kan vector, including anti-PcrV scFv gene, was transformed into Escherichia coli (BL21) cells. The expression and solubility of anti-PcrV scFv protein were investigated at two different temperatures (25 °C and 30 °C) and at different induction times (4, 6, 8, 12, and 24 hours). Results:Increased efficiency was achieved by EnBase® compared to LB broth; owing to the slow release of glucose, the maximum level of solubility and total protein expression was observed in EnBase® cultivation system at 30 °C and 24 h post induction. Furthermore, IC₅₀ for anti-PcrV scFv protein was determined to be approximately 7 μg/mL. Conclusion:Anti-PcrV scFv produced in this study showed promising in vitro results, protecting RBC from lysis by P. aeruginosa (exoU+). Key Words: Fed Batch, recombinant protein, Pseudomonas aeruginosa, scFv     

A molecular approach for identification of paramphistomes from Africa and Asia

Paramphistomiasis is a disease of domestic and wild ruminants caused by some digenetic trematodes of the superfamily Paramphistomoidea. Human infections with certain species of paramphistomes have been reported. Given their ubiquity and their abundance within hosts, it seems likely that the importance of these worms is underestimated globally. Based on the reported difficulties of morphological identification of paramphistomes, the development of alternative approaches to better delineate species is needed. Paramphistome samples examined during this study were cercariae, rediae from snail hosts and adult flukes obtained from slaughterhouses from Kenya, Tanzania, Egypt and Nepal. The results confirm that ITS2 is a good molecular marker for paramphistome identification and can be used to determine the affiliation of samples among the different taxa of Paramphistomoidea. Our 22 samples include eight species of paramphistomes. Ten samples of paramphistome larvae (cercariae or rediae) yielded seven species and the 12 samples of adult flukes from bovines yielded four, only one of which was not also represented among the larvae. We found three cases in which the sequences for adult worms and larvae matched, thus revealing the hosts involved locally in those particular life cycles. We interpret our specimens to include five species from Kenya, two from Nepal, two from Tanzania and one from Egypt. Bulinus forskalii was found infected with three species of paramphistomes. The results of the present study will help construct a framework to facilitate identification and eventually control of this underestimated cosmopolitan group of digeneans.     

Semiarid soils submitted to severe drought stress: influence on humic acid characteristics in organic-amended soils

Purpose  

The objective of this work was to assess the effect of severe drought conditions on the characteristics of semiarid soil humic acids (HAs) as well as the effect of organic amendment on such changes.     

Fine-scale wetland features mediate vector and climate-dependent macroscale patterns in human West Nile virus incidence

Context

Mosquito-borne diseases in the United States are notorious for their seemingly erratic temporal and spatial outbreak patterns in humans. Identifying linkages between fine-scale phenomenon and macroscale outbreak patterns can improve the understanding of these complex socio–ecological systems.

Objectives

Using West Nile virus (WNV) as a model system, we examine whether fine-scale wetland characteristics—wetland size, connectivity, and inundation regime—have an important effect on macroscale human disease outbreak in the northeastern and midwestern United States.

Methods

We take a spatially explicit GIS-based approach, derive new macroscale wetland metrics based on fine-scale wetland characteristics, and use county-level annual human WNV incidence data over 11 years to evaluate linkages between the fine and macroscales (1.6 million km²).

Results

In regions dominated by the Culex tarsalis WNV vector, U.S. counties with a small average wetland size had more than 100 % higher human WNV incidence than counties with a large average wetland size. In regions dominated by the Cx. pipiens and Cx. restuans vectors, a low proportional area of connected wetland was associated with at least 50 % higher human WNV incidence than a high proportional area of connected wetland. Finally, Cx. tarsalis-dominated counties with a high proportional area of semi-permanent wetland that were experiencing drought conditions had over 300 % higher annual WNV incidence than drought-affected counties with a low proportional area of semi-permanent wetland.

Conclusions

Our results suggest that phenomena occurring at the individual wetland scale may aggregate to influence macroscale human WNV outbreak patterns and may be mediated by the interplay of other factors such as vector species-specific traits and climate.

     

Evidence of subclinical foot-and-mouth disease virus infection in young calves born from clinically recovered cow under natural condition

Tropical Animal Health and Production - Foot-and-mouth disease (FMD) is a highly contagious and economically important, transboundary viral disease of cloven-hoofed animals. It is known that an...     

Resistance to insect pests: What do legumes have to offer?

Summary Insect pests are major problems for all crops, worldwide. In this review we will focus on legumes, which are attacked by a range of insect pests including pod/seed feeders, defoliators and sap feeders. We review the history of breeding for resistance to insect pests in legumes, which has had mixed success, and discuss further opportunities in this area. We also review the extraordinary array of direct and indirect mechanisms contributing to insect defence in legumes, the understanding and exploitation of which offer opportunities for both legume and non-legume crops. There is also good potential to improve insect resistance in legume crops through a detailed understanding of the signaling pathways that regulate induced responses to insect feeding, and recent progress in this area, primarily obtained from non-legume systems, is reviewed. The importance legumes play in farming systems, their wide range of novel chemistry and the emergence of model systems suitable for genomic approaches present opportunities for research in this area strongly linked to breeding programs to help develop legume crops with enhanced insect resistance. CSIRO’s right to retain a non-exclusive, royalty-free licence in and to any copyright is acknowledged.     

Prevalence and molecular characterization of Sarcocystis species in water buffaloes (Bubalus bubalus) in Egypt

The present study was planned to investigate the prevalence of Sarcocystis spp. among slaughtered water buffaloes (Bubalus bubalis) at Alexandria province, Egypt. Three hundred blood samples were collected from slaughtered buffaloes (5–7 years old). Two techniques were used to evaluate the seroprevalence of Sarcocystis spp., enzyme-linked immunosorbent assay (ELISA) and indirect haemagglutination assay (IHA). It was revealed that 203 (67.6 %) and 191 (63.6 %) of the tested serum samples were seropositive to Sarcocystis spp. by ELISA and IHA, respectively. The results of sensitivity and specificity of IHA relative to ELISA were 94 and 100 %, respectively. For molecular characterization of inter- and intra-species genetic polymorphism within Egyptian isolates of Sarcocystis spp. of water buffaloes, polymerase chain reaction (PCR) and polymerase chain reaction-restriction length polymorphisms (PCR-RFLPs) were performed on four macroscopic isolates. The isolates represented two different geographical regions of Egypt, Alexandria and Assuit provinces. Alexandria isolates (large and small-sized cyst of the same host) and Assuit isolates (large and small-sized cyst of the same host) were used. The 18S rDNA of the macroscopic cysts were characterized, in tandem, by four restriction endonucleases, RsaI, MboI, SspI and DraI. RsaI and MboI enzymes did not show any restriction sites for all isolates, leaving the amplified fragments without cutting. SspI showed two fragments in Alexandria and Assuit small-sized isolates cut by the enzyme at 600–700-bp fragments, while Alexandria and Assuit large-sized cysts amplicons were not digested by this enzyme. The fourth enzyme, DraI, cut the PCR product of Alexandria large-sized cysts into two fragments (420–780 bp), while Assuit large-sized amplicon was not cut. It could be concluded that there was a far distance between the two local isolates (small and large sized), but there were no differences between the large-sized isolates.