Phytotoxicity of solanapyrones A and B produced by the chickpea pathogen Ascochyta rabiei(Pass.) Labr. and the apparent metabolism of solanapyrone A by chickpea tissues

When chickpea shoots were placed in solanapyrone A, the compound could not be recovered from the plant and symptoms developed. These consisted of loss of turgor, shrivelling and breakage of stems and flame-shaped, chlorotic zones in leaflets. In similar experiments with solanapyrone B, only 9.4% (22 μ g) of the compound taken up was recovered and stems remained turgid but their leaflets became twisted and chlorotic and some abscized.Cells isolated from leaflets of 12 chickpea cultivars differed by up to five-fold in their sensitivity to solanapyrone A and this compound was 2.6–12.6 times more toxic than solanapyrone B, depending on cultivar.Glutathione reacted with solanapyrone A in vitro reducing its toxicity in a cell assay and forming a conjugate. Measurement of reduced glutathione concentration and glutathione-S-transferase (GST) activity among cultivars showed that the differences of their means were highly significant and both were negatively and significantly correlated with their sensitivity to solanapyrone A. Treatment of shoots with solanapyrone A enhanced total, reduced and oxidized glutathione content as well as GST activity 1.26-, 1.23-, 1.50- and 1.94-fold, respectively. Similarly, treatment of shoots with the safener, dichlormid, also raised total, oxidized and reduced glutathione levels and GST activity 1.42-, 1.07-, 1.43-, 1.42-fold, respectively. Cells isolated from shoots treated with dichlormid at 150 and 300 μ g per shoot were 2.45 and 2.66 times less sensitive to solanapyrone A, with LD₅₀values of 71.5 and 77.8 μ g ml⁻¹, respectively, as compared to 29.2 μ g ml⁻¹for controls.     

The Crown Window — a simple device for measuring tree crowns

The paper presents a new method for assessing crown radii at different tree heights, using a simple mechanical device, the crown window. The accuracy of the crown window measuring device is evaluated using measurement data from different objects. The device is easy to manufacture and proved to be more useful than other more sophisticated techniques, such as digital photo analysis or laser based instruments in estimating crown radii and their corresponding heights with acceptable accuracy.     

The controlled evolution of a polymer single crystal

We present a method for controlling the initiation and kinetics of polymer crystal growth using dip-pen nanolithography and an atomic force microscope tip coated with poly-dl-lysine hydrobromide. Triangular prisms of the polymer epitaxially grow on freshly cleaved mica substrates, and their in-plane and out-of-plane growth rates can be controlled by raster scanning the coated tip across the substrate. Atomic force microscope images were concomitantly recorded, providing a set of photographic images of the process as it spans the nanometer- to micrometer-length scales as a function of environmental conditions.     

Spatial association between primary Middle East respiratory syndrome coronavirus infection and exposure to dromedary camels in Saudi Arabia

Middle East respiratory syndrome coronavirus (MERS‐CoV) is an emerging zoonotic disease. Exposure to dromedary camels (Camelus dromedaries) has been consistently considered the main source of primary human infection. Although Saudi Arabia reports the highest rate of human MERS‐CoV infection and has one of the largest populations of dromedary camels worldwide, their spatial association has not yet been investigated. Thus, this study aimed to examine the correlation between the spatial distribution of primary MERS‐CoV cases with or without a history of camel exposure reported between 2012 and 2019 and dromedary camels at the provincial level in Saudi Arabia. In most provinces, a high proportion of older men develop infections after exposure to camels. Primary human infections during spring and winter were highest in provinces characterized by seasonal breeding and calving, increased camel mobilization and camel–human interactions. A strong and significant association was found between the total number of dromedary camels and the numbers of primary camel‐exposed and non‐exposed MERS‐CoV cases. Furthermore, spatial correlations between MERS‐CoV cases and camel sex, age and dairy status were significant. Via a cluster analysis, we identified Riyadh, Makkah and Eastern provinces as having the most primary MERS‐CoV cases and the highest number of camels. Transmission of MERS‐CoV from camels to humans occurs in most primary cases, but there is still a high proportion of primary infections with an ambiguous link to camels. The results from this study include significant correlations between primary MERS‐CoV cases and camel populations in all provinces, regardless of camel exposure history. This supports the hypothesis of the role of an asymptomatic human carrier or, less likely, an unknown animal host that has direct contact with both infected camels and humans. In this study, we performed a preliminary risk assessment of prioritization measures to control the transmission of infection from camels to humans.     

Application of Trichoderma harzianum (T22) and Trichoderma atroviride (P1) as plant growth promoters, and their compatibility with copper oxychloride

Trichoderma strains are used in agriculture because they provide to the plants the following benefits: i) are rhizosphere competence and establish stable rhizosphere microbial communities; ii) control plant disease caused by pathogenic and competitive microflora, by using a variety of mechanisms; iii) improve vegetative growth, root development and yield; iv) make nutrients more available to the plant. In this work we have investigated the ability of T. harzianum T22 and T. atroviride P…     

Effect of acetylene and ethylene gases released from encapsulated calcium carbide on growth and yield of wheat and cotton

Calcium carbide (CaC₂) is a rich source of the nitrification inhibitor acetylene (C₂H₂) and plant hormone ethylene (C₂H₄). C₂H₄ formed from biotic reduction of C₂H₂ released from CaC₂ may accumulate in soil at physiologically active concentrations. Laboratory studies were conducted to evaluate the potential of encapsulated CaC₂ for gradually releasing C₂H₂ and its product C₂H₄ in soil. The GC-FID analysis revealed that encapsulated CaC₂ released a copious amount of C₂H₂ (up to 23700 nmol kg⁻¹ soil), which was gradually reduced to C₂H₄ over a period of time via a strictly biotic reaction as no C₂H₄ was detected in CaC₂-amended sterilized soil. Ammonium oxidation was suppressed by the encapsulated CaC₂ indicating that C₂H₂ acted as a nitrification inhibitor. Results of pot trials conducted in the net house indicated that encapsulated CaC₂ applied at 30 mg kg⁻¹ soil significantly increased the number of tillers (up to 45.5%), root weight (up to 14.9%), straw (up to 32.8%) and grain yield (up to 37.3%) of wheat over the fertilizer application alone. In the case of cotton, the number of bolls, root, shoot and seed weight were also significantly increased in response to the application of encapsulated CaC₂. Moreover, application of encapsulated CaC₂ resulted in greater N-use efficiency (NUE) (up to 61.1%) by both wheat and cotton crops than that observed at the same rates of N fertilizer alone. These findings imply that CaC₂ affects plant growth through hormonal action of C₂H₄ as well as improved NUE; however, the latter factor might be a relatively more contributing. It is desirable that CaC₂ is formulated for gradually slow release of C₂H₂ and C₂H₄ in soil air.     

Genetic survey of cystic echinococcosis in farm animals in Oman

Tropical Animal Health and Production - Echinococcus granulosus sensu lato (s.l.) is the causative agent of cystic echinococcosis (CE) in animals and humans with a worldwide distribution affecting...     

Recent advances toward the sustainable management of invasive Xylosandrus ambrosia beetles

We provide an overview of both traditional and innovative control tools for management of three Xylosandrus ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), invasive species with a history of damage in forests, nurseries, orchards and urban areas. Xylosandrus compactus, X. crassiusculus and X. germanus are native to Asia, and currently established in several countries around the globe. Adult females bore galleries into the plant xylem inoculating mutualistic ambrosia fungi that serve as food source for the developing progeny. Tunneling activity results in chewed wood extrusion from entry holes, sap outflow, foliage wilting followed by canopy dieback, and branch and trunk necrosis. Maintaining plant health by reducing physiological stress is the first recommendation for long-term control. Baited traps, ethanol-treated bolts, trap logs and trap trees of selected species can be used to monitor Xylosandrus species. Conventional pest control methods are mostly ineffective against Xylosandrus beetles because of the pests’ broad host range and rapid spread. Due to challenges with conventional control, more innovative control approaches are being tested, such as the optimization of the push–pull strategy based on specific attractant and repellent combinations, or the use of insecticide-treated netting. Biological control based on the release of entomopathogenic and mycoparasitic fungi, as well as the use of antagonistic bacteria, has yielded promising results. However, these technologies still require validation in real field conditions. Overall, we suggest that management efforts should primarily focus on reducing plant stress and potentially be combined with a multi-faceted approach for controlling Xylosandrus damage.

     

Microbial C,N, and P relationships in moisture‐stressed soils of Potohar,Pakistan

In 11 rain‐fed arable soils of the Potohar plateau, Pakistan, the amounts of microbial‐biomass C (C_mic), biomass N (N_mic), and biomass P (P_mic) were analyzed in relation to the element‐specific total storage compartment, i.e., soil C_org, N_t, and P_t. The effects of climatic conditions and soil physico‐chemical properties on these relationships were highlighted with special respect to crop yield levels. Average contents of soil C_org, N_t, and P_t were 3.9, 0.32, and 0.61 mg (g soil)^–1, respectively. Less than 1% of P_t was extractable with 0.5 M NaHCO₃. Mean contents of C_mic, N_mic, and P_mic were 118.4, 12.0, and 3.9 µg (g soil)^–1. Values of C_mic, N_mic, P_mic, soil C_org, and N_t were all highly significantly interrelated. The mean crop yield level was closely connected with all soil organic matter– and microbial biomass–related properties, but showed also some influence by the amount of precipitation from September to June. Also the fraction of NaHCO₃‐extractable P was closely related to soil organic matter, soil microbial biomass, and crop yield level. This reveals the overwhelming importance of biological processes for P turnover in alkaline soils.     

In Vitro Evaluation of Liquid‐stored Buffalo Semen at 5°C Diluted in Soya Lecithin Based Extender (Bioxcell®), Tris‐Citric Egg Yolk,Skim Milk and Egg Yolk‐Citrate Extenders

This study was designed to compare the quality of liquid‐stored buffalo bull spermatozoa in soya lecithin based extender Bioxcell^® (BIOX), milk (MILK), tris‐citric egg yolk (TEY) and egg yolk‐citrate (EYC) extender at 5°C. Semen was collected from five Nili‐Ravi buffalo (Bubalus bubalis) bulls of 6–7 years of age with artificial vagina over a period of 3 weeks (two consecutive ejaculates once in a week). Semen ejaculates having more than 60% motility were pooled, split into four aliquots, diluted (37°C; 10 × 10⁶ motile spermatozoa/ml), cooled from 37 to 5°C in 2 h (0.275°C/min) and stored for 5 days. Sperm motility, viability, plasma membrane integrity (PMI) and normal acrosomal ridge were studied at first, third and fifth day of storage. Higher values of progressive sperm motility (%), sperm viability (%), sperm PMI (%) and normal apical ridge (%) were observed in BIOX, MILK and TEY extenders at first, third and fifth day of storage than EYC extender. Progressive sperm motility, sperm viability and sperm PMI in BIOX^® extender were not different from MILK and TEY extenders at 1st and third day storage period. However, at fifth day of storage, the values for these parameters remained significantly higher (p < 0.05) in BIOX^® compared with MILK, TEY and EYC extenders. At fifth day of storage, the semen quality parameters for Bioxcell^® were comparable to those with MILK and TEY extenders at third day of storage. In conclusion, motility, viability and PMI of buffalo bull spermatozoa remained similar in Bioxcell^®, milk and TEY extender at first and third days of storage at 5°C. Yet, the values for the aforementioned parameters in Bioxcell^® were higher compared with milk, TEY and EYC extender at fifth day of storage at 5°C.