Water deficit and corn productivity during the post-socialist period. Case study: Southern Oltenia drylands,Romania

Water deficit (WD) typically associated with drylands and poor land use currently represent a major limiting factor for agricultural systems in numerous regions of the world. The present study aims to analyze the relationship between water deficit and corn (Zea mays L) crop yields in southern Oltenia drylands. The study includes the post-1990 period, which is representative for Romania in terms of ample climate changes and poor land planning decisions affecting water resources. This analysis targeted the vegetation period of corn (April–September), the reference period covering a 14-year interval, from 1990 to 2003. The entire analysis was based on spatialized WD data (mm), obtained by interpolation methods used on climate data provided by regional weather stations, and agricultural yield data (tons/hectare/year), recorded in 113 administrative territorial units. Both data sets were analyzed in terms of interannual statistical relationships, established in compact climate zones delineated by Thiessen-Voronoi polygons. The results showed a clear statistical relationship between the two variables, with an average dependence of corn yields on water of approximately 65%. The range was from 55 to 78%, depending on region. The results showed an average yield decrease of 16.5 kg/ha/year for each mm rise of the WD, or loss of 1.65 t/ha/year when considering a deficit rise of 100 mm. Therefore, in the context of increasing future WD, urgent action is needed in order to reintroduce irrigation systems.     

Characterization of spaC‐type Erysipelothrix sp. isolates causing systemic disease in ornamental fish

Since 2012, low‐to‐moderate mortality associated with an Erysipelothrix sp. bacterium has been reported in ornamental fish. Histological findings have included facial cellulitis, necrotizing dermatitis and myositis, and disseminated coelomitis with abundant intralesional Gram‐positive bacterial colonies. Sixteen Erysipelothrix sp. isolates identified phenotypically as E. rhusiopathiae were recovered from diseased cyprinid and characid fish. Similar clinical and histological changes were also observed in zebrafish, Danio rerio, challenged by intracoelomic injection. The Erysipelothrix sp. isolates from ornamental fish were compared phenotypically and genetically to E. rhusiopathiae and E. tonsillarum isolates recovered from aquatic and terrestrial animals from multiple facilities. Results demonstrated that isolates from diseased fish were largely clonal and divergent from E. rhusiopathiae and E. tonsillarum isolates from normal fish skin, marine mammals and terrestrial animals. All ornamental fish isolates were PCR positive for spaC, with marked genetic divergence (<92% similarity at gyrB, <60% similarity by rep‐PCR) between the ornamental fish isolates and other Erysipelothrix spp. isolates. This study supports previous work citing the genetic variability of Erysipelothrix spp. spa types and suggests isolates from diseased ornamental fish may represent a genetically distinct species.     

Density and phenology of the invasive mealybug <Emphasis Type="Italic">Delottococcus aberiae</Emphasis> on citrus: implications for integrated pest management

Delottococcus aberiae De Lotto (Hemiptera: Pseudococcidae) is a new invasive citrus pest in Spain. It causes severe fruit distortions and, as a new invasive mealybug, there is a lack of information about its biology. This research aims to examine the seasonal trend of D. aberiae in citrus, using several sampling methods, as a first step to develop an integrated pest management program. Ten citrus orchards from Eastern Spain were periodically sampled during three years using absolute (plant material) and relative (corrugated cardboard band traps and sticky traps) sampling methods. The three sampling methods showed that D. aberiae completes multiple generations per year, two of them being clearly defined and resulting in high populations. D. aberiae peaked between May and June, damaging the developing fruit. Corrugated cardboard band traps were able to detect prepupa and pupa male instars and gravid females, providing a quantitative measurement of D. aberiae density at its first population peak. The use of corrugated cardboard band traps is recommended to monitor population levels and sticky traps to determine male flight periods, representing simple sampling techniques to monitor D. aberiae. These results will improve the sampling protocols and allow for the development of an integrated pest management program.     

Carbon contents and aggregation related to soil physical and biological properties under a land-use sequence in the semiarid region of central Argentina

Land-use change affects vast areas of the semiarid region of central Argentina, where agriculture becomes predominant over mixed farming systems, and large areas of permanent pastures (PAS) are being converted to agricultural land. This land-use change causes loss of soil structure, but very little is known about the effect of changes in aggregate size distribution on soil physical, chemical and biological properties. We decided to use dry sieved aggregates since this technique is commonly used in semiarid regions. The study was carried out at Anguil, La Pampa, Argentina. The soil was a sandy loam Entic Haplustoll with a carbonate-free A-horizon. The PAS site had been under weeping love grass for more than 40 years. Parts of this PAS were turned to cultivation in 1989 (CULT14) and in 2001 (CULT2). Sampling was carried out at 0.6 m intervals to 0.18 m depth. Bulk density (BD), organic carbon (OC), and water holding capacity and infiltration were determined on these samples. Dry aggregate size distribution and OC content of the size fractions were determined on large undisturbed samples. Samples of pooled aggregate size fractions >4, 1–4, and <1 mm, as well as corresponding samples of non fractionated soil were incubated and respiration was measured by CO₂ evolved. The soil of CULT2 had 29% lower contents of large (>4 mm) and 37% higher contents of very small (<1 mm) aggregates than PAS. The intermediate size aggregates were not affected by the short-term effect of tillage. OC loss in CULT2 was 16% regarding PAS. Longer term effects of cultivation were characterized by 30% loss of intermediate size aggregates, 22% increase of bulk density, 74 and 19% decrease in water infiltration and water retention, respectively of CULT14 compared to PAS. A 32% decrease of OC was observed after 14 years of cultivation. Intermediate size aggregates had highest OC contents and no difference between treatments was found, except for a lower value of large aggregates in CULT14. Respiration rates and total CO₂ evolved was related to OC contents of fractions; however, PAS respired more from its small aggregates than expected from their OC content. The results showed that OC turnover and loss of aggregation was very fast in this soil, but soil hydraulic properties were affected in the longer term. Dry aggregates were found to useful for studying soil degradation, and they showed similar trends as those indicated in the literature for water stable aggregates.     

Selective and Apoptotic Action of Ethanol Extract of Annona cherimola Seeds against Human Stomach Gastric Adenocarcinoma Cell Line AGS

Plant Foods for Human Nutrition - Annona cherimola is a tree belonging to the family Annonacea, whose fruit (cherimoya) is very desirable, but its seeds are considered waste. Present in these seeds...     

Comparative study of PCR as a direct assay and ELISA and AGID as indirect assays for the detection of bovine leukaemia virus

The choice of a diagnostic method depends on the characteristics of the herd to be analysed. Two herds with different prevalences of enzootic bovine leukaemia were chosen to study the concordance between agar gel immunodiffusion (AGID), enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) methods. PCR, an increasingly used virological method, was performed with four sets of primers, amplifying different genomic regions (env, pol and tax), from DNA extracted either from peripheral blood monocytes (PBMCs) or milk leucocytes. The highest percentage of positive animals was obtained using PCR performed with DNA extracted from PBMCs using primers which amplified either env or pol, followed by PCR using PBMCs and primers which hybridized with tax, then ELISA using serum and finally AGID. The results of PCR were more consistent with PBMCs than when milk leucocytes were used.