Characterization of root rot disease of kiwifruit in the Black Sea region of Turkey

Forty-two kiwifruit orchards from Rize and Samsun provinces (Black Sea region, Turkey) exhibiting symptoms of root rot disease were examined between 2009 and 2010. Twenty-four fungal isolates recovered from affected roots were included in this study. Morphological characteristics of all isolates were recorded on potato dextrose agar, malt extract agar and Spezieller Nährstoffarmer agar. The effect of temperature on radial colony growth was also evaluated at 5, 10, 15, 20, 25, 30, and 35 °C. Histone H3 gene (HIS) was amplified with primers CYLH3F and CYLH3R and the amplified fragments were sequenced. The HIS phylogeny grouped all the isolates into six well-supported clades which were in agreement with phenotypical characteristics. Isolates were identified as “Cylindrocarpon” pauciseptatum, Cylindrocladiella parva, Ilyonectria liriodendri, I. torresensis, I. robusta and I. europaea, I. liriodendri being the most frequent species. All of them are reported for the first time on kiwifruit in Turkey, with the exception of I. liriodendri. Pathogenicity tests with selected isolates showed that 10 out of 11 isolates tested were able to induce typical root rot disease symptoms, affecting plant development and leading to the death of some plants. This study shows the high diversity of root rot pathogens found in kiwifruit trees in the Black Sea region of Turkey, being the first step towards a better understanding and management of the disease in local conditions.     

Synthesis and characterization of a potential prebiotic trisaccharide from cheese whey permeate and sucrose by Leuconostoc mesenteroides dextransucrase

The production of new bioactive oligosaccharides is currently garnering much attention for their potential use as functional ingredients. This work addresses the enzymatic synthesis and NMR structural characterization of 2-α-D-glucopyranosyl-lactose derived from sucrose:lactose and sucrose:cheese whey permeate mixtures by using a Leuconostoc mesenteroides B-512F dextransucrase. The effect of synthesis conditions, including concentration of substrates, molar ratio of donor/acceptor, enzyme concentration, reaction time, and temperature, on the formation of transfer products is evaluated. Results indicated that cheese whey permeate is a suitable material for the synthesis of 2-α-D-glucopyranosyl-lactose, giving rise to yields around 50% (in weight respect to the initial amount of lactose) under the optimum reaction conditions. According to its structure, this trisaccharide is an excellent candidate for a new prebiotic ingredient, due to the reported high resistance of α-(1→2) linkages to the digestive enzymes in humans and animals, as well as to its potential selective stimulation of beneficial bacteria in the large intestine mainly attributed to the two linked glucose units located at the reducing end that reflects the disaccharide kojibiose (2-α-D-glucopyranosyl-D-glucose). These findings could contribute to broadening the use of important agricultural raw materials, such as sucrose or cheese whey permeates, as renewable substrates for enzymatic synthesis of oligosaccharides of nutritional interest.     

Girdling effects on fruit set and quantum yield efficiency of PSII in two Citrus cultivars

Girdling effects on fruitlet abscission, leaf chlorophyll, chlorophyll a fluorescence and carbohydrate concentration in various flowering and vegetative shoots were studied during natural fruit drop in two Citrus cultivars. Irrespective of shoot type, girdling delayed fruitlet abscission, but only fruitlets borne on leafy shoots had increased final fruit set. Chlorophyll a fluorescence analysis revealed differences in quantum yield efficiency of photosystem II of light adapted leaves (Phi(PSII)) among shoot types and in response to girdling. In young leaves of vegetative shoots, girdling decreased Phi(PSII), whereas Phi(PSII) increased from Day 30 after girdling in young leaves of leafy flowering shoots; however, Phi(PSII) did not change in mature leaves during fruit set in either control or girdled trees. Girdling altered leaf carbohydrate concentrations and the photosynthetic performance of the various shoot types. Our results indicate that, in Citrus, several carbohydrate-based regulatory mechanisms of photosynthesis coexist during carbohydrate accumulation brought about by girdling. It is concluded that the delay in fruitlet abscission and the increase in Phi(PSII )observed in girdled leafy flowering shoots are the mechanisms underlying the enhancement of fruit set after girdling.     

Genetic parameters for nitrogen fractions content in Mexican Brown Swiss cattle milk

Tropical Animal Health and Production - Nitrogen plays an important role in the metabolism of living organisms due to the variety of physiological functions that involve molecules that contain it....     

Influence of an indigenous European alder (Alnus glutinosa (L.) Gaertn) rhizobacterium (Bacillus pumilus) on the growth of alder and its rhizosphere microbial community structure in two soils

Europeanalder seedlings were inoculated with a suspension of the putative plant growthpromoting rhizobacterium (PGPR) Bacillus pumilus (CECT5105), or left non-inoculated (controls) in two different soils, and grownundercontrolled conditions. Soil A showed a thick texture, slightly acidic with ahigh mineral nitrogen content, while soil B showed a thin texture, basic andwith a lower nitrogen content. At each sampling time, over an 8-week period,shoot and root systems of the plants were measured, nodules counted, and shootand root length and surface were determined. In addition, changes in themicrobial rhizosphere structure were evaluated by the phospholipid fatty acid(PLFA) profile extracted directly from the rhizosphere soil. The increasesdetected in shoot surface were significant only in soil A, while the rootsystemwas affected in both soils. In soil A, inoculation with B.pumilus caused a perturbation that subsequently disappeared, whilethe rhizosphere community structure was seriously altered in soil B. Allbiometric parameters were enhanced to a greater extent in soil A, in which theinoculum did not alter the existing rhizosphere communities and nutrientavailability was better.     

Relating visual crown conditions to nutritional status and site quality in monoclonal poplar plantations (Populus × euramericana)

The area covered by plantations of hybrid poplar in Europe is increasing greatly because of the high profitability of these trees. However, the productivity varies widely depending on nutritional status, and it is therefore essential to identify the limiting nutrients. The aims of this study were (a) to identify the main nutrients limiting the growth and vitality of monoclonal poplar (Populus × euramericana) plantations and (b) to develop a means of early detection of nutrition-related problems in growth, based on visual crown conditions (crown transparency, VCT, and visual crown discoloration, VCD). The study was carried out in one of the most suitable areas for this species in Southern Europe. Thirty-two Populus × euramericana (clone I-214) stands displaying different levels of decline were selected for study, and tree growth, nutritional status (soil properties and foliar nutrient concentrations) and crown conditions were assessed. The stands, which were growing in soils with high contents of coarse fragments, displayed low growth rates, poor crown conditions and deficiencies in Fe, B, N, P, K, and to a lesser extent, Zn and Cu. The deficiencies increased with the age of the stand, presumably because of the higher nutrient demand in older trees. Visual crown conditions were related to growth rates and nutritional status. Predictive models were developed to relate crown conditions to the nutritional status identified by analysis of soil properties and foliar concentrations of nutrients.     

Carbon balance for different management practices for fast growing tree species planted on former pastureland in southern Europe: a case study using the CO2Fix model

Although it is known that forestry mitigates carbon emissions to some degree, there is still a need to investigate the extent to which changes in forest management regimes affect the carbon cycle. In a climate-change scenario, forest management schemes must be optimized to maximize product supply and minimize environmental impacts. It is difficult to predict the mitigating effects of different silvicultural regimes because of differences in the growth characteristics of each species, destination of products, and industrial efficiencies. The objective of the present study was to use a modeling approach to evaluate the effects of different management regimes for fast growing species in southern temperate Europe in relation to mitigating climate change. A comprehensive study was carried out considering the C sink effect in biomass, soil and wood products, the substitutive effect of bioenergy, and particular conditions of the forest industry in southern Europe. The mechanistic CO₂Fix model was parameterized for three species used in fast growing plantations in southern Europe: Eucalyptus globulus, Eucalyptus nitens, and Pinus radiata. Data from 120 plots covering the complete age range observed for each species were used to calculate changes in C stocks in aboveground biomass and organic and mineral soil and to validate the parameterized model for these conditions. Additional information about the efficiency of forest industry processes in the region was also considered. A strong bias in soil organic carbon estimation was observed and attributed to overestimations in the decomposition rates of soil compartments. Slight bias was also observed in the carbon biomass estimation when forest-specific yield models were used to simulate afforestation over former pastureland. As regards the model sensitivity, the Yasso model was strongly robust to turnover of leaves, roots, and branches. The chip wood production alternative yielded higher carbon stock in biomass and products, as well as in bioenergy substitution effect, than the sawn wood production alternative. Nevertheless, the sawn wood alternative was the most effective as regards the C stock in the soil. Site index had an important effect for all species, alternatives, and compartments, and mitigating effects increased with site index. Harvesting of clearcutting and thinning slash for bioenergy use led to a slight decrease in the soil carbon equilibrium but significantly increased the mitigation effect through bioenergy use.     

Effects of Habitat Suitability and Landscape Patterns on Tick (Acarina) Metapopulation Processes

Tick density and population dynamics are important factors in the ecological processes involved in pathogen circulation in a habitat. These characteristics of tick populations are closely linked to habitat suitability, which reflects the limiting ecological factors and landscape features affecting tick populations; however, little work has been done on the regional assessment of habitat suitability. In this study, a regional model for the distribution and abundance of the tick Ixodes ricinus in central Spain is developed. An occurrence and an abundance model were constructed; climate and vegetation variables were found to be the main predictors of both occurrence and density in a relatively homogeneous matrix of habitat patches, whereas topographical variables were found to have small contributions and were therefore discarded. The residuals of the abundance model showed good correlation with the isolation of each patch. The predictive power of the abundance model was greatly enhanced by inclusion of the traversability (a measure of the permeability of each patch to the propagules of the metapopulation) and recruitment (an index of the relative importance of each patch to the traffic through the entire habitat network). The removal from the landscape of the patches whose recruitment values were in the top 10% has a critical effect on tick density, an effect not observed when patches are removed at random. These results indicate that permanent tick populations can be sustained only in landscapes containing a minimum network of viable sites. Graph theory and measurements of patch isolation should prove to be important elements in the forecasting of tick abundance and the management of the features underlying the landscape ecology of tick populations and pathogen circulation in the field.