Effects of nurse shrubs and tree shelters on the survival and growth of two Austrocedrus chilensis seedling types in a forest restoration trial in semiarid Patagonia, Argentina

? Context

Harsh environmental conditions in xeric sites of Andean Patagonia, affect the emergence, survival, and growth of either naturally grown or planted Austrocedrus seedlings.

? Aims

We evaluated the effects of nurse shrubs and tree shelters on the survival and growth of Austrocedrus seedlings as compared to unprotected (control) areas and how differently produced seedling types perform under these treatments.

? Methods

In 2006, two Austrocedrus seedling types (1?+?2?=?S1 and Plug 2?+?1?=?S2) were planted under shrub cover (C1), tree shelter (C2), and control (C3). Soil surface temperature and moisture were measured for each treatment during the first growing season, while seedling survival and height were recorded during 5 years.

? Results

Survival was not affected by cover type the first year, but it was affected by seedling type (S1?>?S2). After an extremely dry second growing season, seedling survival significantly decreased in relation to either cover or seedling type. Five years after plantation, survival was significantly higher for C1 and C2 (40?C60 %) as compared to C3-S2 (18 %). Seedling height was significantly affected by cover, but not by seedling type.

? Conclusions

The use of nurse shrubs and/or tree shelters is useful in Austrocedrus seedling restoration trials. Seedling morphology appears as relevant for survival in semiarid environments.     

Effect of the arbuscular mycorrhizal fungus <Emphasis Type="BoldItalic">Glomus intraradices</Emphasis> on the false root-knot nematode <Emphasis Type="BoldItalic">Nacobbus aberrans</Emphasis> in tomato plants

Information about the interaction between arbuscular mycorrhizal fungi (AMF) and the false root-knot nematode Nacobbus aberrans (Thorne, 1935) Thorne & Allen, 1944 is scarce. The effect of Glomus intraradices Schenk & Smith on tomato (Lycopersicon esculentum L.) cv. Platense inoculated with nematode juveniles from Lisandro Olmos (Argentina) was studied under greenhouse conditions. Six treatments with five replications were performed. After 80 days, nematode reproduction and percentage of AMF colonization in roots were estimated. Some plant growth parameters were also measured. In general, plants with AMF and AMF plus nematodes grew as well as the control without AMF and without nematodes. Furthermore, G. intraradices was beneficial in reducing nematode-induced damage in roots (lower number of galls) as well as in having a suppressive effect on parasite reproduction. This is the first study on the use of G. intraradices as a possible strategy in the control of N. aberrans in tomato.     

Effect of foliar applications of phosphite on post-harvest potato tubers

The utilization of phosphites (Phi) could be considered as another strategy to be included in integrated disease management programmes to reduce the intensive use of fungicides and production costs. The aim of the present work was to analyze whether the beneficial effects of phosphite treatment previously observed in potato plants grown under greenhouse conditions, were reflected after harvest of field grown potatoes, both in disease protection and in yield. In addition, biochemical compounds possibly involved in induced defence responses by Phi, like phytoalexins, pathogenesis related proteins and oxidative stress enzymes were measured. Foliar applications of KPhi to field grown crops resulted in post-harvest tubers with a reduced susceptibility to Phytophthora infestans, Fusarium solani and Erwinia carotovora infections, suggesting that this compound induced a systemic defence response. An increase in phytoalexin content in P. infestans inoculated tubers obtained from Phi-treated plants suggests their participation in the defence response. Chitinase content increased 72 h after wounding or inoculation with P. infestans in tubers from KPhi-treated plants compared to wounded or infected tubers from non-treated plants. Contrary to this, the isoforms of β-1,3-glucanases analyzed did not increase in the tubers of Phi-treated plants. The increment in peroxidase and polyphenol oxidase activities indicated that these enzymes could be part of the Phi defence mechanism. No negative effects were observed in potato yield at harvest, measured as total tuber weight and dry matter, after foliar KPhi treatment. This suggests that the energetic cost involved in the defence response activation would not be detrimental to plant growth.     

Analytical methods assessment for exchangeable cations analysis in soil: MIP OES appraisement

ABSTRACT

Soil monitoring and research often requires a comparison of laboratory data generated by diverse instruments and in different laboratories to demonstrate the reliability and accuracy of the results. The outcomes of this work highlight a performance comparison among different analytical methods for the determination of calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K), in soil. Five soil samples were used for analytical methods comparison, corresponding to an argentine agricultural soil interlaboratory, and four soil samples from the Pampa region of Argentina were used for analytical application of the instrumental methods. The results obtained with flame atomic absorption and emission spectrometry (FAAS-FAES) and microwave-induced plasma optical emission spectrometry (MIP OES) were compared to those obtained by conventional analytical methods as complexometric titration and flame photometry. As there were no significant differences between classical methods with instrumental ones, FAAS-FAES and MIP OES were validated following criteria based on international guidelines. Accuracy, precision, linearity, limits of detection and quantification, sensitivity, analytical sensitivity, and working range were evaluated. The results established the satisfactory performance of FAAS-FAES and MIP OES for exchangeable cations. MIP OES is an efficient alternative to FAAS-FAES, with wide linear dynamic range, which is advantageous concerning to the concentrations in which these exchangeable cations are found in soils, avoiding sample dilutions. The most remarkable advantage of MIP OES is the low running costs as it does not use flammable and toxic gases. Due to its benefits MIP OES could be recommended as the main analytical method for exchangeable cations determination.     

Heavy metal concentrations in some non-vascular plants in an Amazonian rainforest

The presence of acid rain in the remote Amazon rainforest of southwestern Venezuela suggests the possibility of long-range transport of industrial pollutants to that region. Heavy metal concentrations were analyzed in samples of bryophytes and epiphyllous organisms growing on leaves and on bark in this forest. Concentrations of Cd, Pb, Ni, and Cr were higher in leaves with epiphylls than in leaves without epiphylls. All heavy metal concentrations in bryophytes from the Amazon basin site were lower than in bryophytes from temperature zones. The results indicate that long-range transport of air pollutants from industrial centers to the remote Amazon basin is occurring at only extremely low rates. Heavy metal concentrations in bryophytes and epiphylls at this site may still be considered close to present day background levels.     

Land cover change in the Bolivian Amazon and its implications for REDD+ and endemic biodiversity

Tropical deforestation is a major contributor to green house gas emissions in developing countries. Incentive mechanisms, such as reducing emissions from deforestation and forest degradation (REDD), are currently being considered as a possible emissions reduction and offset solution. Although REDD has expanded its scope to include co-benefits such as sustainable management of forests and biodiversity conservation (known as REDD+), current carbon-base methodologies do not specifically target projects for the parallel protection of these co-benefits. This study demonstrates the incorporation of both carbon and biodiversity benefits within REDD+ in the Bolivian Amazon, through the analysis of land cover change and future change scenario modeling to the year 2050. Current protected areas within the Bolivian Amazon were evaluated for REDD+ project potential by identifying concordant patterns of carbon content, species biodiversity and deforestation vulnerability. Biodiversity-based versus carbon-based protection schemes were evaluated and protected areas were prioritized using irreplaceability-vulnerability plots. Deforestation projection scenarios to the year 2050 varied depending on the historical period analyzed, producing low, intermediate and high deforestation scenarios. All scenarios showed increasing deforestation pressure in the northern region of Bolivia along with high levels of biodiversity loss. Expected reductions in the carbon pool ranged from 8 to 48%, for the low and high demand scenarios respectively. Some protected areas presented large numbers of endemic species, high concentrations of carbon and high deforestation vulnerability, demonstrating the potential for win–win REDD+ projects in Bolivia.     

Benzalkonium Chloride Surface Adsorption and Release by Two Montmorillonites and Their Modified Organomontmorillonites

Benzalkonium chloride (BAC) loaded to montmorillonites (Mt) or organomontmorillonites (OMt) generates a functional material that can be incorporated to several systems (polymers, paints, etc) as a controlled release bactericide. Understanding the BAC adsorption sites on these adsorbents is of high importance to clarify their adsorption/desorption characteristics in aqueous media or other solvents. In this work, a thorough study about the adsorption/desorption properties of Mt and OMt with regards to BAC is presented, in order to evaluate further BAC release with the consequent aquatic environment contamination. In this work, the BAC adsorption on two different sites is demonstrated: the interlayer space and the external surface. Depending on BAC concentration in water, sorption of BAC at Mt occurred in two steps. At adsorbed amount <0.5 mmol g^?1, there was an Mt interlayer expansion of 0.49 nm with no change of the external charge. At adsorbed amount >0.5 mmol g^?1, there was a new interlayer expansion attaining 0.75 nm and the external charge shifted to positive value. In the case of OMt, the introduction of BAC produced changes in the interlayer structure and in the external surface charge. BAC desorption was strongly dependent on the type of Mt or OMt and extraction solvent, knowledge of which will allow its safe use in environmental friendly technological applications.     

Serodiagnosis of Babesia gibsoni infection in dogs by an improved enzyme-linked immunosorbent assay with recombinant truncated P50

The surface antigen P50 of Babesia gibsoni is an important candidate for the development of a diagnostic reagent for canine piroplasmosis. In order to establish an effective diagnostic method for practical use, the gene encoding truncated P50 (P50t) lacking a signal peptide and C-terminal hydrophobic regions were cloned and expressed in Escherichia coli as a fusion protein with glutathione S-transferase (GST). More than 90% portion of the GST-P50t was expressed as a soluble form, in contrast with GST-P50f (full-length), which was completely expressed as an insoluble form. This result indicates that removal of the hydrophobic signal peptide and C-terminus had dramatically improved its hydrophilicity. The purified GST-P50t was tested in an enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to B. gibsoni in dogs. The ELISA with GST-P50t clearly differentiated between B. gibsoni-infected dog sera and uninfected dog sera. In addition, the ELISA detected no cross-reactivity with sera from dogs experimentally infected with the closely related parasites, B. canis canis, B. canis vogeli, and B. canis rossi. Field serum samples collected from dogs in Japan and China were examined for the diagnosis of B. gibsoni infection by using the ELISA. 14.5% (9/62), 5.8% (7/120), and 5.4% (2/37) of tested samples were positive for dogs from Okinawa, Yamaguchi, and Osaka prefectures, Japan, respectively. On the other hand, 4.8% (2/41) of tested samples were positive for dogs from Nanjing, China. These results suggest that the GST-P50t could be a reliable reagent for practical use in ELISA for the serodiagnosis of canine piroplasmosis caused by B. gibsoni.     

Detection of equine Babesia spp. gene fragments in Dermacentor nuttalli Olenev 1929 infesting mongolian horses,and their amplification in egg and larval progenies

Babesia equi (EMA-1) and Babesia caballi (BC48) gene fragments were amplified by polymerase chain reaction (PCR), in blood samples, and partially fed-females and egg and larval progenies of Dermacentor nuttalli, collected from horses in Altanbulag, Tuv Province, Mongolia. While Babesia parasite DNA was detected in some horse blood samples during the first PCR, all positive cases in partially fed-female ticks, eggs and larvae were confirmed by nested PCR. Present study reinforces earlier similar findings in unfed D. nuttalli ticks collected from an open space vegetation in Bayanonjuul, Tuv Province in Central Mongolia, pointing to the most likely important role of D. nuttalli in the transmission of equine babesiosis in Mongolia. The detection of parasite DNA in eggs and larval progenies is likewise suggestive of transovarial parasite transmission in this tick species.