Soil Classification and Carbon Storage in Cacao Agroforestry Farming Systems of Bahia,Brazil

Information concerning the classification of soils and their properties under cacao agroforestry systems of the Atlantic rain forest biome region in the Southeast of Bahia, Brazil is largely unknown. Soil and climatic conditions in this region are favorable for high soil carbon storage. This study is aimed to classify soils under cacao agroforestry and further, to quantify carbon stocks in these soil profiles. Soil classification was performed, and the amount of C stored was estimated, based on the thickness of the soil horizons, their bulk density, and total organic carbon stored. In the sites studied under cacao, four general classes of soils were identified: Ultisols, Oxisols, Alfisols, and Inceptisols. Carbon stocks in these soil profiles showed wide variation, ranging from 719.24 to 2089.93 Mg ha^?1. Carbon stocks in soil surface and subsurface layers in different agroforestry systems with cacao (cacao cabruca, cacao?×?rubber tree, and cacao?×?erythrina) were comparable; however, total storage of organic C in these soils was higher than expected, compared to values reported for the International Soil Reference and Information Center (ISRIC), based on the FAO-UNESCO database, and were also higher than estimated regional soil data.     

Detection of Helicobacter and Campylobacter spp. from the aquatic environment of marine mammals

The mechanism by which Helicobacter species are transmitted remains unclear. To examine the possible role of environmental transmission in marine mammals, we sought the presence of Helicobacter spp. and non-Helicobacter bacteria within the order Campylobacterales in water from the aquatic environment of marine mammals, and in fish otoliths regurgitated by dolphins. Water was collected from six pools, two inhabited by dolphins and four inhabited by seals. Regurgitated otoliths were collected from the bottom of dolphins' pools. Samples were evaluated by culture, PCR and DNA sequence analysis. Sequences from dolphins' water and from regurgitated otoliths clustered with 99.8-100% homology with sequences from gastric fluids, dental plaque and saliva from dolphins living in those pools, and with 99.5% homology with H. cetorum. Sequences from seals' water clustered with 99.5% homology with a sequence amplified from a Northern sea lion (AY203900). Control PCR on source water for the pools and from otoliths dissected from feeder fish were negative. The findings of Helicobacter spp. DNA in the aquatic environment suggests that contaminated water from regurgitated fish otoliths and perhaps other tissues may play a role in Helicobacter transmission among marine mammals.     

The control of floating macrophytes by grass carp in net cages: experiments in two tropical hydroelectric reservoirs

The efficiency of grass carp (Ctenopharyngodon idella Val.) for biological control of floating aquatic macrophytes in net cages was assessed in two eutrophic tropical hydroelectric reservoirs through experiments using three macrophyte species (Eichhornia crassipes, Pistia stratiotes and Salvinia auriculata). A total of twenty experiments were performed in these reservoirs with a duration period between 21 and 30 days, during distinct seasons of the year. Sets of experiments were conducted using the three macrophyte species simultaneously in both reservoirs, and additional experiments were performed in one reservoir involving the separate use of each species. All macrophytes demonstrated significant growth in the absence of fish with total per day biomass increase rate ranging from 0.06 to 17.00%. The presence of grass carp significantly reduced macrophyte biomass in both reservoirs independent of fish size, stocking rate and available cage space. In all seasons, grass carp grazing pressure was higher for S. auriculata and lower for P. stratiotes. The results show that grass carp in net cages was able to use aquatic macrophytes as the only food source, controlling massive plant growth (especially S. auriculata and E. crassipes). Fish cages, already implemented in several reservoirs in Brazil, are easily manageable units at relatively low cost. Thus, biocontrol of macrophytes using caged grass carp is proposed as an effective low‐budget ecotechnological tool to control consumable plants while avoiding the removal of desirable aquatic vegetation and the resultant impact on local fauna.     

Gas exchanges and chlorophyll fluorescence of young coffee plants submitted to water and nitrogen stresses

Abstract

This research aims to evaluate the impact of nitrogen deprivation and water stress on gas exchange and chlorophyll fluorescence in young plants of five cultivars of Arabic coffee. A factorial experiment 5 (cultivars) × 3 (treatments: control without stress, water stress of ?1.5?MPa and stress of N – 0.0?mmol L^?1 N) was carried out in a complete randomized block design with three replicates. Before being submitted to the treatments, the plants were grown in a greenhouse for 240?days, and then transferred to a growth chamber under controlled conditions. Subsequently, after the experimental period of 96?h we measured photosynthetic rate (A), stomatal conductance to water vapor (g_s), transpiratory rate (E), internal and external carbon ratio (Ci/Ca), water use efficiency (A/E), electron transport rate (ETR), actual quantum yield of PS II electron transport (φFSII), and maximum photochemical efficiency of PS II (Fv/Fm). Water stress reduced A, g_s, E, A/E, ETR, φFSII, and Fv/Fm. The nitrogen deficiency reduced ETR, φFSII, and Fv/Fm. Under short-term water stress Catuaí Vermelho maintain the A values due to better stomatal control, reduced water lost by transpiration (E) and better water use efficiency A/E, while Mundo Novo and Acauã show lower damage to Fv/Fm. Short-term nitrogen stress has low impact on A of young plants of Coffea arabica cultivars with adequate N-nutrition.     

Cytogenomic characterization of Colletotrichum kahawae,the causal agent of coffee berry disease,reveals diversity in minichromosome profiles and genome size expansion

Colletotrichum kahawae is an emerging fungal pathogen, which has recently undergone a speciation process from a generalistic ‘C. gloeosporioides species complex' background by acquiring the unique capacity to infect green coffee berries, thus causing coffee berry disease. This is a severe and widespread disease in Africa and an imminent threat to Arabica coffee cultivation in Asia and America, if the pathogen enters those continents. Genetic diversity within C. kahawae is low but notorious differences in pathogen aggressiveness have been described. This work characterized two cytogenomic traits (genome size and minichromosome profiles) of a collection of C. kahawae isolates, representing the breadth of its genetic diversity and distinct aggressiveness classes, along with closely related taxa. The results obtained constitute the first flow cytometry‐based genome size estimation in the genus Colletotrichum and show a c. 8 Mb genome size expansion between C. kahawae (79·5 Mb on average) and its closest relatives (71·3 Mb), corroborating evidence indicating that C. kahawae (i.e. the coffee berry disease pathogens) should remain as a distinct species. Results have also shown the presence of two to five minichromosomes in C. kahawae, suggesting a positive relationship between the number of minichromosomes and the level of aggressiveness of the different isolates analysed, while no correlation could be established between aggressiveness and whole genome size. Overall, these results may be the basis for the identification of pathogenicity/aggressiveness‐related factors in such minichromosomes, and may provide clues to the characterization of specific markers for aggressiveness classes.     

Soybean [<Emphasis Type="Italic">Glycine max</Emphasis> (L.) Merrill] rhizobial diversity in Brazilian oxisols under various soil,cropping, and inoculation managements

In this study, soybean nodules were collected from 12 sites in the State of Mato Grosso, in the Brazilian Cerrados, where both exotic soybean [Glycine max (L.) Merrill] and bradyrhizobial strains have been introduced from 1 to 18 years before. All soils were originally devoid of rhizobia capable of effectively nodulating soybean and varied in terms of chemical and physical properties, inoculation procedures, and cropping systems. Rhizobial genetic diversity was assessed on 240 isolates by rep-PCR fingerprinting with BOX primer, and indices of diversity (abundance-based coverage estimator and traditional and modified Shannon indices) were applied to the profiles obtained. The genetic diversity was much greater than expected, as after the introduction of a maximum of four strains, up to 13 profiles were identified, some sharing many similar bands with the inoculant strains, but others quite distinct from the putative parental genotypes. The increase in the number of rep-PCR profiles could be attributed to genetic variability due to the stressful tropical environmental conditions, but also might indicate that indigenous rhizobia become capable of nodulating the host legume. After the third year of cropping with the host legume, inoculation did not affect rhizobial diversity. A high content of clay decreased diversity in comparison with that seen in a sandy soil, probably due to reduced aeration. Diversity was higher under the no-tillage system when compared to the conventional tillage management, highlighting the importance of maintaining crop residues in tropical soils. Understanding the ecology of exotic rhizobia after being introduced into new cropping areas represents a first step towards the establishment of better strategies of inoculation, which in turn may result in sustainability and higher plant yields.     

Microsatellite characterization of grapevine (Vitis vinifera L.) genetic diversity in Asturias (Northern Spain)

The genetic heritage of the Asturian grapevine (Vitis vinifera L.) has been declining over the past century due to the phylloxera attack and the further abandonment of this culture. In addition, efforts in recent years to restore the Asturian vineyard with the pulling-up of old vineyards and replanting with cultivars endorsed by Cangas Quality Wine regulations are contributing even more to this genetic erosion. The aim of this study was the evaluation and identification of the phytogenetic resources of the Asturian grapevine. A total of 293 accessions were collected in old vineyards and analyzed through nine microsatellite markers. Forty-two different genotypes were obtained, including six profiles with allelic variations. Only 27 cultivars were identified when compared with national and international databases; some of them had not been found in this region before. Homonymies and synonymies have also been detected. These results provide an overview of the status of current grapevine phytogenetic resources in Asturias. Despite the substantial genetic erosion that the Asturian vineyard has suffered, a higher variability than expected has been detected. The finding of new grapevine genotypes is a fact of great importance. The genetic grapevine resources are being drastically reduced all over the world, so this new genetic material has to be included in germplasm banks for its conservation and further agronomical and enological evaluation.     

Effect of supplementation of dietary fibre concentrates on biochemical parameters,stress response,immune response and skin mucus of jundiá (Rhamdia quelen)

The aim of this study was to assess the effects of different dietary fibre concentrates (DFC: Mucilage = MG; pectin = PN or β‐glucan+mannan = βg+M), on biochemical parameters, stress and immune response and skin mucus of jundiá (Rhamdia quelen). The fish (7.16 ± 0.06 g) were fed with Control diet (0 g/kg of DFC); diet supplemented with 5 g/kg of commercial prebiotic (CP 5) or diets supplemented with 5 or 10 g/kg of MG; PN or βg+M. After 8 weeks of the feeding trials, biochemical parameters (cholesterol, glucose, albumin and total protein), cortisol, immunoglobulin IgM and mucoproteins of skin mucus were assessed. Results demonstrated that supplementation with PN increased cholesterol levels (p<.05). After application of the stressor, most fish, except those in the PN and 10 g/kg MG groups, showed significant increases (p<.05) in cholesterol, glucose and albumin levels. The jundiás showed no difference in cortisol levels after application of the stressor (p>.05). IgM levels were significantly high in fish supplemented with DFC (p<.05). However, the concentration of mucoproteins in skin mucus was not influenced in the different treatments (p>.05). The results showed that supplementation with DFC promoted beneficial effects on the metabolism of jundiá.