Spanish Journal of Agricultural Research
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Short communication: Natural molecules for the control of Paenibacillus larvae, causal agent of American foulbrood in honey bees (Apis mellifera L.)
No full textAim of study: To evaluate the potential bactericidal activity of natural molecules against Paenibacillus larvae. Moreover, we investigated if molecules that exhibit antimicrobial activity were able to inhibit the proteolytic activity of the bacterium.Area of study: Isolates S1 and S2 were from Balcarce, Buenos Aires province, strain S3 from Rio Cuarto, Cordoba province, strain S4 from Concordia, Entre Rios province, strain S5 and S8 from Necochea, Buenos Aires, strain S6 and S7 from Mar del Plata, Buenos Aires, strain S9 from Modena, Italy and strain S10 from Emilia Reggio, Italy.Material and methods: Bacterial isolates identification was carried out by amplification of a specific 16S rRNA gene fragment of P. larvae using primers PL5 and PL4. Screening of the antimicrobial activity of thirteen molecules against four P. larvae isolates was conducted by the agar diffusion technique. The antimicrobial activity of selected molecules was evaluated by broth microdilution method.Main results: Menadione, lauric acid, monoglyceride of lauric acid and naringenin showed antimicrobial activity against ten P. larvae isolates. Menadione and lauric acid showed the strongest activities, with minimum inhibitory concentration mean values ranging 0.78-3.125 µg/mLand 25-50 µg/mL, respectively.Research highlights: Those concentrations are feasible to be applied at field level, and constitute promissory candidates to be evaluated using in vivo larval models
Phylogenetic analysis and spatial distribution of bovine viral diarrhea virus (BVDV) in dairy cattle from Galicia (NW Spain)
No full textAim of study: To examine the frequency and diversity of bovine viral diarrhea viruses infecting dairy cattleArea of study: The study was carried out in Galicia (NW Spain), the main dairy cattle area of SpainMaterial and methods: A total of 157 BVDV isolates (from 140 dairy herds) were typed. Typing was based on a 288-bp sequence from the 5′ untranslated region of viral RNA genome. Subsequently, to investigate whether the presence of herds diagnosed with a particular strain was higher in some areas or during some specific time period, data were tested using a Bernouille approachMain results: Of the 157 isolates, 137 (87.3%) were typed as BVDV-1b, 10 (6.4%%) as 1d, 7 (4.4%) as 1e and 2 (1.3%) as 1f. One isolate was assigned to type 1p. Three of the strains found in the study (the three belonging to type 1b) showed significant spatial clustering.Research highlights: This report indicates that BVDV-1b was the predominant species, although there was an important genetic diversity in the study population. Spatial analysis indicated important drawbacks in the application of biosecurity measures, especially as regards purchase of cattle or after the reintroduction of animals from cattle concentration points
Winter biodisinfestation with Brassica green manure is a promising management strategy for Phytophthora capsici control of protected pepper crops in humid temperate climate regions of northern Spain
No full textPhytophthora capsici causes root and crown rot of protected pepper (Capsicum annuum L.) crops in the Basque Country (northern Spain), a humid temperate climate area. The objective was to determine the effect of winter biofumigation and plastic cover (biodisinfestation) with Sinapis alba L. (cultivar 'Ludique') fresh green manure on the survival of introduced P. capsici inoculum (oospores) in a greenhouse soil. After autumn-winter Brassica cover crop soil incorporation in February, oospores remained at 15 and 30 cm depth for four weeks´ time exposure in two consecutive years, 2009 and 2010. Oospores viability was estimated with a plasmolysis method and infectivity with a potted pepper bioassay. Viability was significantly higher in biodisinfestated oospores than in the non-treated control in both years (81% and 21% relative increase in 2009 and 2010, respectively) and significantly higher at 30 cm depth than at 15 cm in 2009 (24% relative increase). Conversely, biodisinfestation significantly delayed disease incidence progression until the first half of infectivity bioassays in both years compared to the non-treated soils (83% and 75% relative decrease of dead plants in 2009 and 2010 respectively). The low soil temperatures could explain the low oospore survival reduction and suggest that the suppressiveness expressed in the infectivity bioassay was related with an increase of microbial activity in the biodisinfestation treatment. We conclude that winter biodisinfestation with fresh Brassica green manure is a promising management strategy for Phytophthora root rot control of protected peppers crops in regions of humid temperate climate such us northern Spain
Survival analysis of orange tree varieties in Spain
No full textThe fundamental basis of Spanish citriculture is its varietal composition, which contributes to the existence of a marketing calendar that extends to almost the entire year. As time goes by, the supply of varieties is continuously renewed, requiring significant investments by growers. The guarantee of a quality supply to the markets, on one hand, and the optimal result of the investments made, on the other, require that, in managing the sector, the characteristics determining the survival of the varieties be taken into account. The main purpose of this study was therefore to assess the influence of the attributes affecting the longevity of orange plantations from a technical and commercial point of view. The duration analysis technique applied to the different varieties has been used. The main attributes determining the elimination of a variety were the presence of seeds in the fruit and the tendency towards a decrease in surface size. Permanence- or survival-friendly attributes included the calibre (large size of the variety, within its group) and the price received by farmers. Precocity, frost resistance, commercial quality and resistance to fruit fly did not have the expected level of significance
Nickel and copper accumulate at low concentrations in cacao beans cotyledons and do not affect the health of chocolate consumers
No full textAim of study: Nickel (Ni) and Copper (Cu) are essential metals for the growth and development of plants. In view of the above, the aim of this work was to quantify and correlate Ni and Cu concentrations in the leaf and the parts of the fruit [pod husk, pulp, tegument (seed coating) and cotyledons] of clonal cacao genotype PH 16.Area of study: Cacao genotypes were collected from adult plants grown on farms located in three different climatic regions of southern Bahia, Brazil.Material and methods: Plant material was collected in four plots of twenty farms, located under different edaphic and topographic conditions. They were subjected to chemical analysis and later to statistical analyses.Main results: There was high variability of Ni and Cu concentrations in all evaluated plant materials. Leaf, pulp, and tegument were the plant materials that accumulated more Ni. On the other hand, the greatest accumulation of Cu occurred in the tegument and in the pod husk, while in the cotyledons there was little accumulation of these metals. The concentrations of Ni were influenced by the three climatic regions, a fact not observed for Cu, except at the leaf level. There was interdependence between the accumulation of Ni in the leaves and in the different parts of the fruit, a fact not observed for Cu.Research highlights: Since Ni and Cu accumulated in low concentrations in the cacao beans cotyledons, raw material for the manufacture of chocolate and other food products, these metallic elements do not affect the consumers' health
Differential cytokine response of Escherichia coli lipopolysaccharide stimulated peripheral blood mononuclear cells in crossbred cattle, Tharparkar cattle and Murrah buffalo - An in vitro study
No full textMastitis is a complex disease responsible for huge economic losses to the dairy sector. The causal organisms include a wide variety of micro-organisms including several species of bacteria. Escherichia coli has been identified as one of the most common gram-negative bacteria causing clinical mastitis in cattle. The immune system, of different species and/or breeds, tries to combat these pathogens in an inconsistent manner with differential mode and intensity of immune response, eventually producing contradicting outcomes of this disease. Several reports suggest the existence of variability among different animal breeds/species, resulting in a dissimilar outcome of this disease among them. In order to evaluate the variation among different breeds/species, the present study was undertaken to examine the stimulant effect of E. coli lipopolysaccharide (LPS) on peripheral blood mononuclear cells (PBMCs). The PBMCs were harvested from blood samples of crossbred cattle, Tharparkar cattle and Murrah buffaloes. After 6 h of in vitro stimulation, qRT-PCR was employed to measure the relative mRNA expression levels of CCL5, IL-1β, IL-12β, IFN-γ and IL-10 genes in stimulated and unstimulated PBMCs. The selected genes revealed significant differences in the pattern of innate immune response among crossbred cattle, Tharparkar cattle and Murrah buffaloes. The results clearly indicate the presence of variation in the outcome of immune response even when the immunocytes were stimulated with the same dose of the antigen
Soil biosolarization for Verticillium dahliae and Rhizoctonia solani control in artichoke crops in southeastern Spain
No full textThe efficacy of soil biosolarization for the control of Verticillium dahliae and Rhizoctonia solani fungal pathogens was evaluated over two consecutive artichoke crop cycles in southeastern Spain. Soil biosolarization was applied in mid-June for 42 days. The evaluated soil treatments were: fresh sheep manure (FSM); beer bagasse (BB) plus FSM; broccoli crop residues plus FSM; and a control of non-disinfestated and non-amended soil. Different variables were analyzed: i) soil temperature during biosolarization; ii) soil inoculum density of Verticillium before and after biosolarization; iii) infectivity of V. dahliae and R. solani introduced inoculum after biosolarization treatments at 15 and 30 cm soil depth through bioassays; iv) crop disease incidence; and vi) marketable yield. Treatments were randomized in a complete block design with four replicates. Biosolarization treatments reduced levels of both fungal pathogens in both years and had significant lower percentages of affected plants at the end of the crop. All biosolarization treatments significantly improved marketable yield 22-29% to 38-59% compared to the non-disinfestated control in 2015-2016 and 2016-2017 crop cycles respectively. Biosolarization with different organic amendments can be recommended as an effective management strategy for the control of soil-borne fungal diseases in artichoke crops in southeastern Spain, especially in repeated monocultures which are cultivated intensively
Growth promotion and yield enhancement of barley cultivars using ACC deaminase producing Pseudomonas fluorescens strains under salt stress
No full textPlant growth-promoting rhizobacteria containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase enzyme reduce the level of stress, ethylene and stimulate plant growth under various biotic and abiotic stress conditions. The present study aims at characterizing efficient salt-tolerant, ACC deaminase containing Pseudomonas fluorescens strains with plant growth-promoting activity isolated from the rhizosphere of barley plants and evaluating the influence of potent plant growth-promoting rhizobacteria (PGPR) isolates on growth and yield of five barley cultivars under salinity stress. Plant growth and yield in barley cultivars following inoculation with salt-tolerant, ACC deaminase producing PGPR strains under salt stress were quantified. Results indicated that under various levels of salinity (50, 100 and 150 mM NaCl) inoculation with PGPRs had positive impact on growth parameters and yield of barley cultivars including plant height, spike length, weight and number, peduncle length, number of grains per spike, 1000-grain weight and grain yield, comparing to uninoculated control plants under salinity stress. Inoculation of barley cultivars with bacteria ameliorated the negative effects of salinity and resulted in increase in growth and yield. Besides, as the salinity levels increased, growth and yield of barley cultivars decreased; however, cultivars showed different responses to salt stress. This study demonstrates the vital role of rhizobacteria containing ACC deaminase for increasing salt tolerance and consequently improving the growth and yield of barley plants under salinity stress
Quality assessment of composts officially registered as organic fertilisers in Spain
No full textComposting of organic wastes is a management strategy linked to circular economy models through the transformation of these wastes into an organic product, compost, which can be used as fertiliser, soil amendment or growing media. However, the concept of ‘compost quality’ is not enough defined to take a technical decision about which is its best use or application. In the last decade, different guidelines and regulations about organic fertilisers have been developed. For instance, in Spain the Fertilisers Regulation categorises compost under five kinds according to the raw materials used - organic amendment compost (OaC), manure compost (MaC), green compost (GrC), vermicompost (VC), ‘alperujo’ compost (AlC) -, and under three quality levels (A, B or C) depending exclusively on the heavy metals content. This work analyses the national database of all composts (307) marketed in Spain, considering the analytical parameters declared, with the objective of proposing a methodology to define a global quality index. For this assessment, two indicators are employed: a fertility indicator, related to the nutrients content, and a clean indicator, related to the heavy metals content. Results show an average compost formulation 2.5:2.5:2.5 (N:P2O5:K2O). MaC and OaC present the highest fertility indicator, whereas VC the lowest. Regarding the clean indicator, GrC, MaC and VC are cleaner than OaC. In the future, this new quality assessment should be completed by including other indicators related to physical and biological characteristic (e.g. porosity, stability/maturity, phytotoxicity) that could determine the most proper use of compost