Isozyme Variation and Genetic Structure of Populations of Avena barbata from Argentina

Genetic diversity was analysed in 52 Argentinian populations of Avena barbata, a tetraploid grass introduced in America from Spain during the colonization period. Nine isozyme systems were studied and 14 loci identified, five of which were polymorphic. Cluster analysis based on Hedrick’s index revealed a high similarity among populations. The total diversity (P_t) in the 52 populations was 0.144, the mean diversity (P_s) was 0.04, while between population diversity (D_st) was 0.103. The resulting coefficient of differentiation (G_st) was 0.714, indicating that diversity among populations was an important contributor to the total variability. Genetic diversity was structured into multilocus associations; 122 different complexes were found among 3311 individuals, but only two complexes occurred at a high frequency. The distribution pattern of these frequent multilocus genotypes was associated with environmental factors, mainly rainfall and temperature. The comparison of these results with those of previous studies on A. barbata from Spain indicated that Spanish and Argentinian populations are closely similar in allelic composition on a locus-by-locus basis but different in multilocus genotypic composition. We concluded that selection was the main force involved in the reorganization of the Spanish genepool into novel multilocus associations adapted to specific habitats in Argentina.     

Identification of pathovars and races of <Emphasis Type="Italic">Pseudomonas syringae,</Emphasis> the main causal agent of bacterial disease in pea in North-Central Spain,and the search for disease resistance

A total of 298 bacterial isolates were collected from pea cultivars, landraces and breeding lines in North-Central Spain over several years. On the basis of biochemical-physiological characteristics and molecular markers, 225 of the isolates were identified as Pseudomonas syringae, either pv. pisi (110 isolates) or pv. syringae (112), indicating that pv. syringae is as frequent as pv. pisi as causal agent of bacterial diseases in pea. Most strains (222) were pathogenic on pea. Further race analyses of P. syringae pv. pisi strains identified race 4 (59.1% of the isolates of this pathovar), race 2 (20.0%), race 6 (11.8%), race 5 (3.6%) and race 3 (0.9%). Five isolates (4.6%) showed a not-previously described response pattern on tester pea genotypes, which suggests that an additional race 8 could be present in P. syringae pv. pisi. All the isolates of P. syringae pv. syringae were highly pathogenic when inoculated in the tester pea genotypes, and no significant pathogenic differences were observed. Simultaneous infections with P. syringae pv. pisi and pv. syringae in the same fields were observed, suggesting the importance of resistance to both pathovars in future commercial cultivars. The search for resistance among pea genotypes suitable for production in this part of Spain or as breeding material identified the presence of resistance genes for all P. syringae pv. pisi races except for race 6. The pea cultivars Kelvendon Wonder, Cherokee, Isard, Iceberg, Messire and Attika were found suitable sources of resistance to P. syringae pv. syringae.     

A native Zn-solubilising bacterium from mine soil promotes plant growth and facilitates phytoremediation

Journal of Soils and Sediments - An important bottleneck in phytoremediation technologies, which focus on extraction of potentially toxic trace elements, is the low solubility and bioavailability...     

Cultivation of potato – use of plastic mulch and row covers on soil temperature,growth, nutrient status,and yield

Potato is one of the most important crops in the world because of its high nutritional value; however, traditional cultivation in bare soil may render low yields and poor quality. Crop production efficiency can be increased by using plastic mulching and row covers to modify root zone temperature and plant growth, in addition to reduction in pest damage and enhance production in cultivated plants. However, there is little information demonstrating the effect of row covers in combination with plastic mulch on potato. The aim of this study was to assess the change in root zone temperature and its effect on growth, leaf nutrient, and yield of potato using plastic mulch of different colors, in combination with row covers. Seed of cultivar Mondial was planted in May 2012. The study included four plastic films: black, white/black, silver/black, aluminum/black, and a control with bare soil, which were evaluated alone and in combination with row covers removed at 30 days after sowing in a split-plot design. Higher yields were obtained when no row cover (43.2 t ha^?1) and the white/black film (42.2 t ha^?1) were used. Leaf nitrogen, sulfur, and manganese concentration were higher in plants when row cover was used; in contrast, no–row cover plants were higher in Fe and Zn. Mulched plants were higher in Mn concentration than control plants. There was a quadratic relationship between mean soil temperature and total yield (R² = 0.94), and between plant biomass and total yield (R² = 0.98), between leaf area with total yield (R² = 0.98).     

Changes in lipid classes,fatty acids,protein and amino acids during egg development and yolk‐sac larvae stage in brill (Scophthalmus rhombus L.)

Brill (Scophthalmus rhombus L.) is a flatfish considered of special interest for aquaculture diversification, but the high mortality observed during the early larval rearing is the main obstacle to commercial culture. The objective of this study was to contribute to the knowledge of nutrient utilization of early‐hatched larvae, characterizing the changes in lipid and protein contents during embryogenesis and the yolk‐sac larval stage of S. rhombus. Total lipid, lipid classes and fatty acid contents remained constant during embryogenesis and yolk‐sac larval development, except for phosphatidylethanolamine and phosphatidylinositol, which increased in quantity during the yolk‐sac larval stage. On the other hand, total protein (including non‐protein nitrogen) and amino acids decreased their contents in both periods, especially at hatching. The decrease only in the serine, glutamic acid, proline and lysine contents during embryogenesis suggests a selective use of amino acids during this phase. Unlike embryogenesis, amino acids loss during hatching appears to be non‐selective, and almost all amino acids (essential and non‐essential) decreased. Our results suggest that there is higher catabolism of protein vs. lipid during embryogenesis and the yolk‐sac larval stage of S. rhombus.     

Lumber volume modeling of Amazon Brazilian species

Accurate estimates of lumber volume become an important indicator of production and monetary value for a sawmill. However, such estimates are only obtained directly after logging, and no accurate predictions are made for the Amazonian commercial species. In this sense, the objective was to generate equations of lumber volume for commercial species in Amapá (a state in northern Brazil) by adjusting and selecting regression models. The data of 50 logs processed from 10 commercial species were collected, as well as the quantity and volume of sawn products. Sixteen (16) statistical models were adjusted and statistical weights were performed to evaluate the quality of the estimates and to select the best equation by species. In summary, precise estimates of lumber volume can be obtained by the nº16 model for Carapa guianensis, while the models nº13 and nº15 are the most recommended for Dinizia excelsa and Hymenolobium petraeum, respectively. Model 7 presented the best adjustments for Hymenaea courbaril and Vochysia guianensis. Equations using only the log diameter variable suggest less precise estimates. Also, the log volume should be considered as an important predictor variable to obtain the serrated/lumber volume for the different Amazonian commercial species.     

IBR and BVD control: the key to successful herd management

Control of IBR and BVD should be possible in Europe. Effective vaccines and reliable tools for monitoring are available. Systematic approach and strict implementation of control measures are essential. Voluntary or mandatory programs are ongoing on regional or national level in a lot of countries. Successful programs put pressure on surrounding regions/countries to initiate control program as well.