Yield and nutritional responses to waterlogging of soybean cultivars

Furrow irrigating soybean prior to a large, unexpected rainfall event can reduce nitrogen fixation and crop yield. The objective of this study was to evaluate the tolerance of soybean cultivars to waterlogged alluvial soils. Five cultivars were selected, which showed a range of tolerances to excessive soil water. Flood duration and flood timing experiments were conducted on clay and silt loam soils. Main plots were flooding duration and flood timing and subplots were soybean cultivars. Most cultivars were able to withstand flooding for 48–96 h without crop injury. Cultivars flooded during the V5 growth stage suffered the least amount of yield loss. The greatest yield losses from flooding occurred at the R5 growth stage. Soybean yields from cultivars flooded at R5 were reduced by 20–39% compared to non-flooded checks. Pioneer 94B73 (cv.) had no significant change in yield from flooding for 192 h at any of the three growth stages, compared to non-flooded controls.     

Occurrence of resistance‐breaking strains of Beet necrotic yellow vein virus in sugar beet in northwestern Europe and identification of a new variant of the viral pathogenicity factor P25

Rhizomania, one of the most devastating diseases in sugar beet production, is caused by Beet necrotic yellow vein virus (BNYVV) and transmitted by Polymyxa betae. Previously, disease control was possible by cultivation of sugar beet hybrids carrying a major resistance gene Rz1, which restricts virus accumulation in taproots and suppresses symptom development. Over the last few years, BNYVV strains with four RNA components have arisen, which are able to overcome Rz1‐mediated resistance. All strains described so far possess an A67V amino acid exchange within the RNA3‐encoded P25 pathogenicity factor. In this study, BNYVV was isolated from Rz1 plants, collected in the United Kingdom, the Netherlands and Germany, displaying patches of strong rhizomania symptoms. Sequencing of the coat protein and P25 gene of three isolates showed 100% nucleotide sequence identity and detected AYPR as the P25 tetrad amino acid composition. The ability of this strain to accumulate to higher levels in young plants of Rz1 resistant but not in Rz1 + Rz2 resistant genotypes was initially demonstrated in a greenhouse assay in natural field soil from the Netherlands. This strain was loaded into a virus‐free P. betae population and compared to reference strains. The AYPR strain retained its resistance‐breaking ability in the Rz1 genotypes and displayed replication at a higher rate compared to the Rz1‐resistance‐breaking P type. The strain origin is unclear and it remains speculative whether the occurrence at different geographic locations is the result of independent selection or displacement of infested soil.     

Monophosphoryl lipid A-induced immune enhancement of Brucella abortus salt-extractable protein and lipopolysaccharide vaccines in BALB/c mice.

A study was conducted to determine the effect of monophosphoryl lipid A (MPL) and trehalose dimycolate (TDM) as adjuvants on the protective responses in BALB/c mice vaccinated with Brucella abortus salt-extractable protein (BCSP) or proteinase-K-treated B abortus lipopolysaccharide (PKLPS). Mice were vaccinated with different doses of BCSP or PKLPS given alone or in combination with MPL or TDM. Mice were challenge-exposed 4 weeks later with virulent B abortus strain 2308. Two weeks after challenge exposure, the number of B abortus colony-forming units (CFU) per spleen, spleen weights, and spleen cell interleukin 1 production were measured. Serum IgG and IgM concentrations specific for vaccinal immunogens were measured before and after challenge exposure with B abortus. Spleen weights and mean B abortus CFU per vaccine group were significantly lower in BCSP- and PKLPS-vaccinated mice, compared with those of nonvaccinated control mice. Monophosphoryl lipid A enhanced the suppression of splenic infection when given with the BCSP vaccine, but not when given with the PKLPS vaccine. Trehalose dimycolate had no effect on mean CFU when given with BCSP, but incorporation of TDM resulted in a significant increase in mean CFU when given with PKLPS. Spleen weights in BCSP- or PKLPS-vaccinated mice were not different when these vaccines were combined with MPL or TDM. Because of the wide variation in the results, we could not conclude that vaccination with BCSP or PKLPS alone, or in combination with MPL altered spleen cell interleukin-1 production in B abortus-infected mice.(ABSTRACT TRUNCATED AT 250 WORDS)     

Making ecological science policy-relevant: issues of scale and disciplinary integration

In this paper, we ask why so much ecological scientific research does not have a greater policy impact in the UK. We argue that there are two potentially important and related reasons for this failing. First, much current ecological science is not being conducted at a scale that is readily meaningful to policy-makers. Second, to make much of this research policy-relevant requires collaborative interdisciplinary research between ecologists and social scientists. However, the challenge of undertaking useful interdisciplinary research only re-emphasises the problems of scale: ecologists and social scientists traditionally frame their research questions at different scales and consider different facets of natural resource management, setting different objectives and using different language. We argue that if applied ecological research is to have greater impact in informing environmental policy, much greater attention needs to be given to the scale of the research efforts as well as to the interaction with social scientists. Such an approach requires an adjustment in existing research and funding infrastructures.