MODELING CONSUMER INTENTION TO PURCHASE FRESH PRODUCE

The effect of some fresh‐cut carrot label attributes on consumer purchase intention was evaluated using conjoint analysis. The following three attributes were chosen and manipulated: price (high and low), packaging type (polyethylene bags and expanded polystyrene trays) and production process (organic with certification stamp, organic without certification stamp and no information). A complete factorial design was used, and 12 hypothetical packages of fresh‐cut carrot were developed and evaluated by 96 consumers based on their purchase intention. The consumers were divided into four groups with different opinions. Low price and organic with certification label were the favorite choices of the groups. Only one group preferred expanded polystyrene trays. No interactions were exhibited among the attributes in all groups.     

Isolation and characterization of polymorphic microsatellite markers in the migratory freshwater fish Prochilodus costatus

We isolated six polymorphic microsatellite loci in the migratory freshwater fish Prochilodus costatus, which is an endemic species and important fisheries resource from São Francisco river basin, Brazil. We have evaluated the applicability of these loci to study genetic variation in wild population of this fish. Thus, based on the genotypes of 32–48 individuals, we detected two to 21 alleles per locus, observed and expected heterozygosities ranging from 0.19 to 0.89 and from 0.17 to 0.92, respectively. These polymorphic markers should provide efficient tools to study population genetic structure of this fish.     

Vocalizations and relationships of Brown Creepers Certhia americana: a taxonomic mystery

Two taxa of creepers ( Certhia spp.) occur in Europe, C. familiaris and its sibling species C. brachydactyla. The North American Brown Creeper was considered a close relative of C. brachydactyla by one author, a close relative of or conspecific with C familiaris by others, and more recently as a distinct species, C. americana, by the American Ornithologists' Union. Songs of these three creepers are comprised mostly of social calls which are derived from begging calls. Sequence of syllables (syntax) is very conservative in songs of European population of C. familiaris and C. brachydactyla. In contrast, syntax in songs of western North American C. americana is highly variable; however, syllable morphology and syntax in some populations or individuals within populations is remarkably similar to songs of C. brachydactyla, notably from France and Spain. Two social calls and sleeping behaviour of C. americana are also similar to those of C. brachydactyla. Either C. americana and C. brachydactyla are close relatives or they have characters retained from the ancestor common to all three species whereas those in extant C familiaris have diverged.     

Recovery of Germination from Different Osmotic Conditions by Four Halophytes from Southeastern Spain

Seeds of four halophytes from southeastern Spain (the perennialsHalocnemum strobilaceum,Arthrocnemum macrostachyum and Sarcocorniafruticosa, and the annual Salicornia ramosissima) were exposedto iso-osmotic stress with NaCl, MgCl₂, MgSO₄and Na₂SO₄. Theosmotic potential that enforced dormancy in the majority ofseeds was determined. The percentage of ungerminated seeds thatrecovered when they were transferred to distilled water didnot differ significantly from the percentage germination ofseeds in distilled water controls, irrespective of the saltused to impose the stress. Therefore, the factor responsiblefor the dormancy of seeds seems to be the decrease in osmoticpotential. Such osmotic pretreatments promoted an increase inthe rate of recovery germination which, inArthrocnemum macrostachyumand Sarcocornia fruticosa, doubled their rates of germinationcompared to distilled water controls. The osmotic potentialsof the soils where the four species occur naturally were morenegative than those allowing seeds to germinate after osmoticstress. Copyright 2000 Annals of Botany Company Arthrocnemum macrostachyum, Halocnemum strobilaceum, halophytes, osmotic stimulation, recovery of seed germination, Salicornia ramosissima, Sarcocornia fruticosa.     

Borate promotes the formation of a complex between legume AGP‐extensin and Rhamnogalacturonan II and enhances production of Rhizobium capsular polysaccharide during infection thread development in Pisum sativum symbiotic root nodules

The capacity to bind to biomolecules is considered to be the basis for any physiological role of boron (B). Legume arabinogalactan protein‐extensin (AGPE), a major component of the infection thread matrix of legume nodules is a potential B‐ligand. Therefore, its role in infection threads development was investigated in Pisum sativum grown under B deficiency. Using the AGPE‐specific antibody MAC265, immunochemical analysis revealed that a 175 kDa MAC265 antigen was abundant in +B but much weaker in –B nodule extracts. A B‐dependent complex involving AGPE and rhamnogalacturonan II (RGII) could be co‐purified using anti‐RGII antiserum. Following fractionation of –B nodules, MAC265 antigens were mostly associated with the bacterial pellet. Immunogold staining confirmed that AGPE was closely associated with the surface of rhizobia in the lumen of threads in ?B nodules whereas in +B nodules, AGPE was separated from the bacterial surface by a sheath of capsular polysaccharide. Interestingly, colonies of rhizobia grown in free‐living culture without B developed low capsule production. Therefore, we propose that B could be important for apical growth of infection threads by strengthening thread wall through a B‐dependent AGPE‐RGII interaction and by promoting bacterial advance through a B‐dependent production of a stable rhizobial capsule that prevents AGPE attachment.     

Plankton response to weakening of the Iberian coastal upwelling

Coastal upwelling regions, which are affected by equatorward‐wind variability, are among the most productive areas of the oceans. It has been suggested that global warming will lead to a general strengthening of coastal upwelling, with important ecological implications and an impact on fisheries. However, in the case of the Iberian upwelling, the long‐term analysis of climatological variables described here reveals a weakening in coastal upwelling. This is linked to a decrease of zonal sea level pressure gradient, and correlated with an observed increase of sea surface temperature and North Atlantic Oscillation. Weakening of coastal upwelling has led to quantifiable modifications of the ecosystem. In outer shelf waters a drop in new production over the last 40 years is likely related to the reduction of sardine landings at local harbors. On the other hand, in inner shelf and Ria waters, the observed weakening of upwelling has slowed down the residual circulation that introduces nutrients to the euphotic layer, and has increased the stability of the water column. The drop in nutrient levels has been compensated by an increase of organic matter remineralization. The phytoplankton community has responded to those environmental trends with an increase in the percentage of dinoflagellates and Pseudonitzschia spp. and a reduction in total diatoms. The former favors the proliferation of harmful algal blooms and reduces the permitted harvesting period for the mussel aquaculture industry. The demise of the sardine fishery and the potential threat to the mussel culture could have serious socio‐economic consequences for the region.     

Nest-site selection by Great Bustards Otis tarda suggests a trade-off between concealment and visibility

Great Bustards Otis tarda have expanded their habitat range from historical occupancy of natural steppes to arable farmland, where the species initially benefited from favourable feeding conditions. More recently, the species has suffered severe declines due partly to agricultural intensification. Nest losses and juvenile mortality are amongst the factors most seriously affecting survival probabilities of many populations of this endangered species, suggesting that management of nesting habitats would bring conservation benefits. We studied nest-site selection in a Great Bustard population of central Spain by radiotracking 42 females for periods of between 1 and 4 years. Females selected nest-sites in fallows or cereal fields, in areas of low patch-type diversity, far from human infrastructure, and with good horizontal visibility. These results suggest that females look for shelter, but also need to have good visibility while incubating, and they support the hypothesis that nest selection is a trade-off between concealment and visibility. We interpret both preferences as adaptations to reduce predation pressure, one of the main causes of nest failure in this species. Nests were placed on slopes significantly orientated to the southeast, which suggests that females also seek sites protected from the cold north-westerly winds that are prevalent in the study area. To reduce nest destruction, harvesting should be delayed as long as possible and habitat conservation measures should not be restricted to lek sites but also include nesting areas, which are frequently located far from leks.     

Strong growth limitation of a floating plant (Lemna gibba) by the submerged macrophyte (Elodea nuttallii) under laboratory conditions

1. The asymmetric competition for light and nutrients between floating and submerged aquatic plants is thought to be key in explaining why dominance by either of these groups can be stable and difficult to change. 2. Although the shading effect of floating plants on submerged plants has been well documented, the impact of submerged plants on floating plants has been poorly explored hitherto. 3. Here, we used laboratory experiments to examine how submerged plant (Elodea nuttallii) alter nutrient conditions in the water column and how this affects the growth of floating plants (Lemna gibba). 4. We demonstrate that, at higher nutrient concentrations, Lemna is increasingly likely to outcompete Elodea. 5. Under low nutrient concentrations (0.1–2 mg N L^?1) Elodea can strongly reduce the growth of Lemna. Growth of floating plants virtually stopped in some of the experiments with Elodea. 6. Extremely reduced tissue N, Mn, chlorophyll and elongated roots indicated that the growth inhibition of Lemna by Elodea was predominantly caused by the latter’s impact on the nutrient conditions for floating plants. 7. These results strengthen the hypothesis that submerged plants can prevent colonization of a lake by floating plants.