Ferulic acid crosslinks in asparagus cell walls in relation to texture

Post-harvest toughening of asparagus spears is associated with a large increase in monomeric and diferulic acids in the cell walls of stem tissues. The purpose of this study has been to investigate the distribution of these phenolic components among cell wall polymers and the role they play in the formation of associated pectic-xylan-phenolic complexes in relation to post-harvest toughening. The phenolic esters are found in all the extractable polysaccharide fractions, particularly the 0.5 M KOH fraction, as well as the insoluble cellulose-rich residue. The storage-related increase occurs in all fractions but is most prominent in the 0.5 M KOH-soluble components. Degradation of 0.5 M KOH subfractions with pure polysaccharide degrading enzymes has confirmed the occurrence of pectic-xylan-phenolic complexes in which ferulic acid and its dehydrodimers are attached to the xylan component but not to the pectic component. Studies on cell separation show that the maturation- and storage-related increase in thermal stability of cell adhesion (and therefore texture) is probably due to an increase in phenolic cross linking of xylans mainly in the parenchyma tissues. This overcomes the thermal lability of the pectic polysaccharides that are responsible for cell adhesion in immature tissues. The storage-induced appearance of some of the diferulic acid moieties in a number of wall polymer fractions supports the hypothesis that the storage affect is a wound-induced response rather than a continuation of maturation-related activity.     

Evaluation of effects of transgenic Bt maize on microarthropods in a European multi-site experiment

The effects of maize expressing the Bacillus thuringiensis Cry1Ab protein (Bt maize) on soil microarthropods were assessed in the field at four European locations (two in Denmark and two in France) that differ in their climatic conditions or soil properties. Each site was considered as a separate experiment, with separate statistical comparison. Effects of farming practices using Bt maize were compared with conventional farming practices using near-isogenic non-Bt maize and also (at some of the sites) other conventional varieties. Furthermore, at one field site (Foulum, Denmark), the effects of Bt crops were studied in both conventional tillage and reduced tillage contexts. At another field site (Askov, Denmark), Bt maize effects were also compared to the effects of the chemical insecticide dimethoate. Moreover, at three of the field sites (all except Narbons, France), the possibility of a localised Bt effect around the rhizosphere compared to the bulk soil was assessed by sampling within and between maize rows. There were some significant negative effects of Bt maize on microarthropods in soils with a high clay content. Significant differences of the same magnitude also occurred between different conventional varieties of maize, but the effect of dimethoate appeared clearly greater than Bt effects. It is thus debatable if the Bt maize effect is an effect of the Bt toxin or just an effect of the maize variety. Based on the results, it can be concluded that the effect of Bt maize on soil microarthropods was small and within the normal variation expected in conventional agricultural systems.     

Behavioral responses of bottlenose dolphins, Tursiops truncatus, to gillnets and acoustic alarms

Along the east coast of the United States, by-catches of bottlenose dolphins, Tursiops truncatus, in gillnet fisheries exceed removal levels set under the US Marine Mammal Protection Act. One measure proposed to reduce this mortality is the use of acoustic alarms, or pingers, which have proven effective in reducing by-catches of other small cetaceans, but have not been tested with bottlenose dolphins. We examined the responses of bottlenose dolphins to a commercial gillnet equipped with functional (active) and non-functional (control) Dukane NetMark® 1000 alarms near Fort Macon, NC. Between 5 April and 10 May 2001 we used a theodolite to track 59 groups of dolphins around the net. Choice of treatment was random each day and the two shore-based observers were unaware of whether alarms were active (13 days) or controls (9 days). There were no significant differences in the number of groups observed (P=0.315; 1−β=0.835) or in the closest observed approach to the net (P=0.307; 1−β=0.828) between treatments. However, dolphins entered a circular buffer approximately 100 m around the net more frequently with control than active alarms (P=0.015). We conclude that some dolphins responded to the alarms by avoiding the net, but caution that the potential efficacy of alarms is confounded by dolphin behavior. Most dolphins were aware of the net, regardless of the status of alarms, and some dolphins fed on fish in the net or discarded by the fishing vessel. We believe that it would be unwise to use pingers in these fisheries because of the limited behavioral responses we observed in our experiment. Furthermore, the responses we observed are likely to diminish or change over time as dolphins habituate or sensitize to these alarms. Further research is required to understand the behavior responsible for entanglement.     

Thermal stability of texture in Chinese water chestnut may be dependent on 8,8'-diferulic acid (aryltetralyn form)

Ferulic acid (FA) cross-links have been implicated in the thermal stability of texture in Chinese water chestnut (CWC) tissues. The aim of the current study has been to investigate this concept further. CWC tissue strips were measured for their mechanical properties before and after extraction in increasing strengths of alkali. The mechanical properties were related to the associated mode of fracture (cell separation or breakage) at the fracture surfaces and the phenolic composition of the cell walls. CWC tissue softened after prolonged extraction in cold alkali due to an increase in the ease of cell separation. Analysis of wall-bound phenolics demonstrated that most FA moieties, including five of the six dehydrodimers, were released before tissue strength was reduced. Loss of strength was, however, coincident with the loss of 8,8'-diferulic acid, aryltetralin (AT) form. It has been suggested that this dehydrodimer may be particularly concentrated at the edge of the cell faces. These results provide further evidence for the involvement of this dehydrodimer in conferring thermal stability of cell-cell adhesion and hence texture in CWC. However, they do not exclude the other diferulates from involvement in cell adhesion.     

The dynamics of lucerne (Medicago sativa L.) yield components in response to defoliation frequency

The productive life of lucerne (Medicago sativa L.) stands depends on the rate of mortality of individual plants. However, self-thinning of plant populations may be compensated for by increases in other yield components, namely shoots/plant and individual shoot mass. Frequent defoliation reduces lucerne yield but it is unclear whether this is caused by an acceleration of plant mortality or changes in these other yield components. To investigate this, crops with contrasting shoot yields were created using constant 28 or 42-day regrowth cycles applied to a ‘Kaituna’ lucerne crop in Canterbury, New Zealand during the 2002/2003 and 2003/2004 growth seasons. Two further treatments switched from 28 to 42 or 42 to 28 days grazing frequency in mid-summer (4th February) of each year. The annual yield of shoot dry matter (DM) ranged from 12 to 23 t/ha for the treatments defoliated consistently each 28 or 42 days, respectively. Plant population was unaffected by treatments and declined exponentially from 130 plants/m² in June 2002 to 60 plants/m² in September 2004. The dynamics of plant and shoot population were associated with the light environment at the base of the canopy. The slope of the size/density compensation (SDC) of plants was −1.67 for the treatment defoliated each 42 days, near the expected self-thinning slope of −1.5 for stands at constant leaf area index (LAI). Self-thinning of shoots resumed after each defoliation when the LAI reached 2.1 and the transmission of photosynthetically active radiation (PAR_t) was 0.20. At this point the proportion of aerial DM in the tallest (dominant) shoots increased non-linearly from 30 to >80%, due to the mortality of intermediary and suppressed shoots. The average maximum shoot population in each rotation was 780 shoots/m² and unaffected by the decline in plant population due to a compensatory increase from 6 to 13 shoots/plant as the stand thinned. A lower asymptote of 43 plants/m² was estimated as the minimum plant population at which yield component compensation would maintain the productive potential of these ‘Kaituna’ stands. Differences in shoot yield were explained (R² = 0.97) by changes in the individual shoot mass (ISM) that were consistently lowered by frequent defoliation treatments. Frequent defoliations reduced crop productivity by limiting the assimilation of biomass into each individual shoot with negligible impact on shoot appearance rate, the number of shoots per plant at an LAI of 2.1 or the rate of plant population decay. Inter-specific competition for light was proposed as the main factor controlling self-thinning of plants and shoots regardless of their individual C:N status.     

Local geographies of globalisation: rural agglomeration in the Chinese countryside

China’s rural enterprises were responsible for 48 per cent of the $US 151 billion in exports and absorbed nearly 20 per cent of total foreign direct investment in 1996. Clearly, the significant and increasing role of rural enterprises in China’s integration with the world economy demands attention. The penetration of global capital into the rural enterprise sector and the desire of such enterprises to benefit from expansion into international markets have important implications at the local level. The impact of international, domestic and local forces on institutional and structural reforms is reflected in particular spatial outcomes in rapidly developing non‐urban regions. Local authorities have responded to external forces in ways which do not conform to the conventional expectations. Evidence from the lower Yangtze (Yangzi) delta reveals how the supposedly universalising pressures of globalisation have been mediated and adapted at the local level, particularly in terms of enterprise location and the proliferation of special zones. Expanding on the desakota hypothesis, the notion of rural agglomeration is introduced to capture the paradox of spatial economic transformation as it was linked to local circumstances, and localised responses to external pressures of globalisation.     

Growth‐Oriented Small Firms and the Nature and Extent of Local Embeddedness: The Case of a Traditional Metalworking Cluster

ABSTRACT Clusters now form a central element in many regional economic development policies. Location within a cluster of related industries is thought to increase a firm's competitive advantage resulting in higher output and productivity growth rates than in similar firms located beyond the cluster. This study focuses on owner‐managers operating small firms within a traditional cluster of metalworking industries and empirically examines the relationship between growth‐orientation and the extent and nature of cluster embeddedness. The results indicate only a limited number of differences in growth‐orientation given variations in levels of cluster embeddedness. Contrary to conventional wisdom, many of the most growth‐oriented entrepreneurs focus their activities outside the cluster, especially in terms of market‐based linkages. However, those firms with more advanced process technologies do tend to show above average within cluster linkages.     

Weighing in on a method to discriminate maize haploid from hybrid seed

The doubled haploid breeding method can produce maize inbred lines faster than traditional methods, but there are challenges associated with it. Sorting haploid from hybrid seed based on visual colour markers is time consuming and can be difficult due to colour inhibitors that obscure pigmentation needed to distinguish between haploid, hybrid and outcrossed seed. In this study, weight was evaluated as a method to sort haploid from hybrid seed. A first experiment utilized two families for analysis in a preliminary study. Eleven haploid and hybrid kernels from both families were weighed for a total of 44 experimental units. A second experiment was carried out using six families, using the same format as the previous, for 132 experimental units. Hybrid seed weighed significantly more than haploid seed in both experiments. However, the interaction between line and kernel type was significant in the second experiment. In conclusion, efficacy of sorting haploid from hybrid kernels based on weight depends on the genotypes involved.     

Agronomic performance and genetic progress of selected historical soybean varieties in the southern USA

This study was conducted to compare recently developed and historical soybean varieties and evaluate genetic gain in yield and other agronomic traits in the southern USA. A total of 45 southern varieties from public breeding programs, which were released from 1928 to 2008, were used in this study. Three experiments were conducted in 2007 and 2008 at Keiser, Stuttgart, and Marianna in Arkansas (USA). Varieties with maturity groups (MG) late IV to early V had a yield gain of 21.7 kg/ha/yr from the 1950s to the 2000s, mid to late MG V had a yield gain of 16.4 kg/ha/yr from the 1940s to the 2000s, and MG VIs had a yield gain of 12.4 kg/ha/yr from the 1920s to the 2000s. Yield increased linearly for all combined experiments by 16.8 kg/ha/yr. Plant height remained steady over time for most experiments. No significant changes were observed in maturity. Lodging scores decreased, protein concentration decreased, and oil concentration increased linearly over time for all combined experiments. Hutcheson, Narrow, R97‐1634, and Young were recommended as parent lines in future soybean breeding efforts.