Growth analysis of broccoli in relation to fertilizer nitrogen application

Summary

Six field experiments with different planting dates over three years in the South of Norway were used to analyse biomass production of broccoli. N was applied at rates of 0, 120, and 240 kg ha^–1. Mineralized N levels in soil before planting differed among the experiments. Crop biomass, leaf area index (LAI), and accumulated intercepted photosynthetically active radiation (PAR) increased with enhanced N rate. So did also radiation use efficiency (RUE), but not significantly from 120 to 240 kg ha^–1. Thus, crop biomass increased to the highest N rate rather by more intercepted radiation than by enhanced RUE. RUE reached saturation level when the sum of applied N and Nmin in soil before planting was about 200 kg ha^–1. There was a strong effect of N application on early plantings, when low temperature and possibly oversaturation of light were the most likely reasons for low LAI, RUE, and RGR at low or no N application. The plant N concentration decreased with increasing biomass over time. Of two alternative relationships of critical N concentration (Nc) suggested by Greenwood et al., the linear one, which gave the higher estimates, fitted better. Both equations were evaluated on the correspondence between a relative N concentration N/Nc = 1 and maximum relative values for: biomass, LAI, accumulated intercepted PAR, and RUE. However, a curvilinear function for Nc might produce a higher correlation over the whole range of plant N concentrations. RUE and accumulated intercepted PAR approached a saturation level at a lower relative N concentration than did biomass and LAI, suggesting that N was more limiting for biomass production than for PAR interception and RUE at N rates below the highest application rate. Incident radiation was fully intercepted at a low LAI, resulting in a low RUE.     

Is the ballan wrasse (Labrus bergylta) two species? Genetic analysis reveals within‐species divergence associated with plain and spotted morphotype frequencies

The ballan wrasse (Labrus bergylta) is a marine fish belonging to the family Labridae characterized by 2 main morphotypes that occur in sympatry: spotty and plain. Previous studies have revealed differences in their life‐history traits, such as growth and maturation; however, the genetic relationship between forms is presently unknown. Using 20 recently developed microsatellite markers, we conducted a genetic analysis of 41 and 48 spotty and plain ballan wrasse collected in Galicia (northwest Spain). The 2 morphotypes displayed highly significant genetic differences to each other (F_ST = 0.018, P < 0.0001). A similar degree of genetic differentiation (F_ST = 0.025, P < 0.0001) was shown using the STRUCTURE clustering approach with no priors at K = 2. In this case, the frequency of spotty and plain morphotypes was significantly different (χ² = 9.46, P = 0.002). It is concluded that there is significant genetic heterogeneity within this species, which appears to be highly associated with the spotty and plain forms, but not completely explained by them. Given the previously demonstrated biological differences between morphotypes, and the present genetic analyses, we speculate about the convenience of a taxonomic re‐evaluation of this species.     

Effect of landscape and population variables on immune response in experimentally introduced bush-cricket populations

Despite the growing interest in relationships between ecological variables and individual immune function, few empirical data have been available from wild populations. In this study, I assayed the immune response from 370 wild-caught bush-crickets, Metrioptera roeseli, from 20 experimentally introduced populations, by measuring individual encapsulation responses to a surgically implanted nylon monofilament. Bush-crickets descended from populations introduced into larger habitat patches showed a greater immune response when compared to individuals from smaller habitat-area introductions. Also, there was a significant positive correlation between immune response and the amount of linear elements at the introduction site. However, there was a lack of effect of population variables (i.e., propagule size and rate of population growth) on immune response. These results suggest that large-scale environmental parameters, such as patch size and connectivity, can be important for an individual’s physiological health and its ability to defend against disease-causing agents. Such effects are likely to compound the negative impacts associated with isolation of sub-populations and habitat fragmentation.     

Causes for improvement in nutritive value of broiler chicken diets with whole wheat instead of ground wheat

1. Two experiments were conducted with broiler chicks to compare nutritive values of ground and whole wheat diets containing titanium oxide as indigestible marker. 2. In Experiment 1, a wheat and soy isolate based cold-pelleted diet, in which all the wheat was ground in a hammer mill to pass through a 3 mm sieve, was compared with a diet in which about half (375 g/kg) of the ground wheat was taken out of the diet and supplied as whole wheat mixed into the diet after pelleting. 3. In Experiment 2, a diet based on ground wheat and soy isolate which was pelleted after preconditioning (final temperature 81 degrees C) was compared with a diet in which 500 g of the ground wheat was replaced by whole wheat mixed into the diet before pelleting. 4. In Experiment 1, replacement of ground wheat with whole wheat increased apparent metabolisable energy (AME) content and starch digestibility measured at ileal as well as faecal level, while weight gain and feed conversion efficiency (FCE) were not affected. Jejunal chyme showed increased amylase activity and bile salt concentration. 5. In Experiment 2, replacement of ground wheat with whole wheat increased dry matter content as well as bile content of gizzard, and stimulated an increase in gizzard as well as pancreas weight. Jejunal amylase and bile concentrations were not significantly affected and neither were growth, FCE or AME. 6. Results from this experiment indicate that the improved feed value sometimes observed with whole wheat may be associated with modulation of digestive processes resulting in increased pancreas and liver secretions.     

Response to soy: T-cell-like reactivity in the intestine of Atlantic salmon, Salmo salar L

T-cell-mediated hypersensitivity could be central in soybean meal (SBM)-induced intestinal changes in salmon. However, tools for immunohistochemical detection of T cells have been lacking in teleosts, including Atlantic salmon. Application of a specific histochemical protocol allowed demonstration of T-cell-like reactivities in formalin-fixed, paraffin-embedded tissues using an antibody reacting to a conserved region of human CD3epsilon (Dako A0452). Characteristic staining was observed in cells of the thymus as well as distal intestine, skin, gills and spleen. These cells were negative for immunoglobulin M (IgM). Intestinal intraepithelial leucocytes were CD3epsilon positive. During the SBM-induced enteropathy, the mixed inflammatory infiltrate in the lamina propria of the distal intestine included many lymphocytes with a T-cell-like reactivity. Real-time polymerase chain reaction revealed significantly increased expression of a complex polypeptide (CD3pp), CD4 and CD8beta (P < 0.05) in the distal intestine of SBM-fed fish compared to fish meal-fed reference fish. Increased reactivity for extracellular IgM in the lamina propria and a positive material between the epithelial cells at the tips of the folds was observed, possibly due to leakage of IgM through an abrogated epithelial barrier. In conclusion, a T-cell-like response appears to be involved in this example of a food-sensitive enteropathy.     

Use of 16S rRNA gene sequencing analysis to characterize culturable intestinal bacteria in Atlantic salmon (Salmo salar) fed diets with cellulose or non-starch polysaccharides from soy

Duplicate groups of Atlantic salmon (Salmo salar L.), kept in seawater, were fed fish meal‐based cold‐pelleted diets. Diets with non‐starch polysaccharides (NSP), either cellulose, purified soybean NSP or extruded purified soybean NSP at a dietary level of 100 g kg^?1, were compared with a diet without supplemental NSP and a diet with soybean meal in a 28‐day feeding trial. Isolation and characterizations were limited to culturable bacteria and population levels of aerobic and facultative aerobic heterotrophic autochthonous (adherent) and allochthonous (transient) bacteria present in the mid and distal intestines of Atlantic salmon fed the five different diets estimated using traditional bacteriological techniques. The presence of an autochthonous microbiota was demonstrated using transmission electron microscopy. No significant effects of diet composition were observed on total population levels of culturable bacteria present in the digestive tract, but the study showed that the composition of the gut microbiota (autochthonous or allochthonous) was sensitive to dietary changes. A total of 752 culturable isolates from the intestines were characterized by biochemical and physiological properties. Of these, 188 isolates were further characterized by partial sequencing the 16S rRNA genes. Among these, 146 isolates belonged to 31 phylotypes that were >94% identical to previously described species. However, 42 isolates showed similarity <94% to species available at the National Center of Biotechnology Information. Several of the phylotypes identified in the present study have not been reported previously in the gastrointestinal (GI) tract of fish, including the Gram‐negative bacteria Gelidibacter salicanalis, Pseudoalteromonas elyakovii, Psychrobacter aquimaris, Psychrobacter cibarius, Psychrobacter fozii, Psychrobacter maritimus, Psychrobacter okhotskensis and Psychrobacter psychrophilus. Among the Gram‐positive bacteria identified were Arthrobacter bergeri, Arthrobacter psychrolactophilus, Arthrobacter rhombi, Bacillus pumilus, Bacillus subtilis, Exiguobacterium spp., Microbacterium oxydans, Planococcus maritimus, Sporosarcina ginsengisoli and several bacteria that have been described as unculturable previously. In addition, we identified Carnobacterium inhibens, a lactic acid bacterium that is not frequently isolated from the GI tract of fish. Psychrobacter cibarius was the dominant bacterial species and was isolated from the digestive tract of all fish investigated.     

Product quality deficiencies in the prefabrication industry for single-family houses

In the industry for the prefabrication of single-family houses, previous research had indicated that individual companies have problems in securing the product quality of incoming softwood timber. This implies that they need to carry out a quality inspection and adjust the softwood timber when it arrives at their facility in order to fit their production. Opinions within the industry concerning product quality deficiencies differ with regard to the handling procedures and the percentage of perceived deficiencies. However, there are prefabricators of single-family houses that need to find additional areas for use for their purchased softwood timber, and spend several working hours on softwood timber to meet the quality criteria agreed upon. A previous study by Eliasson and Gustafsson puts forward a number of proposals regarding the quality deficiencies of softwood timber in this context. The present work transforms some of these proposals into hypotheses and aims at describing and understanding what affects the perception of product quality deficiencies. Questionnaires were used to collect data. The paper concludes that the purchase volume is indicated to be related to the volume portion of the deficiency in the product quality and that the level of information- and communication-technology support in production (i.e. the degree of automation) is indicated to be related to the inspection activity point. An extension of the proposed hypotheses concludes that the inspection activity point on arrival and/or on delivery into production also affects how companies do perceive product quality deficiencies. Research regarding what affects product quality deficiencies is lacking in recognizing and knowing what is aligned with the perception of product quality deficiencies; the individual companies will have an opportunity to affect and manage their appearance and thereby enhance the use of softwood timber.     

Recent changes in the deposition of heavy metals in northern Europe

Carpet-forming bryophytes (mosses) have been used extensively since the late 1960's in assessing regional and temporal variability of atmospheric heavy-metal deposition. A large-scale decrease in heavy-metal deposition occurred during the 1970's in Sweden, probably also in other parts of northern Europe. The decrease was closely related to known changes in atmospheric emissions.     

Mercury in forest canopy throughfall water and its relation to atmospheric deposition

A seasonal variation of both particle and gaseous Hg concentrations in the atmosphere is present in south-western Sweden. An average gaseous Hg level of 3.7 ng m⁻³ is found in winter, compared to 2.8 ng m⁻³ in summer. A weak decreasing south-north gradient for gaseous Hg in air over the Nordic countries is also present, with yearly average values from 3.2 to 2.8 ng m⁻³. A gradient for particulate Hg is less clear. An air parcel trajectory sector classification of gaseous Hg levels in air, and to some extent the particulate associated Hg, clearly demonstrates the increased concentrations in the southern sectors, especially in south-western Sweden where the gaseous Hg increase is about I ng m⁻³. These observations are consistent with an influence from the European continent. The average concentrations of Hg in precipitation at the various stations show a pronounced decreasing south-north gradient. A major portion of the total Hg present in precipitation is associated with particles. For the southern stations, a strong correlation between Hg and sulfate, or pH, is present suggesting a connection between Hg in precipitation and anthropogenic activities.