Acclimation of cuttings from different willow genotypes to flooding depth level

Climate change will increase the frequency of extreme rain events, causing more flooding episodes. Willows are usually planted in marginal lands like flood prone areas. For willow plantations developed from rootless cuttings, the establishment phase is crucial, because the cuttings are still developing a shoot and root system and have a higher vulnerability to stress. A flooding episode during this early period may have a negative effect upon plants. We analyzed the responses to flooding of eight willow genotypes, representing important species from the economic and ecological point of view (Salix alba, S. matsudana, S. amygdaloides and S. matsudana × S. nigra hybrids). The treatments started when the plants were 2 months old and lasted for 3 weeks. They were identified as: Control (watered to field capacity); F10 (plants submerged 10 cm above soil surface) and F50 (plants submerged 50 cm above soil surface). The F50 treatment showed a greater growth reduction than the F10 treatment in most clones, either measured in height, diameter or total biomass. Both flooding treatments reduced significantly the root-to-shoot ratio compared to control plants. The F50 treatment increased the leaf nitrogen content and specific leaf area in all genotypes. Both treatments changed plant and leaf traits in different ways according to the depth of the floodwater. These changes may have lasting effects on growth recovery in the post-flooding period. Willow clones with a fast initial growth will be the best option to minimize growth reduction in areas prone to experience flooding episodes.     

An economic analysis of the impact of subclinical (mild) necrotic enteritis in broiler chickens

Costs to broiler producers associated with subclinical (mild) necrotic enteritis (SNE) were estimated using published information on impacts on body weight and feed conversion rate (FCR) associated with SNE and costs and revenues associated with broiler production. Estimates were expressed in U.S. dollars from the perspective of poultry producers. SNE was estimated to result in a 12% reduction in body weight and a 10.9% increase in FCR compared with healthy birds. For the purposes of this analysis, we considered scenarios involving hypothetical flocks of 20,000 birds raised to final body weights ranging from 4.63 to 7.94 lb. The incidence of SNE was assumed to occur at 20% based on the literature. For flocks raised for the length of time required to reach these target weights, SNE resulted in a loss to producers ranging from US$878.19 to US$1480.52 per flock. When feed costs required to obtain SNE flocks having a total live body weight equal to equivalent healthy flocks at market age were calculated, the increased cost to producers ranged from US$370.49 to US$739.38 per flock. SNE has the potential to cause a significant negative economic impact in broiler flocks. Strategies to reduce the incidence of SNE may help to increase the profitability of broiler production.     

Enhanced molecular identification of Botrytis spp. from New Zealand onions

Botrytis spp. associated with neck rot disease were isolated from New Zealand onions. The fungi were identified using molecular sequences of the ribosomal internal transcribed spacer (ITS) and intergenic spacer (IGS) regions, and the glyceraldehyde-3-phosphate dehydrogenase (G3PDH) gene. Analyses of the sequences showed that the majority of the isolates gathered in 2005–07 were B. aclada. A new high resolution melting analysis (HRMA) assay was developed that allowed fast and simple discrimination between B. aclada and other Botrytis spp. causing onion neck rot in New Zealand. To further verify these results, Botrytis isolates from New Zealand onions, stored in the International Collection of Microorganisms from Plants (ICMP), were also examined. Only a single isolate from the ICMP collection was B. aclada while two isolates were B. byssoidea, one B. squamosa and another closely related to Botryotinia porri. Identification of the remaining Botrytis isolates was more difficult; while IGS and ITS sequences indicated a close relationship to B. allii or B. byssoidea, a previously unreported intron insertion was observed at the 3′ end of the ribosomal small subunit gene in these isolates. No evidence of heterogeneity was observed in the G3PDH gene sequences, as might have been expected of the allodiploid B. allii, but the G3PDH sequence ruled out B. byssoidea as the identity of these isolates.     

Enhanced Dechlorination of Carbon Tetrachloride by Immobilized Fulvic Acids on Alumina Particles

Fulvic acids (FA) were immobilized on alumina particles in order to evaluate their catalytic effect as solid-phase redox mediator (RM) during the reductive dechlorination of carbon tetrachloride (CT) by anaerobic sludge. FA were extracted from three different soil samples and two commercial composts. Electron carrying capacity (ECC) was determined in all FA samples in order to select the appropriate source of redox-mediating compounds for CT dechlorination. TiO₂, Al(OH)₃, and γ-Al₂O₃ particles were tested as immobilizing materials for the extracted FA. FA extracted from a temperate pine forest soil showed the highest ECC (291.72 μmol g⁻¹). The highest adsorption capacity of FA, measured as total organic carbon (TOC), was achieved by alumina (γ-Al₂O₃) particles (12 mg TOC-FA g⁻¹). Results suggest that the transfer of electrons rather than their microbial generation through glucose fermentation was the rate-limiting factor during dechlorination of CT. Immobilized FA increase up to 10.4-fold the rate of CT dechlorination as compared with the control lacking FA. Immobilization of FA on alumina particles was very stable, and spectrophotometric screening did not detect any detachment of FA during dechlorination of CT, thus confirming that the enhanced dechlorination achieved could exclusively be linked to the redox-mediating capacity of immobilized FA. The present study constitutes the first demonstration that immobilized FA on alumina particles could serve as a solid-phase RM in dechlorination reactions.     

Corpus luteum vascularization during the maternal recognition of pregnancy in llamas (Lama glama)

The aim of this study was to characterize corpus luteum vascularization and its association with plasma progesterone concentration in early stages of pregnancy, when maternal recognition of pregnancy is expected to occur. In all animals, both plasma progesterone concentration and corpus luteum vascularization increased from Day 6 to Day 8 post-mating and afterwards in non-pregnant llamas they started to decrease to reach basal levels around Days 12 to 14 post-mating, while in pregnant animals, both variables remained elevated until the end of the study. A lineal positive relationship between corpus luteum vascularization and plasma progesterone concentration was observed in pregnant (r² = .46, p < .0001) and non-pregnant llamas (r² = .66, p < .0001). Pregnant animals showed higher plasma progesterone concentration and corpus luteum vascularization than the non-pregnant ones from Day 12 post-mating until the end of the study (p ˂ .05 and p ˂ .01, respectively). These results suggest that maternal recognition of pregnancy should occur before Day 12 post-mating in order to expand luteal lifespan, maintaining corpus luteum vascularization and progesterone production. Also, the assessment of CL vascularization area could be a useful and non-invasive method for early pregnancy diagnosis due to its association with plasma progesterone concentration.     

Growth versus storage: responses of Mediterranean oak seedlings to changes in nutrient and water availabilities

We compare dry mass (DM) and storage of starch (St) and nitrogen (N) in seedlings of three Mediterranean oaks, two evergreens (Quercus coccifera L. and Q. ilex L. subsp. ballota (Desf.) Samp) and one deciduous (Q. faginea Lam.), across different scenarios of nutrient and water availabilities. Three fertilization (5, 50 and 200 mg of N per plant and growing period) and watering (28–39, 55–71 and 70–85 g H₂O 100 g _soil ^?1 gravimetric soil water) treatments were applied to current-year seedlings between May and October 2002 in two independent experiments. The three species showed a similar response to fertilization, storing nitrogen instead of increasing biomass, in agreement with adaptations to nutrient-poor habitats. However, they differed in their responses to water, reflecting the different water requirements in the field: Q. coccifera, from arid zones, showed no response to water regarding DM and St; Q. faginea, from humid zones, required higher water availability to simultaneously increase growth and storage; while Q. ilex, spanning over most of the water availability range, exhibited a balanced increase of both functions when water increased moderately. In the two evergreen species, N concentration increased with water supply, whereas the reverse occurred in Q. faginea. The latter species favoured growth over storage at moderate water supply (according to its more competitive strategy), although it was the species which accumulated more St and N at the end of the experiments (autumn).