Does the application of silvicultural management models drive the growth and stem quality of sweet chestnut coppices towards sustainability?

New Forests - The coppice is a very flexible cultural system producing several calibers adapting to the demands of the market. Small-caliber roundwood from sweet chestnut (Castanea sativa Mill.)...     

Effect of plant growth regulators on floral differentiation and seed production in Jojoba (Simmondsia chinensis (Link) Schneider)

The effect of foliar application of cytokinin (benzyl-adenine, 150 mg L⁻¹) and gibberellin (GA₄ + GA₇, 150 mg L⁻¹) on growth and flower development of 5-year-old plants of two jojoba clones was studied. The plant growth regulators were applied on October 5, 1999 (spring) and the plants were evaluated 120, 240 and 360 days after application. Shoot length, total number of nodes and number of nodes with branching were statistically different between clones but not between the growth regulator treatments.The total number of flowers on both clones was significantly increased by treatment with benzyl-adenine (BA) and significantly reduced by treatment with gibberellin. The seed yields, evaluated 180 days after application, were not statistically different from the control due to an increase in flower abortion. One clone treated with gibberellin showed a significant decrease in number and weight of seeds, the other did not.Histology of axillary buds revealed that BA application on one clone (4.11.32) enlarged the flower meristem, differentiating multiple flower production.     

Acylglycerol and fatty acid components of pulp,seed, and whole olive fruit oils. Their use to characterize fruit variety by chemometrics

The contents of triacylglycerols and diacylglycerols in three kinds of olive fruit oils (pulp, seed, and whole fruit) were determined. The fatty acid composition and the quality ratios 1,2-diacylglycerols/1,3-diacylglycerols and 1,2-diacylglycerols/total diacylglycerols were also assessed. Seven major Italian olive varieties were considered. Results of univariate statistical analyses indicated that the above analytical parameters (glyceridic ratios excepted) were effective in discriminating between pulp and seed oils. The seed oil fraction did not determine any change in the glyceridic indices and the acylglycerol or fatty acid composition concerning the whole fruit oil (mixture of pulp and seed oil fractions), the weight (%) of seed ( approximately 2%) being by far lower than the weight (%) of pulp ( approximately 85%) (fruit weight basis). Based on the data of triacylglycerol or fatty acid composition, and using appropriate parametric or nonparametric multivariate statistics, the genetic origins (olive variety) of the three fruit oil kinds were characterized.     

Enhanced resistance to bacterial infection byErwinia carotovora subsp.atroseptica in transgenic potato plants expressing the attacin or the cecropin SB-37 genes

Blackleg and soft rot diseases, caused by the bacteriumErwinia carotovora, are among the diseases that cause important losses in culture and storage of potato. In this paper, we introduced bacterial resistance into potato, via genes encoding for proteins with antibacterial activity. For this purpose, potato clones were transformed either with the gene encoding the acidic attacin protein fromHyalophora cecropia, or with the gene encoding the cecropin analog peptide SB37. These clones were evaluated for soft rot and blackleg resistance, after inoculation with the bacterial strainErwinia carotovora subsp.atroseptica T7. Results reported in this paper indicate that a considerable percentage of the potato clones (15–22%) showed increased resistance to bacterial infection, revealed by reduced severity of blackleg or soft rot symptoms. Expression of the transgenes was demonstrated in some of the clones by Northern blot analysis. This is the first report indicating that expression of the gene encoding for an attacin protein and for the cecropin SB-37 peptide in transgenic potato confers increased resistance to bacterial infection.     

Detritus accumulation and decomposition in a coastal lake (Acquatina–southern Italy)

• 1. Knowledge about processes and dynamics underlying organic matter accumulation in transitional waters is crucial for the protection of these ecologically important coastal habitats. This study investigated the relationship between large particle accumulation and decomposition in a coastal lake included in a Site of Community Interest (SCI) using sediment trap and litterbag techniques.
• 2. Two sets of sediment traps were deployed at five sites along the longitudinal axis of the lake. One set was emptied once a month for 12 months, and the other twice a year. The contents of the monthly and the 6‐monthly traps and the superficial sediments were then compared to estimate the organic matter accumulation and loss. To determine the mass loss rate of the three major allochthonous sources of detritus (the reed Phragmites australis, the cordgrass Spartina juncea, and the seagrass Posidonia oceanica), litterbags were placed near the sediment traps at three out of the five sites at the beginning of each 6‐month period and retrieved monthly.
• 3. The amount of annual particulate organic matter (POM) deposition in the traps was 1320.2±58.5 g m^?2 y^?1 and consisted of 25% large particles (CPOM). Allochthonous litter comprised an important fraction of CPOM, and its breakdown rate changed with the plant species, site and season. Loss rate of CPOM accumulated at the lake bottom was significantly related with the mass loss rate of reed and cordgrass litter, but not with that of seagrass.
• 4. Due to slow litter breakdown and tidal landward advection, the lake acted as a sediment trap for allochthonous matter, especially from Posidonia. The important role of marine‐derived litter in organic matter sedimentation suggests addressing conservation strategies of the lake functioning towards the selective control of allochthonous CPOM inputs, in particular at the mouth where the incoming tide brings suspended material and salinity decelerates matter flow to the sea and decomposition. This study supports the hypothesis that sedimentation and decomposition dynamics are important factors for coastal lake evolution, and shows litterbag and sediment trap techniques as simple useful investigation tools in management strategies aiming at conserving transitional waters.

Copyright © 2008 John Wiley & Sons, Ltd.     

Susceptibility of Caligus rogercresseyi collected from the native fish species Eleginops maclovinus (Cuvier) to antiparasitics applied by immersion

A major challenge for Chilean salmon farming is infestation by the ectoparasite Caligus rogercresseyi. In addition, there is evidence that a loss of chemotherapeutic treatment efficacy against important fish pathogens is occurring in salmon farming, including antiparasitic efficacy. Currently, there are known techniques that allow the determination of the susceptibility profile of parasites to antiparasitic treatment. However, there is scarce information about both threshold values and categorization of antiparasitic susceptibility for C. rogercresseyi. Bioassay technique allowed the determination of both mean values and the natural variation of EC50%, which were contrasted with available susceptibility thresholds. Results allowed to determine that parasites from the native fish host, Eleginops maclovinus, are susceptible to azamethiphos, deltamethrin and cypermethrin treatments, showing a high susceptibility profile to antiparasitics.     

Restoration of dead wood in Basque stream channels: effects on brown trout population

Abstract – Streams in the Aiako Harria Natural Park (Basque Country, Spain) have excellent water quality, but are physically impoverished after centuries of snagging. In an attempt to restore channel complexity and ecosystem functioning, especially in‐channel retention of sediments and organic matter, large woody debris (LWD) was introduced into four mountain streams (channel width 3–13 m) following a before/after, control/impact (BACI) design. Logs were introduced by means of hand‐held machinery and located uncabled, mimicking the natural amount and disposition of LWD in streams. Floods disrupted most of the structures at the large stream, but caused little damage to those in the small ones. Only minnow and brown trout inhabit in the area. Before wood addition, trout densities were fairly high in the small streams, low in the large one, where recruitment seemed very poor. In the small tributaries, trout populations showed a strong imbalance towards young fish, adults being only found in the spawning season. Wood addition produced some interesting trends in trout, although statistical significance was low as a result of large environmental variability. Fish densities showed small changes, but biomass increased, especially in the spawning season. Also, there was a trend towards more aged 2⁺ or larger, thus suggesting wood addition improved adult habitat. Although restoring LWD is extremely unusual in Spain, the changes in physical habitat and the trends in fish populations detected in the present project suggest it is worth making more experiments, at least in safe settings where there is no risk of flooding or damaging properties.     

Determination of the Bioavailable Fraction of Cu and Zn in Soils Amended with Biosolids as Determined by Diffusive Gradients in Thin Films (DGT), BCR Sequential Extraction, and Ryegrass Plant

This study assessed the effect of biosolids applied at rates, 0, 30, 45, and 60?Mg?ha^?1 on the chemical associations and bioavailability of Cu and Zn in soils from an important agricultural zone of the Metropolitan Region in Central Chile. Three methods were used to determine the bioavailability of Cu and Zn in soils: ryegrass (Lolium perenne) plants, diffusive gradients in thin films (DGT) technique, and Community Bureau of Reference (BCR) sequential extraction. The DGT effective concentration (C _E) and sequential extract acid soluble fraction of the BCR extraction (most labile fraction of the soils, normally associated with bioavailability) were compared with total metal concentration in ryegrass plants as a means to compare the chemical and biological measures of bioavailability. Total Zn was higher in comparison to Cu for all treatments. Concentrations were within the limits set by the Chilean regulations for land-applied biosolids. Metals in the control soil were primarily found in the residual fraction of soils. Biosolids application generally decreased this fraction, with a subsequent increase observed mainly in the acid soluble fraction. The contents of Cu and Zn in ryegrass plants increased with increasing rates of biosolids. Comparison of the Cu and Zn content in ryegrass plants with C _E, showed a good correlation for Zn. However, the C _E for soil Cu was only related to plant Cu for some of the soils studied. Correlation between Zn in ryegrass plants and the labile fraction of Zn as measured by the sequential extraction was excellent, with correlation coefficients >0.9, while for Cu, correlation coefficients were lower.     

Effect of biosolid application to Mollisol Chilean soils on the bioavailability of heavy metals (Cu,Cr, Ni,and Zn) as assessed by bioassays with sunflower (Helianthus annuus) and DGT measurements

Purpose

This study assessed the effect of biosolid application on the bioavailable fraction of some trace elements (Cu, Cr, Ni, and Zn) using a bioassay with sunflower (Helianthus annuus) and a chemical assay, diffusion gradient in thin films (DGT).

Materials and methods

Five surface soil samples (0–20 cm) were collected from an agricultural zone in Central Chile where biosolids are likely to be applied. Municipal biosolids were mixed with the soil at concentrations of 0, 30, 90, and 200 Mg ha^?1. The experiment to determine the bioavailability of metals in the soil using the bioassay was performed using sunflower. The DGT technique and Community Bureau of Reference (BCR) sequential extraction were used to determine the bioavailable fractions of the metals.

Results and discussion

The application of biosolids increased the phytoavailability of Zn, Ni, and Cr in most of the soils, as indicated by the increasing concentrations in sunflower plants as the biosolid application rate increased. In two of the soils, Codigua and Pelvín, this increase peaked at an application rate of 90 Mg ha^?1. Decreases in the bioavailable fractions of Zn, Ni, and Cr were observed with higher biosolid application rates. The bioavailability of metals was estimated through multiple linear regression models between the metals in the sunflower plants and the different chemical fractions of metals in the soils treated with different biosolid rates, which displayed a positive contribution of the labile (water soluble, carbonate, and exchangeable), oxide, and organic metal forms in the soil, particularly with respect to Ni and Zn at application rates of 30 and 90 Mg ha^?1. The bioavailable fraction of metals was determined in soils using the DGT technique. The effective concentration (C _E) results were compared with those in sunflower plants. The DGT technique could effectively predict the bioavailable fractions of Cr, Ni, and Zn in the Taqueral soil but only that of Zn in the Polpaico soil.

Conclusions

The application of biosolids significantly increased the labile fraction of most of the metals in the studied soils, particularly at the highest biosolid application rate. C _E increased as the concentration of biosolids increased for most of the metals. The effectiveness of the DGT technique for predicting the bioavailability of metals was dependent on the soil type and the metal. However, the C _E for soil Cu was not related to plant Cu for all soils studied.