A comparative study of apple and pear tree water consumption measured with two weighing lysimeters

A five-year experiment (2002–2006) was conducted to determine apple (cv ‘Golden Smoothee’) and pear (cv ‘Conference’) crop coefficients (Kc) using two large weighing lysimeters. Daily reference evapotranspiration (ETo) and crop evapotranspiration (ETc) were evaluated. Midday canopy light interception of both crops planted in hedgerows, 4 × 1.6 m, was determined on a weekly basis from bud-break until leaf fall from year 2002 (fourth after planting) to year 2006 of both plantations. Relationships between canopy light interception and calculated Kc (ETc/ETo) were evaluated from bud-break until harvest. There were differences in Kc values between apple and pear trees. When daily Kc values from bud-break until harvest were adjusted to hyperbolic functions each year, adjusted curves for pear trees were very similar regardless of year (maximum Kc around 1.0). In apple trees, the maximum values of Kc increased over time, from 0.49 in 2002 to 1.04 in 2006. Midday light interception in both apple and pear trees increased during the 5 years of experiment from 29.0 to 45.6% in apples and from 27.5 to 41.6% in pears in midsummer. Although there was a significant positive correlation between midday canopy light interception and Kc in apple and pear trees, in different times within a specific year, these relationships were different between crops. While the apple data fitted into the same equation regardless of the year, different equations were needed to fit the pear data in different years. This discrepancy may have been related to differences in the canopy properties between apple and pear trees. Pear canopies had higher porosity than apple canopies and thus improved light penetration. Apple trees were more vigorous and produced taller and denser canopies. Pear Kc values were greatly influenced by the evaporative demands of different years and consequently differences in midday canopy light interception did not adequately reflect the differences in Kc across the two species.     

Gas chromatographic determination of N-nitrosamines in beverages following automatic solid-phase extraction

A semiautomatic method for the determination of seven N-nitrosamines in beverages by gas chromatography with nitrogen-phosphorus detection is proposed. Beverage samples are aspirated into a solid-phase extraction module for preconcentration and cleanup. The influence of the experimental conditions was examined by using various sorbents among which LiChrolut EN was found to provide quantitative elution and the highest preconcentration factors of all. The proposed method is sensitive, with limits of detection between 7 and 33 ng/kg, and precise, with relative standard deviations from 4.3% to 6.0%. The recoveries of N-nitrosamines from beverage samples spiked with 0.5 or 1 microg/kg concentrations of these compounds ranged from 95% to 102%. The method was successfully applied to the determination of residues of the studied N-nitrosamines in beverages including beer, wine, liquor, whisky, cognac, rum, vodka, grape juice, cider, tonic water, and soft drinks. The analytes were only detected in beer samples, positives being confirmed by gas chromatography coupled with impact ionization mass spectrometry.     

Response of Tribolium castaneum (Coleoptera, Tenebrionidae) to Salpichroa origanifolia Withanolides.

Biological effects on Tribolium castaneum larvae were evaluated for three withanolides isolated from Salpichroa origanifolia (Solanaceae), (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-26-hydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide A, 1), (20S,22R,24S,25S,26R)-22,26:24,25-diepoxy-5alpha,6beta,26-trihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide C, 2), and (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-15,26-dihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide G, 3), and for several chemically modified analogues. The compounds were incorporated into the larval diet at concentrations of 500 and 2000 ppm. Salpichrolide C (2) produced a significant delay in the development of neonate larvae to adults at the highest concentration (2000 ppm); development delays and lethal effects were produced by salpichrolides A (1) and G (3) at both concentrations assayed. The size of surviving adults was used as a criterion for assessing feedant deterrent effects; the results suggest that these compounds act as feeding inhibitors. Influence of chemical modifications in development delay was analyzed.     

Whole-tree water balance and indicators for short-term drought stress in non-bearing ‘Barnea’ olives

Drainage-weighing lysimeters allowed monitoring of water balance components of non-bearing olive (Olea europaea cv Barnea) trees over a 3-month period including short-term events of controlled but severe water stress. The objective of the study was to evaluate a variety of soil and plant-based water status and drought stress monitoring methods on the basis of tree-scale evapotranspiration (ET). As the trees entered into and recovered from water stress, meteorological data, actual ET (ET_a), soil water content and changes in leaf turgor pressure were continuously monitored. Additionally, midday measurements of stem water potential, stomatal conductance, canopy temperature, and quantum yield of PSII photochemistry were conducted. Diurnal (dawn to dusk) measurements of all the above were made hourly on days of maximum stress. Shoot elongation rate was measured for periods of stress and recovery. Quantum yield of PSII photochemistry, stomatal conductance, and stem water potential all successfully indicated reductions in whole-tree water consumption beginning at moderate stress levels. These measured parameters fully recovered to the levels of non-stressed trees soon after water application was renewed. Shoot elongation was reduced 25-30% for the 10-day period during and following drought and recovered thereafter to levels of non-stressed trees. Whole-tree ET_a was reduced by as much as 20% even following full recovery of the leaf level parameters, suggesting reduced canopy size and growth due to the stress period. Non-destructive, continuous (turgor pressure) and remotely sensed (canopy temperature) methods showed promising potential for monitoring effects of water stress, in spite of technological and data interpretation challenges requiring further attention.     

Thermal Stability of Selected Natural Red Extracts Used as Food Colorants

The color degradation of aqueous solutions of six natural red pigment extracts (elderberry, red cabbage, hibiscus, red beet, Opuntia fruits and red cochineal) used commercially as food colorants was investigated at temperatures between 50 and 90 °C. Color degradation was studied in respect to both spectral properties and visual color. The remaining absorbance at 535 nm as a function of the incubation time and temperature was used to quantify the degradation process. Red cochineal was the most thermoresistant extract with a remaining absorbance of 95 % after 6 h at 90 °C. Anthocyanin extracts (elderberry, red cabbage, hibiscus) showed remaining absorbance percentages of 63.8, 46.1 and 26.7, respectively. Betacyanin extracts (red beet, Opuntia fruits) were the most thermosensitive maintaining only 12.5 and 1.7 %, respectively, of the initial absorbance at 535 nm. Applying a first-order kinetic model to the degradation processes, reaction rate constants (k) and half-life periods (t _1/2 ) were calculated. The temperature dependence of the degradation rate constant obeyed the Arrhenius relationship, with activation energies (E _a ) ranging between 3.02 and 53.37 kJ?mol^?1. The higher activation energy values indicated greater temperature sensitivity. Changes in visual color attributes corroborated the high thermal stability of the red cochineal extract.     

Detecting hybridization in wild (Coturnix c. coturnix) and domesticated (Coturnix c. japonica) quail populations

Two subspecies of Coturnix coturnix have allopatric distributions in Europe, Maghreb and western Asia (the Common quail C. c. coturnix), and in eastern Asia (the Japanese quail C. c. japonica), except for sympatric breeding areas in the Baikal (Russia) and Kentei (Mongolia) regions, where they could hybridize. Japanese quails have been reproduced in captivity for centuries and domesticated. Massive releasing of Japanese domesticated quails, or hybrids, in west European countries might threaten with hybridization the gene pool of wild quail populations. Here, we used mitochondrial (mtDNA) and nuclear DNA markers (microsatellites), and Bayesian admixture analyses aiming to assess subspecies distinction and identify hybrids in wild and captive-reared quails. A phylogenetic tree identified two major mtDNA clades, corresponding to the two subspecies, and allowed detecting 12 hybrids in wild Common quails sampled in Spain. Additional hybrids were identified in wild quails sampled in Spain, Italy and Senegal using microsatellite markers. Wild quails sampled in Mongolia showed japonica mtDNAs, but their microsatellite genotypes were admixed, suggesting that Common and Japanese quails can hybridize in nature. Some captive-reared stocks of Japanese quails were also admixed. Introgression of domesticated Japanese quail genes in wild Common quail populations might affect the phenotypic expression of functional traits, as body size, feather colours, sexual calls and migratory behaviours. Hence, restocking with captive-reared non-native quails should be banned.     

Study of a germplasm collection of loquat (Eriobotrya japonica Lindl.) by multivariate analysis

Loquat species (Eriobotrya japonica Lindl.) originated in China, later was introduced in Japan. However, introduction in Europe occurred much later, in 18th century, it was introduced as an ornamental tree. Since then, the species was very well adapted to the Mediterranean climate, mainly in South East of Spain, where is located more than 50% of total European crop production. A European Project titled ‘Conservation, evaluation and collection of underutilized fruit species’ supported surveys and collection of plant material from these species in the Mediterranean basin countries. One of these surveys resulted in a germplasm collection of loquat established at IVIA, Valencia, Spain. This collection is being extended with new accessions collected across the world, currently the collection have 123 accessions under study. Germplasm management needs first a characterization of the plant material introduced and second diversity studies into the collection that could point out the variability pattern, to establish groups of accessions with similar traits and the most significant variables. These results allow organizing the information gathered for further uses. In this paper, 62 accessions from the IVIA germplasm collection were studied. Results from 43 variables were gathered and data studied by multivariate analysis. The analysis allowed summarizing the data tables with new variables containing most of the information. These results along with those obtained in the coming years will allow define a nuclear collection (minimum number of accessions that contained all the variability present in the collection).     

Iron,Copper, and Zinc in Some Fish Species of the Atrato River Delta,Colombian Caribbean

The concentrations of iron (Fe), copper (Cu), and zinc (Zn) were evaluated in 96 samples of the following eight fish species: Centropomus undecimalis, Caranx hippos, Scomberomorus brasiliensis, Lutjanus purpureus, Caranx crysos, Megalops atlanticus, Elops saurus, and Epinephelus itajara collected in the Atrato River Delta in the Gulf of Urabá. Three fish were caught from each of the following common fishing grounds: Bahía Candelaria, Bahía Marirrío, Bocas del Roto, and Bocas del Atrato. Fish were captured during a one-year period, with one specimen per species in each climatic period: dry, transient, and wet. The quantification was performed by microwave plasma-atomic emission spectroscopy. The highest levels of Fe and Cu were found in Caranx crysos, and highest level of Zn in Megalops atlanticus. According to the percentage of the daily value per food serving, Caranx crysos and Caranx hippos are good sources of Fe, and Caranx crysos is a good source of Cu.     

A model of meta-population dynamics for North Sea and West of Scotland cod—The dynamic consequences of natal fidelity

It is clear from a variety of data that cod (Gadus morhua) in the North Sea do not constitute a homogeneous population that will rapidly redistribute in response to local variability in exploitation. Hence, local exploitation has the potential to deplete local populations, perhaps to the extent that depensation occurs and recovery is impossible without recolonisation from other areas, with consequent loss of genetic diversity. The oceanographic, biological and behavioural processes which maintain the spatial population structures are only partly understood, and one of the key unknown factors is the extent to which cod exhibit homing migrations to natal spawning areas. Here, we describe a model comprising 10 interlinked demes of cod in European waters, each representing groups of fish with a common natal origin. The spawning locations of fish in each deme are governed by a variety of rules concerning oceanographic dispersal, migration behaviour and straying. We describe numerical experiments with the model and comparisons with observations, which lead us to conclude that active homing is probably not necessary to explain some of the population structures of European cod. Separation of some sub-populations is possible through distance and oceanographic processes affecting the dispersal of eggs and larvae. However, other evidence suggests that homing may be a necessary behaviour to explain the structure of other sub-populations. The consequences for fisheries management of taking into account spatial population structuring are complicated. For example, recovery or recolonisation strategies require consideration not only of mortality rates in the target area for restoration, but also in the source areas for the recruits which may be far removed depending on the oceanography. The model has an inbuilt capability to address issues concerning the effects of climate change, including temperature change, on spatial patterns of recruitment, development and population structure in cod.     

Identification and genetic characterization of an ethylene-dependent polygalacturonase from apricot fruit

During fruit ripening a loss of firmness occurs, which is a key factor limiting postharvest life. In apricot, Prunus armeniaca L., a wide range of fruit firmness at commercial maturity has been observed in different cultivars. Endopolygalacturonase (endoPG) activity has been reported to be associated with differences in firmness in many fruit species, but never in apricot. In this paper, we reported the identification of an apricot cDNA (PaPG) coding for an endoPG-like protein with 393 amino acids. Protein sequence comparison with known polygalacturonases (PGs) revealed that multiple features as conserved domains and functional residues and a predicted signal peptide were present in PaPG. Moreover, a phylogenetic analysis of this and other plant PGs placed PaPG into a clade containing endoPGs expressed in fruit, abscission and dehiscence zones without a propeptide sequence, very close to PRF5 from peach (Prunus persica L. Batsch). PaPG gene expression increased during postharvest storage of the fruit, correlating with fruit softening and ethylene release, and it responded to exogenous ethylene treatments. We localized the PaPG gene in apricot linkage group 4 after genetic mapping based on SNP analysis, in a position apparently syntenic to the PRF5 locus from peach. Results obtained offer genetic evidence supporting the hypothesis that PaPG and PRF5 are orthologous genes, and consequently position PaPG as a gene of interest for studies on fruit softening in apricot, and contribute to the development of molecular tools for breeding apricots with longer shelf life.