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Choice of selectivity coefficients for cation exchange using principal components analysis and bootstrap anova of coefficients of variation
No full textModellers of the exchange of sodium, potassium, calcium and magnesium in soils have to choose from up to six different equations based on the mass action law paradigm (mainly Gapon, Vanselow, Gaines-Thomas and Kerr) and up to six different binary cation combinations. In this article a methodology to choose the most appropriate equation and binary cation combinations is presented. The combination of six equations with six binary cation combinations resulted in 36 selectivity coefficients. Each one of these was assessed for 133 calcareous illitic soil samples. Six principal components analyses (PCA) were carried out to find out which three binary cation combinations accounted most for the variance of the soil exchange selectivity. Then a bootstrap anova and multiple comparison (MC) procedure with orthogonal contrasts were carried out to compare the coefficients of variation of the selectivity coefficients calculated with each equation. According to the PCA, the three binary cation combinations involving calcium, and expressed with whichever of the equations of Kerr, Vanselow and Gaines-Thomas, accounted most efficiently for the variance of the soil exchange selectivity. According to the bootstrap anova and MC analysis, the Gapon equations, either in analytical concentrations or activities of aqueous cations, provide significantly larger coefficients of variation than the equations of Kerr (either in analytical concentrations or activities of aqueous cations), Vanselow and Gaines-Thomas. The use of the Kerr, Vanselow or Gaines-Thomas equations and the three binary cation combinations involving calcium resulted in the most effective way of modelling the exchange equilibria of sodium, potassium, calcium and magnesium in calcareous illitic soils
Productive and environmental characterization of a semi-extensive fattening system for fattening pigs in drought conditions in Uruguay
Get PDFProductive and environmental characterization of a semi-extensive fattening system for fattening pigs in drought conditions in Uruguay In Uruguay, different pig production systems coexist: confinement systems and pastoral systems. These systems differ in terms of production costs, animal welfare and environmental impacts. On the other hand, droughts caused by the phenomenon "La Nina" can change the normal behavior of pastoral systems. In this article we analyze the dynamics of nutrients and their potential environmental impact of two growing cycles of pigs in an outdoor pastoral system. Animals were housed permanently in an area with a shelter, feeders and drinkers. They also could enter in several grazing areas, although each grazing area was used only during one week. Most of the nutrients coming from animal manure accumulate in the area surrounding the shelter and feeding areas, but the increase of concentrations was lower in the grazing area. A slight increase of nutrients in the grazing plots was found between the access to a grazing area and its closing one week later. After closure, nutrient concentration declined with time. The same tendency was found with ammonia emissions. In the conditions of this study, the reduced rainfall resulted in a low loss of nutrients. We conclude that in the pastoral system, due to the low nutrient concentrations in the grazing area, no large-scale environmental risks can be expected. The permanent area, however, may have environmental risks associated to nutrient deposition. Some design changes could reduce the risk of loss of nutrients from the area of permanent closure of animals
Cover crop evapotranspiration in a northeastern US Concord (Vitis labruscana) vineyard
No full textBackground and Aims: Although cover crops are largely used in vineyards, limited information is available on the amount of water they use. The aim of this study was to quantify cover crop evapotranspiration (ETcc) in the inter-row of a Concord (Vitis labruscana Bailey) vineyard. In addition, the hypothesis that ETcc could be accurately estimated through a relationship with incident solar radiation and reference crop evapotranspiration was tested
Effect of chitosan coatings on physicochemical, sensory and nutritional quality of oranges (Citrus sinensis) cv. Valencia
No full textEffects of chitosan coatings on physicochemical and nutritional quality of clementine mandarins cv. 'Oronules'
No full textA commercial solution of chitosan was applied on mandarins 'Oronules' at different solid content (0.6%, 1.2% and 1.8%). Additionally, one group of mandarins was coated with a polyethylene-shellac commercial wax, and another group remained uncoated (control). Mandarins were stored at 5 degrees C up to 28 days followed by 7 days at 20 degrees C simulating retail conditions. One group of mandarins was stored at 20 degrees C for 9 days simulating direct retail conditions. The commercial wax decreased weight and firmness loss of mandarins compared to uncoated samples, whereas the chitosan coating did not effectively decrease weight loss of mandarins. Chitosan-coated mandarins at the highest solid content retained firmness after cold storage and contained more phenolics than uncoated ones. Although all the coatings restricted gas exchange and modified the internal atmosphere of the mandarins, with a greater effect at higher chitosan concentration, sensory quality was not affected. In general, the internal quality and the health-related properties of mandarins were not negatively affected by coating application. However, there is a need to further improve the water barrier properties of the chitosan coating
Autotetraploid trifoliate orange (Poncirus trifoliata) rootstocks do not impact clementine quality but reduce fruit yields and highly modify rootstock/scion physiology
No full textTwo autotetraploid (4x) trifoliate orange (Poncirus trifoliata (L) Rat.) rootstocks and the corresponding diploid (2 x) rootstocks were compared for their impact on clementine "Commune" (Citrus clementina Hort. ex Tan) production and on rootstock/scion physiology. Cumulative fruit yield, fruit quality (sugars, organic acids, carotenoids, hesperidin) and scion physiology (stem growth, leaf starch, sugars, chlorophyll content, phenolic content and gas exchange parameters) were investigated. The cumulative fruit yield over 11 years was lower in 4x rootstock/clementine associations and correlated with reduced vigor of the clementine scion. Fruit quality criteria were not affected by the ploidy level of the rootstocks, with the exception of hesperidin content, which was higher with 4x than 2x rootstock/clementine associations. Leaf chlorophyll and phenolic contents were higher with 4x than 2x rootstock/clementine associations. In leaves, the rate of photosynthesis and stomatal conductance was much higher with 2x rootstocks; however, the maximum electron transport rate was lower when compared to the 4x rootstocks. Similarly, leaf starch and sugar contents were much higher with 4x than 2x. Taken together, these results demonstrate that the use of 4x rootstocks dramatically changes both tree physiology and fruit yield, without promoting large changes in fruit quality criteria. (C) 2011 Elsevier B.V. All rights reserved
Acta Horticulturae
No full textPeach is the main stone fruit grown in Spain. The area devoted to this crop has increased slightly over the past 15 years, however its production has doubled in this period. Spain ranks fourth in the world production after China, Italy and the USA, producing 25% of the total peach crop in the European Union. Although peach production increases, consumption in Spain has decreasing as occurs in other western countries. The lack of internal fruit quality is the main reason claimed by consumers for declining to buy fresh peaches. In addition to fruit quality, the main limitations of this crop are: poor adaptability of many cultivars from foreign countries to the Spanish environment, the dependency from cultivars bred in other countries, the incidence of pests, diseases and abiotic stresses and the high cost of the crop management. These problems can be overcome, in part, by developing breeding programs based on controlled crosses. The Spanish peach breeding programs have the following main objectives: - Fruit quality: many cultivars, mainly the early cultivars, have a good external quality but they lack internal quality. - Adaptability to the environment and a better harvest calendar. There is an increase of cultivars with low or very low chilling requirements which allows to grow peaches in warm climates and to advance harvest season more than 30 days. The aims are to breed for early cultivars in Andalucia, Murcia, Valencia and Extremadura; late cultivars in Aragon; and to extent the harvest season in Aragon, Cataluna and Extremadura. - Resistance or tolerance to pests and diseases: resistance to aphids and fungal diseases like Sphaerotheca pannosa (powdery mildew), Monillia spp. and Taphrina deformans (leaf curl). - To avoid dependency from the foreign materials, which implies to pay royalties and some times have a worse adaptability
Efectos derivados de la aportación de los restos de poda en las propiedades del suelo y estado nutricional del arbolado en una parcela de cítricos
Get PDFSe ha realizado un estudio experimental durante 9 años (2002-2011) en una parcela de cítricos mandarinos Clemenules, dotada con riego por goteo, localizada en la finca experimental del IVIA, en Moncada (Valencia), con la finalidad de evaluar los efectos generados por la aportacíon de los restos de poda en las propiedades químicas y biológicas del suelo, y en el estado nutricional del arbolado. De los resultados obtenidos se ha constatado que la aportación al suelo de los restos de poda de cítricos después de su trituración con una trituradora mecánica, como acolchado o cubierta, ha generado una
mejora en algunas características del suelo, siendo destacables los aumentos registrados
en el contenido de materia orgánica, actividad biológica (carbono de la biomasa microbiana), fósforo, potasio y magnesio asimilables, y potasio soluble. En cambio, no se ha encontrado ninguna modificación significativa en los niveles de nutrientes en las hojas de los cítricos. Por otra parte, se han obtenido unas diferencias bastantes considerables entre los valores de los parámetros edáficos según el punto de muestreo (en el bulbo húmedo de los goteros versus las calles de la parcela), registrándose diferencias
significativas en las propiedades: pH, materia orgánica, nitrógeno orgánico, relación C/N, fósforo y potasio asimilables, calcio, potasio y sodio solubles, micronutrientes (hierro, cobre, manganeso y cinc) asimilables y aniones solubles
A reference genetic map of C. clementina hort. ex Tan.; citrus evolution inferences from comparative mapping
Get PDFBackground: Most modern citrus cultivars have an interspecific origin. As a foundational step towards deciphering the interspecific genome structures, a reference whole genome sequence was produced by the International Citrus Genome Consortium from a haploid derived from Clementine mandarin. The availability of a saturated genetic map of Clementine was identified as an essential prerequisite to assist the whole genome sequence assembly. Clementine is believed to be a 'Mediterranean' mandarin x sweet orange hybrid, and sweet orange likely arose from interspecific hybridizations between mandarin and pummelo gene pools. The primary goals of the present study were to establish a Clementine reference map using codominant markers, and to perform comparative mapping of pummelo, sweet orange, and Clementine. Results: Five parental genetic maps were established from three segregating populations, which were genotyped with Single Nucleotide Polymorphism (SNP), Simple Sequence Repeats (SSR) and Insertion-Deletion (Indel) markers. An initial medium density reference map (961 markers for 1084.1 cM) of the Clementine was established by combining male and female Clementine segregation data. This Clementine map was compared with two pummelo maps and a sweet orange map. The linear order of markers was highly conserved in the different species. However, significant differences in map size were observed, which suggests a variation in the recombination rates. Skewed segregations were much higher in the male than female Clementine mapping data. The mapping data confirmed that Clementine arose from hybridization between 'Mediterranean' mandarin and sweet orange. The results identified nine recombination break points for the sweet orange gamete that contributed to the Clementine genome. Conclusions: A reference genetic map of citrus, used to facilitate the chromosome assembly of the first citrus reference genome sequence, was established. The high conservation of marker order observed at the interspecific level should allow reasonable inferences of most citrus genome sequences by mapping next-generation sequencing (NGS) data in the reference genome sequence. The genome of the haploid Clementine used to establish the citrus reference genome sequence appears to have been inherited primarily from the 'Mediterranean' mandarin. The high frequency of skewed allelic segregations in the male Clementine data underline the probable extent of deviation from Mendelian segregation for characters controlled by heterozygous loci in male parents
Efficacy and residues of selected insecticides for control of cotton aphid (Aphis gossypii) and mealybug (Planococcus citri) in pomegranates
Get PDFMealybug (Planococcus citri Risso) and aphids (Aphis gossypii Glover and Aphis punicae Passerini) are the most important pests of pomegranate production in Alicante (Spain). Due to the minor crop status of pomegranates, registered pest control chemicals for this crop are scarce. Experimental field efficacy of new conventional insecticides and alternative sprays against these sucking pests was assessed. Experiments to deal with these pests were carried out in randomized block design with three replications during 2009-2010, in two experimental pomegranate orchards in the Southeastern region of Spain. Other management practices and natural enemies of these pests were identified and quantified during the crop period. Results of the experiments suggest that the population of cotton aphid was resistant to Pirimicarb. New generation insecticides (Imidacloprid, Flonicamid, Acetamiprid) were more effective in controlling aphids. Moderately effective control can be achieved with soap, citrus oil and other tolerance exempt products, or some combination of these, but more than two applications may be necessary. Pesticide residue levels in ripening fruit after treatments were analysed