ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Laser-light backscattering imaging for early decay detection in citrus fruit using both a statistical and a physical model
No full textThe early detection of decay caused by fungi in citrus fruit is a primary concern in the post-harvest phase, the automation of this task still being a challenge. This work reports new progress in the automatic detection of early symptoms of decay in citrus fruit after infection with the pathogen Penicillium digitatum using laser-light backscattering imaging. Backscattering images of sound and decaying parts of the surface of oranges cv. ‘Valencia late’ were obtained using laser diode modules emitting at five wavelengths in the visible and near-infrared regions. The images of backscattered light captured by a camera had radial symmetry with respect to the incident point of the laser beam, these being reduced to a one-dimensional profile through radial averaging. Two models were used to characterise backscattering profiles: a statistical model using the Gaussian–Lorentzian cross product (GL) distribution function with five parameters and a physical approach calculating the absorption, , and reduced scattering, , coefficients from Farrell’s diffusion theory. Models described radial profiles accurately, with slightly better curve-fitting results (R2 ⩾ 0.996) for the GL model compared to Farrell’s model (R2 ⩾ 0.982), both indicating significant differences in the parameters between sound and decaying orange skin at the five wavelengths. For dimensionality reduction purposes, feature selection methods were employed to select the most relevant backscattering profile parameters for the detection of early decay lesions. The feature vectors obtained were used to discriminate between sound and decaying skin using a supervised classifier based on linear discriminant analysis. The best classification results were achieved using a reduced set of GL parameters, yielding a maximum overall classification accuracy of 93.4%, with a percentage of well-classified sound and decaying samples of 92.5% and 94.3%, respectively. Results also pointed out application limits of Farrell’s diffusion theory at 532 nm laser wavelength, for which high absorption of pigments occurred
One-step multiplex quantitative RT-PCR for the simultaneous detection of viroids and phytoplasmas of pome fruit trees
No full textA one-step multiplex real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) based on TaqMan chemistry was developed for the simultaneous detection of Pear blister canker viroid and Apple scar skin viroid along with universal detection of phytoplasmas, in pome trees. Total nucleic acids (TNAs) extraction was performed according to a modified CTAB protocol. Primers and TaqMan MGB probes for specific detection of the two viroids were designed in this study, whereas for phytoplasma detection published universal primers and probe were used, with the difference that the later was modified to carry a MGB quencher. The pathogens were detected simultaneously in 10-fold serial dilutions of TNAs from infected plant material into TNAs of healthy plant up to dilutions 10(-5) for viroids and 10(-4) for phytoplasmas. The multiplex real-time assay was at least 10 times more sensitive than conventional protocols for viroid and phytoplasma detection. Simultaneous detection of the three targets was achieved in composite samples at least up to a ratio of 1:100 triple-infected to healthy tissue, demonstrating that the developed assay has the potential to be used for rapid and massive screening of viroids and phytoplasmas of pome fruit trees in the frame of certification schemes and surveys. (C) 2014 Elsevier B.V. All rights reserved
A novel grapevine badnavirus is associated with the Roditis leaf discoloration disease
No full textRoditis leaf discoloration (RLD), a graft-transmissible disease of grapevine, was first reported in Greece in the 1980s. Even though various native grapevine viruses were identified in the affected vines, the etiology of the disease remained unknown. In the present study, we used an NGS platform for sequencing siRNAs from a twenty-year old Roditis vine showing typical RLD symptoms. Analysis of the NGS data revealed the presence of various known grapevine viruses and viroids as well as a hitherto uncharacterized DNA virus. The circular genome of the new virus was fully reassembled. It is 6988 nts long and includes 4 open reading frames (ORFs). ORF1, ORF2 and ORF4 code for proteins with unknown functions while ORF3 encodes a polyprotein with motifs related to the replication, encapsidation and movement of the virus. Phylogenetic analysis classified the novel virus within the genus Badnavirus, with closest relationship to Fig badnavirus 1. Further studies showed that the new badnavirus is closely related with the RLD disease and the provisional name grapevine Roditis leaf discoloration-associated virus (GRLDaV) is proposed. Our findings extend the number of DNA viruses identified in grapevine, further drawing attention to the potential importance of this virus group on grapevine pathology
El cultivo del caqui
Get PDFEn este libro se escribe del caqui en toda su amplitud, los mejores investigadores en las diferentes especialidades nos explican los resultados de la investigación y experiencias en fertirrigación, pies y variedades, sanidad vegetal, poda y postcosecha; acompañado y documentado de una amplia bibliografía de los investigadores de los principales países productores del mundo: China, Japón e Israel, e Italia, más que por su producción, por su continua y avanzada investigación. Este libro, fruto del trabajo de las diferentes líneas de investigación del producto, coordinada por el magnífico equipo de investigadores del IVIA, pone a disposición de la producción, postcosecha y comercialización todos los avances conocidos a nivel nacional e internacional
La calidad de los frutos cítricos de producción ecológica
Get PDFEl valor nutricional de los frutos cítricos es una característica diferencial para valorar los alimentos obtenidos de producción agroecológica e incide de manera directa en la salud. En este trabajo se evalúa la calidad intrínseca y nutricional de dos variedades de cítricos, Navelina y Clemenules, en función del sistema productivo (ecológico y convencional) y de la parte del fruto (zumo o fracción comestible de fruta fresca). Los sistemas agroecológicos producen frutos cítricos altamente competitivos por su calibre, diferenciándose positivamente algunos atributos organolépticos, como el índice de color. La fracción de zumo y pulpa es superior en los cítricos de procedencia agroecológica, y sus jugos presentan mayor fracción en sólidos solubles y por tanto un mayor equilibrio en la madurez. Los niveles en vitamina C son superiores en los frutos de producción ecológica, con mayor incidencia para Navelina. La densidad nutritiva es mayor en los cítricos ecológicos y la repercusión en el gasto alimentario menor
El cultivo del caqui
No full textEn los climas semi-áridos de las zonas productoras de caqui en España (Valencia y Andalucía, fundamentalmente) la pluviometría es frecuentemente inferior a 500 mm (500 L/m2 de superficie de suelo). Bajo estas condiciones climáticas, el manejo del riego es sin duda alguna la práctica de cultivo que más puede influir sobre la producción total y el tamaño y calidad de los frutos en recolección. El riego es además una práctica compleja dado que, además de aspectos agronómicos, influyen factores relacionados con las estructuras de las redes de riego y con la tecnología empleada para suministrar el agua al cultivo. Hoy en día, con la extensión del riego localizado por goteo, es posible aplicar con bastante exactitud la cantidad de agua que un cultivo necesita en cada momento, la clave en este punto es disponer de información de cuáles deben ser las dosis de riego adecuadas
Acta Horticulturae
No full textTetranychus urticae Koch (Acari: Tetranychidae) populations in citrus can be regulated through the management of the cover crop. A mono-specific cover of the grass Festuca arundinacea Schreber (Poaceae) enhanced the diversity and abundance of Phytoseiidae mites compared with a multifloral cover. This increase resulted in a better control of T. urticae. Pollen availability and quality could be behind this result. Whereas multifloral cover offers a long-term source of a wide variety of pollen, F. arundinacea offers one single type of pollen in spring only. As a consequence, the generalist pollen feeder Euseius stipulatus (Athias-Henriot), which is a superior intra-guild predator, is highly favored in multifloral covers. Therefore, poor quality pollen may prevent pollen feeders from reaching high numbers and indirectly benefit T. urticae control by specialist phytoseiids
Non-targeted metabolite profiling of citrus juices as a tool for variety discrimination and metabolite flow analysis
Get PDFBackground: Genetic diversity of citrus includes intrageneric hybrids, cultivars arising from cross-pollination and/or somatic mutations with particular biochemical compounds such as sugar, acids and secondary metabolite composition. Results: Secondary metabolite profiles of juices from 12 commercial varieties grouped into blonde and navel types, mandarins, lemons and grapefruits were analyzed by LC/ESI-QTOF-MS. HCA on metabolite profiling data revealed the existence of natural groups demarcating fruit types and varieties associated to specific composition patterns. The unbiased classification provided by HCA was used for PLS-DA to find the potential variables (mass chromatographic features) responsible for the classification. Abscisic acid and derivatives, several flavonoids and limonoids were identified by analysis of mass spectra. To facilitate interpretation, metabolites were represented as flow charts depicting biosynthetic pathways. Mandarins 'Fortune' and 'Hernandina' along with oranges showed higher ABA contents and ABA degradation products were present as glycosylated forms in oranges and certain mandarins. All orange and grapefruit varieties showed high limonin contents and its glycosylated form, that was only absent in lemons. The rest of identified limonoids were highly abundant in oranges. Particularly, Sucrenya cultivar showed a specific accumulation of obacunone and limonoate A-ring lactone. Polymethoxylated flavanones (tangeritin and isomers) were absolutely absent from lemons and grapefruits whereas kaempferol deoxyhexose hexose isomer #2, naringin and neohesperidin were only present in these cultivars. Conclusions: Analysis of relative metabolite build-up in closely-related genotypes allowed the efficient demarcation of cultivars and suggested the existence of genotype-specific regulatory mechanisms underlying the differential metabolite accumulation
Acta Horticulturae
No full textDespite potential benefits granted by genetically modified (GM) citrus trees, their release and commercialization raises concerns about their potential environmental impact. The transfer via pollen of transgenes to cross-compatible cultivars is deemed to be the greatest source for environmental exposure. In this work, three different citrus genotypes carrying the uidA (GUS) tracer marker gene (pollen donors) and a non-GM self-incompatible contiguous citrus genotype (recipient) were used in conditions allowing natural entomophilous pollination to occur. The examination of 603 to 2990 seeds per year showed unexpectedly low frequencies (0.17-2.86%) of transgene flow. Paternity analyses of the progeny of subsets of recipient plants using 10 microsatellite (SSR) loci demonstrated a higher mating competence of trees from another non-GM pollen source population that greatly limited the mating chance of the contiguous cross-compatible and flowering-synchronized transgenic pollen source. This mating superiority could be explained by much higher pollen competition capacity of the non-GM genotypes, as was confirmed through mixed-hand pollinations, indicating that pollen competition strongly contributed to transgene confinement. This is the first study on transgene flow in citrus. It provides crucial information on the safety and field performance of GM citrus that can serve as a basis for further field trials and as a guide for (case-by-case) regulatory policies
Acta Horticulturae
No full textA triploid breeding program has been carried out in Plant Protection and Biotechnology Center at the Instituto Valenciano de Investigaciones Agrarias (IVIA) based on sexual hybridization, embryo rescue and ploidy analysis by flow cytometry in order to obtain new mandarin cultivars with late harvest. 'Safor' and 'Garbi' mandarins are new triploid hybrids recently released characterized by their high quality and seedless fruits. In the Citrus Center and Vegetable Production (IVIA) another breeding program based on budwood irradiation is being conducted in search of new seedless cultivars. At this moment two clones obtained from irradiated budwood of the seedy 'Moncada' mandarin (Moncalina-6S17 and Manrad-2L09) are in process of being registered and exhibit excellent fruit quality. This study aimed at testing the postharvest behavior of these four new cultivars. After harvest the fruit were waxed and stored up to 30 days at 1, 5, or 9 degrees C in order to evaluate the sensibility to chilling injury and the changes in quality parameters that occur during the cold storage. 'Safor' mandarins did not show chilling injury symptoms during 30 days at any temperature studied. In contrast, 'Garbi' mandarins exhibited susceptibility to chilling injury after 15 days of storage at 1 and 5 degrees C; during this period this cultivar showed disorders related with peel dehydration when stored at 9 degrees C. 'Moncalina' and 'Manrad' did not show relevant symptoms related to cold-induced damage or dehydration at 1, 5 and 9 degrees C for 30 days of storage. For all mandarin cultivars assayed, the storage at low temperature was not limited for the changes observed in fruit quality parameters