ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Material vegetal de níspero: Banco de germoplasma de níspero japonés (eriobotrya japonica (thumb) lindl.) del IVIA
Get PDFLa principal zona productora de níspero japonés en España es la Comunidad Valenciana,
principalmente la Provincia de Alicante y más en concreto las poblaciones de
Callosa d’en Sarrià, Altea, Polop, La Bolulla, Guadalest y La Nucía.
La producción se centra prácticamente en una única variedad, ‘Algerie’ (95% de la
producción), con un menor porcentaje (5%) repartido entre otras variedades como
‘Crisanto Amadeo’, ‘Peluches’, ‘Golden Nugget’, ‘Magdal’ y ‘Cardona’. Como se puede
observar existe una producción casi monovarietal, lo cual puede conllevar de forma
implícita, una serie de problemas como un alto riesgo fitopatológico, una vulnerabilidad
a la producción y problemas de comercialización al estar concentrada la
campaña en muy poco espacio de tiempo. Además a estos problemas se unen los
propios de la especie como la mancha púrpura, moteado, problemas de polinización
(especialmente en cultivo bajo malla), y la falta de alternativas precoces de calidad.
La solución a estos problemas está en aumentar la variabilidad con nuevas variedades.
Esta solución se puede abordar principalmente por dos vías: una primera vía mediante
la introducción de nuevas variedades en Bancos de Germoplasma procedentes
de otros países o búsqueda por prospecciones, y una segunda vía sería la creación de
nuevas variedades por hibridación procedentes de programas de mejora genética.
El Banco de Germoplasma Nacional de esta especie, ubicado en el IVIA, está compuesto
en la actualidad por 123 accesiones o entradas. Los trabajos que se han realizado y se están llevando a cabo en este Banco de Germoplasma son los de caracterizar y
evaluar estas accesiones, tanto a nivel pomológico y agronómico utilizando el protocolo
de la UPOV y la escala BBCH descritos para esta especie, como a nivel molecular,
teniendo así perfectamente identificadas y descritas cada una de las accesiones. En
el tiempo que se lleva manejando el Banco de Germoplasma han destacado, no solo
por sus buenas características agronómicas, organolépticas y pomológicas, sino también
porque nos ofrecen una ampliación del calendario de recolección de ‘Algerie’ las
siguientes variedades: ‘Alfonso Gregori’ (-32 días antes que ‘Algerie’), ‘Zaozhong-6
(-21), ‘Cardona’ (-14), ‘Samper II’ (-13), Panisello 71 (-12), ‘Rolhao II’ (+3), ‘Requina’
(+3), ‘Cort’ (+8), ‘Cayetano (+11) y ‘Tanaka’ (+13).
La segunda vía mencionada anteriormente para obtener nuevas variedades es mediante
programas de mejora genética. En el año 2002, la cooperativa de Callosa
d’en Sarrià firmó un convenio con el IVIA para poner en marcha un programa de mejora
genética del níspero japonés con el objetivo de obtener variedades tipo ‘Algerie’
en cuanto aspecto externo, forma, color y calidad, pero que ampliase su calendario
de recolección. Se buscaron fuentes de variación que nos aportasen las características
de los objetivos que nos planteamos, y una vez seleccionadas, se procedió a la
realización de cruzamientos dirigidos. En la actualidad están en fase de evaluación
más de 4.000 híbridos, seleccionándose aquellos individuos que nos están aportando
las características que deseábamos obtener en la descendencia de cada uno de los
cruces realizados, y que se presentan como futuras nuevas variedades.
Los objetivos de futuro que se han establecido tanto en el Banco de Germoplasma,
como en el programa de mejora genética son: establecer una colección nuclear, seguir
introduciendo nuevas accesiones, continuar con la selección y evaluación de
híbridos, y realizar nuevos cruzamientos
Genetic structure and evolution of natural populations of viruses causing the tomato yellow leaf curl disease in Spain
No full textThe population structure and genetic variation of two begomoviruses: tomato yellow leaf curl Sardinia virus (TYLCSV) and tomato yellow leaf curl virus (TYLCV) in tomato crops of Spain were studied from 1997 until 2001. Restriction digestion of a genomic region comprised of the CP coat protein gene (CPR) of 358 TYLC virus isolates enabled us to classify them into 14 haplotypes. Nucleotide sequences of two genomic regions: CPR, and the surrounding intergenic region (SIR) were determined for at least two isolates per haplotype. SIR was more variable than CPR and showed multiple recombination events whereas no recombination was detected within CPR. In all geographic regions except Murcia, the population was, or evolved to be composed of one predominant haplotype with a low genetic diversity (<0.0180). In Murcia, two successive changes of the predominant haplotype were observed in the best studied population. Phylogenetic analysis showed that the TYLCSV sequences determined clustered with sequences obtained from the GenBank of other TYLCSV Spanish isolates which were clearly separated from TYLCSV Italian isolates. Most of our TYLCV sequences were similar to those of isolates from Japan and Portugal, and the sequences obtained from TYLCV isolates from the Canary island of Lanzarote were similar to those of Caribbean TYLCV isolates
Hyperspectral detection of citrus damage with Mahalanobis kernel classifier
Get PDFPresented is a full computer vision system for the identification of post-harvest damage in citrus packing houses. The method is based on the combined use of hyperspectral images and the Mahalanobis kernel classifier. More accurate and reliable results compared to other methods are obtained in several scenarios and acquired images
Effects of gamma-irradiation on midgut proteolytic activity of the mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae).
No full textThe Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), is a key pest of citrus in Spain because of significant yield losses and to quarantine restrictions. Biologically based control methods, such as the Sterile Insect Technique (SIT), which relies on the sterilization by irradiation of large numbers of insects, is gaining an increasing role in the control of medfly in Mediterranean areas. However, gamma-irradiation might damage the midgut epithelium cells, causing a lowering of nutritive assimilation that can negatively affect adult performance. Irradiation effects on digestive physiology are well established for a number of insect pests, but there is no information on medfly. Our aim was to determine the effects of gamma-irradiation on C. capitata digestive protease activity. Both larvae and adults were found to use a similar proteolytic system based on aspartyl-, trypsin-, chymotrypsin-, amino peptidase-, and carboxypeptidase A- and B-like activities. Pupae of the Vienna-7 (tsl) strain were irradiated at 70 or 140 Gy, two days before emergence, and the adults fed during 5 days on sugar-protein (4:1) diets. Protease activity was measured in midgut extracts and compared with males non-irradiated reared in the same conditions. The results showed that the irradiation doses tested had no effect on the digestive proteolytic activities of medfly adults. Moreover, the longevity of irradiated medflies at the highest dose (140 Gy) was similar to that of controls
Control de la “podredumbre marrón” (Monilinia spp.) en los frutales de hueso
Get PDFLa “podredumbre marrón” de los frutos de las Rosáceas (Fig. 1), se debe a la actividad patógena de las especies del hongo ascomiceto Monilinia y actualmente detenta una considerable importancia económica. En las condiciones mediterráneas españolas y hasta la fecha, son dos las especies de Monilinia (anamorfo o estado asexual: Monilia) que se conocen: M. fructigena y M. laxa. Esta última es la más frecuente en los frutales de hueso y por consiguiente la que causa los mayores daños en los mismos
Co-operational PCR coupled with dot blot hybridization for detection and 16SrX grouping of phytoplasmas
No full textA protocol based on Co-operational PCR has been successfully applied to the detection of phytoplasmas. A triprimer reaction coupled with hybridization using general and specific probes permitted detection of 'Candidatus Phytoplasma mali', 'Ca. Phytoplasma prunorum' and 'Ca. Phytoplasma pyri', and their identification as members of 16S ribosomal quarantine group X. The sensitivity of this method was at least one hundred times greater than conventional PCR and similar to that achieved by nested PCR and real-time PCR. The method was validated by testing field samples collected from Malus, Prunus and Pyrus spp. and Olea europaea and compared with seven phytoplasmas maintained in Catbaranthus roseus
Citrus sorting by identification of the most common defects using multispectral computer vision
No full textThe presence of skin defects is one of the most influential factors in the price of fruit. The detection of defects during packing operations ensures that only fruits with a good quality reach the market. Moreover, the identification of the type of each defect will increase both the quality of the fruit and also the producer's profit. At the present time, fruit with slight defects is marketed together with sound fruit, thus depreciating the quality of the batch, or it is removed together with seriously damaged fruit, thereby causing economic losses. Most current computer vision systems used in the automatic quality inspection of food are limited to the visible region of the electromagnetic spectrum as they tend to imitate the human eye. However, non-visible information, such as that provided by near-infrared or ultraviolet regions of the spectrum, can improve the inspection by detecting specific defects or allowing the detection of non-visible damages. This work summarises our research in the application of near-infrared, ultraviolet and fluorescence computer vision systems in the identification of the most common defects of citrus fruits, and proposes a fruit sorting algorithm that combines this different spectral information (including visible) to classify fruit according to the type of defect. Results showed that the contribution of non-visible information can improve the detection and identification of some defects. Compared with the results from colour images, the detection accuracy of anthracnose increased from 86% by using NIR images; and the accuracy of green mould was increased from 65% to 94% by using images of fluorescence. (c) 2007 Elsevier Ltd. All rights reserved
Computer vision detection of peel defects in citrus by means of a region oriented segmentation algorithm
No full textDue to the high sorting speed required during fruit inspection and classification in packing lines, most of the current automatic systems, based on machine vision, normally employ supervised techniques oriented towards individual pixels to segment the images of the fruits. These techniques require previous training given by experts in order to classify the colour of each pixel as belonging to any of the regions of interest and frequent training sessions during normal operation throughout the season to adapt the system to the great colour variability present in biological products like fruits. In region-oriented segmentation algorithms, however, the contrast between different areas in the image becomes more important than the individual pixel colour, thus solving the problem related to the variability of the natural colour of fruits. This work proposes a region-oriented segmentation algorithm for detecting the most common peel defects of citrus fruits. Focused on the detection of the regions of interest consisting of the sound peel, the stem and the defects, this method is an original contribution that allows successful segmentation of smaller defects, such as scale. The algorithm was tested on images of different varieties of oranges and mandarins presenting defects, without any further training being given between inspections of different batches, even species, of citrus fruits. Assuming that the most surface of the fruit corresponds to sound peel, the proposed algorithm was able to correctly detect 95% of the defects under study. (c) 2006 Elsevier Ltd. All rights reserved
Molecular characterization of CEVd strains that induce different phenotypes in Gynura aurantiaca: structure-pathogenicity relationships
No full textTwo Citrus exocortis viroid isolates (CEVd-s and CEVd-129) that induce severe and mild symptoms in Gynura aurantiaca, respectively, have been characterized. They present nucleotide sequences in the pathogenicity motifs PL, C and PR similar to those of “Class A” and “Class B”. Infectivity and symptom expression in G. aurantica and tomato were evaluated with a selection of sequence variants recovered from both isolates. As expected, the two variants selected from CEVd-s induced severe symptoms. The variants selected from CEVd-129 induced mild symptoms, except one of them, named MJ, that presented an unusual genotype and induced severe symptoms in G. aurantiaca. The biological properties of MJ show that the two nucleotide changes of the C domain normally associated with the PL and PR motifs of “Class B” strains are not implicated in symptom expression. The relationship between “Class A” and “Class B” strains with the symptoms induced in clementine trees grafted on trifoliate orange is discussed