ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
Not a member yet
2747 research outputs found
Sort by
Ground-dwelling spiders (Araneae) in citrus orchards in Spain
No full textA survey of the ground-dwelling spiders (Araneae) was conducted in four citrus orchards in the province of Valencia, Spain. The sampling period was extended from August 2003 to August 2007. A total of 12 pitfall traps were diagonally distributed per orchard being regularly changed every 14 days. More than 3,000 individuals belonging to more than 25 species of 12 different families were collected. The family Lycosidae was the prevalent group,
being Pardosa cribata Simon the main species of this family. Otherwise, Zodarion pusio Simon was the most abundant species of all the spiders captured. Ground-dwelling spiders were active throughout the year with peak populations in late spring and early summer
Alternatives to conventional fungicides for the control of citrus postharvest green and blue moulds
Get PDFPurpose of review: This article reviews research based on the evaluation of postharvest control methods alternative to conventional chemical fungicides for the control of citrus green and blue moulds, caused by the pathogens Penicillium digitatum and P.
italicum, respectively. Emphasis is given to advances developed during the last few years. Potential benefits, disadvantages and
commercial feasibility of the application of these methods are discussed.
Findings: Substantial progress has been accomplished in selecting and characterising new effective physical, chemical and biological control methods. However, their widespread commercial implementation relies, in general, on the integration of different
treatments of the same or different nature in a multifaceted approach. For satisfactory penicillium decay control, this postharvest
approach should be part of an integrated disease management (IDM) programme in which preharvest and harvest factors are also
considered.
Limitations: The lack of either curative or preventive activity, low persistence, high variability, inconsistency or excessive
specificity are general limitations associated with the use of alternatives to synthetic fungicides as stand-alone treatments. Furthermore, the risk of adverse effects on fruit quality, technological problems for cost-effective application, or the availability of
new conventional fungicides for traditional markets are additional reasons that may hinder the broad commercial use of such
treatments.
Directions for future research: As we learn more about the fundamental basis underlying host-pathogen interactions and
how they are influenced by direct or indirect protective effects of existing or new single alternative treatments, more effective
methods of applying and combining complementary approaches for additive or synergistic effects will emerge. Research should
provide appropriate tools to tailor the application of these nonpolluting postharvest control systems and, further, the complete
IDM strategy for each specific situation (ie, citrus species and cultivar, climatic and seasonal conditions, destination market,
etc)
Fechas de plantación y recolección de boniato
Get PDFSe han realizado, en cada uno de los años 2006 y 2007, cuatro plantaciones escalonadas de boniato (Ipomea batatas), con intervalo de un mes aproximadamente. En 2007 se efectuaron tres recolecciones en cada plantación, también separadas por períodos de 30 días y en 2008 cinco recolecciones en cada plantación a intervalos de 300º día (a temperatura mayor de 12ºC). La distribución del experimento fue, para cada plantación, un factorial con tres cultivares y tres o cinco recolecciones y dos repeticiones, con parcela elemental de 10 plantas a un marco de 1,1 x 0,4 m. La plantación se realizó con esquejes enraizados en bandeja de 104 alveolos. Se ha empleado riego localizado. En el primer año, en todas las plantaciones la producción comercial aumentó desde la primera recolección (75-90 días desde la plantación) hasta la tercera (140-160 días desde la plantación). Seguramente en ninguna de las plantaciones se llegó al tope de producción. En el segundo año, el período de cultivo llegó, en la primera plantación, hasta los 219 días. El experimento terminó el 20 de noviembre, cuando ya la temperatura no permitía un adecuado desarrollo de la plantación. El cultivar más productivo, especialmente en recolección temprana, es CIP-4 (2,77 kg/m2 a finales de julio). En la recolección más tardía, la producción de tamaño comercial
se iguala con la de Sumor, pero ambas superan siempre a Blanco de Alginet. Este es más sensible al retraso en la fecha de plantación y adelanto en el arranque, necesitando más tiempo para tuberizar y formar boniatos de calidad. La producción comercial y tamaño del tubérculo descienden cuando se retrasa la plantación desde mediados de abril hasta mediados de julio. Las producciones aumentan cuando se atrasa la recolección, dando tiempo a formarse y engrosar los tubérculos. Hay una estrecha correlación entre la producción total comercial y los grados-día a temperatura >12ºC desde la plantación hasta la recolección. La evolución de los grados-día en un determinado lugar marca el inicio de la época de plantación
favorable y el final del período vegetativo o recolección
Entomofauna auxiliar asociada a setos naturales en cítricos ecológicos valencianos
Get PDFSe están realizando estudios sobre la función ecológica de los setos naturales
mediterráneos como hábitat de la entomofauna auxiliar asociada a los cítricos ecológicos
y convencionales, en parcelas citrícolas valencianas. El trabajo se lleva a cabo sobre
setos mixtos compuestos de especies mediterráneas, tales como lentisco, espino blanco,
aladierno o cornicabra, y setos monoespecíficos de cipreses, árbol del cielo y granado,
recolectando los artrópodos mediante trampas pegajosas amarillas y aspiración (soplador
ECHO PB 46-LN + kit aspirador). A su vez, se realiza una comparación con otras parcelas
vecinas conducidas con técnicas convencionales y sin seto propio. También se han
realizado trabajos de identificación de las especies encontradas en las cubiertas
vegetales asociadas a las parcelas ecológicas.
Los resultados muestran que los setos estudiados tienen una gran diversidad de
fauna auxiliar. Las especies encontradas son muy similares a las encontradas en los
cítricos, pero distintas a las habituales en las cubiertas vegetales
Effect of hormonal supplementation (recombinant vs urinary) on in vitro maturation of porcine oocyte and further parthenogenetic embryo development
No full textContenido de nutrientes en varias hortalizas cultivadas en un suelo enmendado con diferentes materias orgánicas sólidas
Get PDFEn un experimento de campo iniciado en septiembre de 2002 en las parcelas
experimentales del Centro de la Fundación Ruralcaja, en Paiporta (Valencia), se estudió
la respuesta que presentan los cultivos hortícolas a siete enmiendas orgánicas sólidas:
estiércol de ovino (S1), compost de RSU (S2), compost de lodos de depuradora (S3),
compost de alperujos (S4), Fem de Sac (producto a base de residuos de ovino) (S5),
compost de purines de porcino (S6) y humus de lombriz (S7). Los productos S1, S2, S3
y S4 se aplicaron a una dosis de 30 t/ha cada 2 años, y los productos S5, S6 y S7 a una
dosis de 6 t/ha cada 2 años, incluyendo un tratamiento testigo (sin enmienda orgánica).
Todos los tratamientos han recibido la misma fertilización mineral. La secuencia de
cultivos implantados ha sido la siguiente: coliflor, patata, sandía, hinojo, pimiento, col
china. En esta comunicación se muestran los resultados de los contenidos de nutrientes
en los respectivos productos cosechados, así como la correspondiente discusión de
los mismos
Hyperspectral system for early detection of rottenness caused by Penicillium digitatum in mandarins
No full textNowadays, the detection of fruit infected with Penicillium sp. fungi on packing lines is carried out manually under ultraviolet illumination. Ultraviolet sources induce visible fluorescence of essential oils present in the skin of citrus and which are released by the action of fungi, thus increasing the contrast between sound and rotten skin. This work analyses a set of techniques aimed at detecting rotten citrus without the use of UV lighting. The techniques used include hyperspectral image acquisition, preprocessing and calibration, feature selection and segmentation using linear and non-linear methods for classification of fruits. Different methods such as correlation analysis, mutual information, stepwise, and genetic algorithms based on linear discriminant analysis (LDA) are studied to select the most relevant bands. image segmentation relies on the combination of efficient band selection techniques and also on pixel classification methods such as classification and regression trees (CART) and LDA. The results were obtained using a large dataset of images of mandarins cv. "Clemenules" by applying the CART method. The hyperspectral computer vision system proposed here is capable of detecting damage caused by Penicillium digitatum in mandarins using a reduced set of optimally selected bands
Identification and characterization of fungi associated with esca in vineyards of the Comunidad Valenciana (Spain)
Get PDFGrapevines sampled in the Comunidad Valenciana in Spain were examined for esca symptoms, and the different vine parts (trunk.. cane and young vine) were surveyed for the presence of esca-related fungi. The fungal species most frequently identified were the mitosporic fungi Diplodia mutila (Dmu), Phaeoacremonium aleophilum (Pal), Phaeomoniella chlamydospora (Pch) and Phomopsis viticola (Pvi) and the basidiomycetes Fomitiporia mediterranea (Fin) and Stereum hirsutum (Shi). PCR and sequencing using the universal pair primers ITS1-ITS4 confirmed the identification, these techniques proved very useful, particularly in cases where fruiting was not evident and/or pure cultures did not display enough diagnostic traits. Dmu and both basidiomycetes were the most frequent fungi associated with esca in this region. Dmu was the only fungal species found in all vine parts studied, being significantly more present in canes (82%) than in trunks (58%) or shoots (28%). Moreover, both basidiomycetes (50% Fin and 56% Shi) and Pch (32%) were most frequently found in trunks
SaPI mutations affecting replication and transfer and enabling autonomous replication in the absence of helper phage
No full textThe SaPIs are chromosomal islands in staphylococci and other Gram-positive bacteria that carry genes for superantigens, virulence factors, resistance and certain metabolic functions. They have intimate relationships with certain temperate phages involving phage-induced excision, replication and efficient packaging in special small-headed infective phage-like particles, resulting in very high transfer frequencies. They generally contain 18-22 ORFs. We have systematically inactivated each of these ORFs and determined their functional groupings. In other reports, we have shown that five are involved in excision/integration, replication and packaging. In this report, we summarize the mutational analysis and focus on two key ORFs involved in regulation of the SaPI excision-replication-packaging cycle vis-a-vis phage induction. These two genes are divergently transcribed and define the major transcriptional organization of the SaPI genome. One of them, stl, encodes a master repressor, possibly analogous to the standard cI phage repressor. Mutational inactivation of this gene results in SaPI excision and replication in the absence of any inducing phage. This replicated SaPI DNA is not packaged; however, since the capsid components are provided by the helper phage. We have not yet ascertained any specific function for the second putative regulatory gene, though it is highly conserved among the SaPIs
Evaluation of selection strategies alternative to nptII in genetic transformation of citrus
No full textThe neomycin phosphotransferase (nptII) selection system has proved successful in citrus transformation; however, it may be recommendable to replace it given the pressure exerted against antibiotic-resistance selectable marker genes in transgenic plants. The present work investigates three different selection alternatives, comparing them to nptII selection in two citrus genotypes, Carrizo citrange and Pineapple sweet orange. The first method used the beta-glucuronidase (uidA) reporter marker gene for selection; the second attempted to generate marker-free plants by transforming explants with a multi-auto-transformation (MAT) vector, combining an inducible R/RS-specific recombination system with transgenic-shoot selection through expression of isopentenyl transferase (ipt) and indoleacetamide hydrolase/tryptophan monooxygenase (iaaM/H) marker genes; while the third exploited the phosphomannose isomerase (PMI)/mannose conditional positive selection system. Firstly, GUS screening of all regenerated shoots in kanamycin-free medium gave 4.3% transformation efficiency for both genotypes. Secondly, workable transformation efficiencies were also achieved with the MAT system, 7.2% for citrange and 6.7% for sweet orange. This system affords an additional advantage as it enables selectable marker genes to be used during the in vitro culture phase and later removed from the transgenic plants by inducible recombination and site-specific excision. Thirdly, the highest transformation rates were obtained with the PMI/mannose system, 30% for citrange and 13% for sweet orange, which indicates that this marker is also an excellent candidate for citrus transformation