ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Pomegranate trees performance under sustained and regulated deficit irrigation
No full textThe effects of sustained and regulated deficit irrigation (SDI and RDI) on "Mollar de Elche" pomegranate tree performance were investigated in a field trial conducted over three consecutive seasons. In the RDI regimes, severe water restrictions were applied during one of three phases: flowering and fruit set, fruit growth, or the final phase of fruit growth and ripening. In another approach, SDI was applied by watering trees at 50 % of the estimated crop water needs (ETc) during the entire season. Results showed that even after three consecutive seasons of water restrictions, similar yield levels were obtained in SDI and Control trees watered at 100 % ETc. This was because a 22 % reduction in average fresh fruit weight recorded in the SDI treatment was compensated by an increase in 28 % in the quantity of fruit collected per tree. This was most likely due to a reduction in the fall of the reproductive organs. However, the SDI strategy led to a reduction in 28 % in the yield value when fruits are sold for fresh fruit markets. Water restrictions applied only during flowering and fruit set also resulted in an increase in the quantity of fruit collected per tree, with only a slight reduction in fruit weight and without affecting the yield value. On the other hand, severe water restrictions applied during the summer (i.e., mid-phase of fruit growth) led to 24 % water savings with only a 7 % reduction in fruit weight. Fruit cracking was very low in all treatments and seasons (2-6 % over the total quantity fruit collected per tree). Only the RDI regime with restrictions during the summer increased cracking in one out of the three seasons. It is concluded that RDI can be used as a measure to cope with water scarcity and high water prices. Among all the RDI explored, the one with restrictions applied early in the season (during flowering and fruit set) was the most convenient strategy
Stabilisation of sewage sludge and vinasse bio-wastes by vermicomposting with rabbit manure using Eisenia fetida
No full textChanges in the chemical characteristics and biological parameters of Eisenia fetida were assessed by VER using (CO + VE) rabbit manure (Vo) spiked with sewage sludge (SS) or vinasse (V). Seven mixtures were used: Vo, control; Vo + SS at 10%, 30%, and 50% (SS1, SS2, and SS3); Vo + V at 10%, 30%, and 50% (V1, V2, and V3). SS vermicomposts had higher humus, nutrient and total metal contents, but less soluble salts (EC) than V vermicomposts. The number and weight of worms were higher in Vo, followed by SS, at decreasing doses. V3 showed the smallest number and size. The EC of the initial mixtures explained reduced weight, whereas EC and avP2O5 accounted for lower numbers. Vermicomposting is an efficient biowaste recycling technology, but the total amount and composition of soluble salts in food influence the quality of end products and are of primary importance for biological parameters of worms. (C) 2013 Elsevier Ltd. All rights reserved
The LOV Protein of Xanthomonas citri subsp citri Plays a Significant Role in the Counteraction of Plant Immune Responses during Citrus Canker
Get PDFPathogens interaction with a host plant starts a set of immune responses that result in complex changes in gene expression and plant physiology. Light is an important modulator of plant defense response and recent studies have evidenced the novel influence of this environmental stimulus in the virulence of several bacterial pathogens. Xanthomonas citri subsp. citri is the bacterium responsible for citrus canker disease, which affects most citrus cultivars. The ability of this bacterium to colonize host plants is influenced by bacterial blue-light sensing through a LOV-domain protein and disease symptoms are considerably altered upon deletion of this protein. In this work we aimed to unravel the role of this photoreceptor during the bacterial counteraction of plant immune responses leading to citrus canker development. We performed a transcriptomic analysis in Citrus sinensis leaves inoculated with the wild type X. citri subsp. citri and with a mutant strain lacking the LOV protein by a cDNA microarray and evaluated the differentially regulated genes corresponding to specific biological processes. A down-regulation of photosynthesis-related genes (together with a corresponding decrease in photosynthesis rates) was observed upon bacterial infection, this effect being more pronounced in plants infected with the lov-mutant bacterial strain. Infection with this strain was also accompanied with the up-regulation of several secondary metabolism-and defense response-related genes. Moreover, we found that relevant plant physiological alterations triggered by pathogen attack such as cell wall fortification and tissue disruption were amplified during the lov-mutant strain infection. These results suggest the participation of the LOV-domain protein from X. citri subsp. citri in the bacterial counteraction of host plant defense response, contributing in this way to disease development
Comparison of ROC Feature Selection Method for the Detection of Decay in Citrus Fruit Using Hyperspectral Images
Get PDFHyperspectral imaging systems allow to detect the initial stages of decay caused by fungi in citrus fruit automatically, instead of doing it manually under dangerous ultraviolet illumination, thus preventing the fungal infestation of other sound fruit and, consequently, the enormous economical losses generated. However, these systems present the disadvantage of generating a huge amount of data, which is necessary to select for achieving some result useful for the sector. There are numerous feature selection methods to reduce dimensionality of hyperspectral images. This work compares a feature selection method using the area under the receiver operating characteristic (ROC) curve with other common feature selection techniques, in order to select an optimal set of wavelengths effective in the detection of decay in a citrus fruit using hyperspectral images. This comparative study is done using images of mandarins with the pixels labelled in five different classes: two types of healthy skin, two types of decay and scars, ensuring that the ROC technique generally provides better results than the other methods
Tetraploid Rangpur lime rootstock increases drought tolerance via enhanced constitutive root abscisic acid production
Get PDFWhole-genome duplication, or polyploidy, is common in many plant species and often leads to better adaptation to adverse environmental condition. However, little is known about the physiological and molecular determinants underlying adaptation. We examined the drought tolerance in diploid (2x) and autotetraploid (4x) clones of Rangpur lime (Citrus limonia) rootstocks grafted with 2x Valencia Delta sweet orange (Citrus sinensis) scions, named V/2xRL and V/4xRL, respectively. Physiological experiments to study rootshoot communication associated with gene expression studies in roots and leaves were performed. V/4xRL was much more tolerant to water deficit than V/2xRL. Gene expression analysis in leaves and roots showed that more genes related to the response to water stress were differentially expressed in V/2xRL than in V/4xRL. Prior to the stress, when comparing V/4xRL to V/2xRL, V/4xRL leaves had lower stomatal conductance and greater abscisic acid (ABA) content. In roots, ABA content was higher in V/4xRL and was associated to a greater expression of drought responsive genes, including CsNCED1, a pivotal regulatory gene of ABA biosynthesis. We conclude that tetraploidy modifies the expression of genes in Rangpur lime citrus roots to regulate long-distance ABA signalling and adaptation to stress
Bicarbonate blocks iron translocation from cotyledons inducing iron stress responses in Citrus roots
No full textThe effect of bicarbonate ion (HCO3-) on the mobilization of iron (Fe) reserves from cotyledons to roots during early growth of citrus seedlings and its influence on the components of the iron acquisition system were studied. Monoembryonic seeds of Citrus limon (L.) were germinated "in vitro" on two iron-deprived media, supplemented or not with 10 mM HCO3- (-Fe+Bic and -Fe, respectively). After 21 d of culture, Fe concentration in seedling organs was measured, as well as gene expression and enzymatic activities. Finally, the effect of Fe resupply on the above responses was tested in the presence and absence of HCO3- (+Fe+Bic or +Fe, respectively). -Fe+Bic seedlings exhibited lower Fe concentration in shoots and roots than -Fe ones but higher in cotyledons, associated to a significative inhibition of NRAMP3 expression. HCO3- upregulated Strategy I related genes (FRO1, FRO2, HA1 and IRT1) and FC-R and H+-ATPase activities in roots of Fe-starved seedlings. PEPC1 expression and PEPCase activity were also increased. When -Fe+Bic pre-treated seedlings were transferred to Fe-containing media for 15 d, Fe content in shoots and roots increased, although to a lower extent in the +Fe+Bic medium. Consequently, the above-described root responses became markedly repressed, however, this effect was less pronounced in +Fe+Bic seedlings. In conclusion, it appears that HCO3- prevents Fe translocation from cotyledons to shoot and root, therefore reducing their Fe levels. This triggers Fe-stress responses in the root, enhancing the expression of genes related with Fe uptake and the corresponding enzymatic activities. (C) 2013 Elsevier GmbH. All rights reserved
Fruit load restricts the flowering promotion effect of paclobutrazol in alternate bearing Citrus spp.
No full textThe floral bud inductive period, PBZ promotes flowering in Citrus; however, our results indicate that this effect is fruit-load dependant. In ‘Salustiana’ and ‘Navelina’ sweet oranges, ‘Hernandina’ Clementine mandarin, and ‘Afourer’ and ‘Moncada’ hybrids, flowering intensity significantly increased the following spring for medium-to-low fruit-load trees treated with either 1–10 g PBZ tree−1 applied to the soil or 15 g tree−1 sprayed on the canopy. PBZ significantly increased the percentage of sprouted buds and leafless floral shoots (both single-flowered shoots and inflorescences) and reduced the number of vegetative shoots. By contrast, heavy fruit load trees receiving the same amount of PBZ in the same season or at floral bud differentiation period scarcely flowered. Fruit nullified the effect of PBZ irrespective to treatment date (inductive period or bud burst) as well as the dose applied (1, 10 or 15 g tree−1) or the treatment method (soil application or canopy spraying). In conclusion, the effectiveness of PBZ in promoting flowering in Citrus depends on the fruit load since the tree showed a cultivar-dependant threshold value above which PBZ is unable to promote flowering
El departamento del arroz: antecedentes y labor actual
Get PDFA finales del siglo XIX y principios del XX , la mayoría de las variedades de arroz
cultivadas en Valencia, Tarragona y Murcia, fueron afectadas, en mayor o menor grado, por
alguna “extraña dolencia”, denominada “fallada” por los agricultores arroceros, que
ocasionaba mermas considerables de producción con la consiguiente apreciable pérdida
económica. Como consecuencia del requerimiento de las autoridades locales de Sueca, el
Ministerio de Fomento (Agricultura, Industria y Comercio), propuso la creación de un
Centro Agronómico que se dedicara fundamentalmente a estudiar los problemas
relacionados con el arroz. De esa forma, las R.O del Ministerio de Fomento de 18 de Octubre
de 1911 y 23 de Noviembre de 1912, aprobaban la creación e instalación en Sueca de dicho
Centro Agronómico que, con el nombre de Granja Arrocera, comenzó a funcionar el 7 de
Febrero de 1913, dependiendo hasta el año 1932 de la Dirección General de Agricultura del
Ministerio de Fomento. Desde entonces, aunque con diferente apelativo y organismo del que
depende (Estación Arrocera dependiente del Instituto Nacional de Investigaciones
Agronómicas en 1932, y Departamento del Arroz adscrito al INIA, en 1969, y al 1VTA en
1983), ha llevado a cabo una importante labor en la obtención de nuevas variedades de gran
calidad, elevados rendimientos y adaptadas a los modernos métodos de cultivo, y ha
realizado estudios de tipo agronómico para proporcionar al agricultor las técnicas de cultivo
adecuadas para obtener un rendimiento productivo y económico.
En esta ponencia se repasan algunos de los estudios que el Departamento del Arroz ha
efectuado en el campo de la agronomía, economía y de la calidad del arroz, en colaboración
con Centros de investigación españoles y extranjeros. Se analizan los objetivos de la mejora
de variedades de arroz a lo largo de los 100 años de existencia del Departamento del Arroz,
profundizando en las nuevas líneas de trabajo actuales, así como en el proceso y método de
selección. La descripción de las variedades obtenidas no se contempla en este trabajo ya que
será objeto de otra ponencia
Variedades del Departamento del Arroz del IVIA
Get PDFDurante mucho tiempo, la Estación Arrocera de Sueca (actualmente
Departamento del Arroz del I.V.I.A.) fue el único lugar de España donde se obtenían nuevas
variedades de arroz. Desde su fundación, en 1913, se obtuvieron primero por selección de
líneas puras dentro de variedades tradicionales, y a partir de 1929, por mejora genealógica
(cruzamiento seguido de selección). Las variedades más importantes del Departamento han
sido: Balilla x Sollana (Secretari), en 1960, de grano redondo perlado, cultivada sobre todo
en Calasparra, en cultivo ecológico; Sequial, en 1967, de grano medio cristalino, productiva,
también cultivada en Grecia; Bahía, en 1968, de grano medio perlado, productiva, también
cultivada en ltalia; estas dos variedades ya estaban adaptadas a la recolección mecánica;
Senia, en 1984, de grano medio perlado, productiva, la variedad más cultivada en España
durante más años; Tebre, en 1986, de grano medio perlado, muy cultivada en el Delta del
Ebro; JSendra, en 2005, de grano medio perlado, productiva; Albufera, en 2007, de grano
redondo perlado, con calidad similar a Bomba. El Departamento también ha obtenido
variedades de grano largo B cristalino, resistentes a pyricularia, como Alena (en 2002) y
Cormorán (en 2006). Una de las variedades recientes (Sarcet, en 2007) fue obtenida por
cultivo de anteras. Actualmente hay cuatro variedades productivas de grano medio perlado
en proceso de registro
The Viable but Non-culturable State in Xanthomonas citri subsp. citri is a Reversible State Induced by Low Nutrient Availability and Copper Stress Conditions
Get PDFXcc (Xanthomonas citri subsp. citri) causes citrus bacterial canker, a leaf, stem and fruit spotting disease that affects most commercial citrus species and cultivars. Copper compounds, widely used for management of this pathogen, have been reported as inducers of a VBNC (viable but non-culturable state) in plant pathogenic bacteria. VBNC may be considered as a state preceding bacterial death or as a survival mechanism under adverse conditions. Several experiments were performed to characterize the reversibility and persistence of the VBNC state in Xcc. VBNC was induced in low nutrient medium or with amendment of copper at concentrations used for field disease control. The VBNC condition was demonstrated to persist up to 150 days after copper treatment and was reversed after the addition of culture media without copper or amendment with citrus leaf extract. Xcc viability was evaluated by recovery of colonies on culture media, confirmed by membrane integrity, respiratory activity and by real-time RT-PCR targeting a sequence from the gumD gene. Besides, the colonies recovered were pathogenic on citrus leaves. These results confirm that the VBNC state in Xcc is inducible and reversible and therefore may occur in the phyllosphere when Xcc is under copper stress or starvation