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Physicochemical properties. of orange juice from ten rootstocks using multivariate analysis
No full textThe dwarfing Spanish rootstock F&A 418 may be recommended as rootstock for juice production of citrus.
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Fruit from trees on Cleopatra mandarin had the highest crude fiber.
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The highest content of total sugars was found on F&A 418, this could be interesting for industrial juice.
Abstract
The objective of the present study was to study and compare physicochemical properties of ‘Lane Late’ navel orange trees on the most commonly used commercial rootstocks in Spain, plus eight new hybrids in order to better characterize rootstocks that may be used for citrus cultivation. The ten rootstocks assessed displayed different characteristics. Cluster analysis has allowed the ten citrus rootstocks grouped into five different group. (i) Carrizo citrange, Cleopatra mandarin and 030230 hybrids, (ii) F&A13, (iii) 020324 and 030127 hybrids, (iv) 030118, 030212 and 030131 hybrids and (v) F&A 418. The results reported in the current study confirmed that new rootstocks are very promising and interesting for physical and chemical properties of ‘Lane Late’ navel orange. According to the results obtained the dwarfing Spanish rootstock F&A 418 may be recommended as rootstock for juice production of citrus
Generación y valoración de líneas tolerantes a la salinidad
Get PDFLa salinidad es un problema creciente en la agricultura que afecta a muchos
cultivos disminuyendo el rendimiento de las cosechas. Para tratar esta problemática en el
cultivo del arroz, el IRTA de Amposta y el IVIA en el 2011 iniciaron un proyecto de 3 años. El
objetivo fue caracterizar molecularmente, fisiológicamente y agronómicamente una colección
de variedades mutantes de arroz obtenidas a partir del Bahía mediante irradiación y
preseleccionadas previamente en base a la mayor tolerancia a elevadas concentraciones de
sal en cultivo hidropónico.
El ensayo de valoración agronómica se realizó en el delta del Ebro, en dos localizaciones con
niveles de salinidad de 5,31 dS/m (zona no salina) y de 53,60 dS/m (zona salina). El diseño
experimental fue de bloques al azar con 4 repeticiones y se testaron 6 variedades mutantes
del Bahía comparadas con el propio Bahía. Durante todo el cultivo se evaluó el desarrollo
agronómico de cada una de las variedades.
En general, las condiciones de salinidad extrema afectaron de forma negativa al vigor de las
plantas, a la altura, a la densidad de panículas, al número de panículas y en consecuencia a
la producción, con una disminución en este último parámetro del 30%. De todas las
variedades mutantes testadas, destacó la MS por presentar los mejores resultados de
desarrollo agronómico en condiciones salinas, obteniendo el valor máximo de densidad de
panículas y de producción
Lethal and sublethal effects of spirotetramat on the mealybug destroyer, Cryptolaemus montrouzieri
Get PDFSpirotetramat is a new systemic insecticide listed in Group 23 of the IRAC mode-of-action classification scheme as an inhibitor of lipid biosynthesis. Side effects assessment on key natural enemies is necessary before incorporating a pesticide in IPM programs. Herein, lethal and sublethal side effects of spirotetramat on adults and larvae of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) were evaluated under laboratory conditions by topical application and by ingestion of treated individuals of Planococcus citri Risso (Hemiptera: Pseudococcidae). The lethal and sublethal effects of spirotetramat were compared to those of chlorpyriphos and pyriproxyfen, two insecticides commonly used in Spanish citrus. Spirotetramat resulted harmless: (1) when directly applied on larvae and adults of C. montrouzieri, since it did not affect survival, longevity, fecundity, egg hatching, and offspring survival. In contrast, chlorpyriphos was classified as moderately toxic for adults due to its effects on fecundity, egg hatching and offspring survival. Pyriproxyfen was classified as harmful for larvae due to the acute effect on pupal mortality. When larvae and adults of C. montrouzieri were fed with treated prey, spirotetramat was also classified as harmless. Adults of C. montrouzieri fed with pyriproxyfen-treated prey exhibited increased fecundity but no eggs hatched. Moreover, the larvae fed on pyriproxyfen-treated prey did not reach the adult stage. The results of this study indicate that spirotetramat may be compatible with augmentative releases of C. montrouzieri in citrus
Deteccion de daños no perceptibles en frutos climatéricos a través de imágenes hiperespectrales
No full textBiological control of a non-honeydew producer mediated by a distinct hierarchy of honeydew quality
No full textParasitoids feed commonly on honeydew. However, a high content of energy reserves in honeydew-fed parasitoids does not imply an increase of their fitness because honeydew may be relatively unsuitable. Herein, we studied the feeding behavior and fitness (longevity and fecundity) of a parasitoid, Aphytis melinus DeBach (Hymenoptera: Aphelinidae), which host does not produce honeydew, when it had access to honeydew excreted by five common hemipterans in citrus: Aleurothrixus floccosus (Maskell) (Aleyrodidae), Aphis spiraecola Patch (Aphididae), Coccus hesperidum L. (Coccidae), Icerya purchasi Maskell (Monphlebidae) and Planococcus citri (Risso) (Pseudococcidae). A. melinus females accepted equally and spent the same time feeding on the five honeydews. The first intake of these honeydews prolonged A. melinus longevity but only between 1 and 2 days, independently of the honeydew source. However, when they had continuous access to honeydew, A. melinus fitness entirely depended on the honeydew source. The longevity and realized fecundity of females with access to honeydew excreted by A. spiraecola was similar to unfed females. Contrarily, C. hesperidum and I. purchasi excreted the honeydew with highest nutritional value. In addition, A. melinus discriminated between honeydews with high and poor nutritional quality in a choice-test. Our results demonstrate that honeydew excreted by hemipterans in citrus show a distinct hierarchy of quality and A. melinus females are able to recognize it. These results indicate that the presence of different types of honeydews in agroecosystems should be taken into account separately in this and future biological control programs to design proper measures. (C) 2013 Elsevier Inc. All rights reserved
Intra-guild interactions between the parasitoid Aphytis lingnanensis and the predator Chilocorus circumdatus: Implications for the biological control of armoured scales
Get PDFThe parasitoid Aphytis lingnanensis and the predator Chilocorus circumdatus are released in different crops to control armoured scales. Both natural enemies compete, to some extent, for the same resource and therefore they can induce intraguild predation interactions (IGP). In the present work, the consequences of these interactions on the parasitism and predatory efficiency of these natural enemies were assessed under laboratory conditions by studying potential changes in their functional responses. A type II functional response to host/prey density was observed in A. lingnanensis and C. circumdatus when acting alone. The predatory efficiency of C. circumdatus was not affected by the presence of A. lingnanensis in the same arena. Conversely, the parasitism efficiency of A. lingnanensis was affected by the presence of the predator. Due to IGP at low host densities there was a shift from functional response type II to type III. No changes in the handling time when the predator was present suggested that parasitism behavior was not influenced by the presence of the predator. C circumdatus did not discriminate between parasitised and unparasitised scales. A recommended strategy in biological control programs could be the use of one of the two natural enemies at low infestation levels and to reinforce these releases with the other one at high densities of the pest. (C) 2013 Elsevier Inc. All rights reserved
In-Line Estimation of the Standard Colour Index of Citrus Fruits Using a Computer Vision System Developed For a Mobile Platform
Get PDFA key aspect for the consumer when it comes to deciding on a particular product is the colour. In order to make fruit available to consumers as early as possible, the collection of oranges and mandarins begins before they ripen fully and reach their typical orange colour. As a result, they are therefore subjected to certain degreening treatments, depending on their standard colour citrus index at harvest. Recently, a mobile platform that incorporates a computer vision system capable of pre-sorting the fruit while it is being harvested has been developed as an aid in the harvesting task. However, due to the restrictions of working in the field, the computer vision system developed for this machine is limited in its technology and processing capacity compared to conventional systems. This work shows the optimised algorithms for estimating the colour of citrus in-line that were developed for this mobile platform and its performance is evaluated against that of a spectrophotometer used as a reference in the analysis of colour in food. The results obtained prove that our analysis system predicts the colour index of citrus with a good reliability (R (2) = 0.925) working in real time. Findings also show that it is effective for classifying harvested fruits in the field according to their colour
Thermographic measurement of canopy temperature is a useful tool for predicting water deficit effects on fruit weight in citrus trees
Get PDFAlternative and more practical methods for plant water stress detection than stem water potential (psi(s)) and stomatal conductance (g(s)) are needed when regulated deficit irrigation (RDI) strategies are applied. The aim of this experiment was to compare sap flow and canopy temperature (T-c) measurements with more classical methods like psi(s) or g(s) to predict the effect of deficit irrigation on fresh fruit weight in citrus trees. The experiment was performed during the summer of 2011 in a "Clementina de Nules" orchard undergoing RDI. Sap flow was determined by means of the compensation heat pulse method in well-watered and RDI trees. T-c was measured continuously with infrared thermometers (IRTs) mounted over the canopies and also weekly with an infrared hand-operated thermographic camera taking frontal images of the sunlit side of tree crowns. Concurrently psi(s) and g(s) were also measured on all trees. Results showed that the evolution of the relative transpiration obtained with the sap flow sensors was in agreement with the plant water stress experienced. The values of T-c obtained with the fixed IRTs, normalized by air temperature (T-c - T-a) were in general poorly related with psi(s) and g(s). However, when T-c was obtained from thermal imaging, there was a good correlation with psi(s) in days of relatively high water stress (i.e. when psi(s) differences among treatments were >1.0 MPa). The average fruit weight at harvest was significantly correlated with all the stress indicators, and the best correlation was that of thermographic followed by psi(s) and g(s). Overall, results showed that in citrus trees T-c measurement obtained from thermal imaging is a good tool to predict the effect of water deficit on fresh fruit weight. (c) 2013 Elsevier B.V. All rights reserved
Can heat-pulse sap flow measurements be used as continuous water stress indicators of citrus trees?
No full textTranspiration of well-watered and regulated deficit irrigated (RDI) citrus trees was determined by sap flow (SF) measurements using the compensation heat-pulse method. Its potential for detection of plant water stress was evaluated in comparison with measurements of midday stem water potential (psi(stem)). The study was carried out during 2 years in two commercial groves of Clementina de Nules (CN) and Navel Lane Late (NLL). SF measurements were taken in two trees per treatment instrumented with two identical gauges per tree in NLL and two different types of gauges (type 1 shorter than type 2) in CN. The absolute SF values underestimated the tree water use. Averaged over the entire period of water restrictions, a reduction of about 50 % in water application in the RDI trees of both species decreased tree transpiration compared to the control trees only by a 15 %. Both the nocturnal-to-diurnal SF ratio and the relative transpiration were in good agreement with differences in psi(stem). Overall, results suggest that SF measurements should be preferentially used in relative terms. Sap flow sensors are useful for detecting plant water stress, but they also highlight some of the problems for accurately measuring transpiration
Effect of supplementation of different growth factors in embryo culture medium with a small number of bovine embryos on in vitro embryo development and quality
No full textWhen embryos are cultured individually or in small groups, blastocyst yield efficiency and quality are usually reduced. The aim of this work was to investigate the effect of supplementation of the embryo culture medium (CM) with several growth factors (GFs) on embryo development and apoptosis rate when a reduced number of embryos were in vitro cultured. Two experimental studies (ES) were carried out. In ES 1, five treatments were tested to study the effect of GF on embryo development: Control (similar to 30 to 50 embryos cultured in 500 mu l of CM); Control 5 (Five embryos cultured in 50 mu l microdrops of CM), without addition of GF in either of the two control groups; epidermal GF (EGF); IGF-I; and transforming GF-alpha (TGF-alpha) (Five embryos were cultured in 50 mu l microdrops of CM with 10 ng/ml EGF, 10 ng/ml IGF-I or 10 ng/ml TGF-alpha, respectively). In ES 2, following the results obtained in ES 1, four different treatments were tested to study their effect on embryo development and quality (number of cells per blastocyst and apoptotic rate): Control; Control 5; EGF, all three similar to ES 1; EGF + IGF-I group (five embryos cultured in 50 mu l microdrops of CM with 10 ng/ml EGF and 10 ng/ml IGF-I). In both ESs, it was observed that a higher proportion of embryos cultured in larger groups achieved blastocyst stage than embryos cultured in reduced groups (22.6% v. 14.0%, 12.6% and 5.3% for Control v. Control 5, IGF-I, TGF-alpha groups in ES 1, and 24.9% v. 17.1% and 19.0% for Control v. Control 5 and EGF in ES 2, respectively; P < 0.05), with the exception of embryos cultured in medium supplemented with EGF (18.5%) or with EGF + IGF-I (23.5%), in ES 1 and ES 2, respectively. With regard to blastocyst quality, embryos cultured in reduced groups and supplemented with EGF, alone or combined with IGF-I, presented lower apoptosis rates than embryos cultured in reduced groups without GF supplementation (11.6% and 10.5% v. 21.9% for EGF, EGF + IGF-I and Control 5 groups, respectively; P < 0.05). The experimental group did not affect the total number of cells per blastocyst. In conclusion, this study showed that supplementation of the CM with EGF and IGF could partially avoid the deleterious effect of in vitro culture of small groups of bovine embryos, increasing blastocyst and decreasing apoptosis rates of these blastocytes