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Acta Horticulturae
No full textThis study discusses the varietal composition of citriculture from 1966/67 to 2007/08 and current trends in the introduction and spread of new cultivars. Data have been taken from three main sources: the Statistical Annual Records of the Ministry of Agriculture; records of the number of plants pertaining to different cultivars sold by nurseries; and, interviews with marketing companies and agricultural co-ops. Concerning trends, we have found that although the Spanish citrus industry encompasses a very wide variety, if one takes into account the number of groups that account for the greatest production, production is focused on three main varietal groups: lemons, Navel oranges and Clementines. In early Clementines, there is constant demand for the supply of new cultivars, which often originate from mutations, despite their disadvantages such as small fruit size, need for thinning, multiple bud formation and short marketing period. There are new cultivars or clones which, although they do not alter the composition of the major groups, represent a qualitative improvement within their group. Thus, the Clemennules group is expanded and improved by the Orogrande and Nulessin; the Navel group with Powell, Rohde, Barnfield and the Valencia group with Barberina, Midknight, Late Frost and Delta Seedless. There is a very wide variety of early clementines, although only Oronules, Arrufatina and Clemenrubi seem commercially viable. The main conclusion confirms that there is continual modification to the varietal composition brought about by the producers, who are driven by the income-risk criterion. When a cultivar becomes commercially obsolete, the producer must substitute it with another more widely accepted one. Markets are witnessing a slow growth in mandarins, while mandarin hybrids have brighter prospects. Late and mid-season Navel cultivars are well accepted on the market, particularly the domestic market
Influencia de la siega de la cubierta vegetal en las poblaciones de fauna auxiliar en cítricos ecológicos
Get PDFSe ha realizado un estudio analizando el efecto de la siega de primavera y del tipo de cubierta vegetal (silvestre, alfalfa, festuca y vallico) en la comunidad de artrópodos de un campo de Clementinos ecológicos en Alzira (Valencia). En junio de 2010 se ha realizado una siega de las cubiertas vegetales dejando una parte sin segar. Se han llevado a cabo muestreos de la fauna auxiliar presente en los árboles y en las cubiertas antes de la siega y en sucesivos días posteriores a ésta (1, 4, 7, 17 días). Como métodos de muestreo se han utilizado un aspirador adaptado y trampas cromáticas pegajosas. Se
han realizado ANOVAS factoriales estudiando la influencia del estrato (cubierta o árbol), de la siega, del tipo de cubierta vegetal y del tiempo. Los resultados indican como el factor más influyente en la comunidad de artrópodos es el factor estrato, siendo menor la influencia del tipo de cubierta vegetal. Los resultados también muestran la evolución de parasitoides y depredadores después de la siega, así como los movimientos de dichas especies entre estratos y/o entre zonas segadas y no segadas
Influence of salinity on pip gene expression in citrus roots and its relationship with root hydraulic conductance, transpiration and chloride exclusion from leaves
No full textThe present work studies the effect of salinity on PIP aquaporins gene expression in citrus roots and its relationship with root hydraulic conductance (Kr), transpiration rate (E) and chloride transport to leaves. To this end, ten-month-old seedlings of Cleopatra mandarin (CM), Carrizo citrange (CC) and Poncirus trifoliara (PT) were tested. No effect was detected of salt treatments on PIP1 and PIP2 aquaporin mRNA transcript abundances from citrus roots, although PIP1 expression in CM roots was lower than in CC and PT. The lowest Kr and E values were detected in CM, whereas PT had the highest. CC seedlings presented intermediate values for these parameters. Addition of HgCl2 to either control or salt solution (200 mM NaCl) led to a decrease in Kr and E, thus implying aquaporin involvement. By contrast, salinity strongly reduced Kr and E in all plants, with this effect being unrelated to aquaporin activity. In salinized seedlings, E values appear to be related with Cl- concentration in leaves. Thus, CM seedlings treated with 80 mM NaCl presented a lower Cl- uptake by leaves than PT, whereas this trend was intermediate in CC. Moreover, Hg2+ treatments significantly reduced leaf Cl- concentration in salt stressed plants, probably through the reduction of E. We can conclude that differences among genotypes in PIP1 expression affect Cl- exclusion from leaves, probably due to effects on water movement. Nevertheless, long-term salt treatments did not affect PIP expression in citrus plants, but reduced root hydraulic conductance and transpiration. (C) 2012 Elsevier B.V. All rights reserved
Detecting rottenness caused by Penicillium genus fungi in citrus fruits using machine learning techniques
No full textPenicillium fungi are among the main defects that may affect the commercialization of citrus fruits. Economic losses in fruit production may become enormous if an early detection of that kind of fungi is not carried out. That early detection is usually based either on UltraViolet light carried out manually. This work presents a new approach based on hyperspectral imagery for defect segmentation. Both the physical device and the data processing (geometric corrections and band selection) are presented. Achieved results using classifiers based on Artificial Neural Networks and Decision Trees show an accuracy around 98%; it shows up the suitability of the proposed approach
Acta Horticulturae
No full textProduction of seedless citrus fruits is required for the fresh market because consumers do not accept seedy fruits. Development of new seedless mandarin cultivars has a high priority for many citrus industries worldwide. The recovery of triploid hybrids is the most promising approach to achieve this goal, since triploids have a very low pollen and ovule fertility and usually are seedless or produce very low numbers of seeds, and do not induce the formation of seeds in other cultivars by cross pollination. The objective of our breeding program is to produce new high quality easy peeling and seedless mandarin cultivars. Citrus triploid plants can be recovered by 2xx4x sexual hybridizations. Triploid embryos are found in normal and undeveloped seeds that do not germinate under greenhouse conditions. Extensive breeding programs based on this type of hybridization require very effective methodologies for recovery of new tetraploid parents, embryo rescue and ploidy evaluation. Different approaches have been implemented to obtain new tetraploid parents. Spontaneous autotetraploid plants of apomictic genotypes have been selected from seedbeds by flow cytometry and autotetraploid plants of non apomictic genotypes have been obtained by chromosome duplication with treatments of micrografted shoot tips with colchicine or oryzalin. Symmetric protoplast fusion is also used to produce tetraploid genotypes. So far, we have obtained more than 4,400 triploid hybrids from 77 parental combinations. Protection of Plant Breeder's Rights of a triploid hybrid named IVIA-600 obtained in a hybridization between 'Hernandina' clementine and tetraploid 'Orlando' tangelo has been requested
Erwinia spp. from pome fruit trees: similarities and differences among pathogenic and non-pathogenic species
No full textThe number of described pathogenic and nonpathogenic Erwinia species associated with pome fruit trees, especially pear trees, has increased in recent years, but updated comparative information about their similarities and differences is scarce. The causal agent of the fire blight disease of rosaceous plants, Erwinia amylovora, is the most studied species of this genus. Recently described species that are pathogenic to pear trees include Erwinia pyrifoliae in Korea and Japan, Erwinia spp. in Japan, and Erwinia piriflorinigrans in Spain. E. pyrifoliae causes symptoms that are indistinguishable from those of fire blight in Asian pear trees, Erwinia spp. from Japan cause black lesions on several cultivars of pear trees, and E. piriflorinigrans causes necrosis of only pear blossoms. All these novel species share some phenotypic and genetic characteristics with E. amylovora. Non-pathogenic Erwinia species are Erwinia billingiae and Erwinia tasmaniensis that have also been described on pome fruits; however, less information is available on these species. We present an updated review on the phenotypic and molecular characteristics, habitat, pathogenicity, and epidemiology of E. amylovora, E. pyrifoliae, Erwinia spp. from Japan, E. piriflorinigrans, E. billingiae, and E. tasmaniensis. In addition, the interaction of these species with pome fruit trees is discussed
Effect of pollen quality on the efficacy of two different life-style predatory mites against Tetranychus urticae in citrus
No full textCover crops can serve as a reservoir of natural enemies by supplying alternative food sources as pollen. However, pollen quality and availability can modulate phytoseiid communities. In clementine trees associated with a cover crop of Festuca arundinacea Schreber, these communities were more diverse than those associated with a multifloral wild cover crop. As a consequence, the former had a better regulation of Tetranychus urticae Koch (Acari: Tetranychidae) populations than the latter. Longer provision of higher quality pollen in the multifloral cover relative to F. arundinacea is suspected to interfere with the biological control of T. urticae by specific phytoseiid predators (Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus (McGregor)) by enhancing the less efficient generalist pollen feeder Euseius stipulatus (Athias-Henriot) which is a superior intraguild predator. To determine whether pollen quality is behind these results, the effect of the provision of two different pollens (Carpobrotus edulis (L.) L. Bolus and F. arundinacea) on the efficacy of two phytoseiid species (E. stipulatus and N. californicus) to regulate T. urticae populations has been studied under semi-field conditions. Results suggest that pollen provision does not enhance the ability of these phytoseiids to reduce T. urticae populations. However, C. edulis pollen resulted in explosive increases of E. stipulatus numbers that did not occur with F. arundinacea pollen. Therefore, poor quality pollen may prevent pollen feeders from reaching high numbers in the field. This effect could benefit phytoseiid species suffering intraguild predation by E. stipulatus, the predominant phytoseiid species in Spanish citrus orchards and explain field results. (C) 2012 Elsevier Inc. All rights reserved
Descripción de variedades de caqui (Diospyros kaki Thunb.) del Banco de Germoplasma del IVIA
No full textEl caqui (Diospyros kaki Thunb.) es una especie frutal perteneciente a la familia Ebenaceae, que tiene una gran importancia en algunos países asiáticos, especialmente en China, de donde es originario. En España, el caqui se extendió como árbol ornamental y por su madera a finales del siglo XIX. Más tarde, como árbol frutal llegó a ser un cultivo tradicional a lo largo del área mediterránea en jardines o huertos familiares destinados al consumo local. Sin embargo, en los últimos 15 años, en España, y sobre todo en Valencia, ha tenido lugar el mayor y más rápido crecimiento de la producción de caqui de toda la cuenca del Mediterráneo. En 2004, el IVIA empezó a constituir un banco de germoplasma de caqui con la introducción de 26 accesiones. Actualmente, mediante sucesivas ampliaciones, el banco cuenta con 108 accesiones de diversas procedencias. En esta publicación se presenta la descripción de aquellas 26 accesiones iniciales del banco, de las cuales existen datos completos de caracterización de 3 años. La descripción de las accesiones va precedida de una breve introducción sobre el origen y descripción botánica de la especie, la clasificación de las variedades y la importancia económica del cultivo. La descripción y caracterización de las variedades se ha realizado utilizando el protocolo de la UPOV (2004) para Diospyros kaki. En todos los casos el cv. “Rojo Brillante”, el más importante de España, se ha tomado como cultivar de referencia. El banco de germoplasma ha mostrado diferencias notables entre accesiones, no solamente en cuanto a caracteres fenológicos, sino en caracteres pomológicos y agronómicos. Tanto el protocolo como los datos obtenidos y las fotografías de las accesiones descritas se incluyen en los anejos correspondientes