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A new methodology to assess the maximum irrigation rates at catchment scale using geostatistics and GIS
No full textSoil hydraulic parameters are important for irrigation scheduling. In the domain of “precision irrigation”, knowledge of the spatial distribution of these parameters is useful in determining the maximum irrigation rate for each field in a catchment. This study focuses on the development of a new methodology to assess the spatial distribution of the maximum irrigation rate depending on the available soil water holding capacity (ASWHC). This methodology combines geostatistical techniques with geographical information system (GIS) tools. A pilot zone of 12 400 ha in a Spanish Mediterranean area was selected to develop this methodology. The linear coregionalization model (LMCR), considering the percentage of sand, carbonates, and ASWHC at others soil depths as covariates, was the best option to model the ASWHC. Other required soil parameters were also spatially modeled. The percent of coarse fragments was modeled by regression kriging considering the soil map as an auxiliary variable. The bulk density was spatially modeled by LMCR, and extended to the rooting depth by linear regression. The spatial distributions modeled were implemented in a GIS with other spatial information layers of irrigation management parameters, such as the maximum allowable depletion of soil water content, the percent of wetted soil and the irrigation depth. The combination of these layers in the GIS was used to estimate the maximum irrigation rates for each field. A propagation error analysis was performed to know the uncertainties in the maximum irrigation rate estimation. Based on this information, the irrigation managers could optimize the irrigation rates for each field
Mobility and efficacy of abamectin and imidacloprid against Rhynchophorus ferrugineus in Phoenix canariensis by different application methods
No full textBACKGROUNDRhynchophorus ferrugineus is the most destructive pest of palms. As detection of early infestation stages is difficult, preventive measures, mostly chemical control, are crucial. Stipe injection of insecticides has developed rapidly as a suitable technique. However, pesticide movement within palms and palm reaction to wounding remain controversial. We used abamectin and imidacloprid applied by crown spray, stipe and frond injections to disentangle how these pesticides move within P. canariensis and how tissues wounded by injection heal. Furthermore, we established their lethal doses to larvae of R. ferrugineus. RESULTSMaximum residues of imidacloprid (0.1mgkg(-1)) were detected in crown and frond samples for up to 2 months after stipe injection, whereas maximum residues of abamectin were found in frond tip samples (0.5mg active substance kg(-1)) 5 months after stipe injection. Based on the lethal concentrations calculated, these doses could satisfactorily protect palms for up to 3 months after treatment. No significant wound damage was observed 2 years after injection. CONCLUSIONStipe injection, irrespective of the active substance considered, resulted in better distribution and higher persistence compared with frond injection and, especially, crown spray. As a consequence, our results point to stipe injection as a good alternative to control R. ferrugineus. (c) 2014 Society of Chemical Industr
Effect of different freezing velocities on the quality and fertilising ability of cryopreserved rabbit spermatozoa
No full textThe freezing step of the cryopreservation protocol negatively influences the quality and fertilising ability of rabbit spermatozoa. This study determines the effect of different rates of freezing on the quality and fertilising ability of rabbit spermatozoa cryopreserved with dimethylsulfoxide (DMSO) (1.75M) and sucrose (0.05M). Ejaculates from meat rabbit line males (n=12) were pooled and each pool (n=7) was split into four aliquots. One group of straws (control, C) was frozen in static liquid nitrogen vapour (5cm above the liquid nitrogen, 10min) and the other groups were frozen at different freezing rates (degrees Cmin(-1)) from -6 degrees C to -100 degrees C using a programmable freezer: slow (-15 degrees Cmin(-1), S), medium (-40 degrees Cmin(-1), M) or fast (-60 degrees Cmin(-1), F). After thawing (50 degrees C, 12s), the quality was highest (P<0.05) in C and M samples and lowest in S and F samples. F samples presented the lowest litter sizes (P0.05) and fertility whilst M samples exhibited the highest values. In conclusion, the freezing rate affects both the quality and the fertilising ability of frozen-thawed rabbit spermatozoa, with both slow (-15 degrees Cmin(-1)) and fast (-60 degrees Cmin(-1)) freezing rates being detrimental for the quality and fertilising ability
El cultivo del caqui
No full textEn este capítulo se describen las fisiopatías más comunes que pueden aparecer en los frutos de caqui, tanto en campo como en poscosecha. Estos desórdenes están causados por factores climáticos, nutricionales, labores culturales no adecuadas o mal manejo del fruto en recolección o poscosecha. Todas estas alteraciones reducen de forma significativa la calidad del fruto y causan graves pérdidas económicas en su comercializació
Acta Horticulturae
No full textSomatic hybridization by protoplast fusion is an effective technique for citrus rootstock breeding. It theoretically allows the accumulation of all genes of the parents irrespective of their heterozygosity level and therefore the addition of complementary dominant traits. In the present work, protoplasts were isolated from callus of C. macrophylla and from leaves of 'Carrizo' citrange (C. sinensis x P. trifoliata). Chemical, electro-chemical and electric fusions were performed and ploidy level of the regenerated plants was evaluated by flow-cytometry. Five tetraploid plants, one pentaploid plant, one mixoploid (3x-6x) plant and one heptaploid plant were recovered. All these plants were analyzed with SSR markers, distributed in the nine chromosomes of citrus. Cytoplasmic genomes were also characterized using chloroplastic and mitochondrial markers. Results showed that mitochondrial genome was inherited from C. macrophylla in all plants while segregation was observed for chloroplastic genome. Nuclear genome analysis revealed the loss of parental alleles in most of the regenerated plants. In tetraploids, it affected mainly C. macrophylla alleles, while the alleles lost in pentaploid and heptaploid plants were mostly from P. trifoliata. Results suggest chromosome instability in this complex intergeneric combination with apparent non-random loss of chromosome fragments. Two allotetraploid somatic hybrids were selected for evaluation as rootstocks
Tomato plant responses to feeding behavior of three zoophytophagous predators (Hemiptera: Miridae)
No full textPlant responses induced by zoophytophagous plant bugs (Miridae) have not been thoroughly studied. Here, we show that three different zoophytophagous predators (Nesidiocoris tenuis, Macrolophus pygmaeus and Dicyphus maroccanus) have different capacities for the induction of responses in tomato plants, resulting in varying degrees of attractiveness of the plants to pests and natural enemies. Tomato plants punctured by N. tenuis were less attractive to the whitefly Bemisia tabaci and to the lepidopteran Tuta absoluta. In contrast, tomato plants punctured by M. pygmaeus and D. maroccanus were not able to repel B. tabaci and, more interestingly, became more attractive to T. absoluta. The ability of N. tenuis to make tomato plants less attractive to B. tabaci was attributed to the activation of the abscisic acid (ABA) signaling pathway, which was only up-regulated in plants punctured by N. tenuis. However, the phytohormones involved in the behavioral responses of T. absoluta could not be identified; therefore, further studies are required. Additionally, all three zoophytophagous mirid predators activated jasmonic acid (JA) signaling pathways, which resulted in the parasitoid Encarsia formosa being attracted to tomato plants. Here, the implications of these results on the efficacy of these three predators as biocontrol agents are discussed. (C) 2015 Elsevier Inc. All rights reserved
Genetic islands in pome fruit pathogenic and non-pathogenic Erwinia species and related plasmids.
Get PDFNew pathogenic bacteria belonging to the genus Erwinia associated with pome fruit trees (Erwinia, E. piriflorinigrans, E. uzenensis) have been increasingly described in the last years, and comparative analyses have found that all these species share several genetic characteristics. Studies at different level (whole genome comparison, virulence genes, plasmid content, etc.) show a high intraspecies homogeneity (i.e., among E. amylovora strains) and also abundant similarities appear between the different Erwinia species: presence of plasmids of similar size in the pathogenic species; high similarity in several genes associated with exopolysaccharide production and hence, with virulence, as well as in some other genes, in the chromosomes. Many genetic similarities have been observed also among some of the plasmids (and genomes) from the pathogenic species and E. tasmaniensis or E. billingiae, two epiphytic species on the same hosts. The amount of genetic material shared in this genus varies from individual genes to clusters, genomic islands and genetic material that even may constitute a whole plasmid. Recent research on evolution of erwinias point out the horizontal transfer acquisition of some genomic islands that were subsequently lost in some species and several pathogenic traits that are still present. How this common material has been obtained and is efficiently maintained in different species belonging to the same genus sharing a common ecological niche provides an idea of the origin and evolution of the pathogenic Erwinia and the interaction with non-pathogenic species present in the same niche, and the role of the genes that are conserved in all of them
Acta Horticulturae
No full textBreeding and selection of new citrus rootstocks is very important in the Mediterranean Basin because citrus faces increasing biotic and abiotic constraints. In Tunisia, citrus contributes significantly to the national economy, and increases in the citrus production area are favored by natural conditions and economic considerations. Sour orange, the most widespread rootstock of the Mediterranean area, is also the main one in Tunisia. In addition to sour orange, other citrus rootstocks well adapted to local environmental conditions are traditionally used and should be important genetic resources for breeding. Prior to initiating any breeding program, determining the genetic diversity of Tunisian citrus rootstocks was a priority. Two hundred and one local accessions belonging to four facultative apomictic species (C. aurantium, sour orange; C. sinensis, sweet orange; C. limon, lemon; and C. aurantifolia, lime) were collected and genotyped using 20 nuclear SSR markers and four indel mitochondrial markers. Sixteen distinct multi-locus genotypes (MLGs) were identified and compared to reference genotypes from French and Spanish collections. The differentiation of the four varietal groups was well-marked. Each group displayed a relatively high allelic diversity, primarily due to very high heterozygosity. The Tunisian citrus rootstock genetic diversity is predominantly due to high heterozygosity and differentiation between the four varietal groups. The phenotypic diversity within the varietal groups has resulted from multiple introductions, somatic mutations and rare sexual recombination events. This diversity study enabled the identification of a core sample of accessions for further physiological and agronomical evaluations. These core accessions will be integrated into citrus rootstock breeding programs for the Mediterranean Basin
Acta Horticulturae
No full textElucidation of genomic sequences is an essential and necessary first step to identify genetic variants associated with agronomic traits of interest. The Citruseq Consortium, a joint effort developed by public institutions and private companies has sequenced the genomes of 150 citrus varieties with the Illumina platform at high average coverage. Paired end genomic DNA libraries of 100 (2x) bp reads and with an average insert size of 500 bp were constructed. The haploid genome of Citrus clementine (www.phytozome.com) was used as reference genome. More than 150 Citrus genomes including rootstocks and species of mandarins, oranges, lemons, grapefruits and limes were sequenced. The consortium also generated a web portal that allows searching and sequence comparisons among approximately 8 million of gene variants and 45 billion of base pairs. Initial analyses suggest that the stored information can help unravel fundamental aspects of biological and evolutionary interest such as the origin of citrus. From the commercial standpoint this information may help to authenticate varieties, to improve marker-assisted breeding and to identify genes of major agronomic interest
Acta Horticulturae
No full textThe phytosanitary surveillance plays an important role in the early detection to prevent the establishment of harmful pests of economic and quarantine importance. The presence of fruit flies belonging to the genera Anastrepha, Bactrocera or Ceratitis (Diptera: Tephritidae) on the American continent constitute a potential risk of introduction, threatening the production of citrus and other hosts of countries in the region. In Cuba, the presence of some Anastrepha spp., as well as Bactrocera carambolae or Ceratitis capitata is not registered, thus surveillance for these quarantine pests and for other species of national interest continues. Results have been obtained from research on preferred host fruits located in the surroundings of citrus plots, revealing the presence and potential risk to citrus of A. suspensa, identified as of quarantine importance in countries such as the United States and others. During the period 2010-2012 three activities were conducted to characterize, diagnose and train staff to strengthen phytosanitary surveillance of Anastrepha fruit flies in citrus production areas in: Ceiba Citrus Enterprises (Artemisa), Victoria de Giron (Matanzas), Arimao (Cienfuegos) and Ciego de Avila citrus enterprises. To fulfill this objective, the composition of host fruit presence in production areas with respect to A. suspensa was evaluated. Host preferences of the main Anastrepha species detected and the effectiveness of traps and attractants were determined, and the monitoring system was relocated. The information obtained allowed designing the monitoring strategy in production areas. Training, one of the most important tools, was developed through seminars and workshops. These results provide inputs to the monitoring programs and the procedures that are essential in the development and implementation of measures for the phytosanitary surveillance and integrated management of fruit flies in Cuban citrus production