ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Efficacy of a micro-encapsulated formulation compared with a sticky barrier for excluding ants from citrus canopies
No full textInesfly IGR FITO (R) is an insecticidal paint containing chlorpyrifos and pyriproxyfen incorporated in a micro-encapsulated formulation that confers the advantage of releasing active ingredients slowly. In this study, a 15-cm band of Inesfly IGR FITO (R) was painted around citrus trunks. The efficacy of this paint and a sticky barrier to exclude ants from foraging in citrus trees was evaluated in two citrus orchards during the season in two different ant communities, one dominated by Lasius grandis and the other by Linepithema humile. Field results demonstrated that a single application of Inesfly IGR FITO (R) at the beginning of the season was highly effective in excluding ants from canopies throughout the season. Inesfly IGR FITO (R) provides an efficient and more economical alternative than current ant exclusion strategies used in many perennial crops. Further studies should be performed to determine the effects of this strategy on other pests and on beneficial arthropods in citrus
The Mn-binding proteins of the photosystem II oxygen-evolving complex are decreased in date palms affected by brittle leaf disease
No full textBrittle leaf disease or maladie des feuilles cassantes (MFC) is a disorder affecting date palms (Phoenix dactylifera L) which after a long declining process eventually leads to the death of the plant. No causal agent for the disease has been found so far but leaflets of affected palms are Mn-deficient despite the existence of adequate exchangeable Mn in the soils in which affected palms grow. The disease is specifically associated with an increase in a series of chloroplastic RNAs. A proteomic analysis of leaflets of affected and unaffected date palms showed differences in quantities of several proteins. Mn-binding PSBO and PSBP proteins, components of the oxygen-evolving complex of photosystem II, were decreased in affected tissue, reinforcing the relation between MFC and Mn deficiency. The quantities of other proteins were increased by disease suggesting a response to stress
Development and characterization of microsatellite markers in pomegranate (Punica granatum L.)
No full textThe pomegranate (Punica granatum L.) is a temperate climate species requiring high temperatures for proper and complete ripening. The species is consumed as a fresh fruit, but also can be used to obtain transformed products such as juice, jam, or preserve. It is a fruit tree species with a high degree of diversity, but the identification of cultivars by morphological traits is very difficult. Thus, the characterization of genotypes through molecular markers is of great value for germplasm preservation, genetic studies, and plant breeding. The number of simple sequence repeat (SSR or microsatellite) markers developed for this genus is too low, so in this work we report the development of 117 microsatellite loci from a CT/AG-enriched pomegranate genomic library. In order to check their utility, eleven accessions were analyzed. The polymorphism information content (PIC) value across all loci ranged between 0.09 and 0.71, with an average of 0.37. These markers will facilitate genetic diversity studies, mapping, and genotyping of pomegranate
Control of citrus postharvest decay by ammonia gas fumigation and its influence on the efficacy of the fungicide imazalil
No full textPostharvest green mold and blue mold, caused by Penicillium digitatum and Penicillium italicum, respectively, were effectively controlled by fumigation of lemons and oranges for 6 h at 22 degrees C with two applied dosages of 3000 mu L L(-1) of ammonia that was injected initially and again 2h later. This treatment did not injure oranges, however, it caused the tissue within previously injured areas on the rind of lemons to become darker in color. Fumigation of lemons with 6000 mu L L(-1) of ammonia slightly accelerated the natural transition of rind color from green to yellow. The germination of conidia of P. italicum was more sensitive to ammonia than those of P. digitatum, although many survived fumigation. About 30% of the conidia of P. digitatum and 10% of those of P. italicum could germinate after a 611 fumigation where two injections of 6000 mu L L(-1) of ammonia were applied, one initially and a second 2 h later. Ammonia fumigation controlled an isolate of P. digitatum with a high level of resistance to imazalil (IMZ). The influence of ammonia fumigation on the effectiveness of this common postharvest fungicide was examined. When fruit were first immersed in 10 or 30 mg L(-1) IMZ (about 10% of typical commercial rates) before ammonia fumigation, a single fumigation with 1500 mu L L(-1) of ammonia was adequate to control both diseases and the increase in effectiveness was usually additive and sometimes synergistic. This effect was probably due in part to the influence of pH on IMZ activity, because the neutral form of IMZ increases with increasing pH and it has markedly higher antifungal activity than the ionized molecule. Fumigation with 1500,3000, or 6000 mu L of ammonia per liter increased the pH (+/- SD) of albedo tissue of pre-existing wounds on oranges and lemons from 5.9 (+/- 0.2) before fumigation by 0.6 (+/- 0.3), 0.9 (+/- 0.4), or 1.3 (+/- 0.3) units, respectively. IMZ can be applied immediately after harvest by drenching fruit within harvest bins with aqueous IMZ solutions. Subsequent ammonia fumigation on their arrival to packinghouses may be a feasible practice, since it could employ the existent ethylene degreening chambers present at all packinghouses, if these were modified to be gas tight. Ammonia could replace synthetic fungicides or augment IMZ performance in citrus postharvest decay management. Its capacity to control IMZ resistant isolates of P. digitatum, common in citrus packinghouses, is particularly valuable. Published by Elsevier B.V
Acta Horticulturae
No full textThe survival of the citrus industry is critically dependent on genetically superior cultivars. Improvements in these traits through traditional techniques are unfortunately extremely difficult due to the unusual combination of biological characteristics of citrus. Genomic science holds promise of improvements in breeding and the main goal of our group is to develop genomics tools for the generation of new genotypes. We pursue the identification of candidate genes, alleles and genotypes improving citrus fruit quality and performance, correlating phenotypic analyses, metabolic profiling and gene expression. At completion, genes and alleles with major functions in nutritional quality and stress tolerance could be selected and genotypes with improved fruit composition searched among existing or generated collections. This goal is supported by two complementary strategies the identification of genes of agricultural interest by the use of mutants and microarrays and the elucidation of the citrus genome sequence. In this communication the efforts we are developing in this first approach are revised while the other strategy will be resumed elsewhere
Performance of hydroxypropyl methylcellulose (HPMC)-lipid edible coatings with antifungal food additives during cold storage of' Clemenules' mandarins
No full textThe performance of edible composite coatings containing hydroxypropyl methylcellulose (HPMC), hydrophobic components (beeswax and shellac), and food preservatives as antifungal ingredients was evaluated on ‘Clemenules’ clementine mandarins. Tested preservatives included potassium sorbate (PS), sodium benzoate (SB), sodium propionate (SP), and their mixtures. Intact fruit or fruit artificially inoculated with Penicillium digitatum or Penicillium italicum, the causal agents of citrus postharvest green (GM) and blue (BM) molds, respectively, were coated and stored up to 30 d at 5 °C plus 7 d at 20 °C of shelf-life. During cold storage, all HPMC-lipid coatings containing food additives significantly reduced the development of both GM and BM, although the performance was better against GM. When coated fruit were transferred to 20 °C, all coatings lost effectiveness. SB + PS-based coating was the most effective to reduce disease severity. All the coatings effectively reduced weight loss and maintained rind firmness of coated ‘Clemenules’ mandarins. The coatings did not adversely affect the ethanol content of the juice, sensory flavor, and fruit appearance. Although the internal gas concentration of coated fruit was modified, the coatings did not induce off-flavor
Effects of temperature, water regime and irrigation system on the release of ascospores of Mycosphaerella nawae, causal agent of circular leaf spot of persimmon
Get PDFExperiments were conducted under controlled conditions to quantify the effects of temperature, water regime and irrigation system on the release of Mycosphaerella nawae ascospores from leaf litter in Spanish persimmon orchards. The effect of temperature on ascospore release was best described by a Gompertz model. The end of the lag phase of ascospore release occurred at 9.75 degrees C, and the end of the exponential phase at 15.75 degrees C. Few ascospores were discharged from dry leaves wetted with 0.1 or 0.5 mm water, but significant amounts were recovered with 1-50 mm water. About half of the total ascospores were released after three wetting and drying cycles, but 32 cycles were necessary for a complete discharge. No significant difference in ascospore release was detected when the leaf litter was wetted by flood and drip irrigation. However, considering the proportion of soil area wetted in both systems, inoculum release was significantly reduced by drip irrigation. The potential of drip irrigation as a cultural control measure should be investigated
Analysis of Bioactive Compounds in Seven Citrus Cultivars
No full textChemical content in peels of fruits belonging to cultivars of Clementine mandarin (Fino, Loretina and Marisol), Satsume mandarin (Owari), Navel orange (Navelate and Navelina) and Common orange (Valencia Late) groups have been analyzed. The influence of the variety on the content of bioactive constituents at the varietal level is discussed. Rind contents showed similar tendencies for the majority of compounds although Satsume group presented the highest amounts on the flavanone glycosides hesperidin and narirutin, as well as the highest amounts of the carotenoid and beta-cryptoxanthin, comparing with the remaining varieties studied. Both mandarin and orange varieties studied showed similar tendencies concerning to other phenolic compounds and total ascorbic acid concentrations. Limonene was the most abundant peel essential oil in all cultivars studied, followed by myrcene. Calcium and potassium were the dominant macronutrients for each cultivar studied, although the proportion of the individual nutrients ranged among different cultivars
Agresividad en conejas reproductoras en función de la edad. Implicaciones en la mezcla de animales
Get PDFLa agresividad puede convertirse en un problema en los alojamientos de hembras en grupo puesto que parece
aumentar con la edad y podría suponer un problema en el momento en que se mezclen animales. Por otra parte,
los animales alojados en una misma sala podrían reconocerse por el olor, y la familiaridad podría resultar en un
comportamiento diferente al esperado al formar los grupos. En este estudio se pretende determinar, mediante la
realización de un test de residente-intruso, la edad a la cual la agresión entre hembras alojadas individualmente
alcanza los niveles más altos y la influencia que puede tener la procedencia del intruso en la intensidad de la agresión.
Setenta y cuatro conejas fueron utilizadas en este estudio actuando treinta y dos como residentes, dieciséis
como intrusos procedentes de la misma sala y las dieciséis restantes como intrusos procedentes de otra sala. De
cada cruce se registró el inicio de los diferentes comportamientos agresivos observados obteniendo la latencia al
primer comportamiento agresivo y la latencia a una pelea que provocara la interrupción del test. La edad tuvo un
efecto claro sobre la latencia a la primera agresión y sobre la latencia a pelea grave de modo que a partir de la pubertad
estas latencias se vieron ampliamente reducidas y, por tanto, incrementado el nivel de agresividad. La procedencia
del intruso únicamente tuvo efecto sobre la latencia a pelea grave, siendo esta inferior cuando éste procedía
de la misma sala que el residente (P<0,0001). Estos resultados tienen implicaciones en la mezcla de animales
sugiriendo que ésta debería hacerse lo antes posible de modo que las tendencias agresivas fueran mínimas. Por
otra parte podría resultar útil mezclar animales procedentes de diferentes salas aunque este supuesto debe ser
corroborado en futuros estudios
Effect of spray volume of two organophosphate pesticides on coverage and on mortality of California red scale Aonidiella aurantii (Maskell)
Get PDFA trial under laboratory conditions was carried out to study the possibility of decreasing the delivered dose of organophosphate insecticides without affecting their efficacy against California red scale (CRS). Aonidiella aurantii (Maskell), by reducing the volume of water used whilst maintaining the concentration of pesticide. In order to establish an optimal application volume, the coverage and the efficacy against different stages of development of CRS of two commercial organophosphate pesticides (chlorpyrifos 750 g kg(-1) WG [Dursban (R) 75 WG] and chlorpyrifos-methyl 224 g l(-1) EC [Reldan (R) E]) at four volumes of water (1, 2, 3 and 4 ml) were compared. Results showed that in general Chlorpyrifos-methyl-based product (CMBP) provided greater coverage and impact size, but did not achieve the highest efficacy. The minimum-deposited volume (1.01 mu l/cm(2)) produced 11% coverage with Chlorpyrifos-based product (CBP) and 22% with CMBP, reaching the highest efficacies (around 89-95%) against the youngest stages (N1 and N2 stages) with both products. To attain similar efficacy with males (prepupal and pupa stages), twice the volume (2.03 mu l/cm(2)) of the CBP was required, producing 28% coverage. The CMBP required higher deposited volumes (3.41 mu l/cm(2)) and higher coverage (51%). The maximum efficacy in the control of adult females (third instar and gravid female stages) was 70% with both pesticides. This level was attained with 3.41 mu l/cm(2) of CBP (36% coverage) and 4.72 mu l/cm(2) of CMBP (62% coverage). The research shows that greater coverage does not result in greater efficacy, so it would be possible to reduce the spray volume in field conditions. Further research will be carried out in order to check these results under real field conditions