ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Ants affect citrus pests and their natural enemies in contrasting ways
No full textAnts are one of the most abundant insect groups in citrus orchards. They help in controlling pests, but they can also facilitate the outbreak of other pests, such as those that produce honeydew. Moreover, ants can also affect natural enemies of pests. Here, we review how ants affect pest abundance, considering whether the pest produces honeydew and whether it spends part of its life-cycle in the soil (edaphic stages). We also investigated the effects of the presence of ants on natural enemies with a meta-analysis and how this effect is modified by honeydew production by the pest, the most abundant ant species, and the specialization and mode of dispersal (winged or wingless) of the natural enemy. The presence of ants decreased the abundance of non-honeydew producing pests, but increased the abundance of honeydew producers. Ants increased the abundance of pests without edaphic stages, but decreased pests with such stages. In addition, the identity of the most abundant ant species affected the abundance of natural enemies; the ants Iridomyrmex rufoniger and Lasius grandis had a negative impact whereas other ant species did not affect the abundance of natural enemies. Moreover, the presence of ants decreased the abundance of generalist and winged natural enemies of honeydew-producing pests. Our review provides crucial information on the effects of ants on biological control practices in citrus orchards, and increases our understanding of the relationships between ants, pests and their natural enemies
Modeling Inoculum Availability of Plurivorosphaerella nawae in Persimmon Leaf Litter with Bayesian Beta Regression
Get PDFCircular leaf spot (CLS), caused by Plurivorosphaerella nawae, is a serious disease affecting persimmon (Diospyros kaki) that is characterized by necrotic lesions on leaves, defoliation, and fruit drop. Under Mediterranean conditions, P. nawae forms pseudothecia in the leaf litter in winter, and ascospores are released in spring, infecting susceptible leaves. Persimmon growers are advised to apply fungicides for CLS control during the period of inoculum availability, which was previously defined based on ascospore counts under the microscope. A model of inoculum availability of P. nawae was developed and evaluated as an alternative to ascospore counts. Leaf litter samples were collected weekly in L’Alcúdia (Spain) from 2010 to 2015. Leaves were soaked and placed in a wind tunnel, and the released ascospores of P. nawae were counted. Hierarchical Bayesian beta regression methods were used to model the dynamics of ascospore production in the leaf litter. The selected model included accumulated degree-days (ADDs) and ADDs taking into account the vapor pressure deficit (ADDvpd) as fixed effects and year as random effect. This model had a mean absolute error of 0.042 and a root mean square error of 0.062. The beta regression model was evaluated in four orchards from 2010 to 2015. Higher accuracy was obtained at the beginning and the end of the ascospore production period, which are the events of interest to schedule fungicide sprays for CLS control in Spain. This same modeling framework can be extended to other fungal plant pathogens whose inoculum dynamics are expressed as proportion data
Blade pitch and air-outlet width effects on the airflow generated by an airblast sprayer with wireless remote-controlled axial fan
Get PDFThe airblast sprayers are equipped with a fan generating an air stream that helps the sprayed droplets to reach out and penetrate the tree canopy. Recently an automatic air regulation system has been developed and integrated in an airblast sprayer equipped with a conventional axial fan (900 mm diameter). This system, thanks to a wireless connection between a dedicated tablet and sprayers actuators, allows to remotely control the blade pitch and the air-outlet section, varying the characteristics of airflow generated by the fan. Therefore, the present work aims to characterize the different air streams derived from the combination of two fan outlet section widths (110 and 150 mm) and three blade pitches (20°, 25° and 30°). For each combination, the three components of air velocity (m s?1) were measured, taking as reference the plane following the theoretical trajectory of the main current leaving the fan. In this plane, velocities were measured at 1.0, 3.0, 5.0 and 10.0 m from the outlet section on both sides of the sprayer. At each distance, the velocities from 0.25 to 4.00 m in height were recorded. This same procedure was repeated in two planes parallel to the reference plane, 0.30 m behind and after respectively. Additionally, the velocities in the fan outlet section were also measured to obtain the airflow rate. In general, the outlet section and the blade pitch had a significant effect on the velocity components. An outlet section of 110 mm meant a smaller airflow rate and a higher initial velocity, while with 150 mm the airflow rate reduced and the initial velocity decreased. Velocities could be bigger by enhancing the blade pitch. The turbulence intensity was similar at 1.0 m distance in all cases
Influence of water regime on grape aromatic composition of Muscat of Alexandria in a semiarid climate
Get PDFIrrigation effects in relation to the environmental conditions on grape aromas are still unknown. This study aims to clarify the effects of water regime on the aromatic composition of “Muscat of Alexandria” grapes under the semiarid climate conditions of eastern Spain and over three seasons. The relationships between total volatile composition in free and glycosidically-bound fractions, vine performance, and grape composition were also assessed. The watering treatments studied were: sustained deficit irrigation (SDI) at 50% of the estimated crop evapotranspiration (ETc); early deficit (EDI), where pre-veraison water deficit was imposed; late deficit (LDI), in which a water shortage was applied during post-veraison; and control (C), irrigated at 100% of ETc during the entire season. The effects of water regimes on volatile and glycosidically-bound composition were different between seasons due to the predominant effect of the environmental conditions on aromatic composition. The seasons with the greater yield were associated to a lower grape aromatic composition, however, this effect at the crop level was less pronounced in the most irrigated treatment. In drier seasons, irrigation delayed ripening and increased the terpene concentration of “Muscat of Alexandria” grapes, showing a high treatment and season interaction. Specific water regimes have the potential to buffer the effects of environmental conditions on the aromatic composition of “Muscat of Alexandria” grapes in a semi-arid climate, as the result of the complex relationships between climatic factors, vine performance and grape maturity
Effects of Orange Pulp Conservation Methods (Dehydrated or Ensiled Sun-Dried) on the Nutritional Value for Finishing Pigs and Implications on Potential Gaseous Emissions from Slurry
Get PDFThe inclusion of orange pulp (OP) in pig diets may promote the circular economy, but drying procedures might influence its nutritional value and environmental impact. The purpose of this study was to determine the energy value and nutrient digestibility of dehydrated (DOP) and ensiled sun dried (ESDOP) orange pulp. The potential ammonia (NH3) and methane (CH4) emissions derived from slurry were also measured. Digestible energies of 14.2 and 13.2 MJ/kg DM for DOP and ESDOP, respectively, were estimated by difference after a 500 g/kg substitution of a basal diet with OPs. A high fiber digestion efficiency was observed for both OPs. Pigs fed the basal diet showed a higher intake and a greater excretion of urine N than pigs fed with OP, but fecal N excretion did not differ among diets. A higher benzoic and hippuric acid content in urine was observed in OP than in basal diet. Altogether, these findings explained a lower pH in slurry of OP diets and a reduction of potential NH3 emissions. The biochemical CH4 potential also decreased, especially with ESDOP. Overall, both OP are relevant sources of energy for pig diets. Their inclusion in feeds generate favorable changes of slurry characteristics that reduce potential NH3 and CH4 emissions
Untargeted Metabolomics of Rind Essential Oils Allowed to Differentiate Two Closely Related Clementine Varieties
Get PDFChemical characterization of clementine varieties (Citrus clementina Hort. ex Tan.) essential oils (EO) can lead to variety identification and valorization of their potential use in food and aroma industries. The goal of this study was the chemometric discrimination between two very closely related and morphologically identical clementine varieties, Clemenules (NL) and Clemenpons (PO), based on their rind EO, to identify the differential volatile organic compounds (VOCs) and to determine their antioxidant capacity. EO rind volatile profile was determined by gas chromatography coupled to mass spectrometry in Citrus fruit at different ripening stages grown two independent years in two different locations. Untargeted metabolomics and multivariate data analysis showed an evolution of EO volatile profiles markedly parallel in both varieties. Although EO qualitative composition was identical in both varieties, PLS-DA allowed the identification of characteristic VOCs, quantitatively discriminating them along all the ripening process. PO showed higher accumulation of several mono- and sesquiterpene compounds such as trans-carveol, while NL showed higher levels of aldehyde and alcohol non-terpenoids like dodecanal. Both varieties evinced identical EO antioxidant
activities, indicating a similar value for food preservation. Hence, untargeted metabolomics approach based on rind EO volatiles was revealed as a powerful technique able to differentiate between morphologically undistinguishable Citrus varieties
Nutraceutical profiles of apricots (Prunus armeniaca L.) as a source of fruit quality traits for breeding
Get PDFAim of study: In a social context of increasing concern about healthy diets, the development of new varieties with enhanced content in nutraceutical compounds is an important objective of the fruit breeding programs currently developed. In this sense, apricot is a fruit crop very appreciated by consumers worldwide due to its organoleptic characteristics, but also plays an important role in human nutrition due to its content of phytocompounds as sugars, organic acids, vitamins and polyphenols. Area of study: The identification of sources of variation for these traits could be useful for apricot breeding worldwide. Material and methods: New selections from the apricot breeding program carried out at the Instituto Valenciano de Investigaciones Agrarias (IVIA, Spain) and traditional varieties have been analysed aimed at identifying sources of genetic variation for fruit quality. For this purpose, sugar content, organic acids and ascorbic acid were studied during three crop years. Main results: Results revealed sucrose and glucose as the major sugars, malic and citric acid as the main organic acids, and diverse ascorbic acid content among the cultivars studied. Research highlights: Some accessions point as potential sources to increase fruit quality. In addition, the study showed that apricot peel is an excellent source of nutraceutical compounds. Moreover, this study opens up new possibilities to study the genetic control of these traits in apricot in the future
Harmonization of plant protection products dose expression and dose adjustment for high growing 3D crops: A review
Get PDFThis review outlines the background and current status of different dose expressions of plant protection products (PPP) applied in three-dimensional (3D) crops that are grown in orchards, groves, berry plantations, vineyards or greenhouses. It describes the course of dose expression harmonization process, and gives an overview of dose adjustment tools. In some EU countries there are used dose expressions that link the recommended amount of PPP with canopy height (CH), leaf wall area (LWA), tree row volume (TRV), or plant row distance (PRD). In the Mediterranean countries, a common way of PPP dosing recommendation is concentration of spray liquid. The advantages and disadvantages of each dose expression are discussed. Harmonization of dose expressions has for long been of great importance for the PPP authorization procedure, which in the EU is performed on a zonal basis. In the Central Zone it was agreed that the LWA model would be a common dose expression that must be used during efficacy trials in pome fruits, vines and high growing vegetables, and then in the subsequent zonal evaluation process. For the crops with wide canopies, such as citruses, olives or nuts, which are mainly grown in the Southern Zone, the TRV model might be a more appropriate dose expression to be agreed for a common use. However, any dose expression method should be corrected based on leaf area density. The crop-specific decision support tools, assisting growers to adjust effective PPP dose in specific circumstances, cover pome and stone fruits, citruses, olives, vines and greenhouse tomatoe
Physico-chemical, sensorial and nutritional quality during the harvest season of ‘Tango’ mandarins grafted onto Carrizo Citrange and Forner-Alcaide no. 5
Get PDF‘Tango’ mandarin is becoming one of the most demanded varieties in the Mediterranean Region. However, no information on the quality of ‘Tango’ fruit in this citrus area has been reported. In this study, the physico-chemical, nutritional and sensorial quality of ‘Tango’ mandarins grafted onto Carrizo Citrange and FA5 rootstocks from two locations (Sevilla and Huelva) was evaluated by harvest season. The fruit from Sevilla exhibited lower levels of acids and sugars than those from Huelva, which was associated with a higher sandy soil percentage in the Huelva orchard. In both orchards, the FA5-produced fruit had higher sugars and acids. Flavonoids were affected mainly by location, and the Huelva fruit exhibited the highest levels. The highest vitamin C was for the FA5 fruit. The decreased antioxidant capacity observed throughout the harvest season was related to reduced vitamin C. The sensorial evaluation corroborated changes in the quality parameters