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Inoculum dynamics and environmental factors associated with the preharvest contamination of citrus fruits by Geotrichum citri-aurantii
Get PDFThe aim of this study was to establish the methodology and determine the relationships
between climatic factors and contamination of citrus fruit by the soil-inhabitant pathogenic
fungus Geotrichum citri-aurantii. This pathogen causes sour rot decay of citrus. The field trial
was set up in a ‘Murcott’ mandarin experimental orchard in Salto, Uruguay. Fruit sampling
was conducted weekly from March to June 2022. Six fruits from 2-3 trees per experimental
unit were arbitrarily selected within 50 cm from the orchard floor. Rainfall, air temperature,
wetness and relative humidity sensors were placed in the center of the orchard. Wind
sensors were placed at each sampling location. The mean number of epiphytic spores of G.
citri-aurantii per fruit (abundance) and the proportion of fruits positive for G. citri-aurantii
(incidence) were determined in the laboratory by washing and plating serial dilutions.
Climatic factors were related to G. citri-aurantii abundance or incidence through generalized
linear models specifying the normal or binomial error structure, respectively. For both
incidence and abundance, a significant negative relationship was observed with rainfall and
wind speed. In contrast, the relationship was significantly positive for wind gusts. The
variables wetness and maximum temperature were negatively and significantly related only
to abundance. Further field trials are necessary to validate the models and confirm the
results obtained in this first year of the study
Rice Thematic Special Issue: Beneficial Plant–Microbe Interactions in Rice
Get PDFPlants associate with a large diversity of microorganisms, collectively known as the microbiome. Some of these microorganisms are capable of establishing symbiotic interactions with their host, and these beneficial plant–microbe interactions have enormous potential to improve plant growth and productivity under stressful environments. Beneficial microorganisms, like rhizobacteria and arbuscular mycorrhizal fungi, are generally recruited from the environment, while others reside in plant tissues (e.g. endophytes)
The combined effect of Trichoderma harzianum and Nesidiocoris tenuis inoculation on water stress in tomato
Get PDFIn tomato crops in southern Europe and North Africa, the zoophytophagous predator
Nesidiocoris tenuis is widely used as a biological control agent. However, this predator also
feeds on the tomato plant, which under certain circumstances, results in plant damage (flower
abortion, necrotic rings and apical desiccation). Recently the use of certain endophytic fungi in
tomatoes has been shown to reduce the damage caused by N. tenuis. In this work, the effect of
using the soil-borne beneficial fungus Trichoderma harzianum and N. tenuis (individually and
combined) in tomato plants was studied under three water stress levels (regular, light and
moderate stress). Our results showed that the greater the water stress, the more damage caused
by N. tenuis. The inoculation of T. harzianum improved the resistance of the tomato against
water stress. Interestingly, in the treatments where N. tenuis was established in plants inoculated
with T. harzianum; the incidence of N. tenuis damage was lower than in plants without
T. harzianum. These results show the benefit of combining both biological control agents in a
global context of climate change, where water stress management will be essential
Understanding Blood versus Blond Orange Consumption: A Cross-Cultural Study in Four Countries
Get PDFUnderstanding consumer perceptions and attitudes to specific fruit is key information for not only increasing fruit consumption, but also for marketing reasons. It may also give clues to breeders to set quality objectives. This study explores different aspects that help to explain blood vs. blond orange consumption: availability and consumption habit, satisfaction attributes, facilitators and consumption barriers, consumption contexts, expectations and purchase intention. The study was conducted in China, Mexico, Spain and Italy, where citrus fruit consumers were invited to respond an online questionnaire. Our results revealed Italy as the country with the highest availability and consumption of blood oranges, followed by China, Mexico and Spain. “Liking” and “healthy properties” were the most important reasons for consumption irrespectively of orange type, but certain differences among countries were detected in secondary reasons. In all the countries, “juicy” was the most relevant attribute for consumer satisfaction, followed by flavour/taste attributes. “Aromatic” and “unfibrous” were substantial requirements for Italians and Chinese, while Spaniards attached importance to the blood oranges colour. Regarding consumption contexts, “eat with salt or chilly powder” was specific for Mexico, while “to improve health”, “as a gift” or “at a restaurant” were contexts mainly cited in China. Despite taste preferences for other fruit being the main consumption barrier in all the countries for both orange types, the relevance of other barriers depended on culture and orange type. Mexican participants seemed to take a more neophobic attitude to blood oranges, while “inconvenient” was reported as a barrier for consuming blond ones in Spain and China. We conclude that blond and blood oranges can co-exist on markets at a high consumption rate, as in Italy. Specific interventions are needed in other countries because consumer attitudes to oranges, mainly blood ones, depend on culture
Los neonicotinoides modifican la composición bacteriana de la melaza y la preferencia de los parasitoides por esta fuente de alimento
Get PDFLos neonicotinoides son los insecticidas sistémicos más ampliamente utilizados a escala global a pesar de que resultan tóxicos para los insectos beneficiosos que se alimentan de néctar o melaza. Varios estudios han demostrado que los insectos beneficiosos no son capaces de discriminar entre néctar contaminado y no contaminado con neonicotinoides. Sin embargo, esto nunca se ha comprobado para la melaza, la principal fuente de carbohidratos en muchos ecosistemas agrícolas. Para abordar esta cuestión, recogimos la melaza excretada por Planococcus citri Risso (Hemiptera: Pseudococcidae) que se habían alimentado de plantas tratadas y no tratadas con el neonicotinoide tiametoxam
Complejo de parasitoides de Pseudococcus longispinus Targioni- Tozzetti (Hemiptera: Pseudococcidae) en caqui
Get PDFActualmente, Pseudococcus longispinus Targioni-Tozzetti (Hemiptera: Pseudococcidae) es la plaga que más pérdidas económicas genera en el cultivo del caqui en España. Los parasitoides juegan un papel clave en la regulación de las densidades poblaciones de los pseudocóccidos. Sin embargo, en el caso de P. longispinus se desconoce el complejo de parasitoides que lo atacan en el cultivo del caqui. En este trabajo se ha estudiado el complejo de parasitoides de P. longispinus en parcelas de caqui de la Comunidad Valenciana, la principal zona de producción en la cuenca Mediterránea
Geostatistical Methods to Build Citrus Cross-Pollination RiskMaps
Get PDFValencian citriculture is oriented towards fresh production, which requires fruits with few seeds or seedless fruits. Consequently, parthenocarpic and self-incompatible varieties are mainly cultivated. However, some mandarin varieties, under favorable circumstances, induce seed formation in other mandarins by cross-pollination. This phenomenon depends on the germination capacity of the pollen of the pollinating variety, the number of ovules of the pollinated variety, the distance between them, and the abundance of pollinating insects. Previous studies in Instituto Valenciano de Investigaciones Agrarias (IVIA) have determined the ability to pollinate and be pollinated by all commercial varieties in Europe. Moreover, the Regional Government, Generalitat Valenciana, has georeferenced information on the cultivated varieties. We present two geostatistical models to estimate the risk of plots to be pollinated, depending on the varieties present in their environment, the number of plants, and their distance. Models are used to generate local and regional cross-pollination risk maps. Moreover, the robustness of these models to changes in the values assigned to their main parameters is assessed using different similarity calculations
Effect of progressive irrigation water reductions on super-high-density olive orchards according to different scarcity scenarios
Get PDFThe cultivation of super-high-density (SHD) olive orchards in the Mediterranean Basin usually faces drought events due especially to low precipitation, high temperature and solar radiation in summer. Hence regulated deficit irrigation (RDI) strategies can be a useful tool for irrigation management to limit yield loss. Therefore, this work aimed to find the most suitable RDI strategy by placing special emphasis on phase II of fruit growth for SHD olive orchards irrigated below theoretical water requirements. Four irrigation strategies were defined according to different water availability scenarios: fully-irrigated, RDI1, RDI2 and RDI3, scaled to respectively supply 450, 350, 250 and 150 mm year-1. Tree water relations, trunk growth, fruit and oil yields, were evaluated. The study was carried out for 5 years in an ‘Arbequina’ commercial orchard (1667 trees ha-1) in Villena, Alicante (Spain). The main results showed that ‘Arbequina’ tree irrigation water productivity (both olive and oil) gradually increased as irrigation dose lowered. Olive yield depended heavily on the applied irrigation dose, with the highest olive yield for the Control trees. However, the oil yield in the RDI1 trees was similar to that of the Control trees, but strategies RDI2 and RDI3 reduced yield. All the RDI strategies diminished vegetative development, and RDI2 was the most efficient strategy for resource distribution (olive yield vs. vegetative growth). Therefore based on oil production, vegetative growth and irrigation water savings, RDI1 was the most recommendable irrigation strategy for the Arbequina’ olive trees cultivated in SHD under semi-arid Mediterranean conditions
Antifungal edible coatings to control Alternaria black spot and maintain the quality of 'Rojo Brillante' persimmon during cold storage
Get PDFSpain is the second persimmon producing and main exporting country in the world, and ‘Rojo Brillante’ is the most important cultivar. Nowadays, the main interest of the Spanish persimmon industry is to extend the marketing period to reach off-season markets and technologies such as 1-methylcyclopropene in combination with cold storage are being used to reduce chilling injury and maintain fruit firmness. However, ‘Rojo Brillante’ persimmon is quite susceptible to postharvest Alternaria black spot, caused by Alternaria alternata
Induction of plant defenses: the added value of zoophytophagous predators
Get PDFSeveral biological control agents of the hemipteran insect families Miridae, Anthocoridae and Pentatomidae, as well as mites of the family Phytoseiidae are known as zoophytophagous predators, a subset of omnivores, which are primarily predaceous
but also feed on plants. It has been recently demonstrated that zoophytophagous predators are capable of inducing defenses in plants through their phytophagy. Despite the vast fundamental knowledge on plant defense mechanisms in response to herbivores, our understanding of defense induction by zoophytophagous predators and applied implications is relatively poor. In this review, we present the physiological basis of the defense mechanisms that these predators activate in plants. Current
knowledge on zoophytophagous predator-induced plant defenses is summarized by groups and species for the predators of
economic importance. Within each group, feeding habits and the effects of their induced-plant defenses on pests and natural enemies are detailed. Also, the ecological implications of how the induction of defenses mediated by zoophytophagous
predators can interact with other plant interactors such as beneficial soil microorganisms and plant viruses are addressed. Based on the above, we propose three approaches to exploit zoophytophagous predator-induced defenses in crop protection and to guide future research. These include using predators as vaccination agents, employing biotechnological approaches, as well as applying elicitors to elicit/mimic predator-induced defenses