Central Valley Of Chile Research Articles

Distribution of Microplastics in an Urban Soil: The Case of a Medium-Sized City in the Central Valley of Chile

Distribution of Microplastics in an Urban Soil: The Case of a Medium-Sized City in the Central Valley of Chile

Effect of storage temperature on viral RNA accumulation in Plum pox virus-infected Red Lyon plum fruit from the Central Valley of Chile

Plum pox virus (PPV), the causative agent of Sharka disease, causes serious economic losses to the stone fruit industry. As PPV is not transmitted by seed, fruit from countries with Sharka present are considered low-risk for spreading the disease. However, there have been cases raising concerns about the safety of exporting fruit from countries with Sharka disease. Due to this, the generation of new scientific evidence becomes important to address these concerns. This study aimed to compare the relative accumulation of PPV viral titer between freshly harvested infected fruit with fruit subjected to cold storage, simulating transit conditions to export markets. During two consecutive seasons, the fruit was collected from a PPV-infected ’Red Lyon’ plum orchard, and divided into three treatments (T): freshly harvested fruit (T1); fruit exposed to cold (0 °C) for seven days (T2), and fruit exposed to cold (0 °C) for 15 days (T3). Semi-quantitative RT-PCR was used to estimate the viral titer; band density values obtained for products of amplification of a PPV genome fragment were normalized with the density values obtained from the constitutive gene nad5 and plotted relative to treatment T1, which served as a control for this purpose. The results showed a significant difference (p < 0.05) between T1 and other treatments. For the first season, the viral RNA reduction was of 50% in T2 and 61% in T3, compared to T1. For the second season, the corresponding RNA viral reductions were 45% in T2 and 56% in T3, compared to T1.

Reduced Root Volume at Establishment, Canopy Growth and Fruit Production in ‘Lapins’/‘Colt’ and ‘Regina’/‘Gisela 12’ Sweet Cherry Trees

The success of establishing fruit orchards has traditionally been attributed to the vigor of the nursery plant used. This study aimed to evaluate the post-transplant survival, canopy growth and fruit productivity of two sweet cherry (Prunus avium L.) cultivars (‘Lapins’/‘Colt’ and ‘Regina’/‘Gisela 12’) with different radicular basal volumes of 100%, 50% and 25% and nursery plant types: (i) bare root (BR) or (ii) bagged (B). The initial stem diameter of the plants ranged from 12 to 19 mm, and their height ranged from 1.4 to 1.8 m. Plants grafted onto ‘Colt’ rootstock exhibited twice the initial root volume compared to those grafted onto ‘Gisela 12’. Evaluations were carried out in three commercial orchards during three seasons in the Central Valley of Chile. The results indicated that root volume and nursery type did not affect plant survival and productivity. For ‘Regina’/‘Gisela 12’, only the bag treatment resulted in less trunk cross-sectional area (TCSA) and shoot length, and for ‘Lapins’/‘Colt’, the BR25 treatment showed a lower initial TCSA than other treatments, although without a negative effect on yield. Hence, the presumption about the influence of root volume and plant type on the successful establishment of a sweet cherry on ‘Colt’ and ‘Gisela 12’ rootstock can be discarded. The survival, growth and precocity of the orchard depend more on post-planting conditions and water management than on the number or type of nursery plant roots. It is important to prioritize proper post-planting care and water management for optimal orchard health.

Chilean Botrytis cinerea Isolates with Reduced Sensitivity to Fludioxonil Exhibit Low to Null Fitness Penalties.

The main phytosanitary problem for table grape production in Chile is gray mold caused by the fungus Botrytis cinerea. To manage this issue, the primary method utilized is chemical control. Fludioxonil, a phenylpyrrole, is highly effective in controlling B. cinerea and other plant pathogens. Consistently, there have been no field reports of reduced efficacy of fludioxonil; however, subpopulations with reduced sensitivity to fludioxonil are on the rise globally, as per increasing reports. Our study involved a large-scale evaluation of B. cinerea's sensitivity to fludioxonil in the Central Valley of Chile's primary table grape production area during the growing seasons from 2015 to 2018. Out of 2,207 isolates, only 1.04% of the isolates (n = 23) exceeded the sensitivity threshold value of 1 μg/ml. Remarkably, 95.7% are concentrated in a geographic region (Valparaíso Region). Isolates with reduced sensitivity to fludioxonil showed growth comparable with sensitive isolates and even more robust growth under nutritional deficit, temperature, or osmotic stress, suggesting greater environmental adaptation. When table grape detached berries were stored at 0°C, isolates less sensitive to fludioxonil caused larger lesions than sensitive isolates (2.82 mm compared with 1.48 mm). However, the lesions generated by both types of isolates were equivalent at room temperature. This study found no cross-resistance between fludioxonil and fenhexamid, an essential fungicide integrated with fludioxonil in Chilean B. cinerea control programs. All the Chilean isolates with reduced sensitivity to fludioxonil were controlled by the fludioxonil/cyprodinil mixture, a commonly employed form of fludioxonil. The cyprodinil sensitivity in the isolates with reduced sensitivity to fludioxonil explains their low field frequency despite their null fitness penalties. However, the emergence of fludioxonil-resistant isolates inside the Chilean B. cinerea population demands a comprehensive analysis of their genetic bases, accompanied by monitoring tools that allow the permanence of field fludioxonil efficacy.

Calcium absorption by fruit and leaves of sweet cherry trees (Prunus avium L.) by isotope labeling

In sweet cherry, foliar Calcium–based products are used to mitigate rain–cracking in fruit and to improve its firmness during storage. Information on foliar Calcium (Ca) absorption efficiency by fruit and leaves in the field is scarce. In part, this is due to the limitations of the traditional analytical techniques for assessing Ca levels in these organs. Here, we hypothesize that leaves and fruit differ in their abilities to uptake surface applications of Ca and, moreover, that their abilities are influenced by phenology. To test this hypothesis, foliar 44Ca (0.05% 44CaCl2) was used to enrich sweet cherry fruit and leaves of the combination ‘Lapins’/‘Colt’ during the 2019–2020 growing season in the Central Valley of Chile (34° 0’ S, 71° 41’ W). Six treatments were applied, represented by different timings (days after full bloom, DAFB) of isotopic labeling of either fruit or leaves. Labeling was applied at Stage I, SII and SIII of fruit development. Fruit or leaves were ‘painted’ with 44CaCl2 (0.05%, 97 atom%) using a brush. Each labeling date considered a different group of similar fruiting spurs on the two-year-old wood of individual vertical branches. Additional samples were collected to measure natural abundance of 44Ca. Labeled fruit were removed 48 h after aerial 44Ca enrichment and at harvest (87 DAFB).Uptake of 44Ca by fruit and leaves was observed throughout the period of fruit development. Fruiting spur leaves (FSL) and fruit absorbed 44CaCl2 and were highly enriched 48 h after labeling. The earlier the labeling date, the higher the 44Ca tracer recovery detected in both organs. However, FSL showed higher δ44Ca ‰, 44Ca concentrations and 44Ca contents than fruit during the whole period of fruit development. After 48 h, the aerial uptake at SI (expressed as δ44Ca ‰) was 3.4 times higher in immature FSL and 5.7 times higher in immature fruit than SIII of fruit development, which indicates that Ca sprays should start soon after fruit set. We conclude that in sweet cherry, foliar Ca is absorbed by fruit and spur leaves, but the absorption is more efficient in the early stages of fruit development and for young leaves.

Disentangling the spread dynamics of insect invasions using spatial networks

IntroductionDescribing and understanding spatiotemporal spread patterns in invasive species remains a long-standing interdisciplinary research goal. Here we show how a network-based top-down approach allows the efficient description of the ongoing invasion byDrosophila suzukiiin Chile.MethodsTo do so, we apply theoretical graph methods to calculate the minimum cost arborescence graph (MCA) to reconstruct and understand the invasion dynamics ofD. suzukiisince the first detection in 2017. This method estimates a directed rooted weighted graph by minimizing the total length of the resulting graph. To describe the temporal pattern of spread, we estimate three metrics of spread: the median dispersal rate, the median coefficient of diffusion, and the median dispersal acceleration.ResultsThe estimated MCA shows that over four years,D. suzukiicolonized a ~1,000km long strip in the central valley of Chile, with an initial phase with long paths and connections and no clear direction pattern, followed by a clearer north–east propagation pattern. The median dispersal rate for the entire period was 8.8 (7.4–10.6, 95% CI), while the median diffusion coefficient was 19.6 meters2/day (13.6–27.9, 95% CI). The observed spread dynamics and the log-normal distribution of accelerations are consistent with long-distance dispersal events.DiscussionThe complexities of real landscapes cannot be summarized in any model, but this study shows how an alternative top-down approach based on graph theory can facilitate the ecological analysis of the spread of an invasive species in a new territory.

Evapotranspiration and Water Productivity of Microirrigated Wine Grape Vineyards Grown with Different Trellis Systems in the Central Valley of Chile

Evapotranspiration and Water Productivity of Microirrigated Wine Grape Vineyards Grown with Different Trellis Systems in the Central Valley of Chile

Spatial Prediction Model of Plant Water Status of an Olive Orchard (Olea europaea L.) cv. Arbequina Under Semiarid Conditions in the Central Valley of Chile

The Olive (Olea europaea L.) is a typical fruit tree of Mediterranean areas characterized by high-quality oil production and high tolerance to water deficit. Due to worldwide water scarcity in Mediterranean regions, it becomes indispensable to monitor plant water status, in example, through xylem water potential (&amp;Psi;x). Unfortunately, measurement is difficult to perform with high spatial resolution at field scale (&amp;gt; 50 measurements per hectare), due to the large amount of manpower required in the prosses which turned this technique into a high-cost solution. This situation drastically hinders its applicability in large production areas. Thus, the objective of this research is implementing a spatial prediction model of plant water status in an olive orchard, using a single &amp;Psi;x measurement performed in a reference site over the orchard. The experimental site was established in 2.2 hectares of commercial olive trees in the Pencahue valley located in the Maule region (Chile) during the 2013/14 growing season. Measurements of &amp;Psi;x were performed at key phenological stages of olive trees. The proposed methodology allowed to estimate the behavior of &amp;Psi;x in unsampled olive trees from reference site measurements, with an average spatial error less than &amp;plusmn;0.6 MPa and correlation of 0.8 (R2) ratifying the high spatial dependence between different sites sampled at field scale. Therefore, distribution of spatial variability would be adequate for the application of irrigation in homogeneous management zones, facilitating water management practices in clearly identified zones within the olive orchard under study.

Traditional Architecture as a Typological Basis for Ecological and Sustainable Architectural Design from a Climatic Perspective. The Colonial Houses of the Central Valley; Santiago, Chile.

The present study aims to explore the Colonial House in the central valley of Chile, as a typological basis for an ecological and sustainable architectural design, mainly in relation to passive climate conditioning strategies, thinking about the minimization of external agents that take care of this. The city of Santiago is selected as a case study because it is a highly urbanized area, implying constant challenges about sustainable urban development. Regarding the object, these are traditional constructions with local materials and vernacular techniques, therefore they are related to the material heritage of the area and present proven climatic strategies that can be extrapolated to establish them within a contemporary context. The methodology is carried out through a constructive analysis of a typical house to understand the decisions taken and how they influence the habitability of the building. This will be complemented with the study of secondary sources and the comparison with contemporary examples to explore the application of the referenced strategies. It is concluded that traditional typologies allow the development of new proposals associated with sustainable logics due to the constructive and climatic understandings that vernacular notions imply.

Calcium Sprays and Crop Load Reduction Increase Fruit Quality and Postharvest Storage in Sweet Cherry (Prunus avium L.)

In many fruit trees, the thinning of buds, flowers, or fruits is used to increase the leaf area-to-fruit ratio (LA:F) and reduce competition for carbohydrates. Meanwhile, calcium (Ca) sprays during fruit development are also used to increase fruit quality and postharvest storage. Such practices have been recommended to increase fruit firmness and reduce fruit cracking in sweet cherries. To understand the effects of foliar Ca sprays and crop load reductions in the combination ‘Lapins’/‘Colt’, trained as the Kym Green Bush, a factorial experiment to determine the interactions between both managements was established in the Central Valley of Chile during the 2018/2019 growing season. Two levels of crop load (CL) were established—thinned (50% crop load) and unthinned (100% crop load) during Stage I of fruit development (31 days after full bloom, DAFB). Three timings of foliar applications of CaCl2 (TFA; 0.8%) were evaluated: early 26 DAFB, later 39 DAFB, or late 62 DAFB. Natural fruit contents and concentrations of Ca were determined on unsprayed control trees. Fruit from the thinned trees were significantly larger and heavier and had a higher titratable acidity than unthinned trees did. Significant interactions between TFA and CL were observed for SSC, without a clear trend. Thinned trees were less affected by pedicel detachment, browning, and fruit decay after 45 d of storage (0 °C). In unthinned trees, a foliar CaCl2 spray at Stage I allowed a higher fruit firmness than CaCl2 sprays at Stage II and III of fruit development. The CaCl2 applications at 39 or 62 DAFB reduced the incidence of cracking in thinned trees. Natural Ca concentrations decreased during fruit development, indicating a cessation of Ca import and a dilution by subsequent growth. Our results suggest that the early reduction of crop load has positive effects on fruit quality and condition during storage, and early Ca sprays (Stage I) improve fruit textural properties, even under high crop loads.

Triggering factors, behavior, and social impact of the January 2021 hail-debris flows at the Central Valley of Chile

Triggering factors, behavior, and social impact of the January 2021 hail-debris flows at the Central Valley of Chile

Preliminary impact of cover protection systems in kiwifruit cultivars in the Central Valley of Chile

Preliminary impact of cover protection systems in kiwifruit cultivars in the Central Valley of Chile

PFA in walnut at the Central Valley of Chile

PFA in walnut at the Central Valley of Chile

Characterization of Botrytis cinerea and B. prunorum From Healthy Floral Structures and Decayed 'Hayward' Kiwifruit During Post-Harvest Storage.

Gray mold is the primary postharvest disease of 'Hayward' kiwifruit (Actinidia deliciosa) in Chile, with a prevalence of 33.1% in 2016 and 7.1% in 2017. Gray mold develops during postharvest storage, which is characterized by a soft, light to brown watery decay that is caused by Botrytis cinerea and B. prunorum. However, there is no information on the role of B. prunorum during the development and storage of kiwifruit in Chile. For this purpose, asymptomatic flowers and receptacles were collected throughout fruit development and harvest from five orchards over two seasons in the Central Valley of Chile. Additionally, diseased kiwifruits were selected after storage for 100 days at 0°C and 2 days at 20°C. Colonies of Botrytis sp. with high and low conidial production were consistently obtained from apparently healthy petals, sepals, receptacles, and styles and diseased kiwifruit. Morphological and phylogenetic analysis of three partial gene sequences encoding glyceraldehyde-3-phosphate dehydrogenase, heat shock protein 60, and DNA-dependent RNA polymerase subunit II were able to identify and separate B. cinerea and B. prunorum species. Consistently, B. cinerea was predominantly isolated from all floral parts and fruit in apparently healthy tissue and diseased kiwifruit. During full bloom, the highest colonization by B. cinerea and B. prunorum was obtained from petals, followed by sepals. In storage, both Botrytis species were isolated from the diseased fruit (n = 644), of which 6.8% (n = 44) were identified as B. prunorum. All Botrytis isolates grew from 0°C to 30°C invitro and were pathogenic on kiwifruit leaves and fruit. Notably, B. cinerea isolates were always more virulent than B. prunorum isolates. This study confirms the presence of B. cinerea and B. prunorum colonizing apparently healthy flowers and floral parts in fruit and causing gray mold during kiwifruit storage in Chile. Therefore, B. prunorum plays a secondary role in the epidemiology of gray mold developing in kiwifruit during cold storage.

Spatial and Temporal Variation in the Aphid–Parasitoid Interaction under Different Climates

Global warming will increase pest insect population sizes and diminish the effectiveness of biological control. This biological control failure scenario appears to be of particular concern for areas with a significant increase in maximum temperatures, such as the increase experienced in the Central Valley of Chile over the last 40 years. We assessed the impact of different climatic zones and maximum temperatures along the coast and the Chilean Central Valley on the grain aphid (Sitobion avenae) density, parasitism rate, and facultative endosymbionts in wheat fields during the growing season in the springs of 2017 and 2018. A significant effect on aphid density due to zones and maximum temperatures was detected; however, this depended on the zone and year analyzed. Changes between zones and seasons were observed for parasitism rates, while maximum temperatures only significantly affected the parasitism rate in 2017. The main parasitoid wasp found was Aphidius ervi in both zones and seasons. Regiella insecticola infected 95% of the samples in both zones, although it does not seem to have a protective role at the field level. Our findings suggest that, at present, global warming does not significantly affect the grain aphid outbreaks and their biological control in Chile. However, this study points out the importance of pre-emptive monitoring to detect aphids and the synchrony loss of their parasitoid wasps.

Effects of the number of drip laterals on yield and quality of apples grown in two soil types

The effects of water distribution patterns in drip irrigation on fruit production and fruit quality were evaluated during two seasons in two commercial orchards of Gala Brookfield apple trees, grafted on M.9 dwarf rootstock. Research was conducted at El Manzano farm, with a clay-loam soil irrigated three times per week, and in Santa Mercedes farm, with a stony loam soil irrigated daily. Both farms are located in the Central Valley of Chile. The farm irrigation system was modified to establish three treatments which differed in the number of drip laterals per row (one, two and four), with 4.0, 2.0, and 1.0 L h−1 emitters spaced at 50 cm in both farms, respectively. All treatments received the same amount of water per week in each farm, based on the technical criteria of the farm advisor. Applied water in each farm was compared against the water use estimated by the AQUASAT platform. In the clay-loam soil, the volume of applied water was similar to the AQUASAT estimate. However, in the stony loam soil applied water was less than that estimated by AQUASAT. The results showed significant differences in production among treatments which varied only in the volume of wetted soil. The best results pooled over the two years were obtained with one lateral per row (T1) in the clay-loam soil (yield of 59.3 t ha−1), and with four laterals per row (T3) in the stony loam soil which yielded 50.8 t ha−1. Higher yields were associated with a tendency of greater fruit numbers per tree in both farms. Fruit quality requirements for export (equatorial diameter > 60 mm, weight > 90 g) were achieved but not the firmness in the second season at the stony loam soil, due to an irrigation deficit. Our results in apple emphasize the need to wet sufficient soil volume under drip irrigation, regardless of irrigation amounts, in light textured soils in particular.

A Holocene history of monkey puzzle tree (pehuén) in northernmost Patagonia

AbstractAimAlthough it is established that climate and fire have greatly influenced the long‐term ecosystem dynamics of Patagonia south of 40°S, the environmental history from northernmost Patagonia (37–40°S), where endemic and endangered monkey puzzle tree (Araucaria araucana) occurs, is poorly known. Here we ask: (a) What is the Holocene vegetation and fire history at the north‐eastern extent of A. araucana forest? (b) How have climate and humans influenced the past distribution of A. araucana?LocationNorthernmost Patagonia, Argentina and Chile (37–40°S).TaxaAraucaria araucana, Nothofagus, Poaceae.MethodsSedimentary pollen and charcoal from Laguna Portezuelo (37.9°S, 71.0°W; 1,730 m; 11,100 BP) were evaluated using statistical methods and compared with other palaeoecological, independent palaeoclimate, and historical records to assess how changes in climate and land use influenced local‐to‐regional environmental history.ResultsAn open forest‐steppe landscape persisted at L. Portezuelo throughout the Holocene with generally low‐to‐moderate fire activity. Increased Nothofagus pollen after ~6,590 BP suggests increases in shrubland and moisture in association with cooler conditions and greater seasonality and ENSO activity. Araucaria pollen appeared at L. Portezuelo at ~6,380 BP, but was low in abundance until ~370 BP, when it rose with charcoal levels. This increase in Araucaria and fire coincided with a regional influx of Mapuche American Indians. Nothofagus deforestation and Pinus silviculture marked Euro‐American settlement beginning in the 19–20th century.Main conclusions(a) Rapid postglacial warming and drying limited the distribution of Araucaria in the central valley of Chile. In the middle and late Holocene, decreased temperatures and greater seasonality and ENSO activity increased precipitation variability allowing Araucaria expansion at its north‐eastern limit. (b) Greater abundance of Araucaria and heightened fire activity at L. Portezuelo after 370 BP coincided with increased Mapuche‐Pehuenche American Indian land use, suggesting that Araucaria may have been managed in a human‐altered landscape.

Simulation of Water-Use Efficiency of Crops under Different Irrigation Strategies

Irrigation management is a key factor in attaining optimal yields, as different irrigation strategies lead to different yields even when using the same amount of water or under the same weather conditions. Our research aimed to simulate the water-use efficiency (WUE) of crops considering different irrigation strategies in the Central Valley of Chile. By means of AquaCrop-OS, we simulated expected yields for combinations of crops (maize, sugar beet, wheat), soil (clay loam, loam, silty clay loam, and silty loam), and bulk density. Thus, we tested four watering strategies: rainfed, soil moisture-based irrigation, irrigation with a fixed interval every 1, 3, 5, and 7 days, and an algorithm for optimal irrigation scheduling under water supply constraints (GET-OPTIS). The results showed that an efficient irrigation strategy must account for soil and crop characteristics. Among the tested strategies, GET-OPTIS led to the best performance for crop yield, water use, water-use efficiency, and profit, followed by the soil moisture-based strategy. Thus, soil type has an important influence on the yield and performance of different irrigation strategies, as it provides a significant storage and buffer for plants, making it possible to produce “more crop per drop”. This work can serve as a methodological guide for simulating the water-use efficiency of crops and can be used alongside evidence from the field.

Microplastics occurrence and frequency in soils under different land uses on a regional scale

The growing evidence of microplastic pollution in terrestrial ecosystems reveals adverse effects of microplastics on soil biota and plant growth. However, since large scale assessments are lacking, it is possible that the laboratory based experiments conducted have assumed unrealistic microplastic concentrations in soils. In this paper we present regional scale data on the presence of microplastics in soils under different land uses in the central valley of Chile, which is characterized by urbanization, agricultural, and mining operations. We identified microplastics in soils under four different land use systems having different management intensities (crop lands, pastures, rangelands, and natural grasslands), and all somewhat prone to accumulate microplastics from different sources. We analyzed 240 soil samples from Chile's central valley, trying to identify the most probable sources of the microplastics. Our hypothesis was that microplastics were ubiquitous in the environment and that their concentration peaks follow the intensity of fertilizer use (phosphorus), soil heavy metals concentrations derived from nearby mining operations (Zn and Cu), and distance to roads and urban areas. We did find evidence of microplastic pollution in crop lands and pastures (306 ± 360 and 184 ± 266 particles kg−1, respectively), but we did not observe pollution of rangelands and natural grasslands. Distance to mining operations, roads, or urban areas did not increase the microplastic particles count. Our observations contradict the common belief that microplastics are ubiquitous in the environment and relate the pollution problem more to agricultural activities. However, our data do not provide sufficient evidence to identify the pollution source. This is the first study that reports on microplastic occurrence in soils at a broad geographical scale. For greater insight on this topic more studies that contribute monitoring data about microplastics in soils are urgently needed.

Assessment of runoff using 7Be in vineyards in the central valley of Chile

ABSTRACT In Chile, erosion processes (on-site and off-site impact) affect at least 36.9 million ha–1, representing 49% of the total land area. Different regions show severe soil degradation mainly caused by water erosion processes. The importance of sediment-associated transport and the key role of soil erosion affect the fertility of the land and the contamination of water bodies. The aim of this work was to estimate the erosion rate, caused by the rainfall in Apalta vineyards in the Libertador General Bernardo O'Higgins Region of Chile using isotope techniques, assessing the 7Be runoff during four years (2009–2012). The 7Be distribution mass depth at a reference site ranged from 7 to 24 kg m–2 in the first two centimetres soil layer. Even when the vineyards have been well managed, the topographic characteristics and the climatic conditions facilitated soil erosion, with average rates of 50.4, 23.5, 50.6 and 67.3 tons ha–1 y–1 in 2009, 2010, 2011 and 2012, respectively. The robustness of the 7Be technique demonstrated the advantage of a non-soil-destructive methodology to calculate soil distribution and erosion rates.