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Item Uterus histomorphometry of alpacas (Vicugna pacos) in induced luteal phase, with GnRH or Copulation(2024-09-30) Goicochea-Vargas, José; Rondón-Jorge, Wilson; Acosta-Pachorro, Fidel; Salvatierra-Alor, Max; Ratto-Fuster, Marcelo; Silva-Jimenez, Mauricio; Valderrama-Linares, Ximena; Acosta-Galvez, Roberto; Morales-Parra, EdsonBackground: Alpacas have reproductive traits such as induced ovulation and a higher gestation rate in the left uterine horn. Additionally, low fertility and high embryonic mortality are significant challenges in alpaca breeding. To address these issues, it is essential to study the histological changes occurring in the uterine wall during day 8 of the luteal phase. Aim: This research aims to describe these changes in alpacas with induced ovulation using GnRH or copulation. Methods: The study was conducted on 8 sexually mature fertile alpacas with a preovulatory follicle of ≥ 7 mm. Ovulation was induced with GnRH (G1, n=3) and natural mating’ (G2, n=5), confirmed by ultrasound showing the disappearance of the follicle and formation of the corpus luteum. On day 8 of the luteal phase, samples of the uterine wall from the right and left uterine horns were obtained through a midline laparotomy. A uterine lavage with PBS was also performed, and no embryo-ova was found. The tissues were fixed, processed, and stained with Hematoxylin and Eosin. Measurements of the myometrium and endometrium, the area of the superficial and deep endometrial glands, the height of the gland cells, and the height of the endometrial mucosal cells were performed using microscopy and software. The Measurements were taken in microns (um), from 12 different photographs per animal. Results: In G2 (copulation), greater thickness of the endometrium and myometrium, as well as a larger area of the superficial glands and cell height, were observed (p < 0.005). Additionally, the area of the superficial glands in the left horn was greater compared to the right. Conclusion: The thickness of the myometrium and endometrium, and the area of the superficial glands of the left uterine horn in alpacas during the luteal phase (day 8), induced by copulation (G2), show better development. This research provides new insights into changes in the histomorphometry of the alpacas uterus during this stage and is the first report in this species.Item Introducing Chaos Theory: A Life Sciences Students’ Perspective(2024-10-18) Perea Martins, João E. M.; Oyanedel, Eduardo; Campos-Soto, RicardoThis article details a concise in-class workshop to introduce life science students to basic chaos theory concepts, which is a modern subject and has high potential for applications in life sciences and other fields, justifying its knowledge. The teaching approach is based on a pragmatic strategy that uses only the essential mathematical and computing concepts required to reach the learning outcome, which this article explains step-by-step and, therefore, at least in expectation, even students or professors with no previous software knowledge could understand them. The proposed educational approach uses a meaningful learning approach, and population growth models as an educational anchor subject, which is a common subject for life science students and may be intuitive for students from other areas. Feedback from 70 students surveyed after the workshop yielded positive results, and 72.9% of the students expressed confidence in explaining basic chaos theory concepts following the session, and 94.7% stated they would recommend it to their peers, which underscores the present proposal feasibility.Item DETECCIÓN DE Trypanosoma cruzi EN LAGARTOS Microlophus atacamensis DE UNA ISLA COSTERA DEL DESIERTO DE ATACAMA(2024-06) Borcosque. Josefa; Campos-Soto, Ricardo; Quiroga, Nicol; Cianferoni, Franco; Díaz-Campusano, Gabriel; Marcos, José Luis; Botto-Mahan, Carezza; Torres-Pérez, FernandoLa enfermedad de Chagas es producida por el parásito Trypanosoma cruzi, el cual está presente en vinchucas y sangre/tejidos de mamíferos, considerándose las aves refractarias a la infección. Mepraia es un género de vinchuca responsable de transmitir T. cruzi en el ciclo silvestre de Chile. Se ha evidenciado la presencia de ejemplares de Mepraia infectados con T. cruzi en la Isla Santa María (Región de Antofagasta). En esta isla no se ha registrado presencia de micromamíferos y los vertebrados más comunes son el lagarto Microlophus atacamensis, jotes y aves marinas. En las vinchucas de esta isla se ha reportado un alto porcentaje de infección e incluso infecciones mixtas, con más de un DTU de T. cruzi, lo que está comúnmente asociado a ecosistemas con una alta biodiversidad y abundancia de mamíferos. Esto contrasta con la nula captura de micromamíferos reportada en esta isla. Considerando que recientemente se ha publicado que los reptiles también son hospederos de T. cruzi, se puede inferir que los lagartos M. atacamensis podrían estar manteniendo la infección de T. cruzi en la Isla Santa María. El objetivo de este estudio es determinar si individuos de M. atacamensis de la Isla Santa María son hospederos de T. cruzi. En 33 muestras de sangre de M. atacamensis se detectó T. cruzi mediante la amplificación de un segmento de ADN kinetoplastídico por PCR convencional y un segmento nuclear de T. cruzi por real time PCR. Se determinó un 60.6% de infección mediante PCR convencional, mientras que por real time PCR un 51.1%. Se concluye que M. atacamensis es un hospedero de T. cruzi, sugiriendo que podría ser un reservorio clave que está mantenido la infección en la Isla Santa María. Estos resultados contribuyen al entendimiento del ciclo de vida que desarrolla T. cruzi en esta particular isla del extremo norte del desierto de Atacama.Item Phylogenetic Analyses of Lizards from the Chilean Humboldt Archipelago Reveal a New Species for the Chañaral Island (Squamata: Liolaemidae)(2023-11-19) Campos-Soto, Ricardo; Rodríguez-Valenzuela, Evelyn; Bruna, Yareta; Díaz-Campusano, Gabriel; Cianferoni, Franco; Boric-Bargetto, Dusan; Torres-Pérez, FernandoThe Humboldt Archipelago, situated on Chile’s north-central coast, is renowned for its exceptional biodiversity. However, lizards of the Liolaemus genus are a particularly understudied group in this archipelago. Liolaemus genus is divided into two clades: chiliensis and nigromaculatus. Within the nigromaculatus clade the zapallarensis group is restricted to the semi-arid and arid coastal habitats of the Atacama Desert in north-central Chile. While it has been reported that lizards from the zapallarensis group inhabit various islands within the Humboldt Archipelago, there has been limited knowledge regarding their specific species identification. To identify the lizard species inhabiting these islands, we conducted phylogenetic analyses using a mitochondrial gene and examined morphological characteristics. Our findings reveal that lizards from the Damas, Choros, and Gaviota islands belong to Liolaemus silvai. In contrast, the lizards on Chañaral Island form a distinct and previously unrecognised group, clearly distinguishable from Liolaemus silvai. In conclusion, our study not only confirms the presence of L. silvai on the Damas, Choros, and Gaviota islands but also describes a new lizard species on Chañaral Island named Liolaemus carezzae sp. nov. These findings contribute valuable insights into the biodiversity of these islands and introduce a newly discovered endemic taxon to the region, enriching our understanding of Chile’s unique island ecosystems.Item An Assessment of the Feasibility of Phytoextraction for the Stripping of Bioavailable Metals from Contaminated Soils(2022-12-29) Santa‐Cruz, Javier; Robinson, Brett; Krutyakov, Yurii A.; Shapoval, Olga A.; Peñaloza, Patricia; Yáñez, Carolina; Neaman, AlexanderPhytoextraction has been proposed in many papers as a low-cost method for remediating contaminated soil. However, if national regulation is based on total metal(loid) concentrations in soil, phytoextraction is generally infeasible because of the long time required for remediation. Assessing phytoextraction requires determination of the dynamic rate of metal removal from soil. Phytoextraction may be feasible if the main goal is to reduce the soluble fraction of the metal(loid) with the goal of reducing bioavailability. However, it has been reported that there is a large mass balance mismatch between the reduction of the soluble metal fraction in contaminated soil and metal uptake by plants. Several studies report that the decrease of soluble fraction of metals in soil is higher than can be accounted for by plant uptake. In other words, studies generally overestimate the feasibility of bioavailable contaminant stripping. Therefore, a more rigorous approach is advisable to ensure that papers on bioavailable contaminant stripping include relevant information on mass balances. Furthermore, to implement the concept of bioavailable contaminant stripping, regulations must distinguish between the bioavailable fraction and the total metal concentration in soil.Item Impact of monochromatic lights on the in vitro development of Cattleya walkeriana and effects on acclimatization(2023-06-03) Nadal, Michele Carla; Bernardes Machado, Natalia; dos Santos, Cyntia Stephânia; Nunes Flores, José Henrique; Dória, Joyce; Pasqual, MoacirLight quality is an important factor for the adequacy of plant production through plant tissue culture, as it directly interferes with morphogenesis and photosynthetic capacity of explants. The objective of this study was to analyze the impact of monochromatic lights such as light emitting diode (LED) on the in vitro development of Cattleya walkeriana G. and their effects on acclimatization. The plants were developed in vitro under the colors of green, blue, yellow, red, 2 red:1 blue, and white LED lights. For in vitro cultivation, Knudson medium was used, supplemented with 20 mg L-1 sucrose, 5.5 mg L-1 agar, 2% activated charcoal, 100 mL coconut water, and pH 6.0. For ex vitro cultivation, the plants were acclimatized in styrofoam trays containing sphagnum as a substrate. In general, the supplied light lengths impactedin vitro growth and acclimatization analyses. There was influence on the cuticle thickness of plants in vitro. Chlorophyll and carotenoid contents were not significant. We can conclude that light lengths formed by 2 red:1 blue, red and yellow LEDs can be indicated for better performance in the production of C. walkeriana. The 2 red:1 blue and red LEDs provide superior in vitro development than the others, with gains for the species in acclimatization. The yellow LED provided a possible in vitro hardening, which ensured the greatest success of the seedlings during acclimatization.Item Veronica Cymbalaria (Plantaginaceae): A New Species For The Exotic Flora Of Chile(2023-06) Cisternas, Mauricio A.; Cádiz Véliz, Arón; Novoa, Patricio; Macaya Berti, JorgeBackground and aims: Botanic gardens play a fundamental role in conservation due to the maintenance of seed and live plant collections. However, the exchange of ornamental plant seeds between botanic gardens can facilitate the entry of seeds of alien species with invasive potential. In 2018, during a visit to the collections of the National Botanical Garden (Chile), we discovered populations of an herb of the genus Verónica (Plantaginaceae). The aim of this paper is to report for the first time the presence of Verónica cymbalaria as a new exotic feral species for the flora of Chile. M&M: Live material was studied and compared with the original description of the species. The collected material was deposited in the herbarium of the National Botanical Garden (JBN). Results: Verónica cymbalaria, which grows abundantly in and around the biological collections of the National Botanical Garden, is described. Images of the species, a map of the site of occurrence and a key to distinguish Verónica species growing in Chile are included. Conclusions: Verónica cymbalaria is reported for the first time for the flora of Chile. The distribution range of this alien species is extended to southern America. The genus Verónica is represented by ten allochthonous species in Chile.Item Matching global and regional distribution models of the recluse spider Loxosceles rufescens: to what extent do these reflect niche conservatism?(2018) Taucare Ríos, A.; Nentwig, W.; Bizama, G.; Bustamante, R.The Mediterranean recluse spider, Loxosceles rufescens (Dufour, 1820) (Araneae: Sicariidae) is a cosmopolitan spider that has been introduced in many parts of the world. Its bite can be dangerous to humans. However, the potential distribution of this alien species, which is able to spread fairly quickly with human aid, is completely unknown. Using a combination of global and regional niche models, it is possible to analyse the spread of this species in relation to environmental conditions. This analysis found that the successful spreading of this species varies according to the region invaded. The majority of populations in Asia are stable and show niche conservatism, whereas in North America this spider is expected to be less successful in occupying niches that differ from those in its native region and that do not support its synanthropic way of living.Item Obesogenic Diet-Induced Neuroinflammation: A Pathological Link between Hedonic and Homeostatic Control of Food Intake(2023-01-11) Marcos, José Luis; Olivares-Barraza, Rossy; Ceballo, Karina; Wastavino, Melisa; Ortiz, Víctor; Riquelme, Julio; Martínez-Pinto, Jonathan; Muñoz, Pablo; Cruz, Gonzalo; Sotomayor-Zárate, RamónObesity-induced neuroinflammation is a chronic aseptic central nervous system inflammation that presents systemic characteristics associated with increased pro-inflammatory cytokines such as interleukin 1 beta (IL-1β) and interleukin 18 (IL-18) and the presence of microglia and reactive astrogliosis as well as the activation of the NLRP3 inflammasome. The obesity pandemic is associated with lifestyle changes, including an excessive intake of obesogenic foods and decreased physical activity. Brain areas such as the lateral hypothalamus (LH), lateral septum (LS), ventral tegmental area (VTA), and nucleus accumbens (NAcc) have been implicated in the homeostatic and hedonic control of feeding in experimental models of diet-induced obesity. In this context, a chronic lipid intake triggers neuroinflammation in several brain regions such as the hypothalamus, hippocampus, and amygdala. This review aims to present the background defining the significant impact of neuroinflammation and how this, when induced by an obesogenic diet, can affect feeding control, triggering metabolic and neurological alterations.Item Rosuvastatin Synergistically Enhances the Antinociceptive Efficacy of Duloxetine in Paclitaxel-Induced Neuropathic Pain in Mice(2023-05-06) Lobos, Nicolás; Lux, Sebastián; Zepeda, Ramiro Javier; Pelissier, Teresa; Marcos, José Luis; Bustos-Quevedo, Gonzalo; Hernández, Alejandro; Constandil, LuisPaclitaxel, a widely used cancer chemotherapeutic agent, has high incidence of neurotoxicity associated with the production of neuropathic pain, for which only duloxetine has shown significant but moderate analgesic effect. Since statins, classically used to reduce hypercholesterolemia, have shown antinociceptive effect in preclinical studies on neuropathic pain, we studied whether the antinociceptive efficacy of duloxetine could be synergistically potentiated by rosuvastatin in a model of paclitaxel-induced neuropathy in mice. The astrocytic and microglial responses in the spinal cord of paclitaxel-treated mice were also assessed by measuring GFAP and CD11b proteins, respectively. Paclitaxel treatment did not impair motor coordination and balance in rotarod testing. Rosuvastatin, duloxetine, and the rosuvastatin/duloxetine combination (combined at equieffective doses) dose-dependently decreased mechanical allodynia (ED30, von Frey testing) and thermal hyperalgesia (ED50, hot plate testing) in paclitaxel-treated mice. Isobolographic analysis showed a superadditive interaction for rosuvastatin and duloxetine, as both the ED30 and ED50 for the rosuvastatin/duloxetine combination contained only a quarter of each drug compared to the individual drugs. The rosuvastatin/duloxetine combination reversed paclitaxel-induced GFAP overexpression, indicating that such effects might depend in part on astrocyte inactivation. Results suggest that statins could be useful in synergistically enhancing the efficacy of duloxetine in some chemotherapy-induced neuropathic conditions.Item Changes in Dynamic Thiol/Disulfide Homeostasis, and Substance P, B-Endorphin and α-Tocopherol Concentrations in the Spinal Cord of Chronically Lame Dairy Cows(2023-05-12) Müller, Heine; Herzberg, Daniel; Chihuailaf, Ricardo; Strobel, Pablo; Werner, Marianne; Bustamante, HedieInitial lameness inflammation leads to chronic lameness and development of chronic pain due to the release of pro-inflammatory mediators such as reactive oxygen species (ROS), which are implicated in the transition from acute to chronic pain, and free radical scavengers countering thiol, substance P (SP), and β-endorphin (BE). The present study aimed to evaluate the dynamic thiol–disulfide homeostasis, α-tocopherol concentrations and SP and BE concentrations in the spinal cord of chronically lame dairy cows. Ten lame and 10 non-lame cows with a parity range of 2–6 were selected for the study. Lame cows had a history of up to 3 months of lameness. Spinal cord samples were obtained from the L2 to L4 lumbar vertebrae aspect of each animal. A thiol–disulfide homeostasis assay was performed using absorbance, and the α-tocopherol concentration was determined by HPLC. SP and BE concentrations were measured using ELISA kits. The results indicated that SP and BE were significantly higher in the spinal cord of lame cows. In contrast, disulfide levels and α-tocopherol concentrations were significantly lower in the spinal cord of lame cows. In conclusion, disulfide levels and α-tocopherol concentrations indicated a defective antioxidant response in cows with chronic lameness. The results of SP and BE concentrations suggested chronic pain and a defective endogenous analgesic response.Item Protocol for in vitro rooting of Pyrus comunnis rootstocks(2023-04-15) Nadal, Michele Carla; Bernardes Machado, Otávio; Araújo, Ronilson Carlos; Rodrigues, Filipe Almendagna; Rufato, Leo; Dória, Joyce; Pasqual, MoacirEffective protocols for in vitro rooting for woody fruit trees are still a challenge for in vitro seedling production, especially when there is a need to insert new cultivars or rootstocks. These protocols are essential to accelerate studies in plant breeding programs and for seedling distribution. This study evaluated the use of 6-Benzylaminopurine (IBA) in in vitro rooting of Pyruscomunnis rootstocks, clones ‘OHxF87’ and Pyrodwarf. Explant exposure times (0, 24, 48, 72, and 96 hours) to 20 mg L-1 IBA were tested for in vitro rooting. The exposure to IBA resulted in rooting rates above 80%, surpassing some results reported in the literature. The 24-hour treatment provided 81,81% survival, leading to an average growth of five roots with 19 mm length, for ‘OHxF87’ rootstock. The same exposure time resulted in the highest survival rate (75%) and the highest mean root number, seven roots per plant with 10 mm length, for ‘PDW’ rootstock. Root formation did not occur in the absence of synthetic auxin. Therefore, it can be concluded that a 24-hour exposure at 20 mg L-1 IBA was sufficient to promote in vitro rooting in ‘OHxF87’ and Pyrodwarf rootstocks’.Item Dendrobium nobile in vitro flowering induction(2023-05-22) Nadal, Michele Carla; Silva Andrade, Gracielle Vidal; Nunes Flores, José Henrique; dos Reis, Michele Valquíria; Rodrigues, Vantuil Antonio; Pasqual, MoacirIn vitro flowering is a technique used in genetic improvement that accelerates generations and favors the faster fixation of new traits of agronomic and market interest. The study aimed to establish a protocol for the in vitro flowering of Dendrobium nobile, through the combined temperature and of the growth regulator thidiazuron (TDZ) effects. Experiments was performed in a flask that was kept in a BOD incubator at 18, 21, or 24 °C or in a growth room at 26 °C. The TDZ concentrations were 0.0, 0.5, 1.0, and 2.0 mg L-1. The highest percentage of flowering shoots of 13.7% occurred at a concentration of 2 mg L-1 of TDZ grown at a temperature of 18 °C. Dendrobium nobile in vitro flowering was promoted in plants cultivated in ½ MS supplemented with 30 g L-1 sucrose, 5.5 g L-1 agar, 100 mL L-1 coconut water, pH 6.0, and 2.0 mg L-1 TDZ at a controlled temperature of 18 °C and a photoperiod of 16 h. The in vitro flowering induction protocol of the D. nobile species could be used or improved for future studies.Keywords: flowering, temperature, thidiazuron, Orchidaceae.Item Humans as blood-feeding sources in sylvatic triatomines of Chile unveiled by next-generation sequencing(2023-07-06) San Juan, Esteban; Araya‑Donoso, Raúl; Sierra‑Rosales, Catalina; Correa, Juana P; Quiroga, Nicol; Campos‑Soto, Ricardo; Solari, Aldo; Llewellyn, Martin; Bacigalupo, Antonella; Botto‑Mahan, CarezzaBackground Triatomines are blood-sucking insects capable of transmitting Trypanosoma cruzi, the parasite that causes Chagas disease in humans. Vectorial transmission entails an infected triatomine feeding on a vertebrate host, release of triatomine infective dejections, and host infection by the entry of parasites through mucous membranes, skin abrasions, or the biting site; therefore, transmission to humans is related to the triatomine–human contact. In this cross-sectional study, we evaluated whether humans were detected in the diet of three sylvatic triatomine species (Mepraia parapatrica, Mepraia spinolai, and Triatoma infestans) present in the semiarid–Mediterranean ecosystem of Chile. Methods We used triatomines collected from 32 sites across 1100 km, with an overall T. cruzi infection frequency of 47.1% (N=4287 total specimens) by conventional PCR or qPCR. First, we amplifed the vertebrate cytochrome b gene (cytb) from all DNA samples obtained from triatomine intestinal contents. Then, we sequenced cytb-positive PCR products in pools of 10–20 triatomines each, grouped by site. The fltered sequences were grouped into amplicon sequence variants (ASVs) with a minimum abundance of 100 reads. ASVs were identifed by selecting the best BLASTn match against the NCBI nucleotide database. Results Overall, 16 mammal (including human), 14 bird, and seven reptile species were identifed in the diet of syl‑ vatic triatomines. Humans were part of the diet of all analyzed triatomine species, and it was detected in 19 sites representing 12.19% of the sequences. Conclusions Sylvatic triatomine species from Chile feed on a variety of vertebrate species; many of them are detected here for the frst time in their diet. Our results highlight that the sylvatic triatomine–human contact is noteworthy. Education must be enforced for local inhabitants, workers, and tourists arriving in endemic areas to avoid or minimize the risk of exposure to Chagas disease vectors.Item The use of filamentous hemagglutinin adhesin to detect immune responses to Campylobacter hepaticus infections in layer hens(2022-12-21) Muralidharan, Chithralekha; Quinteros, José A.; Anwar, Arif; Wilson, Timothy B.; Scott, Peter C.; Moore, Robert J.; Hao Van, Thi ThuCampylobacter hepaticus is the aetiological agent of Spotty Liver Disease (SLD). SLD can cause significant production loss and mortalities among layer hens at and around peak of lay. We previously developed an enzyme linked immunosorbent assay (ELISA), SLD-ELISA1, to detect C. hepaticus specific antibodies from bird sera using C. hepaticus total proteins and sera pre-absorbed with Campylobacter jejuni proteins. The high specificity achieved with SLD-ELISA1 indicated the presence of C. hepaticus specific antibodies in sera of infected birds. However, some of the reagents used in SLD-ELISA1 are time consuming to prepare and difficult to quality control. This understanding led to the search for C. hepaticus specific immunogenic proteins that could be used in recombinant forms as antibody capture antigens in immunoassay design. In this study, an immunoproteomic approach that combined bioinformatics analysis, western blotting, and LC MS/MS protein profiling was used, and a fragment of filamentous hemagglutinin adhesin (FHA), FHA1,628−1,899 with C. hepaticus specific antigenicity was identified. Recombinant FHA1,628−1,899 was used as antigen coating on ELISA plates to capture FHA1,628−1,899 specific antibodies in sera of infected birds. SLD-ELISA2, based on the purified recombinant FHA fragment, is more user-friendly and standardizable than SLD-ELISA1 for screening antibody responses to C. hepaticus exposure in hens. This study is the first report of the use of FHA from a Campylobacter species in immunoassays, and it also opens future research directions to investigate the role of FHA in C. hepaticus pathogenesis and its effectiveness as a vaccine candidate.Item Obesogenic Diet-Induced Neuroinflammation: A Pathological Link between Hedonic and Homeostatic Control of Food Intake(2023-01-11) Marcos, José Luis; Olivares-Barraza, Rossy; Ceballo, Karina; Wastavino, Melisa; Ortiz, Víctor; Riquelme, Julio; Martínez-Pinto, Jonathan; Muñoz, Pablo; Cruz, Gonzalo; Sotomayor-Zárate, RamónObesity-induced neuroinflammation is a chronic aseptic central nervous system inflammation that presents systemic characteristics associated with increased pro-inflammatory cytokines such as interleukin 1 beta (IL-1β) and interleukin 18 (IL-18) and the presence of microglia and reactive astrogliosis as well as the activation of the NLRP3 inflammasome. The obesity pandemic is associated with lifestyle changes, including an excessive intake of obesogenic foods and decreased physical activity. Brain areas such as the lateral hypothalamus (LH), lateral septum (LS), ventral tegmental area (VTA), and nucleus accumbens (NAcc) have been implicated in the homeostatic and hedonic control of feeding in experimental models of diet-induced obesity. In this context, a chronic lipid intake triggers neuroinflammation in several brain regions such as the hypothalamus, hippocampus, and amygdala. This review aims to present the background defining the significant impact of neuroinflammation and how this, when induced by an obesogenic diet, can affect feeding control, triggering metabolic and neurological alterations.Item Quantifying effects of irrigation and soil water content on electricalpotentials in grapevines (Vitis vinifera) using multivariate statisticalmethods(2014-05-20) Gil, Pilar M.; Saavedra, Jorge; Schaffer, Bruce; Navarro, Rosa; Fuentealba, ClaudiaSeveral studies have shown that physiological responses in plants, including fruit crops, are associated with changes in electrical potentials (EP), but it is often difficult to statistically quantify these responses. This study tested the effects of irrigation on EP in grapevines (Vitis vinifera), taking into account vapor pressure deficit (VPD) and position of electrodes along the stem by using multivariate analytical methods and a suite of statistical pretreatments. In two separate experiments, plants were exposed to one of two irrigation treatments in a greenhouse: (T1) irrigation once per day (Experiment 1), or no irrigation (Experiment 2); or (T2) irrigation three times or twice per day (Experiments 1 and 2, respectively). In each experiment, EP at three positions along the stem, soil (potting medium) water content, and VPD were continuously measured. In Experiment 2, stomatal conductance (gs) and stem water potential (SWP) were also measured for plants in each irrigation treatment as indicators of plant water status. Data were analyzed by Principal Component Analysis (PCA) to determine the effects of irrigation treatment on EP and difference in EP between pairs of electrodes (ΔEP) at various locations along the stem. Data were also analyzed by partial least squares (PLS) analysis to determine if EP or ΔEP could be used as predictors of changes in soil water content due to different irrigation treatments. Significant differences in soil water content due to irrigation treatments could be readily detected by difference in EP or ΔEP using PCA with Orthogonal Signal Correction pre-processing. Also, PLS showed that differences in soil moisture can be predicted by EP and/or ΔEP measurements at specific locations along the stem. Thus, the use of multivariate statistical methods was effective for relating EP and ΔEP measurements in grapevines to soil moisture due to differences in irrigation.Item Simazine transport in undisturbed soils from a vineyard at the Casablanca valley, Chile(2013-01-20) Suárez, Francisco; Guzmán, Edwin; Muñoz, José F.; Bachmann, Jaime; Ortiz, Cristian; Alister, Claudio; Kogan, MarceloSimazine is a soil-active herbicide that has been applied worldwide in agricultural soils, being the second most commonly detected herbicide in groundwater and surface waters. Although its use has been restricted in many countries of Europe, it is still applied in many locations around the world in orchards, vineyards and forestry. Therefore, it is important to study its fate and transport in the environment. This paper investigates simazine transport in undisturbed bare soils from a vineyard at the Casablanca valley, Chile. In the study site, shallow groundwater tables (<1.0 m depth) and high simazine levels (>15 μg L−1) in the groundwater were observed and thus, there is potential for simazine to be transported further away through the saturated zone. The soils from the study site were characterized and the hydrodynamic transport parameters were determined. Column leaching experiments showed that the two-site chemical non-equilibrium model correctly represented simazine transport. It was found that 36.3% of the adsorption sites achieve instantaneous equilibrium and that the first-order kinetic rate of the non-equilibrium sites was 6.2 × 10−3 h−1. Hydrus 2D was used to predict the transport of simazine in the study site under natural field conditions. Simulation results showed that simazine concentrations at depths shallower than 2.1 m are above the maximum contaminant level of 4 μg L−1 (defined by the U.S. Environmental Protection Agency). The timing of herbicide application was found to be important on simazine leaching and the main processes involved in simazine transport were degradation and adsorption, which accounted for 95.78 and 4.19% of the simulated mass of pesticide, respectively. A qualitative agreement in the timing and magnitude of simazine concentration was obtained between the simulations and the field data. Therefore, the model utilized in this investigation can be used to predict simazine transport and is a valuable tool to assess agricultural practices to minimize environmental impacts of simazine.Item Competitive Strategies and Growth of Neighbouring Bromus valdivianus Phil. and Lolium perenne L. Plants Under Water Restriction(2013-05) López, F.; Kemp, P. D.; Dörner, J.; Descalzi, C. A.; Balocchi, O. A.; García, S.Often perennial pastures have to tolerate soil water restriction during summer, which can affect the relative abundance of the most desired species. In the south of Chile, Bromus valdivianus and Lolium perenne are preferred species. The competitiveness of B. valdivianus and L. perenne was evaluated when sown in pots in a glasshouse as monocultures or a mix (50/50 %) with restricted water availability. The water restriction treatments were as follows: 80–85 % field capacity (FC), 45–50 % FC and 20–25 % FC, maintained for 1196 growing degree days. For both species, dry matter (DM) accumulated per plant and per pot decreased similarly with increasing water restriction, but at tiller level, resource allocation differed, for B. valdivianus root growth was accentuated over aerial development, but this was less so for L. perenne. The foliage mass per tiller for B. valdivianus decreased relatively more than that for L. perenne with increasing water restriction. As monocultures, B. valdivianus produced larger tillers than L. perenne, such that B. valdivianus tillers had 2.2 times greater lamina mass, 3.6 times more leaf area and 2.5 times greater root mass than those of L. perenne. However, L. perenne produced a larger number of smaller tillers that enabled foliage, root and total mass at plant level, to be similar to that of B. valdivianus. Within the mixed pasture, L. perenne tiller density increased compared with when grown as a monoculture, but not for B. valdivianus. The results of the study suggested that L. perenne and B. valdivianus have differences in growth strategies that allow them to survive under environmental stress and competition. Competitiveness increased for L. perenne aboveground without water restriction and that for B. valdivianus increased belowground as water restriction was increased.Item Water and sediment dynamics of penoxsulam and molinate in paddy fields: field and lysimeter studies(2011-07-15) Kogan, Marcelo; Araya, Manuel; Alister, ClaudioBACKGROUND: In Chile, rice is cultivated under water-seeded and continuously flooded conditions. Because herbicide dynamics in paddy fields and non-flooded fields is different, 3 year experiments were performed to study the dissipation of molinate and penoxsulam in water and sediment. RESULTS: In field experiments, both herbicides dissipated by 45–55% from the initial applied amounts during the first 6 h after application in all crop seasons; in lysimeter experiments, dissipation amounts were approximately 10% for penoxsulam and 16% for molinate. Penoxsulam field water DT50 values varied from 1.28 to 1.96 days during the three study seasons, and DT90 values from 4.07 to 6.22 days. Molinate field water DT50 values varied from 0.89 to 1.73 days, and DT90 values from 2.82 to 5.48 days. Sediment residues were determined 2 days after herbicide application into the paddy water, and maximum concentrations were found 4–8 days after application. In sediment, DT50 values varied from 20.20 to 27.66 days for penoxsulam and from 15.02 to 29.83 days for molinate. CONCLUSIONS: Results showed that penoxsulam and molinate losses under paddy conditions are dissipated rapidly from the water and then dissipate slowly from the sediment. Penoxsulam and molinate field water dissipation was facilitated by paddy water motion created by the wind. Sediment