Institute of Agricultural Research

Santiago, Chile

Institute of Agricultural Research

Santiago, Chile
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Urrutia N.L.,Pennsylvania State University | Urrutia N.L.,Institute of Agricultural Research | Harvatine K.J.,Pennsylvania State University
Journal of Nutrition | Year: 2017

Background: Acetate is a short-chain fatty acid (FA) that is especially important to cows because it is the major substrate for de novo FA synthesis. However, the effect of acetate supply on mammary lipid synthesis is not clear. Objective: The objective of this experiment was to determine the effect of increasing acetate supply on milk fat synthesis in lactating dairy cows. Methods: Six multiparous lactating Holstein cows were randomly assigned to treatments in a replicated design to investigate the effect of acetate supply on milk fat synthesis. Treatments were 0 (control), 5, 10, and 15 mol acetate/d continuously infused into the rumen for 4 d. Rumen short-chain FAs, plasma hormones and metabolites, milk fat concentration, and milk FA profile were analyzed on day 4 of each treatment. Polynomial contrasts were used to test the linear and quadratic effects of increasing acetate supply. Results: Acetate increased milk fat yield quadratically (P < 0.01) by 7%, 16%, and 14% and increased milk fat concentration linearly (P < 0.001) by 6%, 9%, and 11% for 5, 10, and 15 mol acetate/d, respectively, compared with the control treatment. Increased milk fat yield predominantly was due to a linear increase in 16-carbon FAs (P < 0.001) and a quadratic increase in de novo synthesized FAs ( < 16-carbon FAs; P < 0.01), indicating that there was stimulation of de novo synthesis pathways. Apparent transfer of acetate to milk fat was 33.4%, 36.2%, and 20.6% for 5, 10, and 15 mol/d, respectively. Acetate infusion linearly increased the relative concentration of rumen acetate (P < 0.001) before feeding, but not after feeding. Acetate linearly increased plasma β-hydroxybutyric acid by 29%, 50%, and 78%, respectively, after feeding compared with the control treatment (P < 0.01). Conclusions: Increasing acetate supply to lactating cows increases milk fat synthesis, suggesting that nutritional strategies that increase ruminal acetate absorption would be expected to increase milk fat by increasing de novo FA synthesis. © 2017 American Society for Nutrition.

Jacobo-Velazquez D.A.,Texas A&M University | Gonzalez-Aguero M.,Institute of Agricultural Research | Cisneros-Zevallos L.,Texas A&M University
Scientific Reports | Year: 2015

Plants subjected to wounding stress produce secondary metabolites. Several of these metabolites prevent chronic diseases and can be used as colorants, flavors, and as antimicrobials. This wound-induced production of plant secondary metabolites is mediated by signaling-molecules such as reactive oxygen species (ROS), ethylene (ET) and jasmonic acid (JA). However, their specific role and interactions that modulate the wound-respond in plants is not fully understood. In the present study, a subtractive cDNA library was generated, to better understand the global response of plants to wounding stress. Carrot (Daucus carota) was used as a model system for this study. A total of 335 unique expressed sequence tags (ESTs) sequences were obtained. ESTs sequences with a putative identity showed involvement in stress-signaling pathways as well as on the primary and secondary metabolism. Inhibitors of ROS biosynthesis, ET action, and JA biosynthesis alone and in combination were applied to wounded-carrots in order to determine, based on relative gene expression data, the regulatory role of ET, JA, and ROS on the wound-response in plants. Our results demonstrate that ROS play a key role as signaling-molecules for the wound-induced activation of the primary and secondary metabolism whereas ET and JA are essential to modulate ROS levels.

Antoniadis V.,Democritus University of Thrace | Tsadilas C.D.,Greek National Agricultural Research Foundation | Dalias P.,Institute of Agricultural Research
Agrochimica | Year: 2010

Nitrate leaching may be a major problem in certain soils after intensive use of nitrogen fertilizers. Moderate use of organic amendments, i.e. sewage sludge, can supply available N and reduce the accelerating use of conventional fertilizers, which may lead to slower nitrate leaching. The aim of this study was to examine nitrate mobility in Mediterranean soils of low organic matter content using soil leaching columns amended with sewage sludge and inorganic fertilizer. Eight soil samples from the Gulf of Kalloni, Lesvos Island, which typically bear the above mentioned characteristics, were used. It was found that sludge application at 10 t ha-1 increased nitrate retention capacity of soils either by rendering a smaller amount of nitrates available to leaching or by reducing the rate of NO3-N release. Average NO3-N leaching was 0.016 in control, 0.092 in sludge treatment, and 0.130 in fertilizer treatment (units in mg N kg-1 soil mm-1 eluted water). After about 100 mm of added water, cumulative leaching of NO 3-N reached a plateau in most soils, but nitrate recovery was a fraction of the added, probably due to denitrification- and immobilization- related N losses.

Lamichhane J.R.,University of Tuscia | Lamichhane J.R.,Hazelnut Research Center | Grau P.,Institute of Agricultural Research | Varvaro L.,University of Tuscia | Varvaro L.,Hazelnut Research Center
Journal of Phytopathology | Year: 2012

Severe attacks of bacterial blight were observed on young plants throughout the hazelnut growing areas in Chile. The incidence of the disease in nurseries and fields ranged from 60-90%. The causal agent was identified as Xanthomonas arboricola pv. corylina, based on phenotypic and genetic tests. © 2012 Blackwell Verlag GmbH.

Developmental time, parasitism, emergence, longevity, fecundity and demographic parameters of population of Encarsia bimaculata Heraty and Polaszek (Hymenoptera: Aphelinidae), a parasitoid attacking Bemisia tabaci (biotype B) (Gennadius) (Homoptera: Aleyrodidae) infesting soybean, Glyine max L. (Merr), cowpea, Vigna unguiulata L. and garden bean, Phaseolus vulgaris L. (Fabeles: Fabaceae) were quantified and compared. Encarsia bimaculata was able to complete its life cycle independent of the B. tabaci instar parasitized. However, parasitoid development was significantly slower when first (19 d), second (15 d) instars or pharate adults (14 d) were parasitized compared to the third (13 d) or fourth (13 d) instars. Consequently, percent parasitism was higher when the third (51%) or fourth (46%) instars were parasitized compared to the first (22%), second (25%) instars or pharate adults (36%) of B. tabaci. Similarly, percent parasitoid emergence was significantly higher when third (83%) or fourth (76%) instars were parasitized compared to when the first (34%), second (64%) or pharate adults (54%) were parasitized. Host plant species significantly influenced egg to adult developmental time, percent parasitism and the day on which E. bimaculata nymphs hatching from eggs was first observed. More nymphs were parasitized on cowpea (40%) followed by garden bean (36%) and soybean (32%), while percent hatching was significantly higher on soybean (76%) followed by cowpea (68%) and garden bean (42%). Adult parasitoid females lived an average of 6.7 d on soybean, 7.6 d on cowpea and 7.2 d on garden bean and laid a lifetime average of 27 eggs on soybean, 31 eggs on cowpea and 30 eggs on garden bean. The daily mean fecundity of E. bimaculata was not significantly different on the three bean species. Life table parameters showed that the net reproductive rate (R(o)) was 14.50, generation time (T(c)) was 17.16, intrinsic rate of natural increase (r(m)) was 0.16, finite rate of growth (lambda) was 1.17 and doubling time (T(d)) was 4.44 for parasitoids on soybean. On cowpea, R(o) was 15.32, T(c) was 18.59, r(m) was 0.15, lambda was 1.16 and T(d) was 4.72, while, on garden bean, R(o) was 8.95, T(c) was 19.28, r(m) was 0.11, lambda was 1.12 and T(d) was 6.08. Given these life table parameters, higher population build up of the parasitoid will be expected on cowpea and soybean, respectively, compared to garden bean. Thus, for an effective augmentative release program involving E. bimaculata for the control of B. tabaci, it is important to take into consideration both the host stage of B. tabaci and the nature of the host plant on which it is developing.

Acourene S.,Institute of Agricultural Research | Djafri K.,Institute of Agricultural Research | Ammouche A.,Algeria 3 University of Constatntine | Amourache L.,Algeria 3 University of Constatntine | And 3 more authors.
Biotechnology | Year: 2011

The aim of the present study was to investigate the potential of date wastes as substrate for the production of Baker's yeast and Citric acid using strains of Saccharomyces cerevisiae ATCC 1102 and Aspergillus niger ATCC 16404 and the determination of optimized production conditions. Submerged fermentations was carried out in a fermentor of 3 litters capacity. So, the obtained results show that the optimal Baker's yeast production was obtained at dilution rate of 0.22 h-1. On the other hand, the strain of Sacccharomyces cerevisiae SC-DB-A12 produced high yield biomass compared to other strains. Also, the use of ammonium phosphate provides better biomass yields compared to other nitrogen source. Concerning the citric acid production, the optimal fermentation period was 144 h. The maximum citric acid production was obtained at 30°C and at 150.0 g L-1 of sugars. In the same way, the addition of methanol at concentration up to 3.0% resulted in a marked increase in the citric acid production. In addition, the optimum pH for maximum citric acid production was 3.5. The aeration rate kept at a level of 1.0 L/L/mni was found to be optimum. Finally, the best results were observed when 2.5 g L-1 ammonium nitrate and 2.5 g L-1 of potassium phosphate were added into the medium. In summary, a maximum citric acid production i.e., 126.4 g L-1 was obtained at these optimal conditions. It is concluded from these results that the date wastes could serve as a potential substrate for Baker yeast and Citric acid production. © 2011 Asian Network for Scientific Information.

Defilippi B.G.,Institute of Agricultural Research | Manriquez D.,Institute of Agricultural Research | Robledo P.,Institute of Agricultural Research
Acta Horticulturae | Year: 2011

Ethylene plays an important role in coordinating the ripening process in climacteric fruit, including pears. Regarding 'Abate Fetel', despite having good storage potential, little information is available about the effect of ethylene inhibition (pre-and postharvest) in the development of quality attributes. Therefore, the main objective of this study was to evaluate the effect of two formulations of 1-methylcyclopropene (1-MCP), one applied preharvest (Harvista TM Technology) and the second one after harvest (SmartFresh TM). In order to develop a commercial strategy, including doses of both formulations, timing of application and storage potential, the trials were performed during three seasons in the same orchard: 2006-2007, 2007-2008 and 2008-2009. Evaluations included both quality and physiological parameters, such as total soluble solids, titratable acidity, flesh firmness, color development, ethylene production and respiration rate, amongst others. In general, the fruit treated with either formulation of 1-MCP maintained higher firmness than the non-treated fruit during cold storage, especially with SmartFresh TM. Similarly, during shelf-life the fruit treated with 1-MCP took longer to reach the ready-to-eat stage, both in terms of firmness and color development. As shown for other species, there was an important effect of the maturity stage at harvest and storage time on the effectiveness of both formulations.

Defilippi B.G.,Institute of Agricultural Research | Robledo P.,Institute of Agricultural Research | Manriquez D.,Institute of Agricultural Research
Acta Horticulturae | Year: 2011

A major challenge during long term storage of kiwifruit is the maintenance of fruit firmness, which could be seriously affected by ethylene levels due to contamination events. In order to reduce ethylene effects during storage several tools are commercially used, including air ventilation and ethylene scrubbers such as catalytic converters and potassium permanganate. The ethylene antagonist 1- methylcyclopropene (1-MCP) has shown benefits in extending kiwifruit storage life, but its effect has not been tested under ethylene contamination conditions, which was the main objective of this work. To perform the assay, kiwifruit applied with 1 ppm 1-MCP for 24 h immediately after harvest were stored for 90 days at 0°C. Ethylene contamination was performed with 400 ppb of ethylene applied for 72 h at four times during storage, i.e., 0, 30, 60 and 90 days. As already reported, fruit applied with 1-MCP remained firmer after storage than untreated fruit. In terms of contamination, ethylene applied in the first 30 days of storage was the most detrimental in inducing fruit softening. This effect on firmness was evident after 60 days of storage when half the fruit not treated with 1-MCP was at a firmness less than 3 lbf. In contrast, less than 10% of the fruit treated with 1-MCP was under this commercial threshold. No other quality attributes were affected by 1-MCP application or ethylene contamination. Therefore, 1-MCP could be considered as an effective tool for reducing the negative effects of ethylene contamination during storage.

Manriquez D.,Institute of Agricultural Research | Defilippi B.G.,Institute of Agricultural Research
Acta Horticulturae | Year: 2011

One of the main postharvest problems in kiwifruit is flesh softening, this process being in part coordinated by ethylene. Therefore, many postharvest strategies have been developed in order to reduce fruit softening, including early harvest, controlled/modified atmosphere storage, ethylene scrubbers and 1-MCP (1-methylcyclopropene) (SmartFresh SM) applications after harvest, being SmartFresh SM extensively used in the last 3 years in Chile. Under Chilean growing conditions the harvest window is quite extend depending on the growing area, going from March to May, which could be affecting the postharvest behavior of the fruit in terms of quality attributes, including firmness among others. During the last three years, a new formulation of 1-MCP has been developed for applying this molecule in preharvest (Harvista™ Technology), being the objective of this study to evaluate the effect of this molecule during harvest and postharvest of kiwifruit. For the trials we considered two applications times before harvest and two harvest opportunities based on maturity. At harvest no differences were observed for all the attributes evaluated. But for harvest time, an effect in fruit softening was observed during cold storage showing all the fruit applied with 1-MCP a higher firmness compared to control fruit, being this effect more evident in the second harvest. This effect could be explained by the effect of 1-MCP in ethylene production and respiration rate, where lower rates in both parameters were measured in kiwifruits applied with 1- MCP. In other attributes, such as total soluble solids, titratable acidity and physiological disorders, not major differences were observed.

Defilippi B.G.,Institute of Agricultural Research | Robledo P.,Institute of Agricultural Research | Ferreyra R.,Institute of Agricultural Research | Soto S.,Institute of Agricultural Research | Saavedra J.,Pontifical Catholic University of Valparaíso
Acta Horticulturae | Year: 2015

Avocado quality variability is due to the broad range of conditions in which trees are grown, especially in terms of climate and soil, and also associated with different cultural practices used among avocado growers. In the last four years, we have been performing a project in order to understand this variability by determining the effect of preharvest factors (climate, nutrition, cultural management, etc.) on the postharvest life of 'Hass' avocados, shipped under regular air (RA) and controlled atmosphere (CA) conditions. Fruit was collected from 11 commercial orchards during the 2009/10, 2010/11 and 2011/12 seasons, stored under RA and CA (4%O2and 6% CO2) for 40 and 55 days at 5°C and 90% RH, and ripened at 20°C after cold storage until reaching the ready to eat stage. The postharvest parameters evaluated included flesh firmness, color, physiological disorders and days to reach ripening. A multivariate analysis was performed to determine a possible relationship between preharvest factors and postharvest avocado quality. Under both storage conditions, a high fruit variability among experimental sites was observed in the different quality attributes evaluated after storage. Among the variables studied, the days between flowering and harvest had an inverse effect on fruit firmness level after storage. A similar behavior was found for N/Ca ratio and oil content at harvest. Other factors that directly affected fruit firmness were calcium content at harvest and orchard elevation.

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