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Paruelo J.M.,University of Buenos Aires | Pineiro G.,University of Buenos Aires | Baldi G.,National University of San Luis | Baeza S.,University of Montevideo | And 3 more authors.
Rangeland Ecology and Management | Year: 2010

Grasslands are one of the most modified biomes on Earth. Land use changes had a large impact on carbon (C) stocks of grasslands. Understanding the impact of land use/land cover changes on C stocks and fluxes is critical to evaluate the potential of rangeland ecosystem as C sinks. In this article we analyze C stocks and fluxes across the environmental gradients of one of the most extensive temperate rangeland areas: the RÃ-o de la Plata Grasslands (RPG) in South America. The analysis summarizes information provided by field studies, remote sensing estimates, and modeling exercises. Average estimates of aboveground net primary production (ANPP) ranged from 240 to 316 g C·m-2·yr-1. Estimates of belowground NPP (BNPP) were more variable than ANPP and ranged from 264 to 568 g C·-2·yr-1. Total Carbon ranged from 5004 to 15008 g C·-2. Plant biomass contribution to Total Carbon averaged 13% and varied from 9.5% to 27% among sites. The largest plant C stock corresponded to belowground biomass. Aboveground green biomass represented less than 7% of the plant C. Soil organic carbon (SOC) was concentrated in the slow and passive compartments of the organic matter. Active soil pool represented only 6.7% of the SOC. The understanding of C dynamics and stocks in the RPG grasslands is still partial and incomplete. Field estimates of ANPP and BNPP are scarce, and they are not based on a common measurement protocol. Remotely sensed techniques have the potential to generate a coherent and spatially explicit database on ANPP. However, more work is needed to improve estimates of the spatial and temporal variability of radiation use efficiency. The absence of a flux tower network restricts the ability to track seasonal changes in C uptake and to understand fine-scale controls of C dynamics. © 2010 Society for Range Management.

Correa J.,Instituto Nacional Of Investigaciones Agropecuarias | Correa J.,University of Chile | Laborie D.,Instituto Nacional Of Investigaciones Agropecuarias | Casanueva X.,Instituto Nacional Of Investigaciones Agropecuarias | And 5 more authors.
Acta Horticulturae | Year: 2014

The genotypic effect and the interaction between genotype and gibberellic acid (GA3) treatment (g×t) of 23 traits associated with cluster architecture was characterized with a progeny 'Ruby Seedless' × 'Sultanina' (n = 140). The genotypic effects were significant for all the traits and g×t effect was significant only for rachis length (rl), fresh weight (rw), lateral shoulder length (sl) and number of berries per cluster (rb). Best linear unbiased predictors (BLUPs) of these effects were calculated. Multivariate factorial analyses of BLUPs showed highly significant correlations and a latent correlation structure among the traits. The BLUPs of rl, rw, number of internodes (ri), and sl were responsible for 27.8% of the total variance (first factor). A quantitative trait loci (QTLs) analysis showed that the linkage group 18 (LG18) and LG5 harbored several significant QTLs for the first factor. These QTLs were supported mainly by a paternal additive effect. Considering g×t, six significant QTLs were mapped in LG17, LG10, LG14 and LG18. These QTLs had mainly maternal and dominant effects. The correlation structure together with QTL analyses revealed possible pleiotropic effects. In conclusion the QTLs detected indicate that rl, rw, ri and sl have a clear genetic basis and due to their importance in the total variance they are good determinants of the genetic diversity of cluster architecture.

Sotomayor-Ramirez D.,University of Puerto Rico at Mayaguez | Espinoza Y.,Instituto Nacional Of Investigaciones Agropecuarias
Journal of Agriculture of the University of Puerto Rico | Year: 2010

Cultivation affects soil organic matter loss through decreased soil structural stability. Sparse information is available for highly weathered soils. The objective of this study was to evaluate the effects of soil order (Ultisols and Inceptisols) and land use (agriculture and forest) on the formation of water stable aggregates, concentration of aggregate-associated C, and quality of C In aggregates from selected soils in a humid tropical watershed. Ultisols and soils under forest had increased soil C as a result of increased C concentrations in aggregates. Nearly 90% of the soil C was found in macroaggregates of soils under forest and In Ultisols. In forest and agriculture land use, soil silt+clay content was an important determinant for C storage in the bulk soil but not in aggregates. Cultivation reduced the percentage of soil mass in large macroaggregates (>2,000 μm) relative to that in forest soils, whereas Ultisols had greater soil mass percentage in large macroaggregates than Inceptisols. Overall, macroaggregates have higher labile and stable C than microaggregates. Ultisols had greater amounts of labile C but similar proportions of stable C. As has been found in other soils dominated by mixed-mineralogy and 1:1 clays and oxides, aggregate-associated C is not the sole determinant for the formation of macroaggregates.

Morales-Salinas L.,University of Chile | Acevedo E.,University of Chile | Castellaro G.,University of Chile | Roman-Osorio L.,Instituto Nacional Of Investigaciones Agropecuarias | And 2 more authors.
Ciencia e Investigacion Agraria | Year: 2015

In the past 20 years, different areas of research concerning native and exotic species, herbaceous crops and forest plantations have been oriented toward satisfying domestic, industrial and transportation energy requirements. Because bioenergy species constitute an important resource, it would be strategic for a country to have a method for identifying areas suitable for their cultivation to properly incorporate the establishment of energy crops into land use planning. In this study, we sought to define the suitable territories for 16 bioenergy species and their energy potential based on their soil and climate requirements in Central and Southern Chile. We used an adapted version of the FAO EcoCrop database implemented through DIVA-GIS software to predict the crop suitability of different geographical areas, and our results indicate that this method is a simple way to identify land suitable for the establishment of bioenergy species, which is information that can be used in land use planning. Furthermore, spatially explicit regression and ordinary kriging proved to be satisfactory tools for interpolating data from weather station networks through the generation of continuous climatic information grids. Land suitability is presented at a scale of 1:1,000,000 in a continuous digital format expressed in probabilistic terms. © 2015, Cien. Inv. Agr. All Rights Reserved.

Navarrete B.,Instituto Nacional Of Investigaciones Agropecuarias | Carrillo D.,University of Florida | Reyes-Martinez A.Y.,Antonio Narro Agrarian Autonomous University | Sanchez-Pena S.,Antonio Narro Agrarian Autonomous University | And 3 more authors.
Florida Entomologist | Year: 2014

Studies were conducted under controlled laboratory conditions to evaluate the effect of the predator, Zelus longipes (Hemiptera: Reduviidae) on mortality of Diaphorina citri (Hemiptera: Liviidae) as well as its effect on the specialized parasitoid, Tamarixia radiata (Hymenoptera: Eulophidae). All tested life stages of Z. longipes consumed significantly more D. citri adults than nymphs. Zelus longipes nymphs were only effective as predators of D. citri adults at a predator density of 8 individuals (or specimens) per arena. The mortality of D. citri nymphs caused by Z. longipes adult females was higher at the densities of 2 or more predators per arena. All densities of male and female adult Z. longipes resulted in mortality of nearly all the T. radiata adult parasitoids offered. The importance of intraguild predation and possible interference with T. radiata are discussed. © Florida Entomologist 2014.

Sundry V.G.,Instituto Naciomnal Of Investigaciones Agricolas | Salazar E.,Instituto Naciomnal Of Investigaciones Agricolas | Dickson L.,Instituto Nacional Of Investigaciones Agropecuarias | Castro L.,Instituto Naciomnal Of Investigaciones Agricolas
Zootecnia Tropical | Year: 2014

Cattle Carora breed originated from empiricalcrossing of cattle breeds Criollo Amarillo deQuebarada Arriba and Brown Swiss. Carora is the creole cattle breed that makes the greatestcontribution to local cattle farming economy and itis part of a scarce number of local breeds that formVenezuela’s invaluable genetic patrimony. Theexhaustive knowledge of its genetic characteristicsis indispensable to contribute to its preservation.Main objective of present study was to undertakea genetic characterization, genetic variability determining and establishing of philo genetic relationships with its known ancestors. SinceCriollo Amarillo of Quebrada Arriba is extinct20 samples of closest relative Criollo Limonerowere used among 35 of Carora and 20 BrownSwiss blood samples. 10 DNA molecular markersre commended by FAO/ISAG microsatellites wereused to estimate a number of population genetic variables, test for Hardy and Weinberg, and todetect the formation of genetically distinct groups.Results show that the Carora breed possessesa high genetic variability. Five subtypes wereobserved. It can be concluded that despite of beinga hybrid product of at least two races, Carora cattlehas evolved and developed a proper identity. © 2014, Instituto Nacional de Investigaciones Agricolas (INIA). All rights reserved.

Barrowclough M.,Virginia Polytechnic Institute and State University | Stehouwer R.,Pennsylvania State University | Alwang J.,Virginia Polytechnic Institute and State University | Gallagher R.,Clinton | And 2 more authors.
Journal of Soil and Water Conservation | Year: 2016

Small-scale farming in Ecuador's highlands is associated with excessive soil erosion, degradation of soil health, and agricultural productivity loss. Conservation agriculture (CA) offers promise in these areas. Minimum disruption of soil and maintenance of permanent groundcover, two CA pillars, reduce erosion and can increase soil health and productivity. Despite its promise, CA has not been widely adopted by Andean region farmers, and factors such as uncertainty about CA benefits, risk aversion, and high discount rates have been offered as explanations for lagging adoption. This paper combines an analysis of CA trial data from farmer fields and an analysis of two farm-household surveys to measure potential benefits from adoption and identify correlates of adoption. The analysis reveals actions to promote more widespread adoption of CA. Data are from a unique five-year research project in Bolivar Province, Ecuador. Yield and cost of production data from on-farm trials are used to estimate costs and benefits of CA, household data are used to analyze the determinants of CA adoption, and data from a choice experiment help estimate willingness to pay for CA attributes, such as increased yield and reduced erosion. We find that CA practices yield more and cost slightly less (over five years) than conventional practices, but differences are not large. The adoption analysis shows that farm size and labor access are not associated with adoption, but farmers who perceive soil loss on their farm to be severe are much more likely to adopt. This aversion to soil loss is examined in the choice experiment, which finds that farmers are most interested in economic considerations, such as increasing yields and saving increasingly costly labor. CA holds promise in such systems, but diffusion efforts must be carefully tailored to address farmer needs. Copyright © 2016 Soil and water Conservation Society All right reserved.

Stewart R.D.,Virginia Polytechnic Institute and State University | Stewart R.D.,Oregon State University | Abou Najm M.R.,American University of Beirut | Rupp D.E.,Oregon State University | And 4 more authors.
Hydrological Processes | Year: 2015

Irrigation experiments on 12 instrumented field plots were used to assess the impact of dynamic soil crack networks on infiltration and run-off. During applications of intensity similar to a heavy rainstorm, water was seen being preferentially delivered within the soil profile. However, run-off was not observed until soil water content of the profile reached field capacity, and the apertures of surface-connected cracks had closed >60%. Electrical resistivity measurements suggested that subsurface cracks persisted and enhanced lateral transport, even in wet conditions. Likewise, single-ring infiltration measurements taken before and after irrigation indicated that infiltration remained an important component of the water budget at high soil water content values, despite apparent surface sealing. Overall, although the wetting and sealing of the soil profile showed considerable complexity, an emergent property at the hillslope scale was observed: all of the plots demonstrated a strikingly similar threshold run-off response to the cumulative precipitation amount. © 2014 John Wiley & Sons, Ltd.

PubMed | Instituto Nacional Of Investigaciones Agropecuarias, University of Greenwich and Pontifical Catholic University of Ecuador
Type: | Journal: Journal of economic entomology | Year: 2016

Delia platura Meigen is an important pest in crops around the world. Its host range includes almost 50 species, and it can develop in soil organic matter. In Ecuador, D. platura is a serious problem for the crop, Lupinus mutabilis Sweet (Chocho), and it also attacks broccoli (Brassica oleracea L.). After broccoli is harvested, crop residue is mixed with soil or collected and stored close to Chocho fields. The objectives of this study were to determine the adaptive responses of larvae reared on different hosts and whether D. platura females are preferentially attracted to germinating L. mutabilis seeds or broccoli residue. Accordingly, larval performance and attraction of female D. platura reared on broccoli residue and L. mutabilis seeds were evaluated. The number of larvae, pupae, and adults were higher when reared on broccoli. Conversely, pupal weight was higher and time from larva to pupa, pupa to adult, and total life cycle were longer in flies reared on L. mutabilis. Although D. platura developed more quickly on broccoli, L. mutabilis was also a good host since pupae were heavier compared with flies reared on broccoli. Delia platura females reared on broccoli preferred broccoli residue to L. mutabilis in an olfactometer. Volatiles from broccoli residue in soil may attract D. platura females and stimulate oviposition on L. mutabilis seeds. Environmentally benign production of L. mutabilis crops with minimal insecticide applications may require the elimination of fresh broccoli residue as fertilizer in soils where L. mutabilis is cultivated.

PubMed | Santa Catarina State University, Proterra, University of Reunion Island, Box 2312 and 31 more.
Type: | Journal: Persoonia | Year: 2016

Novel species of fungi described in the present study include the following from Australia: Neoseptorioides eucalypti gen. & sp. nov. from Eucalyptus radiata leaves, Phytophthora gondwanensis from soil, Diaporthe tulliensis from rotted stem ends of Theobroma cacao fruit, Diaporthe vawdreyi from fruit rot of Psidium guajava, Magnaporthiopsis agrostidis from rotted roots of Agrostis stolonifera and Semifissispora natalis from Eucalyptus leaf litter. Furthermore, Neopestalotiopsis egyptiaca is described from Mangifera indica leaves (Egypt), Roussoella mexicana from Coffea arabica leaves (Mexico), Calonectria monticola from soil (Thailand), Hygrocybe jackmanii from littoral sand dunes (Canada), Lindgomyces madisonensis from submerged decorticated wood (USA), Neofabraea brasiliensis from Malus domestica (Brazil), Geastrum diosiae from litter (Argentina), Ganoderma wiiroense on angiosperms (Ghana), Arthrinium gutiae from the gut of a grasshopper (India), Pyrenochaeta telephoni from the screen of a mobile phone (India) and Xenoleptographium phialoconidium gen. & sp. nov. on exposed xylem tissues of Gmelina arborea (Indonesia). Several novelties are introduced from Spain, namely Psathyrella complutensis on loamy soil, Chlorophyllum lusitanicum on nitrified grasslands (incl. Chlorophyllum arizonicum comb. nov.), Aspergillus citocrescens from cave sediment and Lotinia verna gen. & sp. nov. from muddy soil. Novel foliicolous taxa from South Africa include Phyllosticta carissicola from Carissa macrocarpa, Pseudopyricularia hagahagae from Cyperaceae and Zeloasperisporium searsiae from Searsia chirindensis. Furthermore, Neophaeococcomyces is introduced as a novel genus, with two new combinations, N. aloes and N. catenatus. Several foliicolous novelties are recorded from La Runion, France, namely Ochroconis pandanicola from Pandanus utilis, Neosulcatispora agaves gen. & sp. nov. from Agave vera-cruz, Pilidium eucalyptorum from Eucalyptus robusta, Strelitziana syzygii from Syzygium jambos (incl. Strelitzianaceae fam. nov.) and Pseudobeltrania ocoteae from Ocotea obtusata (Beltraniaceae emend.). Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.

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