Ecosystem Services of Grazed Grasslands in the Flooding Pampa

The Flooding Pampa grasslands are the last remnant of the Rio de la Plata grasslands in Argentina.Anthropo-genic interventions have led to severe degradation and,as a result,the ecosystem services provided by the grass-lands are declining,in terms of provisioning,regulating,and supporting services.We synthesized the existing literature on the ecosystem goods and services provided by these grasslands under grazing in different conditions and conservation status.We found that plant and animal diversity and primary production are the most studied ecosystem services,while climate regulation,water supply,nutrient cycling,meat production and erosion control,in that order,are less studied.Cultural services are under-researched.Continuous grazing and glyphosate spraying are the main drivers of grassland degradation.Controlled grazing and conservative stocking rates have been shown to reverse degradation and demonstrate that livestock production is compatible with ecosystem conserva-tion by maintaining regulating and provisioning services.As these management strategies are poorly integrated,improving their implementation will require important changes in farmers’decisions and the development of policies that create the economic conditions for this to happen.Research is needed to understand the conditions that prevent the knowledge generated from being transferred to producers and translated into practices that would improve the provision of ecosystem services.

The Effect of Water and Salt Stress on Paspalum dilatatum,a Constituent of Pampas Natural Grasslands

The effects of the salt stress on plant growth are usually increased by the water stress.We studied the impact of both stresses in simultaneous pulses of drought and salinity on Paspalum dilatatum.This forage species is native to South America,spread in grasslands in many tropical,subtropical,and temperate areas of the world,and very common in grasslands of the Flooding Pampas of Argentina.Mimicking what happens in nature.We compared a pot experiment,a non-stressed control against water stress for a month(midpoint between field capacity and wilting point),and two saline stresses(moderate,6 d·Sm^(−1)and strong,12 d·Sm^(−1)),also for a month.Aerial biomass(green leaf;non-leaf green material,and dry material)and roots were harvested,weighed,and analyzed for nitrogen,phosphorus,and cations.The biomass of all components significantly decreased when both stresses were applied.Water plus strong saline stress reduced by half the total biomasses,compared to the control.The proportion of aerial biomass/root biomass ratio as well as aerial green component/dry materials ratio tend to decrease when subjected to both stresses.Nitrogen concentration in plants was not significantly affected,but phosphorus concentration increased in aerial biomass components,from 0.10 to 0.18 mg·kg^(−1)between the extreme treatments,but did not change in roots.Sodium concentration in plants increased(i.e.,in green leave sodium(Na)increased from 0.27 to 2.01 mg·kg^(−1)between the extreme treatments),whereas other cations either did not change or decreased,affecting the ratios between them.Sodium performance allows us to infer that the Na accumulation of P.dilatatum behaves in an intermediate range,compared to very tolerant to salts or non-salt tolerant species of the Paspalum genus.In agreement,when salts were applied in the form of a pulse,P.dilatatum tolerated higher salinity than that found by other authors for the same species,using continuous salinity.

Morphometric Attributes of Two Native Forage Species According to Water Source Distance in Semiarid Central Grasslands of Argentina

The semiarid grasslands of Argentina’s central region have been modified by domestic livestock grazing,both in their composition and structure.The increase in the proportion of woody and non-forage species and the decrease in forage species are some of the most evident results of this process.There is limited available information about the effect of differential grazing pressures on morphometric attributes of native species,and it also depends on the life histories of the species in this grassland.The objective of this work was to evaluate some morphometric aspects in the grasses Poa ligularis Nees ex Steud and Piptochaetium napostaense(Speg.).Hack according to distance from the water source in communities in the central semiarid region of Argentina.The study area included areas of low grassland,golden forests,and secondary forests in grasslands(6 fields with 9 paddocks).Grazing pressure was established based on the distance to the water source,so sampling areas were designated near the water source(grazing pressure is greater)and far from the water source(grazing pressure light)in each of the pastures.In both species,specimens were selected at random,and the following attributes were measured:crown diameter at ground level(cm),burial depth(cm),average tiller weight per plant(g.Marcello^(−1)),and the density of tillers per unit of crown surface(tillers.cm^(−2)crown).The morphometric attributes evaluated showed differences according to the distance to the watering hole and in the different pastures.Both species presented similar behaviors for the attributes.There were significant differences in the depth of burial and the average weight of tillers per plant,being greater in the areas close to the water source.Regarding the distance to the watering hole,there were no significant differences in crown diameter and tiller density,but the highest values were recorded for the former near the watering hole and for the second far from the watering hole.In pastures with low grassland or secondary forest on the plain,the greatest depth of burial and weight of tillers was recorded closer to the water.In forest areas,the highest density of tillers was found far from the water.For crown diameter,although there was no interaction,the largest diameters were found in plain grassland areas near the waterhole.In general,both species had a differential behavior depending on the grazing pressure that was evident along the physiognomic gradient from plain grassland to forest and that could be interpreted as a strategy to perpetuate themselves against herbivory.

Agronomic Use of Slurry from Anaerobic Digestion of Agroindustrial Residues: Effects on Crop and Soil

In a greenhouse experiment we evaluated the application of slurry generated by a biogas reactor of agroindustrial residues. The objectives of this study were to determine the response to slurry application on dry matter production and nutrients absorption of Setaria italica (setaria), and to evaluate the effect of the slurry on soil properties. Two soils, of different texture, were mixed either with slurry or with diammonium phofsphate (DAP) at 0, 80, and160 kgN ha-1 equivalent rates. The setaria was harvested 68 days after planting, and separated into leaves plus stems, ears, and roots. Total biomass and content of N, P, K, Ca, Mg, Cu, Fe, Mn, and Zn were determined in each fraction. In the soil we determined pH, electric conductivity (EC), organic C, available P, mineral N, and exchangeable cations. Although the biomass produced and the amounts of nutrients absorbed were different in the two soils, in both of them setaria responded to the slurry application. The amounts of N absorbed from slurry and DAP were similar, indicating that the N from the slurry was readily available. The slurry application also increased the absorption of other macro and micro nutrients (P, Ca, Mg, and Zn). No significant changes in soil exchangeable cations, pH, and EC were observed at setaria harvest. In the silty soil the crop almost depleted the mineral N in all treatments, but in the sandy soil large amounts were left, especially in the treatments with slurry. This fact highlights the importance of a careful dosage of this soil amendment, to avoid the excess of mineral N, which is potential pollutant for the environment. It can be concluded that the use of slurry from the reactor had a positive effect on the nutrients availability, without negative effects on soil properties.

Divergent molecular and growth responses of young“Cabernet Sauvignon”(Vitis vinifera)plants to simple and mixed infections with Grapevine rupestris stem pitting-associated virus

Grapevine rupestris stem pitting associated virus(GRSPaV)is one of the most widely distributed viruses;even so,little is known about its effect on Vitis vinifera.To provide new insights,the effects of single and mixed GRSPaV infections on the V.vinifera cultivar“Cabernet Sauvignon”were studied by evaluating growth parameters,such as measurements of the total plant length,the number and distance of internodes and the number of leaves per shoot.In addition,parameters relating to gas exchange,i.e.,the stomatal conductance,net photosynthetic rate,internal CO2 concentration and leaf transpiration,were also assessed.All the measurements were performed in one-and two-yearold plants with a single GRSPaV infection or mixed infections of GRSPaV and Grapevine fanleaf virus(GFLV).The results show that the plant phytosanitary status did not significantly alter the growth and gas exchange parameters in oneyear-old plants.However,in two-year-old plants,single GRSPaV infections increased shoot elongation,which was accompanied by the overexpression of genes associated with the gibberellic acid response pathway.The gas exchange parameters of these plants were negatively affected,despite exhibiting higher LHCII gene expression.Plants with mixed infections did not have modified growth parameters,although they presented a greater reduction in the primary photosynthetic parameters evaluated with no change in LHCII expression.The results presented here confirm the co-evolution hypothesis for V.vinifera and GRSPaV during the early stages of plant development,and they provide new evidence about the effects of GRSPaV and GFLV co-infections on the“Cabernet Sauvignon”cultivar.

Statistical evaluation of fluoride contamination in groundwater resources of Santiago del Estero Province, Argentina

This study investigates the suitability of statistical techniques for evaluating the fluoride content and the groundwater quality from Robles Department(RD)and Banda Department(BD)in Santiago del Estero(Argentina).For the original statistical study,evaluation of nine parameters(fluoride,pH,conductivity,atmospheric and water temperature,total dissolved solids,chloride,hardness,and alkalinity)of 110 collected underground water samples from 23 dispersed rural areas was proposed.Groundwater samples were obtained by sampling taken from wells at different depths.Fluoride levels were determined by a standard colorimetric method in two seasonal periods,the dry(from April to September)and rainy(from October to March)period.The analytical results obtained for physicochemical parameters such as pH,total dissolved solids(TDS),and temperature does not reveal any notable difference between the rainy and dry seasons studied.In both seasons,the atmospheric temperature average was 22℃.With respect to fluoride content,approximately 50%of the analysed groundwater samples exceeded the limit established by current legislation(1.0 mg/L),obtaining concentration levels in the range of 0.01-2.80 mg/L.This study demonstrates the usefulness of the univariate statistical method(quartiles calculation,interquartile range IQR),multivariate principal component analysis(PCA),and cluster analysis to establish a better understanding of the state of the contamination of the waters in the region studied.

Natural variability of essential oil and antioxidants in the medicinal plant Turnera diffusa

Objective:To evaluate differences in yield and composition of the essential oil and antioxidant contents in T.diffusa plants from localities in central region of Tamaulipas.Methods:Samples were collected in Tamaulipas,Mexico in the arid zone.Essential oil was obtained through steam distillation and analyzed using GC-MS.Polyphenol contents,antioxidant activities using ABTS and ferric reducing antioxidant power(FRAP) methods also were evaluated.Results:A total of 21 compunds were identified in the essential oils;nevertheless,only Eucalyptol,1,4-Methanocycloocta[d]pyridazine,1,4,4a,5,6,9,10,10a-octahydro-11,11-dimethyl-,(1à,4à,4aà,10aà) y Ethanone,1-(1,3-dimethyl-3-cyclohexen-1-yl) were detected in the three sites.Highest contents were registered in the sample from Padrón y Juárez with phenolic content of 33.85 mg GAE/g of dry material and antioxidant activities with ABTS 72.32% and with FRAP 21.33 mg GAE/g of dry material.Statistical differences were observed in essential oil,phenolics and antioxidants contents between populations.Conclusions:Results suggest that climatic differences and origin influence the phytochemicals in the medicinal plant T.diffusa,and thus,it is worth to consider such effects for industrial and medicinal purposes.

Design and Construction of a Pneumatic Temporary Immersion Bioreactor System for the Multiplication of <i>Ananas comosus</i>var. Trujillana Red

The present work initially identified the design parameters of a temporary immersion bioreactor to later scale it to a complete system for the in vitro multiplication of Ananas comosus var. Trujillana Red. Thus, a low-cost pneumatic temporary immersion bioreactor system was designed and built with 24 tanks of 2 L each. The automation of the system was designed and implemented by means of a timer circuit whose design parameters were: duration of the propagation process, which depends on the multiplication period of the crop and is an open variable, which means that the operator decides when to turn off the system;the duration of each dive, which for reasons of complexity of the algorithm was standardized as one minute;immersion frequency, which was programmed for intervals of 1, 2, 3, 4, 5, 6, 7, 8 hours respectively and duration of aeration, which from a test run times of 0.20 were chosen, 30, 40, 50, 60, 70, and 80 seconds that correspond to the time of delivery of compressed air;additionally, the multiplication rate of Ananas comosus var. Trujillana Red in the immersion system which was 6.5 times per propagative unit inoculated in thirty days.

Fungicide tolerance of <i>Trichoderma asperelloides</i>and <i>T. harzianum strains</i>

Tolerance in isolations of Trichoderma was developed by exposing two strains of T. harzianum and three of T. asperelloides to increasing concentrations of chemical fungicides. These isolation of Trichoderma were exposed to three fungicides: Captan, Thiabendazol and the mixture Captan-Carboxin. Some selected lines of these strains reached tolerance to Captan and partial tolerance to the mixture Captan-Carboxin. The biological and genetic changes in these tolerant lines were monitored by determining the relative growth rate of the fungus, inhibition of Fusarium and by analyzing the genomic changes through UP-PCR. The results show that the tolerance to fungicides can be developed without affecting the parameters of biological activity in these lines of Trichoderma (growth and parasitism against Fusarium). Chemical tolerance to the fungicide was verified by means of changes at the DNA level (UP-PCR), mainly in the lines tolerant to Captan. This suggests that Trichoderma survives in environments with remnants of fungicide molecules.

<i>Jatropha curcas L</i>. and <i>J. macrocarpa</i>Griseb: Seed Morphology, Viability, Dormancy, Germination and Growth of Seedlings

To achieve a good production of a crop, it is essential to know the ability of the species to successfully complete two critical stages in the life cycle such as germination and seedling establishment. In this paper we study in comparative form structure of the seed, the importance of tegument in dormancy, the effect of accelerated aging on seed germination and viability, and the early and late growth in J. curcas and J. macrocarpa. External morphology of the seeds allow difference and internally also the embryos show evident differences. J. macrocarpa germination is around 0% - 4%. The total removal of tegument showed a 50% increase and the other treatments between 0% - 10%. Aging accelerated by Tetrazolium test allowed a comparative analysis of VP and GP. J. curcas maintains both to 96 h, while J. macrocarpa the seed viability is registered along the all treatment. J. macrocarpa seeds have less synchronicity than those of J. curcas. ABA and JAs were detected in tegument of J. macrocarpa and J. curcas seeds. JA could have a roll in inhibition of germination of J. macrocarpa seeds. Early and late growth, FW and DW of root, hypocotyl, epicotyl and leaf of J. curcas were significantly different in both species.

Secretory Structures in <i>Flourensia campestris</i>and <i>F. oolepis</i>: Ultrastructure, Distribution, and (-)-Hamanasic Acid A Secretion

In this work, the localization, density, morphology and ultrastructure of secretory structures in aerial organs of Flourensia campestris (FC) and F. oolepis (FO) (Asteraceae) by means of a combination of light, fluorescence, transmission (TEM) and scanning electron microscopy (SEM) were examined. The possible role of secretory structures in the production and secretion of the phytotoxic sesquiterpene (-)-hamanasic acid A ((-)HAA) in both species was also assessed. Capitate glandular trichomes were found in all reproductive organs of FC and FO, and were being reported for the first time. These glandular trichomes, typically associated to edges and veins, were of the same type as those already described for vegetative organs, and were abundant in involucral bracts and corolla of tubulose and ligulate flowers. Their density in reproductive organs of both species was similar (ca. 30/mm2) and lower than that found in leaves (ca. 100/mm2) and stems (ca. 160/mm2 in FC, and up to 650/mm2 in FO). Glandular trichomes in vegetative organs followed a species-specific pattern of distribution. TEM and SEM observations suggest that each species differs in the way in which secretory materials are released to the outside: through cracks or pores in FC, or through a loose cuticle in FO. Similar inspections of the secretory ducts revealed lipophilic vacuoles localized in subepithelial and epithelial cells, in which secretions accumulated before being transferred to the duct. The presence of wall ingrowths in subepithelial cells suggests that granulocrine secretion operates in these species. Secretory ducts varied in density and diameter among the organs in both species, with the combination being maximal in woody stems. (-)HAA was only detected in surface secreted resins of both species, and its concentration (2D-TLC, GC-FID) was intimately associated with the distribution and density of glandular trichomes in each organ (capitula, leaves, and stems with primary or secondary growth). In addition, no (-)HAA was detected internally in the resins collected from secretory ducts. The composition of these resins showed distinctive profiles for FC and FO, and only four from ca. 30 compounds detected (GC/MS) were shared by both species. In addition to the elucidation of ultrastructural traits, distribution and density of secretory structures in aerial organs of FC and FO, present findings suggest a functional role for glandular trichomes in the secretion of the putative phytotoxic allelochemical (-)HAA.

Metabolic Adaptations Due to the Inclusion of Pasture in the Diet of Dairy Cows Fed Total Mixed Ration during Early Lactation

The aim of this study was to evaluate the metabolic adaptations due to the inclusion of pasture in the diet of dairy cows fed on a total mixed ration (TMR) ad libitum during early lactation. Multiparous cows (n=18) were used in a randomized complete block design and were randomly assigned according to parity, BW and BCS to one of two feeding strategies from calving to 60 DIM: 1) cows fed TMR ad libitum (without access to pasture;100% TMR) and 2) cows fed on a mixed system with pasture grazing (6 h of access to paddock in one grazing session, 8:00 to 14:00 h) and supplemented with 50% of ad libitum TMR (Pasture Group, PG). At 61DIM, TMR fed cows were assigned without an adjustment period to a similar feeding and management routine than PG group (Post-TMR), while PG cows remained in their original routine throughout the experiment. Thus, at 61DIM and thereafter, both, PG and Post-TMR cows grazed a second-year pasture and were supplemented with 50% TMR (DM basis). Milk production was determined daily until 80 DIM, and cow BCS and BW were registered and blood samples and liver biopsies were obtained one week before and one week after dietary change (-1 to +1 wk;+55 and +69 DIM). Milk yield, BW and BCS did not differ between treatments but decreased or tended to decreased from -1 to +1 wk only in Post-TMR cows. Serum IGF-1 tended to increase in Post-TMR cows. Hepatic expression of IGFBP5 and IGFBP6 mRNA, were greater while IGF1 and IGFBP3 mRNA tended to be greater for Post-TMR than PG cows. Hepatic expression of IGF1, IGFBP5 and IGFBP6 mRNA increased from -1 to +1 wk only in Post-TMR cows. Expression of ACADVL and PDH1A mRNA had a 2-fold increase in both groups from wks -1 to +1. The results confirm that changes in feeding strategy without an adaptation period modified animal metabolism. The inclusion of grazing to cows that were fed TMR during early lactation, increased IGF-1 concentrations and modified hepatic expression of genes related with IGF system and fatty acid metabolism indicating redistribution of nutrients and energy towards maintenance requirements (increased due to walking and grazing activity) in detriment of milk production.

Phenotypic Variation among and within Three Peppers Species(Capsicum)from Mexico

The phenotypic variation and its distribution among species,morphotypes,and among and within populations was estimated in 71 populations pertaining to 15 morphotypes of three domesticated species of Capsicum from Mexico.Collections were made in the states of Sinaloa,Nayarit,Oaxaca,Tabasco,and Yucatán in two agroecosystems:Backyard-garden and monoculture.Fifteen phenotypic characteristics were analyzed through one-way variance analysis and multivariate analyses of principal components analysis(PCA)and hierarchical clustering using Ward’s method.The study was performed in a uniform greenhouse experiment.A high variation was found among and within populations in all the measured characteristics.Of the total variation,13.0%was distributed among species,27.9%among morphotypes,8.1%among populations,and 51.0%within populations.Because plants grew in a uniform environment,these results indicate that the differences observed among and within species,morphotypes,and populations have a genetic basis.Univariate and multivariate analyses clearly differentiated morphotypes,suggesting that the category of morphotypes must be used to nominate the infraspecific variation in the domesticated Capsicum.The principal components analysis identified a total of 15 principal components that contributed to explain the total variation.The first two components explained 59.64%of the total variation and seven components explained more than 90%of the total variation.Among the measured characteristics,number of seed per fruit,weight of the fruit,width of the fruit,length of the fruit,stem diameter,days to flowering,and height of the plant contributed to component 1 variation,whereas width of the leaf,length of the leaf,and number of locules,number of fruits and number of seeds per plant contributed to component 2.The hierarchical clustering separated the populations and the morphotypes in two large different groups.One group consisted of populations collected in monoculture conditions and the other group corresponded to population collected from backyard-garden conditions.The monoculture populations were characterized mainly by their longer,wider,and higher weight fruits,plants were of less height,had smaller stem diameters,and lower number of fruits than the populations collected from the backyard-garden conditions.The backyard-garden populations of the Capsicum annuum and Capsicum frutescens species,considered wild or semi-domesticated,constituted a non-differentiated phenotypic group that does not allow dividing them in different species.

Disease Prevalence and Symptoms Caused by <i>Alternaria tenuissima</i>and <i>Pestalotiopsis guepinii</i>on Blueberry in Entre Ríos and Buenos Aires, Argentina

About 60% of blueberry (Vaccinium corymbosum) plantations in Argentina are located in the provinces of Entre Ríos and Buenos Aires. Alternaria tenuissima and Pestalotiopsis guepinii have been reported as pathogens of blueberry, causing leaf spots and branch cankers. The aims of this research were to estimate the prevalence of these microorganisms on leaves and fruits taken from crops located in Entre Ríos and Buenos Aires, as well as to differentiate leaf symptoms after target inoculations with each pathogen individually and in mixtures. Both fungi were present in blueberry fields from 2010 to 2013. A. tenuissima was the most prevalent pathogen, as most of the symptoms detected in the fields had been caused by this species. As a result of inoculations on cv. O’Neal, injured tissues showed symptoms before undamaged ones. Leaf symptoms caused by A. tenuissima differed from those caused by P. guepinii because of their predominant reddish color and the absence of drop-off of the central part of the lesions. When inoculated in a mixture, incubation period on leaves was intermediate between the registered for individual inoculations. The leaves showed reddishbrown spots typical of A. tenuissima and dark brown spots typical of P. guepinii, both with red margins. Blight, defoliation and canker symptoms caused in each case were undistinguishable.

A Soil Quality Index to Evaluate the Vermicompost Amendments Effects on Soil Properites

The aims of this work were 1) to evaluate the changes in soil properties with the application of different amounts of vermicompost (10 and 20 Mg?ha–1), and 2) to construct a soil quality index that allows the evaluation of changes in the most sensitive soil parameters. The study was carried out in a cattle field of General Alvear, Buenos Aires, Argentina. Vermicompost application showed a positive effect on most of the chemical and biological soil properties evaluated, especially with the higher dose (20 Mg?ha–1). There were slight but significant increases in electrical conductivity and soil pH with the higher dose of vermicompost. Physical soil properties were not affected by the vermicompost amendment. The SQI showed a significant increase of soil quality with the vermicompost dose of 20 Mg?ha–1, especially by enhancing the biochemical and biological properties.

Differential Response to Moderate UV-B Irradiation of Two Heterocystous Cyanobacteria Isolated from a Temperate Ricefield

In cyanobacteria both photosynthesis and nitrogen fixation can be affected by UV radiation. Two of the most abundant heterocystous cyanobacteria isolates from a temperate ricefield in Uruguay belonging to Anabaena and Calothrix genus were exposed for 1 or 3 hours to UV-B dosis similar to those to which they are exposed in summer. Anabaena survival after 1 h of UV-B exposure was 10% whereas in Calothrix’s was 30%. Both the quantum yields of photosybtem II fluorescence and O2 photoevolution decreased with time of UV-B exposure for Calothrix and only till 1 h for Anabaena. Only the Calothrix strain presented phycoerithryn as antenna pigment and constitutive UV-B screening mycosporine like aminoacids. In the Anabaena strain, nitrogenase activity was drastically reduced with UV-B irradiation but in Calothrix was not affected. Proline content and lipid peroxidation increased after 3 hours of UV-B exposure only in Anabaena sp. The antioxidant enzyme activities evaluated followed different trends for both isolates, with an increase in superoxide dismutase activity in the Calothrix isolate. These results show that the two nitrogen-fixing cyanobacteria studied have different responses to UV-B radiation and that cyanobacteria diversity may be considered when selecting strains to be used as biofertilizers.

Nutrient Export with Logs, and Release from Residues, after Harvest of a <i>Pinus taeda</i>Plantation in Uruguay

In Uruguay, Pinus taeda is usually planted a few months after harvest of the former turn, therefore;decomposing residues represents a nutrient source for the new plantation. The aim of this study was to determine the biomass and nutrient extraction off site, following the harvest of a P. taeda plantation. Residue decomposition patterns, and nutrient release were also examined. The site will be referred as S1, corresponding to the clear cut of a 22-year-old P. taeda plantation. Before the clear cut 10 trees were harvested, and logs, branches, twigs, and needles separately weighed. Additionally, forest litter at harvest time was quantified in three different areas. To assess decomposition, mesh bags with residues were allocated in three areas over the forest litter, and samples were taken periodically for 26 months. The remaining biomass, N, P K, Ca, and Mg contents were determined in the different fractions, calculating decompositon rates. Most of the harvested biomass was removed in logs, but the proportion of nutrients exported was considerably lower. Needles showed the highest biomass loss and only 39.1% remained after 26 months, while branches presented high rates in the first two months after cut, but slower thereafter, and at the end of the study more than two thirds of the woody residues remained. Potassium was rapidly released from the residues, while Ca, and Mg, were slowly released, and there was evidence of N and P immobilization in the early stages of decomposition. It was concluded that, although a lower proportion of nutrients were exported, compared to biomass, in the long term, nutrient export with logs could be significant for the sustainability of this production system. While K release from residues did not depend on biomass decay, the slow decomposition, and release of the other nutrients, indicates that this process could have been delayed by nutrient scarcity.

Bioactive Compounds and Insecticidal Activity of Hysterionica pinifolia, a Native South American Plant

Phytochemical investigation of the purified fractions of the active dichloromethane extract of Hysterionica pinifolia (Poir.) Baker led to the identification of five compounds. New acetylenic alcohol (E)-undec-3-en-5,7-diyne-1-ol (1) and three other compounds (3), (4), and (5) were reported for the first time in this species. Furthermore, forty-six components from the volatile fraction of H. pinifolia were identified. These compounds were elucidated using 1D and 2D NMR spectroscopy as well as MS-ESI and GC-FID-MS experiments. The dichloromethane extract, its fractions, and the methanolic extract were tested for insecticidal activity against Tribolium castaneum under laboratory conditions. The dichloromethane extract and the fraction F2 were found to be active, showing high larval mortality. The dichloromethane extract was also active against T. castaneum adults. The results have shown that H. pinifolia could be considered, in a near future, as a potential source for the development of a botanical insecticide for pest control.

<i>Cladosporium</i>: Causal agent of scab in purple passion fruit or gulupa (<i>Passiflora edulis</i>Sims.)

The Scab of purple passion fruit or gulupa (Passiflora edulis Sims.) is a serious disease, affecting all aerial organs of the plant, but also to reducing the visual quality of the fruits, which reduces export production. To determine the primary causal agent of disease in Colombia, associated microorganisms were isolated from scab lesions on stems, leaves, flowers and fruits, recovering in PDA. Obtaining Cladosporium, Colletotrichum and Botrytis. Cladosporium had the highest frequency of fungal isolates. 15 strains were evaluated for their pathogenicity on fruits and leaves of gulupa in laboratory and greenhouse conditions. 9 strains caused symptom expression at 95% humidity and 17°C - 20°C, validating Cladosporium as causal agent of gulupa scab. For those pathogenic strains, were determinate incubation and latency periodsin leaves (7 - 11 and 8 - 12 DPI) and fruits (6 - 10 and 8 - 12 DPI) revealing differences or virulence levels in the pathogen populations.

Intake, Energy Expenditure and Methane Emissions of Grazing Dairy Cows at Two Pre-Grazing Herbage Masses

A grazing experiment was undertaken to assess the effects of two levels of herbage mass (HM) on herbage DM intake (DMI), fat and protein corrected milk yield (FPCM), grazing behaviour, energy expenditure (HP), and methane emissions (CH4) of grazing dairy cows in spring. Treatments were a low HM (1447 kg DM/ha;LHM) or a high HM (1859 kg DM/ha;HHM). Pasture was composed mainly of cocksfoot (Dactylis glomerata) and lucerne (Medicago sativa), offered at a daily herbage allowance of 30 kg DM/cow, above 5 cm. Eight multiparous Holstein cows were used in a 2 × 2 Latin Square design in two 10-day periods. Despite the differences in pre-grazing HM between treatments, OM digestibility was not different (P = 0.28). Herbage mass did not affect DMI or FPCM. Grazing time was not different between treatments, but cows had a greater bite rate when grazing on LHM swards. However, HP did not differ between treatments. Daily methane emission (per cow), methane emission intensity (per kg FPCM) and methane yield (as percentage of gross energy intake) were not different. The lack of effect of the amount of pre-grazing HM on energy intake, confirms that the difference between HM treatments was beyond the limits that impose extra energy expenditure during grazing.