Agronomía Mesoamericana <p>Agronomía Mesoamericana journal is a periodical publication (January-April, May-August and September-December) edited in the Universidad de Costa Rica, its objective is to disseminate scientific information in Spanish or English language, through the publication of articles, short communications, technical notes and literature reviews, related with food and agriculture sciences from anywhere in the world, emphasized in tropical and subtropical zones, especially from Mesoamerica and the Caribbean.&nbsp;</p> <p>&nbsp;</p> <p><strong>URL OAI-PMH</strong>&nbsp;<a href=""></a></p> Universidad de Costa Rica en-US Agronomía Mesoamericana 2215-3608 <p><strong>1. Proposed policy for open access journals</strong></p> <p>Authors who publish in this journal accept the following conditions:</p> <p><br>a. Authors retain the copyright and assign to the journal the right to the first publication, with the work registered under the Creative Commons attribution license, which allows third parties to use the published work as long as they mention the authorship of the work and the first publication in this journal.</p> <p>b. Authors may enter into additional independent contractual arrangements for the non-exclusive distribution of the version of the article published in this journal (e.g., including it in an institutional repository or publishing it in a book) provided that they clearly indicate that the work was first published in this journal.</p> <p>&nbsp;</p> <p>c. Authors are permitted and encouraged to publish their work on the Internet (e.g. on institutional or personal pages) before and during the review and publication process, as it may lead to productive exchanges and faster and wider dissemination of published work (see <a href="">The Effect of Open Access</a>).</p> Effect of nitrogen and phosphate fertilization on perennial ryegrasses and red clovers <p><strong><span class="CharOverride-2">Introduction. </span></strong>Specialized dairy systems are forage based, which makes necessary to generate recommendations that promote the efficient and sustainable use of this resource. <strong><span class="CharOverride-2">Objective. </span></strong>The objective of this work was to evaluate increasing levels of nitrogen and phosphate fertilization on forage yield and compositional quality of ryegrass (<span class="CharOverride-3">Lolium perenne</span>) and red clovers (<span class="CharOverride-3">Trifolium repens</span>). <span class="CharOverride-2"><strong>Materials and methods.</strong> </span>In September 2016, two perennial ryegrasses plots and two red clovers were established in two Colombian departments (Boyacá and Cundinamarca), in 4 m<span class="CharOverride-1">2</span>. The first one received 0, 50, 100 or 150 kg N ha<span class="CharOverride-1">-1</span>; and 0, 25 or 50 kg P<span class="CharOverride-4">2</span>O<span class="CharOverride-4">5</span> ha<span class="CharOverride-1">-1</span>; and the second one received 0, 12.5, 25 or 37.5 P<span class="CharOverride-4">2</span>O<span class="CharOverride-4">5</span> ha<span class="CharOverride-1">-1</span>. After the establishment period (120 days) and a uniform cut, forages were harvested at 21, 35 and 49 regrowth days, during two evaluation periods (April-May and June-July 2017). The variables were evaluated through a split-plot design with repeated measures. <strong><span class="CharOverride-2">Results.</span> </strong>Nitrogen fertilization increased (p&lt;0.05) dry matter yield, chlorophyll and crude protein concentration; and decreased neutral detergent fiber. Phosphatic fertilization did not modify (p&gt;0.05) ryegrass and clover yield and composition. Furthermore, the extension in the age of regrowth increased (p&lt;0.05) the concentration of components less soluble in clovers and ryegrass, which are related to the lower nutritional value. <span class="CharOverride-2"><strong>Conclusion.</strong> </span>The application of increasing levels of nitrogen, but not phosphorus, elevated the production and quality of ryegrasses. Phosphorus application did not modify clovers yield nor composition.</p> Andrea Milena Sierra-Alarcón Yesenia Moreno-Oviedo Edgar Augusto Mancipe-Muñoz Yesid Avellaneda-Avellaneda Juan de Jesús Vargas-Martínez ##submission.copyrightStatement## 2019-09-01 2019-09-01 841 854 10.15517/am.v30i3.35170 Emission of greenhouse gases in the soil under the green manure effect <p><span class="CharOverride-4">Introduction. </span>Soil management practices in agroecosystems, such as the use of green manures (GM), positively affect greenhouse gas (GHG) emissions.<span class="CharOverride-4"><strong> Objective.</strong> </span>The objective of the research was to evaluate CO<span class="CharOverride-5">2</span>,CH<span class="CharOverride-5">4</span>, and N<span class="CharOverride-5">2</span>O emission of a soil cultivated with corn and soybean under the use of green fertilizers, fallow (B), and nitrogen fertilization. <span class="CharOverride-4"><strong>Materials and methods.</strong> </span>Between July 2011 and June 2012, in a Typic Haplustert located in Valle del Cauca, Colombia, corn and soybeans were planted in a intervleaved manner, and the monocultures of corn and soybeans were managed in a conventional manner. The association between<span class="CharOverride-6"> Mucuna pruriens</span> var. <span class="CharOverride-6">utilis</span> and maize was established as GM, ninety days after sowing, the total residues were incorporated as GM or disposed on the soil surface as organic mulch (AO). Eleven treatments were used under the design of randomized complete blocks, with 3<span class="CharOverride-2">2</span> + 2 factorial arrangement, with three repetitions. The main plots were GM, AO and B. Each was divided into sub-plots corresponding to compost fertilization, industrial chemical synthesis fertilizer and no additions. In the flowering and grain filling stage of the crops, variables such as N<span class="CharOverride-5">2</span>O, CH<span class="CharOverride-5">4</span>, CO<span class="CharOverride-5">2</span> and total water-filled porosity were analyzed. <span class="CharOverride-4"><strong>Results</strong>. </span>CO<span class="CharOverride-5">2</span> flow was higher in the intercrops added with GM/AO compared to monocultures. In the main plots, the use of industrial chemical synthesis fertilizers significantly stimulated N<span class="CharOverride-5">2</span>O and CH<span class="CharOverride-5">4</span> fluxes. <span class="CharOverride-4"><strong>Conclusion.</strong> </span>The use of high quality organic materials such as GM/AO did not ensure GHG sink soils in the short-term, since soil conditions and nitrogen fertilization significantly influenced emissions.</p> Breno Augusto Sosa-Rodrigues Yuly Samantha García-Vivas ##submission.copyrightStatement## 2019-09-01 2019-09-01 767 782 10.15517/am.v30i3.36103 Evaluation of arboreal and shrub strata in a silvopastoral system in Colombian high Andean tropics <p class="Resumen"><strong><span class="CharOverride-4">Introduction.</span> </strong>Silvopastoral systems are presented as an alternative for the sustainable use of natural resources, so there is a need to identify potential species for their establishment in the high tropics. <span class="CharOverride-4"><strong>Objective.</strong> </span>The objective was to evaluate the initial growth of eight woody species in a silvopastoral design for water source protection. <strong><span class="CharOverride-4">Materials and methods. </span></strong>The study was carried out in the Obonuco research center of Corporacion Colombiana de Investigacion Agropecuaria (Pasto, Colombia) between September 2017 and June 2018. A randomized block design was developed in a factorial arrangement, where tree/bush species differentiated by their growth habit interacted (high stratum: <span class="CharOverride-5">Cedrela montana</span>, <span class="CharOverride-5">Quercus humboldtii</span>, <span class="CharOverride-5">Ficus andicola</span>; middle stratum: <span class="CharOverride-5">Salix babylonica</span>, <span class="CharOverride-5">Alnus acuminata</span>, <span class="CharOverride-5">Smallanthus pyramidalis</span>; lower stratum: <span class="CharOverride-5">Morella pubescens </span>and <span class="CharOverride-5">Sambucus nigra</span>) and altitude (2750, 2770 and 2800 masl) with four repetitions to evaluate morphometric variables and seedling quality.<strong> <span class="CharOverride-4">Results. </span></strong>In the variable height the best behavior was presented in <span class="CharOverride-5">Ficus andicola </span>at 2750 masl with 191.37 cm and <span class="CharOverride-5">Alnus acuminata </span>at 2800 masl with 181.83 cm. In stem diameter <span class="CharOverride-5">Ficus andicola</span> stood out at 2750 masl with 42.98 mm, <span class="CharOverride-5">Smallanthus pyramidalis </span>at 2800 masl with 37.24 mm, and <span class="CharOverride-5">Sambucus nigra</span> at 2800 masl with 8.16 mm. The number of regrowths did not show a significant effect of the interaction, and as seedlings, <span class="CharOverride-5">Quercus humboldtii </span>at 2750 and 2700 masl and <span class="CharOverride-5">Ficus andicola</span> at 2750 masl showed the best quality of individuals; while <span class="CharOverride-5">Cedrela montana</span> showed mortality at the three altitudes evaluated. <span class="CharOverride-4"><strong>Conclusions.</strong> </span>Native species stood out for their adaptibility, reflected in fast and optimal growth and development, which evidences its great potential to be evaluated in silvopastoral systems in an associated way to decide its multiple benefits and potential contribution to the sustainable development of the livestock in the region.</p> Laura Dayana Escobar-Pachajoa Carolina Guatusmal-Gelpud Diego Hernán Meneses-Buitrago Juan Leonardo Cardona-Iglesias Edwin Castro-Rincón ##submission.copyrightStatement## 2019-09-01 2019-09-01 803 819 10.15517/am.v30i3.35645 Ex-ante impact evaluation of the L23 rice genotype on the colombian Altillanura plains <p class="Resumen"><strong><span class="CharOverride-2">Introduction.&nbsp;</span></strong>The Colombian Altillanura is going through a process of transformation, marked by the expansion of its agricultural border. In the region, it is being implemented a research agenda that seeks to develop and validate promising technologies for the improvement of productivity and sustainability of agricultural production systems. Economic evaluation plays an important role in prioritizing activities, allocating resources, and guiding agricultural research towards rural development objectives.<strong>&nbsp;</strong><span class="CharOverride-2"><strong>Objective.</strong>&nbsp;</span>The objective of this work was to implement an ex-ante economic evaluation to estimate the results and potential impacts of the new promising L23 rice line improved for the Colombian Altillanura.&nbsp;<strong><span class="CharOverride-2">Materials and methods.&nbsp;</span></strong>The impact was measured on the L23 rice genotype, which was developed as a collaboration between the Colombian Corporation of Agricultural Research (AGROSAVIA) and the International Center for Tropical Agriculture (CIAT), for the Colombian Altillanura. The ex-ante evaluation combined a partial budgets analysis with information from experimental tests and economic surpluses model.&nbsp;<strong><span class="CharOverride-2">Results.&nbsp;</span></strong>The two methodological approaches were consistent and showed that with the adoption of the L23 genotype at least 29.7%, a probability of 17.1 % could be achieved for rice producers in the Altillanura due to the expected increase in crop yield. However, a sensitivity analysis of the assumptions warns that a low potential level of adoption along with non-significant changes in yield would make the research and development of the new genotype economically unfeasible.&nbsp;<strong><span class="CharOverride-2">Conclusion.</span></strong>&nbsp;For the research, development and, introduction of the L23 rice genotype to be profitable, it is required a diffusion process that allows the reproduction of the seed and facilitates the access to producers, so that they can reach higher levels of adoption.</p> Diego Armando Marín-Salazar Robert Santiago Andrade-López Ricardo Antonio Labarta-Chaverri Ángela Rocío Vásquez-Urriago Samuel Caicedo Guerrero ##submission.copyrightStatement## 2019-09-01 2019-09-01 613 630 10.15517/am.v30i3.36027 Pathogenicity and autodissemination of promising entomopathogenic fungi strains on Rhynchophorus palmarum L. (Coleoptera: Dryophthoridae) <p><strong><span class="CharOverride-4">Introduction.</span>&nbsp;</strong>In Latin America, the weevil (<span class="CharOverride-5">Rhynchophorus palmarum</span>&nbsp;L.) is an important pest of oil palm and coconut palm because it is associated with the transmission of red ring (RRD) and bud rot (BR); diseases that cause high management costs and mortality of plantations; the entomopathogens&nbsp;<span class="CharOverride-5">Metarhizium anisopliae</span>&nbsp;and&nbsp;<span class="CharOverride-5">Beauveria bassiana</span>&nbsp;(Hypocreales: Clavicipitaceae) represent an microbiological control alternative.&nbsp;<span class="CharOverride-4">Objective.&nbsp;</span>The objective of this work was to determine the pathogenicity of promising strains of&nbsp;<span class="CharOverride-5">M. anisopliae&nbsp;</span>and&nbsp;<span class="CharOverride-5">B. bassiana</span>&nbsp;on adults of&nbsp;<span class="CharOverride-5">R. palmarum</span>&nbsp;and to evaluate the spread of the best strains, from inoculated weevil male adults to not-inoculated females.<span class="CharOverride-4">&nbsp;<strong>Materials and methods.&nbsp;</strong></span>The study was carried out in two phases in the La Libertad Research Center of the Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA), Department of Meta, Colombia through factorial arrangements in completely random designs; in the first one, four strains of<span class="CharOverride-5">&nbsp;M. anisopliae</span>, one of&nbsp;<span class="CharOverride-5">B. bassiana</span>, and one commercial product based on&nbsp;<span class="CharOverride-5">M. anisopliae</span>&nbsp;were evaluated; in the second one, to determine the self-dissemination of the entomopathogen, the two highest effectiveness strains from the first experiment (CPMa1104 and Mt008) were evaluated by two methods of application to males (immersion and powder).&nbsp;<strong><span class="CharOverride-4">Results.&nbsp;</span></strong>The CPMa1104 strain showed the highest efficacy (1x10<span class="CharOverride-3">4</span>&nbsp;and 1x10<span class="CharOverride-3">8</span>&nbsp;conidia ml<span class="CharOverride-3">-1</span>), followed by Mt008 (1x10<span class="CharOverride-3">8</span>&nbsp;conidia ml<span class="CharOverride-3">-1</span>) with mortalities of 78.6 % and 67.9 %, respectively. Contact dissemination capacity of&nbsp;<span class="CharOverride-5">M. anisopliae</span>&nbsp;strains CPMa1104 and Mt008 was observed from inoculated male adults to non-inoculate females. Female mortality reached 100 % when the males were inoculated with powdered CPMa1104.&nbsp;<strong><span class="CharOverride-4">Conclusion.&nbsp;</span></strong>The dissemination of CPMa1104 and Mt008 strains of&nbsp;<span class="CharOverride-5">M. anisopliae</span>&nbsp;by inoculated males to non-inoculated females was tested, which makes the use of this entomopathogen a promising control alternative.</p> Guillermo Adolfo León-Martínez Juan Carlos Campos-Pinzón Jorge Humberto Arguelles-Cárdenas ##submission.copyrightStatement## 2019-09-01 2019-09-01 631 646 10.15517/am.v30i3.36184 Beauveria bassiana with flupyradifurone for the control of Trialeurodes vaporariorum Vuill in French beans crop <p class="Resumen"><strong><span class="CharOverride-4">Introduction</span>.&nbsp;</strong><span class="CharOverride-3">Trialeurodes vaporariorum&nbsp;</span>(Westwood) is one of the main pests of the French bean (<span class="CharOverride-3">Phaseolus vulgaris</span>&nbsp;L.), legume for consumption in inmature pods, and is a vector of the golden mosaic virus, which affects the quality and yield of the crop reaching losses of up to 100%, being difficult to control because many chemicals no longer control the pest. The French bean within the non-traditional products in Guatemala, occupies the second place in the export. Ensuring a good phytosanitary management with low chemical load by pesticides are important factors to be able to export it.<span class="CharOverride-4">&nbsp;<strong>Objective.</strong>&nbsp;</span>The objective of the investigation was to determine the effectiveness of the combination between Flupyradifurone and&nbsp;<span class="CharOverride-3">Beauveria bassiana</span>&nbsp;for the control of whitefly in French bean cultivation.&nbsp;<strong><span class="CharOverride-4">Materials and methods.</span>&nbsp;</strong>The study was conducted from February to December 2018 in Parramos, Chimaltenango, Guatemala. Seven plots of 100 m² were established corresponding to each treatment. Weekly, whiteflies were sampled during two cultivation cycles, and natural enemies of these were also collected on each plot. Three applications of each treatment were made in each crop cycle, and the plants were sampled divided into three strata (high, medium, low).&nbsp;<strong><span class="CharOverride-4">Results.</span>&nbsp;</strong>The treatments that showed the best control of the whitefly population (nymphs and adults) when performing the Tukey test (0,05), were flupyradifurone (1 l ha<span class="CharOverride-2">-1</span>) +&nbsp;<span class="CharOverride-3">B. bassiana</span>, and flupyradifurone (0.75 l ha<span class="CharOverride-2">-1</span>) +&nbsp;<span class="CharOverride-3">B. bassiana</span>. The largest distribution of whitefly populations was found in the upper and middle strata.&nbsp;<span class="CharOverride-4"><strong>Conclusion.</strong>&nbsp;</span>The combination of flupyradifurone (0,05) with&nbsp;<span class="CharOverride-3">B. bassiana</span>&nbsp;can be used within an integrated pest management, and is presented as an alternative control of whiteflies, which has acquired resistance to some agrochemicals.</p> Claudia Elizabeth Toledo-Perdomo ##submission.copyrightStatement## 2019-09-01 2019-09-01 647 658 10.15517/am.v30i3.36327 Potential distribution and fundamental niche of Moniliophthora spp in cocoa of America and Africa <p><strong><span class="CharOverride-7">Introduction.</span>&nbsp;</strong><span class="CharOverride-8">Moniliophthora</span>&nbsp;spp. species are endemic from South America and infect America’s cocoa crops.&nbsp;<strong><span class="CharOverride-7">Objective.&nbsp;</span></strong>The objective of the study was to analyze the potential distribution and the fundamental niche of&nbsp;<span class="CharOverride-8">Moniliophthora roreri (Mr)</span>&nbsp;and&nbsp;<span class="CharOverride-8">M. perniciosa (Mp)</span>&nbsp;in America and Africa.&nbsp;<strong><span class="CharOverride-7">Materials and methods.</span></strong>&nbsp;The occurrence records were obtained from a bibliographic review. Bioclimatic variables were used as predictors in the maximum entropy niche model (MaxEnt) and for its visualization in Niche Analyst 3.0.&nbsp;<strong><span class="CharOverride-7">Results.</span></strong>&nbsp;The areas where&nbsp;<span class="CharOverride-8">Mr&nbsp;</span>was most likely to occur were Esmeraldas and Los Ríos, Ecuador, coastal zones of Costa Rica, Santander and Antioquia of Colombia, and for&nbsp;<span class="CharOverride-8">Mp</span>&nbsp;the States of Bahia and Acré of Brazil. The variables that most influenced the distribution of&nbsp;<span class="CharOverride-8">Mr&nbsp;</span>are those associated with precipitation. Tem<span class="CharOverride-8">p</span>erature-related conditions were more important in the&nbsp;<span class="CharOverride-8">Mp&nbsp;</span>model. The risk of&nbsp;<span class="CharOverride-8">Mr&nbsp;</span>invasion was identified in the Acre and Pará regions, Brazil. The transfer of the models evidenced the potential of&nbsp;<span class="CharOverride-8">Mr&nbsp;</span>and&nbsp;<span class="CharOverride-8">Mp</span>&nbsp;invasion in cocoa crops in Africa. The fundamental niche of pathogens and cocoa showed average similarity values, while the niche of fungal species showed a low similarity. Low pathogen niche similarity and differences in bioclimatic variables affecting pathogens distribution were related to a process of niche partitioning.&nbsp;<strong><span class="CharOverride-7">Conclusion.</span>&nbsp;</strong>Geographical regions with a greater potential distribution of pathogens and bioclimatic characteristics that would favor their probability of presence in America’s cocoa crops were identified. It is necessary to regulate the transport of contaminated plant material and equipment between regions to avoid the introduction of pathogens in healthy cocoa crops.</p> Julian Esteban Másmela-Mendoza ##submission.copyrightStatement## 2019-09-01 2019-09-01 659 679 10.15517/am.v30i3.35038 Variability of the total oil content and fatty acid profile of creole avocados from Nuevo Leon, Mexico <p><strong><span class="CharOverride-2">Introduction.</span>&nbsp;</strong>The State of Nuevo Leon is considered the depositary of a wide genetic diversity of creole avocados (<span class="CharOverride-3">Persea americana</span>&nbsp;var&nbsp;<span class="CharOverride-3">drimyfolia</span>).<span class="CharOverride-2">&nbsp;<strong>Objective.</strong>&nbsp;</span>The aim of this work was to determine the variability of the total oil content and the fatty acids profile in creole avocados from Nuevo Leon, Mexico.&nbsp;<strong><span class="CharOverride-2">Materials and methods.</span></strong>&nbsp;During the spring and summer of 2016, 36 varieties of creole avocados were collected in the northern and southern region of the State of Nuevo Leon, Mexico for chemical characterization. The commercial variety “Hass” was included as a control. To determine the variability that exists in the content of total oils and fatty acids in the collected materials, analyzes of the main components and conglomerates were carried out.&nbsp;<strong><span class="CharOverride-2">Results.&nbsp;</span></strong>Six fatty acids were detected in the total oil of the creole avocados: palmitic, stearic, oleic, palmitoleic, linoleic and linolenic. The outstanding varieties were “Platano temprano”, “Platano delgado”, “Huevo de toro”, “Cuerno”, “Pato”, and “Especial”, which presented an average of 17.28, 24.93 and 66.29 % more in the content of oleic, linoleic and linolenic acids respectively, and an average of 28.12 % less stearic acid compared to the commercial variety “Hass”. According to the analysis of main components, materials with high oleic acid content usually have low palmitic and palmitoleic acid contents. The dendrogram presented six groups within the evaluated materials, most of the outstanding materials are located in groups one and four.&nbsp;<strong><span class="CharOverride-2">Conclusion.&nbsp;</span></strong>High variability in the content of total oils and fatty acids was determined in creole avocados from Nuevo Leon. Therefore, they are considered promising for their incorporation into genetic improvement programs.</p> Efraín Acosta-Díaz María Genoveva Álvarez-Ojeda Salvador Horacio Guzmán-Maldonado Isidro Humberto Almeyda-León ##submission.copyrightStatement## 2019-09-01 2019-09-01 705 719 10.15517/am.v30i3.34490 Productivity and quality of male green asparagus in Buenos Aires, Argentina <p><strong><span class="CharOverride-2">Introduction.</span></strong>&nbsp;In asparagus cultivation, as it is a perennial productive alternative, evaluation is required to know the response of different genotypes to the area in which are being introduced.&nbsp;<strong><span class="CharOverride-2">Objective.&nbsp;</span></strong>The aim of the present work was to determine the productivity of seven Italian male hybrids and an American control of green asparagus from an adult plantation in its stage of stable productivity.<strong>&nbsp;<span class="CharOverride-2">Materials and methods.&nbsp;</span></strong>The study was carried out in Azul, Argentina (19/8/2016-17/11/2016), where the following genotypes were evaluated: Italo, Zeno, Eros, Ercole, H-668, Marte, Giove, and the control UC-157. Large and small seedling and two cutting lengths (22 and 17 cm) were compared. The variables were: total fresh commercial productivity of long and short spears, number of long and short total commercial spears, mean weight of long and short spears, calibre distribution: very small (asparagina) (A&lt;6 mm), small (S; 6-9 mm), medium (M; 9-12 mm), large (L; 12-16 mm), extra-large (XL; 16-18 mm) and giant (J; &gt;18 mm), and the defects: very short spears, sprouted spears, plague damaged spears and other such as twisted, double or diseased spears. Data were analysed by ANOVA (p≥0.05) and Fisher’s restricted LSD test.&nbsp;<span class="CharOverride-2"><strong>Results</strong>.&nbsp;</span>The average first quality commercial production achieved with both harvested lengths was 4.41 t ha<span class="CharOverride-1">-1</span>&nbsp;(37 % short and 63 % long spears). Seventeen spears were obtained per plant (44 % short and 56 % long spears). In number of total commercial spear (267,189 spears ha<span class="CharOverride-1">-1</span>), Ercole, Giove, Eros, and H-668 exceeded the mean. The genotypes with the highest commercial productivity were Giove and Ercole, while by number of spears Eros and H-668. The main defect was sprouting (93 %).&nbsp;<strong><span class="CharOverride-2">Conclusions.</span></strong>&nbsp;In order to optimize the commercial yield and minimize the sprouting defect, it is suggested to harvest daily and to use two cutting lengths to increase commercial spear percentage.</p> Ana María Castagnino Karina Elizabeth Díaz Andrea Paola Guisolis William John Rogers Agostino Falavigna María Belén Rosini ##submission.copyrightStatement## 2019-09-01 2019-09-01 721 732 10.15517/am.v30i3.34471 Heat stress effect on dairy cattle production in Costa Rica <p><span class="CharOverride-2"><strong>Introduction.</strong>&nbsp;</span>Dairy production in tropical zones is characterized by a high dependence on the forage resource, which makes it sensitive to climatic variables of which there is limited information on their effect on the performance of specialized dairy breeds.&nbsp;<strong><span class="CharOverride-2">Objective.</span>&nbsp;</strong>The objective of this study was to evaluate the association between temperature and humidity index (THI) and daily milk production (kgl) of cows breeds Holstein, Jersey, and their crosses.<strong>&nbsp;</strong><span class="CharOverride-2"><strong>Materials and methods.</strong>&nbsp;</span>The study was conducted in the northern and central regions of Costa Rica, with data collected between 1990 and 2015. THI values were obtained using linear predictive models and spatial autocorrelation models, applied to 3,547 monthly records of maximum temperature and relative humidity from seventeen weather stations. 6,478,582 kgl records from 418 dairy herds were analyzed, using a generalized mixed linear model (GLMM), which considered the fixed effects of breed, year and month, birth number, lactation stage, breed × lactation stage, ENSO (Effect “El Niño”), ITH and breed×ITH, in addition to a random effect of the cow.<strong>&nbsp;</strong><span class="CharOverride-2"><strong>Results.</strong>&nbsp;</span>All factors had a highly significant effect (p&lt;0.0001) on kgl. For the ITH range between 72-88, linear reductions of 0.41 (r<span class="CharOverride-1">2</span>=0.94), 0.36 (r<span class="CharOverride-1">2</span>=0.95) and 0.29 (r<span class="CharOverride-1">2</span>=0.82) kg day<span class="CharOverride-1">-1</span>&nbsp;were estimated for Holstein, Holstein×Jersey and Jersey, respectively. No significant trends were observed for kgl when ITH &lt;72. The economic losses attributable to the greater stress exposure in the north compared to the central region were estimated at $680, $587 and $477 per lactation and cow for Holstein, Holstein×Jersey and Jersey, respectively.&nbsp;<strong><span class="CharOverride-2">Conclusion.</span>&nbsp;</strong>There was an inverse relationship between temperature and humidity index and milk production in Holstein, Jersey and crossbreed cows for this tropical region.</p> Juan Ismael Ruiz-Jaramillo Bernardo Vargas-Leitón Sergio Abarca-Monge Hugo G. Hidalgo ##submission.copyrightStatement## 2019-09-01 2019-09-01 733 750 10.15517/am.v30i3.35984 Grazing intensity on the lipid profile in bovine milk in the Colombian dry tropic <p><strong><span class="CharOverride-3">Introduction. </span></strong>It has been suggested that the lipid profile in bovine milk affects human health, and it has been identified that conjugated linoleic acid (C9 t11 ALC) could have anticarcinogenic effects.In the high tropics the effect of feeding on lipid profile of milk has been investigated, but few studies have been done in the low tropics. <strong><span class="CharOverride-3">Objective. </span></strong>The objective was to evaluate the effect of three grazing intensities (1, 2 and 3 animals ha<span class="CharOverride-1">-1</span>) in Guinea cv Tanzania (<span class="CharOverride-4">Megathyrsus maximus</span>) on the production, composition and lipid profile in the milk of cross breed cows in different thirds of lactation.<strong> <span class="CharOverride-3">Materials and methods. </span></strong>From september to october 2013, two groups of nine animals (three cows in each third of lactation) were selected, and one cow per third of lactation was assigned to each grazing intensity (treatment), during 42 days of evaluation in a replicated 3 x 3 Latin Square design. <strong><span class="CharOverride-3">Results. </span></strong>Milk production did not differ (p&gt;0.05) among treatments and was higher (p&lt;0.05) in cows in early lactation. The treatments did not affect (p&gt;0.05) the composition of the milk, but solids and fat concentration tended (p&lt;0.10) to increase with third of lactation. Bovine milk fat in pasture managed with grazing intensity of 2.0 and 3.0 animals ha<span class="CharOverride-1">-1</span> had a higher (p&lt;0.05) concentration of CLA (c9 t11) and of polyunsaturated fatty acids (PUFA) than when the grass was managed with 1.0 animal ha<span class="CharOverride-1">-1</span>. The third of lactation did not influence (p&gt;0.05) the concentration of CLA (c9 t11) and PUFA.<strong><span class="CharOverride-3"> Conclusion.</span></strong> Management of the cv Tanzania with grazing intensities of 2.0 and 3.0 animals ha<span class="CharOverride-1">-1</span> resulted in the highest levels of CLA (c9 t11) and PUFA in milk fat, which could have positive effects on human health.</p> Edwin Mojica-Rodríguez Edwin Castro-Rincón Juan Evangelista Carulla-Fornaguera Carlos Eduardo Lascano-Aguilar ##submission.copyrightStatement## 2019-09-01 2019-09-01 783 802 10.15517/am.v30i3.36312 Mechanical removal of senescent material for pasture recovery <p><strong><span class="CharOverride-2">Introduction.</span> </strong>The accumulation of senescent material in tropical pastures is the result of high biomass production and low level of utilization. By removing senescence pastures, cattle can graze at lower levels, allowing regrowth with higher nutrient content. <strong><span class="CharOverride-2">Objective.</span></strong> The objective of this study was to evaluate the response of African stargrass (<span class="CharOverride-3">Cynodon nlemfuensis</span> Vanderyst.) and Mombasa (<span class="CharOverride-3">Megathyrsus maximus </span>Jacq.) to removal of senescent material based on its structural components, biomass and nutrient content.<span class="CharOverride-2"><strong> Materials and methods.</strong> </span>This experiment was carried out between April to August 2017 in two farms, one located in Turrialba, Cartago, and the other in San Carlos, Alajuela. A chi-squared design was used to evaluate the removal of senescent material versus the respective controls. <strong><span class="CharOverride-2">Results. </span></strong>Senescence grass removal increased the proportion of leaves in both kinds of grasses. Yielded biomass in senescence material removal plots had higher protein and lower cell wall content, producing more digestible forage. The structural changes had a longer duration in the Mombasa grass, which was attributed to the diffrerences in plant architecture with respect to the Star grass. <strong><span class="CharOverride-2">Conclusion. </span></strong>Removing senescent material from tropical pastures is a strategy to modify the structure and enhance the nutritional value of dry matter yield. Both the type of system and grazing intensity may contribute to reducing senescence accumulation, increasing the nutritive value of forages in the long term.</p> Luis A. Villalobos-Villalobos Rodolfo WingChing-Jones ##submission.copyrightStatement## 2019-09-01 2019-09-01 821 840 10.15517/am.v30i3.36625 Technical and economic characterization of lamb meat production in Córdoba, Colombia <p><strong>Introduction.</strong> The knowledge of the biophysical, technological, and economic variables of lamb production systems represents valuable elements to delve into the productive characterization and analysis of the species. <strong><span class="CharOverride-1">Objective. </span></strong>The aim of this study was to characterize technically and economically, the lamb meat production system in the department of Córdoba, Colombia, to generate a baseline that allows comparing technological options with local technology. <span class="CharOverride-1"><strong>Materials and methods.</strong> </span>The information was obtained from a fieldwork carried out in four productive units with 108 male lambs under semi-extensive management. The data were obteined between January to September 2018. Structured surveys, as well as statistical techniques were applied, including central tendency and dispersion measures. For the economic analysis a cost pattern was used for each productive unit and the calculation of return indicators such as the internal rate of return and the net present value. The technical coefficients were analyzed economically. <strong><span class="CharOverride-1">Results. </span></strong>The daily weight gains were 80-132 g day<span class="CharOverride-3">-1</span>, with an average weight per animal of 31.7±3.2 kg. Meat production was 18.450 kg. The best gains of daily weight (p&lt;0.0001) and final weight were observed in the Campanario farm with 33.47±4.1 kg as a response to the technical management that generated greater productive units and higher incomes. The average unit cost was USD$1.05 kg<span class="CharOverride-3">-1</span>, the profitability of 28%, and the internal rate of return was 4.5 %. <span class="CharOverride-1"><strong>Conclusions.</strong> </span>The production systems evaluated were profitable with the capacity to recover the investment. The analysis of marketing margins showed the inequality in the producers’ participation in the value paid by the consumer for the product since they receives only 18 cents for each monetary unit paid the rest is captured by the intermediation.</p> Lorena Inés Mestra-Vargas Antonio María Martínez-Reina Martha Oliva Santana-Rodríguez ##submission.copyrightStatement## 2019-09-01 2019-09-01 871 884 10.15517/am.v30i3.36931 In situ characterization of the ackee (Blighia sapida) and its commercial potential in Costa Rica <p><strong><span class="CharOverride-3">Introduction.</span> </strong>The ackee, <span class="CharOverride-4">Blighia sapida</span>, is a tree native to the African continent and in Costa Rica the fruits are consumed mainly by Afro-descendants living in the Atlantic. <span class="CharOverride-3">Objective. </span>The objective of this work was to describe the geographical distribution, phenotypic diversity and management of the ackee crop in the Huetar Atlantic Region of Costa Rica. <strong><span class="CharOverride-3">Materials and methods.</span> </strong>A vegetative and reproductive prospection and characterization was carried out, in addition to the measurement of the yield index (IR) of ackee materials in the Region, between 2015 and 2016. <span class="CharOverride-3"><strong>Results.</strong> </span>Sixty-six trees growing along the Braulio Carrillo highway and the road to the South Atlantic, were evaluated. The cantons with the highest number of genotypes were Siquirres and Limon. The great majority of these materials were found growing near the houses, which denotes a rooting of this species in the local culinary culture. Of the forty genotypes characterized, little phenotypic variability was found in the vegetative characters. As for the fruits, they showed greater diversity, with variation in the weight, size, color and number, and weight and firmness of the arils. A 86.9 % of the genotypes presented arils with firm consistency before and after the cooking test. IR values were between 8 and 20, with the best genotypes having an index close to 8. The agronomic management of the trees in terms of fertilization, pruning, pests and pathogens, control is almost non-existent. <strong><span class="CharOverride-3">Conclusion.</span></strong> It is suggested to validate the use of the trees selected for their good productive performance, and to create the bases to establish the simple agronomic management, which includes the use of fertilization, pruning, higher planting densities, among other tasks, and measure the impact on the productivity and quality of the fruits of this species.</p> Patricia Quesada-Rojas Walter Vicente Barrantes-Santamaría ##submission.copyrightStatement## 2019-09-01 2019-09-01 885 898 10.15517/am.v30i3.34701 Fodder shrubs: relevance in cattle systems of Colombian low altitude lands <p><strong><span class="CharOverride-2">Introduction. </span></strong>Low tropics lands cattle, face the challenge to adapt the production systems to the climate change consequences, wich has generated longer dry seasons and more food shortage for the animals during these periods. <span class="CharOverride-2"><strong>Objective.</strong> </span>The objective of this literature review was to collect and analyze research results on shrubs forage species <span class="CharOverride-3">Tithonia diverfisolia, Gliricidia sepium, Cratylia argentea</span>, and <span class="CharOverride-3">Crescentia cujete</span> as a strategy to improve the nutritional offer in livestock in the low tropics.<strong> <span class="CharOverride-2">Development. </span></strong>In Colombia, beef cattle production is mainly located in the low tropics, and usually have feeding problems due to poor grasses quality and low availability in drought period. Silvopastoral systems (SSP) contribute to improve the productive and reproductive performance of cattle, since they integrate trees and/or shrubs, and grasses, combining diverse forage strata, with a greater nutritional and forage offer than conventional systems. The shrubs <span class="CharOverride-3">T. diverfisolia, G. sepium, C. argentea, </span>y<span class="CharOverride-3"> C. cujete </span>due to their multipurpose characteristics, biomass production, and adaptation to diverse climatic and edaphic conditions, have been used in grazing, fodder banks, live fences and forage conservation, <span class="CharOverride-3">e.g.</span> silage. <strong><span class="CharOverride-2">Conclusion.</span> </strong>Due to their characteristics, uses, biomass production, and nutritional profile, it would be pertinent to evaluate the behavior of these species in feeding strategies in cattle farms under tropics conditions.</p> Jeraldyn Argüello-Rangel Liliana Mahecha-Ledesma Joaquín Angulo-Arizala ##submission.copyrightStatement## 2019-09-01 2019-09-01 899 915 10.15517/am.v30i3.35136 Sugar cane and by-products of the sugar agro-industry in ruminant feeding: A review <p><strong><span class="CharOverride-5">Introduction.</span> </strong>Sugarcane tends to increase its production demands, considering the world macroeconomic perspectives, due to the high demand of sugar and molasses for agro-industrial production. <span class="CharOverride-5"><strong>Objective.</strong> </span>The objective of this review was to determine the state of the art about the use of sugarcane (<span class="CharOverride-6">Saccharum </span>spp.) crop and by-products derived from its agro-industrial processing in ruminant feeding. <strong><span class="CharOverride-5">Development. </span></strong>The sugarcane industry, as a species supplier of different raw materials and by-products resulting from the transformation to raw cane sugar or sugar, presents in the majority of countries dedicated to cultivation, some technological issues related mainly to the waste and wastage of bagasse, the cachaza and dehydrated cachaza. However, there are several studies showing the use of by-products in animal feed especially ruminants through various technologies, that improve the quality and availability of nutrients in them to be used by the animal.&nbsp;<span class="CharOverride-5"><strong>Conclusions.</strong> </span>The sugarcane by-products have been used to make flours, silage, and supplementary blocks. This opens new paths for a sustainable and environmentally friendly production system. Furthermore, they allow to put aside the conception that was had in Colombia that the agro-industrial by-products were of low value and their obtaining generate a negative environmental impact.</p> Elizabeth Lagos-Burbano Edwin Castro-Rincón ##submission.copyrightStatement## 2019-09-01 2019-09-01 917 934 10.15517/am.v30i3.34668 Native lactic acid bacteria as a starter culture for the production of Mexican cream cheese <p><strong><span class="CharOverride-2">Introduction. </span></strong>The bacterial starter cultures are successfully used in the production of artisan cheeses, since they help to maintain sui generis sensory characteristics, as well as controlling the presence of pathogens. It has been reported that natives strains are the best options to perform this function. <span class="CharOverride-2"><strong>Objective.</strong> </span>The aim of this research was to evaluate the effect of the addition of lactic acid bacteria (LAB) isolated from the traditional process of cheese making, as a starters in the manufacture of cream cheese from pasteurized milk.<strong><span class="CharOverride-2"> Materials and methods.</span> </strong>The research was done in the Ocosingo city, Chiapas, Mexico, during the months of February to November from 2016. 37 strains with different morphology were isolated, from milk, cheese and whey, of which 21 were Gram positive, catalase and peroxidase negative. For their acidifying capacity, eight strains were selected, with which six treatments were formulated (combinations of three strains). <strong><span class="CharOverride-2">Results. </span></strong>The treatment that was most accepted by consumers was restructured into three new treatments (three combinations of two strains). Of these new treatments, that one (T8) where two LABs (2S and 30Q) were combined was similar in color, firmness and fat content to the control (cream cheese made with unpasteurized milk). Although they were slightly different in protein, moisture and ash content, however, expert panelists found no significant differences (proof of discrimination A not A) between the T8 cream cheese and the control. This same treatment promoted microbiological counts (aerobic mesophilic, total coliforms, and molds and yeasts) lower than those established by the sanitary standards.<strong><span class="CharOverride-2"> Conclusion.</span> </strong>The use of BAL 2S and 30Q as starter culture allowed a cream cheese to be obtained from pasteurized milk with similar characteristics to traditional cream cheese, besides microbiologically safe.</p> Rodrigo Cobo-Monterroza Raymundo Rosas-Quijano Didiana Gálvez-López Lourdes Adriano-Anaya Alfredo Vázquez-Ovando ##submission.copyrightStatement## 2019-08-14 2019-08-14 855 870 10.15517/am.v30i3.34673 Heat stress and blood-sucking diptera count in multi-level silvopastoral systems <p><strong><span class="CharOverride-3">Introduction.&nbsp;</span></strong>Silvopastoral systems are livestock scheme production schemes with the potential to mitigate the negative effect of the environment on animal productivity.<span class="CharOverride-3">&nbsp;<strong>Objective.&nbsp;</strong></span>The objective of this work was to evaluate the effects of multi-stratum silvopastoral systems on heat stress and the population of hematophagous dipterans in beef cattle.&nbsp;<strong><span class="CharOverride-3">Materials and methods.</span>&nbsp;</strong>Between May and October 2014, in the Turipaná research center in Córdoba, Colombia, the behavior of Cebu Brahman and Romosinuano animals was analyzed in two silvopastoral arrangements (aSSP) with diversity in their composition and plant stratification (p-Arbust with two strata and p-Arbust-Arbor with three strata) and in a treeless prairie, with a random complete block design. In each treatment, the environmental temperature (TA) and relative humidity (RH) were evaluated, and a temperature-humidity index (ITH) was constructed. In animals the skin temperature (TP) and respiratory rate (FR) were evaluated at two hours of the day (6:00 and 13:00), and hematophagous diptera (CDH) were counted between 8:00 and 10:00 a.m. The data were submitted to a variance analysis for mixed models in the variables TA, HR, TP and ITH and generalized mixed models for CDH and FR.<strong>&nbsp;</strong><span class="CharOverride-3"><strong>Results.</strong>&nbsp;</span>The environmental variables were influenced by multiple factors including: the change in sampling schedules, and the silvopastoral arrangement. The highest environmental load (ITH) was observed during the afternoon, an evaluation that significantly influenced the response in FR with increases that reached 2.1 times more in the Pasto treatment, against 0.8 in p-Arbust-Arbor.<strong>&nbsp;</strong><span class="CharOverride-3"><strong>Conclusions.</strong>&nbsp;</span>The aSSP evaluated presented comparative advantages against the reduction of heat stress and the count of hematophage flies under conditions of the middle valley of the Sinu River. The aSSP p-Arbust managed to keep fly counts lower over time.</p> Wilson Andrés Barragán-Hernández Juan Carlos Benavidez-Cruz Aldemar Zúñiga-López Amado Espitia-Pacheco Jaime Cardozo-Cerquera ##submission.copyrightStatement## 2019-08-13 2019-08-13 751 765 10.15517/am.v30i3.36296 Evaluation of irrigation and pruning on the phenology and yield of Theobroma cacao L. <p><strong><span class="CharOverride-3">Introduction.</span></strong>&nbsp;It is believed that only 0.5 % of the area planted worldwide with cocoa is irrigated. Water availability influences the rate of expansion of the tree canopy and thus light interception. Another extremely important factor is pruning, which influences the production of floral sprouts that will give rise to new fruits, influencing productivity.<strong>&nbsp;</strong><span class="CharOverride-3"><strong>Objective.</strong>&nbsp;</span>The objective of this study was to evaluate the effect of drip irrigation and pruning on the performance, phenology and phytosanitary behavior of cacao trees.&nbsp;<strong><span class="CharOverride-3">Materials and methods.</span></strong>&nbsp;The study was developed between 2015 and 2016 in the Cauca department, Colombia. The six-year-old trees were subjected to two watering layers: L-100 % and L-0 % and two pruning levels: soft and strong. Total number of fruits, number of healthy and sick fruits, kg of wet and dry cocoa, fruit index and seed index, longitudinal and equatorial diameters and incidence of&nbsp;<span class="CharOverride-4">Moniliopthora roreri</span>,&nbsp;<span class="CharOverride-4">Phytophthora palmivora</span>&nbsp;and&nbsp;<span class="CharOverride-4">Monalonion dissimulatum</span>&nbsp;were evaluated. The growth and development curves of the fruit throughout time were built. An experimental design of complete random blocks was used in an arrangement of divide plots.&nbsp;<strong><span class="CharOverride-3">Results.</span></strong>&nbsp;Fruit index varied from 22 (T2) up to 33 fruits (T3), the seed index varied from 0.91 g (T4) to 1.14 g (T2). There were no other significant results for other variables.<strong><span class="CharOverride-3">&nbsp;Conclusion.&nbsp;</span></strong>From a technical and economic point of view an optimal response to the interaction of irrigation with the two levels of pruning was observed because, with a timely application of watering and an adequate pruning management, crop performance can be increased, harvests can be programmed and better quality fruits can be obtained.</p> Diego Hernán Meneses-Buitrago Martha Marina Bolaños-Benavides Luis Fernando Gómez-Gil Housseman Steven Ramos-Zambrano ##submission.copyrightStatement## 2019-08-07 2019-08-07 681 693 10.15517/am.v30i3.36307 Retention of Vanilla planifolia Jacks ex Andrews fruits with growth regulators <p><strong><span class="CharOverride-3">Introduction.&nbsp;</span></strong>The vanilla production in Mexico has decreased by 70 % in the last fifteen years, due to the fall of its fruits. This occurs in extreme climatic conditions when the temperature is higher than 32 °C and the relative humidity is less than 80 %.&nbsp;<strong><span class="CharOverride-3">Objective.&nbsp;</span></strong>The objective was to determine the effect of some commercial growth regulators (GR) on the retention of vanilla (<span class="CharOverride-4">Vanilla planifolia</span>&nbsp;Jacks ex Andrews) fruits Mansa cultivar.&nbsp;<span class="CharOverride-3"><strong>Materials and methods.</strong>&nbsp;</span>The study was carried out in 2016 in the Tecolutla Municipality, Veracruz, Mexico. The treatments evaluated were: aminoethoxyvinylglycine hydrochloride (AVG; 250 ppm), 1-naphthaleneacetic acid (ANA; 27 ppm), benzyl-adenine (BA; 150 ppm), forchlorfenuron (CPPU; 5 ml l<span class="CharOverride-2">-1</span>&nbsp;of water), 2,4-Dichlorophenoxyacetic acid (2,4-D; 32 ppm), 2,4-D (32 ppm) + CPPU (5 ml l<span class="CharOverride-2">-1</span>&nbsp;of water) and control, which consisted of applying only one acidifier (8 ml in 10 l of water). Treatments were applied three times to the same fruits, at 6, 20 and 31 days after the last flowers pollinated by bunch.&nbsp;<span class="CharOverride-3"><strong>Results.</strong>&nbsp;</span>All GR retained more labelled fruits than the control. Treatments 2,4-D and 2,4-D + CPPU retained more fruits per raceme and produced significantly longer fruits than the control. In addition, the 2,4-D + CPPU mixture produced fruits with larger diameter than the control. The growth regulators AVG, ANA BA and CPPU did not differ in the number of labelled fruits, fruits per raceme, fruit length, and fruit diameter.&nbsp;<strong><span class="CharOverride-3">Conclusion.</span></strong>&nbsp;GR had a positive effect on vanilla fruit retention, mainly the 2,4-D + CPPU mixture with which more labelled fruits and per bunch were obtained compared to the control. The use of GR was effective in reducing vanilla abortion.</p> Juan Hernández-Hernández Sergio Alberto Curt-Díaz Ángel Ríos-Utrera ##submission.copyrightStatement## 2019-08-07 2019-08-07 695 704 10.15517/am.v30i3.33988 Analysis of statistical methods to evaluate the performance of simulation models in horticultural crops <p><strong>Introduction. </strong>Every simulation model must be calibrated and validated, in order to avoid speculative and inaccurate conclusions. The methods to evaluate simulation models are usually applied “by habit”, without specifying &nbsp;basic methodological details which leads to the use of terminology and symbology that could cause confusion <strong>Objective. </strong>The objective in the present study was to analyze the different statistical methods employed to evaluate the performance of simulation models in agriculture, and thus propose which is the most suitable from the practical point of view. <strong>Materials and Methods. </strong>Statistical methods based on difference and regression analysis, between measured and simulated values were analyzed. Regarding the difference analysis group, the used methods were root mean square error (RMSE), mean absolute error (MAE), relative error (RE), adjustment index (<em>d</em>), me bianas error (MBE) and the model efficiency (E). In the case of the regression analysis the intercept, linear regression (b) and determination (R2) coefficients, and the estimation confidence limits were scrutinize. <strong>Results. </strong>The ER, <em>d </em>and E, are measures which objective is the comparison between different models to simulate a given variable, instead of evaluating the performance of the model as such. The root square mean error usually used to evaluate differences between observed and simulated values is different from the RMSE regression. The different cases illustrated with the “Eurotate_N” model demonstrated the apropriate practical application of the regression analysis as statistical tool to evaluate its capacity to simulate fruit yield, volumetric soil moisture, evapotranspiration and dry matter in tomato crop under greenhouse. <strong>Conclusion. </strong>The most appropriate statistical method proposed to evaluate a simulation model in tomato was the regression analysis.</p> Freddy Soto-Bravo María Isabel González-Lutz ##submission.copyrightStatement## 2019-05-01 2019-05-01 517 534 10.15517/am.v30i2.33839 Endophytic bacteria of Capsicum frutescens antagonistic to Fusarium spp. <p>&nbsp;<strong>Introduction. </strong>In the last decades, there has been an increased on the interest of Tabasco Chilli pepper cultivation in Colombia; however, production limitation has been observed due to phytosanitary problems. Species of the&nbsp;genus <em>Fusarium </em>cause root and stem rots with large losses for farmers; whereby, it is important to find alternatives to vascular wilt management caused by <em>Fusarium </em>spp. <strong>Objective. </strong>The objective of this research was to isolate and characterize endophytic foliar bacteria with <em>in vitro </em>antagonistic potential against <em>Fusarium </em>spp. in Tabasco Chili pepper (<em>Capsicum frutescens</em>) plants. <strong>Materials and methods. </strong>In the period between February 2014 and February 2016, the <em>in vitro </em>antagonistic capacity of 68 bacterial endophytes of leaf tissue <em>C. frutescens</em>, from two municipalities of Valle del Cauca, Colombia, was evaluated. The isolated bacteria were confronted with six pathogenic isolates of <em>Fusarium </em>spp. by dual growth method. <strong>Results. </strong>Fifty of the bacterial isolates showed percentages of inhibition against at least one <em>Fusarium </em>isolate, and of these sixteen had percentages of inhibition above 40 %. The morphology, biochemical profile and molecular characterization allowed to determine that the isolates identified as <em>Bacillus subtillis </em>and <em>Pseudomonas aeruginosa </em>showed inhibition averages between 62 and 89%, high averages compared to those previously reported in other studies. In addition, stand out as new findings of bacteria associated with endophytic plant tissue of <em>C. frutescens</em>, in Valle del Cauca, Colombia, the <em>Enterobacter cloacae</em>, <em>Microbacterium arborescens</em>, and <em>Stenotrophomonas maltophilia </em>species. <strong>Conclusion. </strong>These results constitute a potential source for pathogen management and productivity improvement in tabasco chili pepper in Colombia.&nbsp;</p> Martha Lucia Velasco-Belalcázar Carlos Alberto Hernández-Medina Eyder Daniel Gómez-López Celina Torres-González Paola Andrea Caro-Hernández ##submission.copyrightStatement## 2019-05-01 2019-05-01 367 380 10.15517/am.v30i2.31760 Climate change perceptions and adaptive responses of small-scale farmers in two Guatemalan landscapes <p><strong>Introduction. </strong>The productivity of certain crops such as coffee (<em>Coffea arabica </em>L.), maize (<em>Zea mays</em>) and beans (<em>Phaseolus vulgaris </em>L.) is expected to decline in Central America because of climate change. This will impact regional economies and livelihoods of smallholder farmers relying on these crops for their food security and livelihoods. There is a need to understand how climate change is already impacting smallholder farmers in Guatemala in order to promote adaptation measures that will allow them to face these impacts. <strong>Objective. </strong>The objectives of this study were to characterize two Guatemalan small-scale agricultural systems, describe farmers’ perceptions of climate change and impacts, and document their adaptation efforts. <strong>Materials and methods. </strong>Structured surveys were carried out in households growing coffee or basic grains in Acatenango and Chiquimula landscapes, two climate change vulnerable landscapes, between June and July 2014. The research was based on farmers’ perceptions of changes in temperature and rainfall, the impacts related to these changes, and the adaptation actions implemented in response to perceived changes. <strong>Results. </strong>Results indicated that 95% of farmers perceived changes in climate, and 81% of them considered these changes to have negatively affected their production. Only 41% of farmers had implemented measures to adapt to these changes, mainly those farmers growing coffee. The implemented adaptation measures differed between landscapes , crops, and usefulness against perceived change with tree planting being the most common adaptation practice to buffer against temperature increases. <strong>Conclusion. </strong>In order to improve the adaptive response ofsmallholder farmers and to promote the use of practices that increase resilience, it is neecessaryto provide more technical, financial and political support to facilitate the adaptation of small farmers facing climate change.&nbsp;</p> Bárbara Viguera Francisco Alpízar Celia A. Harvey M. Ruth Martínez-Rodríguez Milagro Saborío-Rodríguez Lucía Contreras ##submission.copyrightStatement## 2019-05-01 2019-05-01 313 331 10.15517/am.v30i2.33938 Climate change perceptions and adaptive responses of small-scale coffee farmers in Costa Rica <p><strong>Introduction. </strong>Climate change will affect the distribution, productivity and profitability of coffee production in Central America, negatively impacting national economies and small farmer livelihoods. There is a need to understand how climate change affects small coffee farmers in the region in order to promote measures that allow them to cope with and adapt to these changes. <strong>Objective. </strong>The objective of this study was to describe Costa Rican small-scale coffee systems in two vulnerable agricultural landscapesand explorethe adaptation efforts that coffee farmers have implemented in these two coffee systems. <strong>Materials and methods. </strong>Structured surveys were conducted with coffee-producing households in two highly vulnerable landscapes, Turrialba and Los Santos, in Costa Rica, from March-May 2014. The study was based on farmers’ perceptions of changes in temperature and rain, reported impacts of these changes and the adaptation actions implemented at farm level. <strong>Results. </strong>Ninety-eight percentof farmers perceived changes in local climate and most of them related these changes with impacts on production (increase in pests and diseases, floweringproblems and other reported impacts). Sixty percentof the surveyed farmers had modified the management of their farms in order to reduce climate change impacts. The most common adaptation measures used by farmers were the planting of trees and the increased use of agrochemical inputs, mostly in response to perceptions of increasing temperatures. <strong>Conclusion. </strong>This study highlights the need for greater technical, financial and policy support to help smallholder coffee farmers implement adaptation practices and become more resilient to climate change.&nbsp;</p> Barbara Viguera Francisco Alpizar Celia A. Harvey M. Ruth Martínez-Rodríguez Milagro Saborío-Rodríguez ##submission.copyrightStatement## 2019-05-01 2019-05-01 333 351 10.15517/am.v30i2.32905 Assessment of counting chambers on boar sperm parameters analyzed by a CASA-Mot system <p><strong>Introduction. </strong>Understanding the variability in sperm kinetic values through different chambers depths, shows the importance to create a standard for quality control methods in the artificial insemination (AI) industry. Objective. The work aimed was to evaluate the spermatozoa kinetic parameters based on different depths of the visualization chamber by means of a commercial system of computer-assisted sperm analysis, CASA-Mot. <strong>Materials and Methods. </strong>Twenty seminal doses of ten pietrain boars were used. The experimental period was from February to July 2017. The Integrated Semen Analyses System (ISAS®v1) with 50 Hz capture frequency was used. ISAS®D4C16 and ISAS®D4C20 counting chambers with a height of 16 and 20 μm respectively and pre-heated to 37 °C were employed. <strong>Results. </strong>Higher values (p&lt;0.05) were found for all kinetic parameters when the height of the counting chamber was 20 μm. The zone effects within the counting chamber were constant between the two heights, and the variations observed in the kinetic parameters were due to a random effect of the boar. When analyzing the zone effect within the counting chamber, the first three fields of analysis showed higher curvilinear and rectilinear velocity (p&lt;0.05) than the following fields, which is attributed to the presence of passive movement (drifting). <strong>Conclusion. </strong>The greater amplitude and volume capacity within the counting chamber (20 μm versus 16 μm), could promote the unrestricted movement of the cells, which would explain the increase in the kinetic values as the chamber height increased. Studies on the technical conditions of seminal analysis should be continued in order to standardize valuation methods with CASA systems.&nbsp;</p> Anthony Valverde Mónica Madrigal-Valverde ##submission.copyrightStatement## 2019-05-01 2019-05-01 447 458 10.15517/am.v30i1.34145 Extraction of apitoxin with an electric collector in Irapuato, Guanajuato, Mexico <p><strong>Introduction. </strong>The toxin (apitoxin) produced by <em>Apis mellifera </em>bees, is a product with important expectations in the medical industry, due to the therapeutic use in various diseases. <strong>Objetive. </strong>The objective of the present study was to estimate the annual production potential of apitoxin, collected through an automated equipment operating with electrical impulses of 10 s of duration and a voltage of 12 v. <strong>Materials and methods. </strong>Five beehives were used from a beekeeping farm located in Irapuato, Guanajuato, Mexico, where the apitoxin was harvested from August 2016 to June 2017, at biweekly intervals for a period of 20 min at a time, suspending the collection in those periods with abundant flows of nectar, to not affect the production of honey. <strong>Results. </strong>According to the conditions in which&nbsp;this study was developed, the average (± standard deviation) per harvest with biweekly extraction was 52,41±13,83 mg.hive-1, production that was increased to 62,48±1,37 mg.hive-1, considering only colonies with low levels of <em>Varroa destructor </em>infestation. <strong>Conclusion. </strong>The apicultural region where this research was developed, presented potential for the production of apitoxin, being proposed as an additional apicultural product that allows increasing the profitability of the apiary.&nbsp;</p> Carlos Manuel Bucio-Villalobos Oscar Alejandro Martínez-Jaime ##submission.copyrightStatement## 2019-05-01 2019-05-01 459 467 10.15517/am.v30i2.33987