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 1659-1321 <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 attribution, non-commercial and no-derivative license from Creative Commons, which allows third parties to use what has been published as long as they mention the authorship of the work and upon first publication in this journal, the work may not be used for commercial purposes and the publications may not be used to remix, transform or create another work.</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> Productivity of dairy cows supplemented with silage of fava bean or fodder beet <p><strong><span class="CharOverride-7">Introduction. </span></strong>Milk production systems are affected by climate change, presenting seasonality in forage production, and added to this, breeds with high nutritional requirements predominate, which leads producers to permanently use concentrates that increase the costs of production. <span class="CharOverride-7"><strong>Objective.</strong> </span>The objective of this work was to evaluate milk production and quality in cows supplemented with espadrille bean (<span class="CharOverride-8">Vicia faba</span> L.) and fodder beet (<span class="CharOverride-8">Beta vulgaris </span>L.) silage. <strong><span class="CharOverride-7">Materials and methods. </span></strong>The study was conducted at the Obonuco Research Center of AGROSAVIA, municipality of Pasto, Nariño, Colombia. Twelve cows of the F1 breed (Kiwi Cross X Holstein) were used, of first childbirth (93 days of breastfeeding), with an average live weight of 460 kg. Cows were kept in paddocks with grasses, legumes, and water ad libitum. For three periods of fifteen days each, three levels of silage inclusion (0, 4 and 8 kg day<span class="CharOverride-5">-1</span>) of bean and beet were evaluated, using a 3x3 Latin square experimental design for each species. Daily production of each animal was recorded and the compositional quality of the milk (fat, protein, total solids and milk urea nitrogen MUN) was determined. <strong><span class="CharOverride-7">Results. </span></strong>With the highest level of inclusion (8 kg cow<span class="CharOverride-5">-1</span> day<span class="CharOverride-5">-1</span>), the alpargata bean silage had an effect (p&lt;0.05) on the protein percentage, while the fodder beet silage influenced (p&lt;0,05) in the percentage of fat. Both species did not influence production, total solids, and MUN. <strong><span class="CharOverride-7">Conclusion.</span> </strong>The supply of bean and beet silage influenced the compositional quality of milk, providing food alternatives in the milk production systems of the upper tropics of Nariño, allowing seasonality and the replacement of common sources to be reduced.</p> David Felipe Nieto Sierra Elizabeth Lagos Burbano Yesid Avellaneda Avellaneda Edwin Castro Rincón ##submission.copyrightStatement## 2020-05-01 2020-05-01 341 351 10.15517/am.v31i2.37806 Productive performance of Holstein and the crossbreding Kiwi Cross x Holstein cattle <p><strong>Introduction. </strong>During decades, milk production in the Nariño state has depended on the Holstein breed. For this reason, it is necessary to evaluate a model of milk production that allows to decrease production costs and in turn improves the compositional quality of the milk. Objective. This study aimed to compare milk production and compositional quality of Holstein (HO) and the crossbreed between Kiwi Cross (KC) x HO. <strong>Materials and methods</strong>: Monthly milk production in HO cows (n=30) and the ones from the F1 of the KC x HO cross (n=40), was measured by adjusting the day in milk (DIM) and milk production by third of lactation, fat, protein and total solids. For the period between October 2016 and May 2017, 9,809 dairy production records were analyzed. <strong>Results:</strong> Maximum production was 25.8 ± 0.53 vs. 23.2 ± 0.53 l day<sup>-1</sup> for HO vs. KC cows (p&lt;0.05), respectively. The DIM was not different; however, in days 60, 90, 150, 180, 210 and 240 the HO group produced more milk than the KC group, with a persistence in the lactation peak until day 60, and from that point onwards milk production showed decreasing rates in both groups. Furthermore, the production per third of lactation was higher (p&lt;0.05) in the first third compared to the second and third periods for HO (13.6±0.56 vs. 11.3±0.5723 and 9.9±0.47 l day<sup>-1</sup>, respectively) and KC (12.8±0.4505 vs. 10.6±0.66 and 9.5 ± 1.69 l day<sup>-1</sup>, respectively). Fat content was higher (p&lt;0.05) in KC compared to HO in week one, three and five (4±0.07, 4±0.07, 4±0.07 vs. 3.6±0.12, 3.6±0.11, 3.7±0.09 %, respectively); likewise, protein in week one and four was higher in the KC group compared to HO (3.3±0.04 vs. 3.1±0.05 %; p&lt;0.05). Total solids were 13.3±0.17 vs. 12.5±0.23% (p&lt;0.05) for KC and HO cows, respectively in weeks two and five. <strong>Conclusion: </strong>Milk production in KC and HO was similar; however, KC improved performance in compositional milk quality, increasing the percentages of fat, protein and consequently, total solids.</p> Henry David Mogollón García David Felipe Nieto Sierra Edwin Castro-Rincón ##submission.copyrightStatement## 2020-05-01 2020-05-01 329 339 10.15517/am.v31i2.38541 Productive performance and adaptation of Jatropha curcas L. in three ecoregions in Colombia <p><strong><span class="CharOverride-9">Introduction.</span></strong> <span class="CharOverride-10">Jatropha curcas </span>L., is a species with high oil content suitable for biofuel; however, due to its wild condition, the yield of fruit and oil is low; therefore, it warrants genetic improvement. <strong><span class="CharOverride-9">Objective. </span></strong>To know the productive performance of <span class="CharOverride-10">J. curcas</span> in three ecoregions of Colombia. <strong><span class="CharOverride-9">Materials and methods.</span></strong> The work was carried out from 2012 to 2014. A randomized complete block design with fifteen genotypes in three ecoregions (dry Caribbean, Inter-Andean Valley and Orinoquia) was established. The AMMI model and its biplot graph were used to determine phenotypic stability of the fruit yield and with the oil yield the net benefit and the benefit-cost ratio were determined. <strong><span class="CharOverride-9">Results.</span></strong> In two of the three ecoregions used; dry Caribbean and Inter-Andean Valley, <span class="CharOverride-10">J. curcas</span> presented an accumulated fruit yield of 3.6 t ha<span class="CharOverride-6">-1 </span>and 6.7 t ha<span class="CharOverride-6">-1</span>, respectively; in the Orinoquia region the yield was less than 0.1 t ha<span class="CharOverride-6">-1</span>. The cost of a liter of <span class="CharOverride-10">J. curcas</span> oil was US$1.07 for Albania (dry Caribbean) and US$1.24 for Espinal (Inter-Andean Valley), higher than that of African palm oil (<span class="CharOverride-10">Elaeis guineensis</span>) of US$0.89. <strong><span class="CharOverride-9">Conclusion. </span></strong>The fifteen<span class="CharOverride-10"> J. curcas </span>genotypes used in this study showed the best productive performance in Albania (dry Caribbean) and Espinal (Inter-Andean Valley), and the CJC3 genotype was the one with the best fruits and oil production.</p> Luis Fernando Campuzano Duque Ramon Gualdrón Acosta Luis Fernando Chávez Oliveros ##submission.copyrightStatement## 2020-05-01 2020-05-01 277 290 10.15517/am.v31i2.39213 Methane fluxes in soils with pasture covers in the North of Colombia <p><strong><span class="CharOverride-2">Introduction.</span></strong> <span class="CharOverride-2">Traditional livestock production systems in Colombia are based on the establishment of pastures on large tracts of land, which generate greenhouse gases such as methane.</span><strong><span class="CharOverride-2"> Objective. </span></strong><span class="CharOverride-2">The objective of the present study was to monitor the monthly methane fluxes that occur in meadows with three soil covers and three levels of nitrogen fertilization.</span><strong><span class="CharOverride-2"> Materials and methods. </span></strong><span class="CharOverride-2">Methane fluxes were monitored for a year from November 2014 to November 2015, on a Vertic Endoaquepts soil, placed in the middle valley of the Sinu river, Colombia. A full block design was used at random, arranged in divided plots, with two replications. The main plots constituted of two grasses (</span><span class="CharOverride-2"><span class="CharOverride-7">Brachiaria humidicola</span> CIAT679 and <span class="CharOverride-7">Panicum maximum</span> cv. Tanzania) and one with bare soil, and the subplots by three nitrogen fertilization levels (0, 150, 300 kg N ha<span class="CharOverride-5">-1</span></span><span class="CharOverride-2">). Additionally, soil physicochemical properties were evaluated.</span><strong><span class="CharOverride-2"> Results. </span></strong><span class="CharOverride-2">During most of the year (rainy and dry season) methane oxidation occurred, associated with the loam texture and porosity of the soil in the study area, which allowed the free diffusion of gases in the soil. Correlation analyzes showed a close relationship between methane fluxes, porosity, moisture, soil bulk density, and ambient temperature, suggesting these parameters as the main factors that affect the monthly methane flow.</span><strong><span class="CharOverride-2"> Conclusions. </span></strong><span class="CharOverride-2">Methane fluxes were independent of the type of plant material and nitrogen fertilization evaluated. These flows depended on the time of year (dry and rainy) and exhibited a negative annual balance in the study area, which suggests that these systems have the conditions to behave as methane sinks during most of the year.&nbsp;</span></p> Manuel Espinosa Carvajal Jose Luis Contreras Santos Jorge Cadena Torres Judith del Carmen Martínez Atencia Camilo Ignacio Jaramillo Barrios María del Pilar Hurtado ##submission.copyrightStatement## 2020-05-01 2020-05-01 291 309 10.15517/am.v31i2.38387 In vitro gas production to estimate net energy of lactation <p><strong><span class="CharOverride-2">Introduction.</span></strong> The energy content of forages is a limitation for milk production in grazing systems, and the net energy of lactation is the parameter most used to express the energy requirements of dairy cattle.<strong><span class="CharOverride-2"> Objective. </span></strong>To compare the net energy of lactation in feeds, obtained from equations based on <span class="CharOverride-5">in vitro</span> gas production, with that estimated by the National Research Council (NRC) model.<span class="CharOverride-2"><strong> Materials and methods.</strong> </span>The experiment was carried out from August to December 2017 at the Animal Nutrition Research Center of the Universidad de Costa Rica, San Jose, Costa Rica. <span class="CharOverride-5">In vitro</span> gas production was determined in samples of star grass, ryegrass, corn silage, mulberry, and concentrate. Five equations that incorporated accumulated gas production at 24 hours were evaluated.<strong><span class="CharOverride-2"> Results. </span></strong>Gas production showed differences (p&lt;0.001) between feeds. The highest volume of gas produced and content of net lactation energy (NE<span class="CharOverride-6">L</span>) was obtained with concentrate. Equation 3 showed de highest precision for the estimation of NE<span class="CharOverride-6">L</span>, which also reached the highest concordance correlation index (r<span class="CharOverride-4">2</span>=0.92). The use of equations by type of feed improved the accuracy for the NE<span class="CharOverride-6">L</span> prediction. Equation 1 was more precise in concentrate while in corn silage it was equation 4, and in mulberry, star grass and ryegrass it was equation 3. Lin’s concordance index explained the differences in prediction of NE<span class="CharOverride-6">L1x </span>better than the Pearson correlation index. <strong><span class="CharOverride-2">Conclusion.</span> </strong>The<span class="CharOverride-5"> in vitro</span> gas production technique with the application of equation 3 was a reliable method to estimate the NE<span class="CharOverride-6">L1x</span> content in five feeds used in dairy cows</p> Jorge Luis Sobalvarro Mena Jorge Alberto Elizondo Salazar Augusto Rojas Bourillón ##submission.copyrightStatement## 2020-05-01 2020-05-01 311 328 10.15517/am.v31i2.38497 Technical-economic assessment of supplementation frequency over grazing steer in Córdoba, Colombia <p><strong><span class="CharOverride-2">Introduction.</span></strong> Beef production is affected by stationarity forage production and fed cost. Feed frequency evaluations according to pasture could suggest an appropriate practice for profitability improvement. <strong><span class="CharOverride-2">Objective. </span></strong>To evaluate technically and economically the frequency of supplementation of Brahman fattening steers in grazing. <strong><span class="CharOverride-2">Materials and methods.</span></strong> In the middle valley of the Sinú river, Colombia, 108 steers were used distributed in a split-plot design into three pastures (<span class="CharOverride-5">Cynodon nlemfuensis</span>, <span class="CharOverride-5">Megathyrsus maximus</span>, and <span class="CharOverride-5">Brachiaria hybrida</span>, main plot) and three supplementation schemes (subplot): daily (STD), every two days (SDpM) and without supplementation (SS). The daily weight gain (GPD) and morphometric characteristics were evaluated in steers. In the carcass: weight, yield, length, leg perimeter, fat thickness, and compactness index. The biophysical data results fed the financial evaluation of the implemented technology. <strong><span class="CharOverride-2">Results. </span></strong>An interaction of pasture and supplementation frequency over daily weight gain was detected (p&lt;0.05). The highest GPD was observed in animals of the STD treatment for the grass <span class="CharOverride-5">C. nlemfuensis </span>(680 g day<span class="CharOverride-4">-1</span>), while a <span class="CharOverride-5">B. hybrida</span> cv Mulato II in SDpM recorded the lowest GPD with 500 g day<span class="CharOverride-4">-1</span>. An effect (p&lt;0.05) of the diet on body length was observed (150 vs. 152 cm for not supplemented and supplemented steers, respectively). There were no differences (p&lt;0.05) between treatments over carcass characteristics. <strong><span class="CharOverride-2">Conclusions. </span></strong>The biological response in GPD did not compensate for the differential operating cost in the supplemented animals. It is necessary to evaluate new diets with raw materials and inclusion levels that contribute to the increase in animal production, to generate a detectable change in the animal and economic response.</p> Lorena Inés Mestra Vargas Wilson Andrés Barragán Hernández Diego Andrés Medina Herrera Hernando Flórez Díaz ##submission.copyrightStatement## 2020-05-01 2020-05-01 353 366 10.15517/am.v31i2.38389 Analysis of the sector structure and the public-private partnership of maize seed in Mexico <p class="Resumen"><span class="CharOverride-2"><strong>Introduction.</strong> </span>The rapid growth of private investment in the maize seed sector poses challenges for public breeding organizations and smaller seed companies that have increasingly less access to technologies and markets. The International Maize Improvement Consortium (IMIC-LA) created in Mexico in 2011, seeks to increase the size and competitiveness of the seed sector through access to germplasm and breeding tools. However, there are no recent basic data and measures of the sector structure that allow evaluating this and other sector initiatives. <strong><span class="CharOverride-2">Objective. </span></strong>To update and analyze the structure indicators of total seed sales, participation in sales by categories of companies and type of seed varieties, and coverage with improved seeds in Mexico. <span class="CharOverride-2"><strong>Materials and methods.</strong> </span>Maize seed sales data from interviews and surveys with seed companies and official seed production statistics from the Servicio Nacional de Inspeccion y Certificacion de Semillas (SNICS) from 2011 to 2016 were used. <strong><span class="CharOverride-2">Results. </span></strong>The results showed a larger and more competitive seed sector after twenty-five years of opening, especially in the most recent years in which the rapid increase in volume and the share of sales of the national business subsector stands out. <strong><span class="CharOverride-2">Conclusion. </span></strong>The broad participation of seed companies as members of the consortium and the development and commercialization of new seed varieties suggest a positive impact and a role of the consortium in the growth and competitiveness of the national subsector.</p> <p>&nbsp;</p> M. Laura Donnet Iraís Dámaris López Becerril Ciro Domínguez Méndez Juan Arista Cortés ##submission.copyrightStatement## 2020-05-01 2020-05-01 367 383 10.15517/am.v31i2.34894 Comparison of agricultural and economic productivity of sustainable and conventional papaya in Michoacan, Mexico <p class="Resumen"><strong><span class="CharOverride-2">Introduction. </span></strong>In Buenavista, Michoacan, Mexico, the area planted with papaya (<span class="CharOverride-4">Carica papaya</span> L.) is of the Maradol Roja variety and most farmers use a conventional agricultural production model, where the productivity and profitability of the crop is not known with certainty. culture; therefore, it is important to know these two variables in order to obtain an efficient production that in the medium term allows them to improve the socio-economic environment of the farmers. <strong><span class="CharOverride-2">Objective. </span></strong>Compare a sustainable agricultural production model against the conventional papaya production model, to identify agricultural production and the cost-benefit ratio. <strong><span class="CharOverride-2">Materials and method</span>s.</strong> The experiment was carried out in the municipality of Buenavista, Michoacan, Mexico during 2015. It was characterized by having two experimental units, one treatment per unit [sustainable and conventional] with a simple randomized sampling. Fruit weight, total soluble solids, and fruits per plant were evaluated. Statistical analysis included Levene’s test, Kolmogorov-Smirnov, and Lilliefors test, ANOVA and non-parametric Mann-Whitney U test. Economic analysis was carried out with the indicators: total investment cost, total income, cost-benefit ratio, profitability, and break-even point. <strong><span class="CharOverride-2">Results. </span></strong>The sustainable model showed for fruit weight 1.71 kg, 38.06, fruits per plant, total investment cost of USD $ 8,736.83 ha<span class="CharOverride-3">-1</span>, cost-benefit ratio of 2.24, and an equilibrium point of 38.47 %. The conventional model showed 2.20 kg in fruit weight, 53.72 fruits per plant, a total investment cost of USD $ 9,262.03 ha<span class="CharOverride-3">-1</span>, cost-benefit ratio 1.08, and an equilibrium point of 90.11 %. <strong><span class="CharOverride-2">Conclusion.</span></strong> The conventional model was economically unfavorable, so it is suggested to gradually improve it until it becomes profitable. The sustainable model proved to be very economically attractive and to have efficient use of local natural resources.</p> <p>&nbsp;</p> José Mario Miranda Ramírez Omar Aguilar García Diana Miranda Medina ##submission.copyrightStatement## 2020-05-01 2020-05-01 385 403 10.15517/am.v31i2.38615 Mapping of a gene involved in distorted segregation in interspecific tomato populations <p><strong><span class="CharOverride-2">Introduction.</span></strong> Distorted segregation (SD) occurs when the expected genotypes do not correspond to those observed, which favors single parent alleles. This phenomenon was observed in intermediate populations from the cross between <span class="CharOverride-5">Solanum pimpinellifolium</span> and the Moneymaker cultivar of <span class="CharOverride-5">Solanum lycopersicum</span>, developed during the construction process of a library of introgression lines. <strong><span class="CharOverride-2">Objective. </span></strong>Obtain informative recombinants that allow physically mapping a region with SD associated with the wild <span class="CharOverride-5">Solanum pimpinellifolium </span>species. <strong><span class="CharOverride-2">Materials and methods. </span></strong>The research was carried out at the Institute of Molecular and Cellular Biology of Plants (IBMCP) attached to the Higher Council for Scientific Research (CSIC) based at the Universidad Politecnica de Valencia, Spain. A population of 2000 plants was screened to identify recombinants in that region, with a modification of the high-resolution melting technique (HRM-Multiplex). These recombinants were self-fertilized, and through the Chi-square statistic it was determined whether SNP markers identified within the target region had a normal (1:2:1) or distorted segregation for each informative recombinant selected.<strong><span class="CharOverride-2"> Results. </span></strong>Fifty-four informative recombinants were generated and identified, grouped into 10 bins according to the physical recombination site. It was possible to delimit the region with distorted segregation until obtaining a final size of 84 Kb, which was located at the distal end of the long arm of chromosome 4. This region contains a large number of genes, some of which are related to fertilization processes, sterility and cell division among others, which could be related to the studied phenomenon. <strong><span class="CharOverride-2">Conclusion.</span></strong> A gene was found, that causes a segregation distortion in an interval of 84 Kb and possibly is the gene Ge described by Rick in 1966.</p> Walter Barrantes Santamaría Antonio Granell Antonio Jose Monforte ##submission.copyrightStatement## 2020-05-01 2020-05-01 419 431 10.15517/am.v31i2.39485 Molecular study of six strains of Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) and Cochliomyia macellaria <p><strong><span class="CharOverride-2">Introduction. </span></strong>The cattle borer worm, <span class="CharOverride-5">Cochliomyia hominivorax</span> (Coquerel), is an economically important pest for warm-blooded animals, mainly cattle. <span class="CharOverride-2"><strong>Objective.</strong> </span>Molecularly characterize six strains of <span class="CharOverride-5">Cochliomyia hominivorax </span>(Coquerel) and the <span class="CharOverride-5">Cochliomyia macellaria</span> species using the mtDNA sequences. <strong><span class="CharOverride-2">Materials and methods. </span></strong>The study was conducted during 2006 and 2007, using six strains from colonies of Mexico, Panama, and Costa Rica, located in the Molecular Biology Laboratory of the Smithsonian Tropical Research Institute, Panama. Three out of six primers were optimized and evaluated, using the cyclic sequencing method. Parsimonia, NJ (Neighbor-Joining), Maximum Likelihood, and Bayesian analyzes were performed to establish the phylogenetic relationships between the strains. Three primers used for <span class="CharOverride-5">C. hominivorax </span>were evaluated for <span class="CharOverride-5">C. macellaria</span>. <strong><span class="CharOverride-2">Results.</span></strong> The regions of the mitochondrial genome NADH4-tRNA-NADH5 were obtained. All the analyzes showed the same topology forming four defined clades. The first formed by the strains from Oaxaca and Quintana Roo, the second by the strains from Chiapas, the third by the strains from Costa Rica and Panama, and the fourth by the population from Brazil, obtained from GenBank. In <span class="CharOverride-5">C. macellaria </span>two primers were able to amplify the NADH4 region and one NADH5 region.<strong><span class="CharOverride-2"> Conclusion. </span></strong>The amplifications obtained in this research provide information to continue the molecular studies between the species of <span class="CharOverride-5">C. macellaria </span>and <span class="CharOverride-5">C. hominivorax</span>; also to identify the geographical origin of the strains.</p> Claudia Elizabeth Toledo Perdomo Steven R. Skoda ##submission.copyrightStatement## 2020-05-01 2020-05-01 433 444 10.15517/am.v31i2.38308 Soybean protease inhibitors increase Bacillus thuringiensis subs. israelensis toxicity against Hypothenemus hampei <p><span class="CharOverride-2"><strong>Introduction.</strong> </span>The coffee berry borer (<span class="CharOverride-6">Hypothenemus hampei</span> Ferrari, CBB) is one of the most devastating pests on coffee plantations around the world. Although CBB is susceptible to the effect of δ–endotoxins of <span class="CharOverride-6">Bacillus thuringiensis </span>subs. israelensis (Bti) at laboratory level, the efficacy of this control method is poor in the field, presumably due to the inactivation by digestive proteases different to those required for protoxin activation. <strong><span class="CharOverride-2">Objective. </span></strong>To study whether the addition of a soybean flour extract enriched with protease inhibitors (PI), mixed with Bti crystals and spores (Bti-sc) in an artificial diet, could improve the toxicity of Bti against CBB. <strong><span class="CharOverride-2">Materials and methods.</span></strong> This study was performed in San José, Costa Rica, between 2012 and 2013. A set of adult female CBB insects was exposed to a mixture containing different concentrations of a partially purified soybean meal extract with active PI and lyophilized Bti-sc, and were tested through a bioassay in artificial diet to estimate the sub-lethal concentration (LC<span class="CharOverride-7">50</span>). The mortality results were validated by observing the dissected midgut, whose ultrastructure was analyzed by transmission electron microscopy. <strong><span class="CharOverride-2">Results. </span></strong>The soybean extracts partially degraded the Bti-sc complex, it reduced its LC<span class="CharOverride-7">50</span> by almost four times (from 1.135 to 0.315 µg µl<span class="CharOverride-4">-1</span>) and enhanced CBB mortality in a concentration-dependent manner. Histological analyses of the midgut confirmed this synergistic effect, since severe epithelial damage to the intestinal epithelium of CBB exposed to Bti-sc + PI was visualized compared to Bti-sc alone. <strong><span class="CharOverride-2">Conclusions. </span></strong>The combination of a soybean extract enriched in PI and Bti-sc enhanced the mortality effect over CBB, which was confirmed by the midgut collapse. Soybean flour is a cost-effective supplement that could increase Bti effectiveness against CBB and delay the appearance of biological resistance.</p> Esteve A. Mesén-Porras, Lic. Sergio Dahdouh-Cabia, Bach. Catherine Jiménez-Quirós, Bach. Rebeca Mora-Castro, M.Sc. César Rodríguez, Ph.D. Adrián A. Pinto-Tomás ##submission.copyrightStatement## 2020-05-01 2020-05-01 461 478 10.15517/am.v31i2.36573 White spot syndrome virus and Enterocytozoon hepatopenaei in shrimp farms in Costa Rica <p><strong><span class="CharOverride-2">Introduction. </span></strong>The white spot syndrome virus (WSSV) causes systemic destruction of ectodermal and mesodermal tissues in shrimp and can cause 100 % mortality. <span class="CharOverride-5">Enterocytozoon hepatopenaei</span> (EHP) is an intracellular microsporidian that causes lysis of epithelial cells in hepatopancreatic tubules in shrimp. <strong><span class="CharOverride-2">Objective. </span></strong>Detect the presence of WSSV and EHP in fifteen shrimp farms in the Gulf of Nicoya and the Central Pacific from Costa Rica. <strong><span class="CharOverride-2">Materials and methods.</span> </strong>Between January 2017 and July 2018 water during the filling process of the pond, postlarvae, and juvenile shrimp of <span class="CharOverride-5">Penaeus vannamei</span> was collected, during a production cycle in each one of the fifteen farms. Samples were analyzed through polymerase chain reaction (PCR) using primers and protocols to detect the VP41B gene in WSSV, and the small subunit ribosomal RNA gene of EHP. <span class="CharOverride-2"><strong>Results.</strong> </span>The presence of WSSV was detected in one farm, while EHP was not detected in any of the fifteen farms. The sequencing of the amplified segments of the VP41B gene showed 100 % identity with isolated shrimp sequences in Taiwan and Mexico. <strong><span class="CharOverride-2">Conclusion.</span> </strong>WSSV was detected at a very low frequency and EHP was not detected in this study. It is necessary to continue monitoring these agents in the country’s shrimp farms.</p> Nelson Peña Navarro Ruth Castro Vásquez Gaby Dolz ##submission.copyrightStatement## 2020-05-01 2020-05-01 479 489 10.15517/am.v31i2.39627 Effect of temperature and scarification over the germination of Ischaemum rugosum Salisb. <p><strong><span class="CharOverride-2">Introduction. </span></strong>The rupture of the <span class="CharOverride-6">Ischaemum rugosum</span> Salisb. latency is a critical aspect of its physiology, so its knowledge is indispensable to establish accurate measurements regarding its management. <strong><span class="CharOverride-2">Objective.</span> </strong>Determine if storage temperature and scarification influence the germination of <span class="CharOverride-6">I. rugosum</span>under controlled conditions. <strong><span class="CharOverride-2">Materials and methods. </span></strong>The work was carried out in October 2015 at the Fabio Baudrit Moreno Experimental Station and the Official Seed Quality Analysis Laboratory, both at the Universidad de Costa Rica. The effect of scarification (seeds with glumes and seeds without glumes), the seed storage temperature (refrigerated at 5 °C and environment temperature 23.9 °C), and the germination chamber temperature (27 °C and 30 °C) were evaluated. Germinated seeds were counted for each treatment. <strong><span class="CharOverride-2">Results.</span></strong> Double interactions were significant. Seed stored at room temperature had the advantage of higher germination than non-scarified seed (2.35 to 1), and in this type of seed occurs equally in the two temperatures of the germination chamber. In relation to the seed stored in refrigeration, scarified seed had an advantage of germinating at 11.9 to 1 over the non-scarified seed. In the case of germination temperature, 27 °C had an advantage of 11.3 to 1 over 30 °C. <span class="CharOverride-2"><strong>Conclusion.</strong> </span>The storage and germination temperature had an influence on the scarified and non-scarified seed’s germination.</p> Mary Pamela Portuguez Ana María Rodríguez Ruiz Carolina Porras Martínez María Isabel González Lutz ##submission.copyrightStatement## 2020-05-01 2020-05-01 491 498 10.15517/am.v31i2.38417 Spodoptera spp. monitoring in sugarcane: use of sex pheromone traps <p><strong><span class="CharOverride-2">Introduction. </span></strong>The fall armyworm, <span class="CharOverride-6">Spodoptera frugiperda</span>, is one of the world’s most devastating pests. Although originally from the Americas, this insect has become a global food security threat. The reason is that its polyphagia and adaptability combine with the effects of climate change. In Costa Rica, the species of the <span class="CharOverride-6">Spodoptera </span>order, are considered minor pests in sugarcane production. Nevertheless, there is a knowledge gap in population dynamics of the moths of this genus. <strong><span class="CharOverride-2">Objective. </span></strong>Monitor the populations of <span class="CharOverride-6">S. frugiperda</span>, <span class="CharOverride-6">S. sunia</span>, and <span class="CharOverride-6">S. exigua</span> species in a sugarcane field. <strong><span class="CharOverride-2">Materials and methods. </span></strong>The study was conducted in a sugarcane plantation of the variety CC 01-1940, located in Guanacaste, Costa Rica between February 2018 and May 2019. Sexual pheromone-baited traps formulated for <span class="CharOverride-6">S. frugiperda</span>, <span class="CharOverride-6">S. sunia</span>, and<span class="CharOverride-6"> S. exigua </span>were used, each pheromone corresponded to a treatment and ten replicates of each one were established. The abundance of each species was compared and correlated with several climatological variables. <span class="CharOverride-2"><strong>Results.</strong> </span>The highest percentage of catches corresponded to <span class="CharOverride-6">S. frugiperda</span>, followed by<span class="CharOverride-6"> S. sunia</span>, while the captures of <span class="CharOverride-6">S. exigua</span> were marginal. For both<span class="CharOverride-6"> S. frugiperda </span>and <span class="CharOverride-6">S. sunia</span>, the dry season months favored larger populations, so factors such as higher average temperature, thermal amplitude, and lower relative humidity were associated with higher captures in the traps. <span class="CharOverride-2"><strong>Conclusions.</strong> </span>Increases in the average temperature and decrease in rainfall periods could increase the incidence of <span class="CharOverride-6">Spodoptera genus </span>as pests in sugarcane production.</p> Jose Daniel Salazar Blanco Eduardo Cadet Piedra Francisco González Fuentes ##submission.copyrightStatement## 2020-05-01 2020-05-01 445 459 10.15517/am.v31i2.39046 Ecosystem-based adaptation: effect of shade trees on ecosystem services in coffee plantations <p><span class="CharOverride-2"><strong>Introduction.</strong> </span>The management of shade trees in a production system is considered an ecosystem-based adaptation practice capable of providing multiple ecosystem services. <strong><span class="CharOverride-2">Objective.</span></strong> Contribute to the understanding of the effects of trees in coffee plantations on ecosystem services for provisioning and regulation and how the analysis of relationships between services can contribute to improve the design and management of these systems. <span class="CharOverride-2"><strong>Development.</strong> </span>The study was carried out between July and October 2017. Shade trees have an effect on coffee yield, attributed to their influence on the regulation of fruit load. This effect can have positive results with an adequate agroforestry management, as it would reduce extreme biennial fluctuations in coffee production. The trees also regulate the climate within the coffee plantation (microclimate), in addition, they have positive effects on soil fertility, the amount of organic matter, the recycling of nutrients, decrease soil evaporation, reduce erosion and sequester carbon. However, there are some aspects that are still complex and sometimes contradictory. Overall, the documentation of the positive aspects of the trees on provisioning and regulation services is greater than the negative ones. <span class="CharOverride-2"><strong>Conclusion.</strong> </span>This review shows an effect of shade trees on ecosystem services. Knowledge of these effects, considering the interest and expectations of the social systems, must be complemented with analysis of relationships between services with the aim to identifying best agroforestry practices or model systems that can provide multiple services simultaneously.</p> Rogelio Antonio Villarreyna Jacques Avelino Rolando Cerda ##submission.copyrightStatement## 2020-05-01 2020-05-01 499 516 10.15517/am.v31i2.37591 Regulated deficit irrigation and its effect on the nutrition, productivity and quality on passionfruit <p><strong><span class="CharOverride-2">Introduction. </span></strong>Water stress has been recorded as one of the main environmental factors responsible for seasonal fluctuations in passion fruit yields. However, there is a shortage of information on the influence of water stress on different components of growth.<strong><span class="CharOverride-2"> Objective. </span></strong>To evaluate the controlled deficit irrigation (RDC) technique in the passion fruit cultivation (<span class="CharOverride-4">Passiflora edulis</span> Sims) and its possible effects on plant nutrition, efficient use of water, crop productivity and fruit quality. <strong><span class="CharOverride-2">Materials and methods. </span></strong>An trial was conducted during the years 2013 and 2014 in the Experimental Field of the Institute of Agronomy, Universidad Central de Venezuela, Maracay, Venezuela; under tropical dry forest conditions. The statistical design was randomized blocks with three irrigation treatments (R1= 100 % of Eto (reference evapotranspiration), R2= 66 % of Eto, and R3= 33 % of Eto), in the non-critical phenological phases of the crop, four replications and twelve plants per experimental unit. Flowering and fructification were defined as critical phases. Nutritional variables (N, P, K, Ca and Mg content in leaf tissue, and N, K and Ca content in sap), production efficiency (efficient water use, kg fruit plant<span class="CharOverride-3">-1</span>and kg fruit ha<span class="CharOverride-3">-1</span>) and fruit quality ( physical and chemical variables) were evaluated. <span class="CharOverride-2"><strong>Results.</strong> </span>The application of RDC did not affect the nutritional variables or the crop yield. As regard to fruit quality, only significant differences were presented for percentage (%) of peel and juice, however, the values with R2, the values were not limiting in both variables. <span class="CharOverride-2"><strong>Conclusion.</strong> </span>The restriction of the water supply in non-critical phases did not affect the agronomic performance of the plant.</p> Gustavo Adolfo Rodriguez Yzquierdo Carmen Amalia Basso-de-Figuera Gabriel Díaz Reyes Rommel Igor León Pacheco ##submission.copyrightStatement## 2020-04-16 2020-04-16 405 418 10.15517/am.v31i2.39647 Fatty acids composition of genotypes of Jatropha curcas L., in Colombia <p><strong><span class="CharOverride-4">Introduction.</span></strong> <span class="CharOverride-5">Jatropha curcas </span>L. (JC) is a specie with the potential to use its oil as a biofuel and its quality is recognized by the composition of the fatty acids present. <strong><span class="CharOverride-4">Objective.</span> </strong>The objective of this work was the identification and quantification of fatty acids of JC genotypes of the Jatropha Colombia Collection.<strong><span class="CharOverride-4"> Materials and methods. </span></strong>During the years 2012-2014 the experiment was conducted in Espinal-Tolima, Colombia, in a randomized complete block design with fifteen genotypes. The lipid profile of the genotypes was determined by chromatography GC-MS and GC-FID. <strong><span class="CharOverride-4">Results. </span></strong>Ten types of fatty acids were detected in the oil: five saturated (myristic, palmitic, margaric, stearic, arachidic); three monounsaturated (palmitoleic, oleic and eicosenoic), and two polyunsaturated (linoleic and linolenic). The proportion was higher in monounsaturated acids (45.44 %) and polyunsaturated acids (34.18 %) and lower in saturated acids (20.37 %). In the monounsaturated, the oleic predominated (44.62 %); in polyunsaturated linoleic (33.95 %) and in saturated palmitic (12.41 %) and stearic (7.43%). The results found allowed the classification of JC oil as monounsaturated-polyunsaturated (oleic-linoleic), which coincided with what was reported worldwide. <strong><span class="CharOverride-4">Conclusion.</span></strong> Based on the lipid profile, it can be inferred that the oil of the fifteen genotypes evaluated in Colombia is suitable for use as biodiesel.</p> Luis Fernando Campuzano-Duque Fernando Cardeño-López ##submission.copyrightStatement## 2020-01-01 2020-01-01 95 104 10.15517/am.v31i1.37574 Detection of the 35S promoter by real-time PCR as a transgenicity indicator in food and Gossypium sp. <p><span class="CharOverride-2"><strong>Introduction.</strong> </span>Genetically modified crops (GMC) are of particular interest due to their impact on the global economy. Therefore, as a general concern, many countries have established some regulations in regards to genetically modified organisms (GMOs). In Costa Rica, the cultivation of GMOs has been practiced since 1991; however, there´s a lack of studies that monitor the execution and compliance with the biosafety regulations. <strong><span class="CharOverride-2">Objective.</span></strong> The objective of the present study was to identify the presence or absence of transgenicity in processed foods for human and animal consumption, as well as in cotton seeds. <span class="CharOverride-2"><strong>Material and methods.</strong> </span>The real-time PCR technique was used to target the 35S promoter sequence, derived from the cauliflower mosaic virus (CaMV), as a marker to detect the presence of transgenes in processed foods for human and animal consumption as well as in wild or cultivated cotton seeds collected nearby a GM cotton farm in May 2017. <span class="CharOverride-2"><strong>Results.</strong> </span>In the analyzed samples there was a high incidence of an 82 bp fragment, corresponding to the 35S promoter sequence, being absent only in organic corn crops and their derivatives (tortillas, corn powder). Results suggest the presence of GMO traces in the Costa Rican food market, additionally it reveals the urgency of implementing adequate labeling for food traceability. Furthermore, the presence of transgenic cotton in the vicinity of a GM cotton farm was identified, suggesting the relevance of surveillance in aspects of biosafety and genetic manipulation of crops. <strong><span class="CharOverride-2">Conclusion. </span></strong>The presence of traces for GMOs in Costa Rican processed food, demonstrates the importance of continuing this monitoring to provide enough elements for a critic discussion about food traceability and potential transgene flow into wild plant material.</p> Karen Oviedo-Bolaños Jaime García-González Stefany Solano-González Claudio Martínez-Debat Carolina Sancho-Blanco Rodolfo Umaña-Castro ##submission.copyrightStatement## 2020-01-01 2020-01-01 209 221 10.15517/am.v31i1.37151 Selection criteria in tomato lines with determinate growth habit <p><strong><span class="CharOverride-2">Introduction. </span></strong>The selection of genotypes with a determined growth habit in tomato should contemplate adequate selection criteria to increase the efficiency of the plant breeding program.<strong> <span class="CharOverride-2">Objective. </span></strong>The objective of this research was to estimate selection criteria for “chonto” tomato lines with determined growth habit. <span class="CharOverride-2"><strong>Materials and methods.</strong> </span>The research was developed in the Universidad Nacional de Colombia campus Palmira in 2016, using seven determinate habit growth lines (D) and a control with undetermined habit growth. The heritability in a broad sense (h<span class="CharOverride-3">2</span>g), coefficient of environmental variation, coefficient of genetic variation, selection efficiency, and genetic gain was determined, in morphologic, phenological, quality fruit, fruit shape, and productions parameters using the RELM/BLUP process, from the SELEGEN software. <span class="CharOverride-2"><strong>Results.</strong> </span>Three ranges of h<span class="CharOverride-3">2</span>g were found, the first with values of h<span class="CharOverride-3">2</span>g greater than 0.76, the second between 0.53 and 0.38, and the third with a value less than 0.38. The highest values of h<span class="CharOverride-3">2</span>g were for final height plant with 0.92, height plant to harvest with 0.88, production per plant with 0.83, days to flowering with 0.83, fruit number with 0.82, and days to harvest with 0.82. For genetic gain it was found that the control presented the highest values within the main parameters for final height plant, plant height to harvest, internode length, days to harvest, crop duration, soluble solids content, number of fruits per plant, weight fruit, and plant production; however, in some parameters such as height and phenology for effects of selection by habit of determined growth lower values were better. <span class="CharOverride-2"><strong>Conclusion.</strong> </span>Genetic parameters were evidenced that could be considered as selection criteria for “chonto” tomato lines with determined growth of habit.</p> Esteban Burbano-Erazo Iván Javier Pastrana-Vargas Julián Roberto Mejía-Salazar Franco Alirio Vallejo-Cabrera ##submission.copyrightStatement## 2020-01-01 2020-01-01 1 11 10.15517/am.v31i1.37093 The value chain of tree tomato (Solanum betaceum) network in Ecuador <p><strong> <span class="CharOverride-2">Introduction. </span></strong>The fruit and vegetable sector in Ecuador has shown promising performance in domestic and international markets. Likewise, this sector has faced problems of a social, economic and productive nature in its structure and articulations, which until now require intervention.<strong> <span class="CharOverride-2">Objective. </span></strong>The objective of this study was to analyze in a descriptive way the structure of the tree tomato agro-food network.<strong> <span class="CharOverride-2">Materials and methods. </span></strong>This study was carried out in the provinces of Cotopaxi, Tungurahua, and Chimborazo, Ecuador, during the period between the second quarter of 2016 and the end of 2017. The study applied a systemic methodology aimed at the identification and characterization of stages, agents and activities (primary and support), and the analysis of network governance mechanisms.<strong> <span class="CharOverride-2">Results. </span></strong>The present study showed the main social and productive characteristics, horizontal and vertical sizing; and the proposal of strategies focused on improving their productive performance.<strong> <span class="CharOverride-2">Conclusions. </span></strong>The inclusion of women, the sense of associativity of processors and distributors, and the training of producers in topics related to post-harvest, and good agricultural practices, would significantly improve the economic performance of the network, and also encourage greater participation of the agents involved. The network requires increasing the area allocated to tree tomato cultivation, and the application of greenhouse production systems that increase yields.</p> Carlos Moreno-Miranda José Isaac Molina Jacqueline Ortiz Carla Peñafiel Raúl Moreno ##submission.copyrightStatement## 2020-01-01 2020-01-01 13 29 10.15517/am.v31i1.36887 Genotype by environment interaction of nine cotton varieties for inter Andean Valleys in Colombia <p><strong><span class="CharOverride-2">Introduction. </span></strong>The use of stability estimators for agronomic characteristics of interest allows understanding the behavior of the genotype in relation to those environmental factors that influence its expression.<span class="CharOverride-2"><strong> Objective.</strong> </span>The objective of this study was to determine genotype by environment (GE) interaction to select cotton varieties with a high seed yield potential and fiber percentage. <span class="CharOverride-2"><strong>Materials and methods.</strong> </span>Nine varieties of transgenic cotton were evaluated in ten localities distributed in two geographically different ecoregions: geographical valleys of the Magdalena and Cauca rivers, by means of random complete block design, between the months of March and August in 2013.<strong><span class="CharOverride-2"> Results.</span> </strong>Cotton seed yield had significant GE interaction, where the three principal components (PC) of the Additive Main Effects and Multiplicative Interaction (AMMI) model were significant (p&lt;0.01), with contributions of 86.9, 6.4, and 3.3 %, respectively. The average yield for the two ecoregions were 3.3 t ha<span class="CharOverride-3">-1</span> (Magdalena river geographical valley) 4.5 t ha<span class="CharOverride-3">-1</span> (Cauca river geographical valley), and for all the evaluated localities in the ecoregions was 3.9 t ha<span class="CharOverride-3">-1</span>. Fiber percentage did not present significative GE interaction and had an average value of 43,34%. The V004 variety showed the best performance with an average yield of 4.9 t ha<span class="CharOverride-3">-1</span>. The varieties with greater adaptability were V001 and V002. A high correlation was observed between the most productive varieties and the most productive environments. <strong><span class="CharOverride-2">Conclusion. </span></strong>The differential behavior between varieties and localities for yield allowed to select varieties for specific environments, or with phenotypic plasticity for several environments.</p> Julian Roberto Mejia-Salazar Carlos Hernando Galeano-Mendoza Esteban Burbano-Erazo Franco Alirio Vallejo-Cabrera Miguel Arango ##submission.copyrightStatement## 2020-01-01 2020-01-01 31 42 10.15517/am.v31i1.37178 Productive performance of seven soybeans genotypes in acid soils of the Colombian Orinoquía <p><strong><span class="CharOverride-2">Introduction.</span></strong> In Colombia, soy is one of the main raw materials for the production of feed for animals, demand that was only satisfied in 7% in 2007. In the country, this legume is only produced in the Orinoquía region, as part of the rice-corn-soybean rotation system, and its current commercial production is associated with the Soyica P-34 (Altillanura) and Corpoica Superior 6 (Piedemonte) varieties, which are susceptible to <span class="CharOverride-4">Cercospora sojina</span>, which compromise yield. <strong><span class="CharOverride-2">Objetive.</span> </strong>The objective of this work was to identify soy genotypes with specific adaptation for acid soils oxisoles (Altillanura) and inceptisoles (Piedemonte) with superior grain yield a lower affectation by <span class="CharOverride-4">Cercospora sojina </span>K. Hara.<span class="CharOverride-2"><strong> Materials and methods.</strong> </span>An agronomic evaluation test (PEA) consisting of seven genotypes and two commercial varieties was carried out as controls in six localities located in two sub-regions of the Orinoquía (Altillanura and Piedemonte) during 2011, in a randomized complete block design (DBCA) and four repetitions. The AMMI model and its biplot graph were used to determine the phenotypic stability with the variable grain yield.<strong> <span class="CharOverride-2">Results.</span></strong> The AMMI model explained 81.8% of the genotype x locality interaction with the first two main components, the biplot graph allowed to identify three soy genotypes candidates for variety, two with specific adaptation for the Altillanura (L-062 and L-103), and one for Piedemonte (L-189). These genotypes showed higher grain yields by 8% and a lower affectation by <span class="CharOverride-4">Cercospora sojina</span> in relation to commercial witnesses.<strong> <span class="CharOverride-2">Conclusion.</span></strong> The study allowed three soy genotypes to be selected and registered as commercial varieties in the National Cultivation System of the ICA as Corpoica Guayuriba (L-189), Corpoica Achagua (L-062) and Corpoica Iraca (L-103), according to their specific adaptation by sub-region.</p> Samuel Caicedo-Guerrero Yuli Stephani Tibocha-Ardila Luis Fernando Campuzano-Duque Deisy Lorena Flórez-Gómez Jorge Arguelles-Cardenas ##submission.copyrightStatement## 2020-01-01 2020-01-01 59 68 10.15517/am.v31i1.34440 Chemical control of Pogonomyrmex barbatus with corn attractants, in Irapuato, Guanajuato, Mexico <p><strong><span class="CharOverride-2">Introduction. </span></strong>Granivorous ants have an economic and ecological impact because they are considered agricultural pests that transport seeds and defoliate cultivated plants.<strong> <span class="CharOverride-2">Objective. </span></strong>The objective of this work was to evaluate the effectiveness of the insecticides Imidacloprid and Novaluron in mixture with three cornflour-based attractants for the control of <span class="CharOverride-11">Pogonomyrmex barbatus</span> in field trials in Irapuato, Guanajuato, Mexico. <strong><span class="CharOverride-2">Materials and methods. </span></strong>This research was conducted from August to November 2014, six tratments were considered, the first three consisted of the mixture of Imidacloprid with cornflour (in finely milled pellet, in milled pellet and without pelletizing), the fourth was Novaluron combined with cornflour in milled pellet, and the last two consisted only of cornflour (in finely milled pellet and without pelletizing), in addition to an absolute control. Individuals counts per minute were performed before (reading at 0 h), and after the application of the treatments (readings at 1, 24, 72, 144, and 240 h) on the outside of three anthills previously selected for this purpose. The analysis of variance of the design was completely randomized according to sub-subdivided stripes with three repetitions, and three factors that were the following: six treatments and the absolute control, six readings over time including the count prior to the application of the treatments and the three anthills. <span class="CharOverride-2"><strong>Results.</strong> </span>There were highly significant statistical differences for the factors: treatments and readings, as well as for the interaction between both. <strong><span class="CharOverride-2">Conclusion</span>.</strong> The treatments with insecticide showed their maximum control at 72 h of its application, the best were the Imidacloprid combined with cornflour in two presentations (in milled pellet and without pelletizing), showing greater effectiveness after 24 h of its application.</p> Manuel Darío Salas-Araiza Luis Gerardo Lara-´Álvarez Oscar Alejandro Martínez-Jaime José Antonio Díaz-García ##submission.copyrightStatement## 2020-01-01 2020-01-01 69 75 10.15517/am.v31i1.37166 Leaf litter and Mycena citricolor inoculum on the American leaf spot epidemic <p><span class="CharOverride-4"><strong>Introduction.</strong> </span>The American leaf spot caused by <span class="CharOverride-5">Mycena citricolor</span> is among the main coffee diseases in Costa Rica. Cyclic attacks occur approximately every fourteen years, related to increased rainfall and inoculum. <strong><span class="CharOverride-4">Objective. </span></strong>Determine the impact of litterfall and primary inoculum on the epidemiology of this disease. <strong><span class="CharOverride-4">Materials and methods. </span></strong>In coffee plantations located in the coffee region of Tarrazú, Costa Rica, the effect of the manual elimination of diseased leaves attached to the plant and the layer of fallen leaves on the American leaf spot epidemic in 2013 and 2014 was assessed. 1200 branches were evaluated in an experiment of divided plots, where the four treatments were obtained by combining the “with and without” levels for each factor. The disease was described by quantifying the number of diseased leaves, lesions, and geminifers. The disease development curves were constructed and the area under the curve was calculated for each variable. The growth and defoliation of coffee plants was calculated.<strong><span class="CharOverride-4"> Results. </span></strong>Based on the disease incidence curve for each treatment in each year, it was determined that the logistic growth of epidemics is the best fit model. The rates of apparent infection (<span class="CharOverride-5">r</span>) were close to 0.04 units per day in 2013 and there was no significant statistical difference in the developed epidemics; but for 2014, where they varied between 0.03 and 0.05. A main effect of the initial inoculum factor was observed on the presence or absence of litterfall. <span class="CharOverride-4"><strong>Conclusion.</strong> </span>Litterfall had no significant effect on the development of the American leaf spot epidemic. This is the first investigation that determines the impact of possible sources of inoculum other than the lesions present in coffee leaves.</p> María del Milagro Granados-Montero Jacques Avelino Felipe Arauz-Cavallini Sebastián Castro-Tanzi Natalia Ureña ##submission.copyrightStatement## 2020-01-01 2020-01-01 77 94 10.15517/am.v31i1.36614 Effect of doses of nitrogen in the agronomy and physiology of yellow passion fruit <p><strong><span class="CharOverride-2">Introduction.</span></strong> The passion fruit plant is important as fresh fruit and in the agroindustry, since its rich in minerals and vitamins and also has potential for domestic consumption and exportation. It has been shown that nitrogen (N) has an influence on fruit yield but there is no information on the optimal N range for maximum production. <strong><span class="CharOverride-2">Objective. </span></strong>Determine the agronomic, physiological, and phenological response, yield and quality of fruit in the cultivation of parchita passion fruit against different doses of nitrogen. <strong><span class="CharOverride-2">Materials and methods. </span></strong>At the Universidad Central de Venezuela, Maracay, Venezuela from April 2014 to march 2015, passion fruit plants were planted in a completely randomized design, six replicates, and six plants per experimental unit, a control (8 g N plant<span class="CharOverride-3">-1</span> (T1)) was evaluated and three doses of N (100 (T2), 200 (T3) and 300 (T4) g plant<span class="CharOverride-3">-1</span>), an a dose of 50 and 300 g plant<span class="CharOverride-3">-1</span> of P<span class="CharOverride-4">2</span>O<span class="CharOverride-4">5</span> and K<span class="CharOverride-4">2</span>O, respectively were evaluated. The evaluated variables were: plant height, number of leaves, photosynthesis rate (A), transpiration (E), stomach conductance (Gs), chlorophyll index (CI), total leaf N content in doses at flowering and fruiting, yield, and fruit quality. <strong><span class="CharOverride-2">Results.</span></strong> Higher doses of N obtained higher values in height, number of leaves, plant precocity, chlorophyll index, net photosynthesis, and foliar N content and lower values in T1. The variables Gs, A and E, did not show significant differences between the treatments. A 55 % yield reduction was obtained in the control treatment compared to the 200 g N plant<span class="CharOverride-3">-1</span> treatment which obtained the highest yield. The average fruit weight was significantly higher in T3. <strong><span class="CharOverride-2">Conclusion.</span></strong> The best nitrogen dose in passion fruit plants was 200 g N plant<span class="CharOverride-3">-1</span>.</p> Gustavo Adolfo Rodríguez-Yzquierdo Héctor Eduardo Pradenas-Aguila Carmen Amalia Basso-de-Figuera Marta Barrios-García Rommel Igor León-Pacheco Mercedes Pérez-Macias ##submission.copyrightStatement## 2020-01-01 2020-01-01 117 128 10.15517/am.v31i1.36815 Pea production and commercialization in the department of Nariño-Colombia <p class="Resumen"><strong><span class="CharOverride-2">Introduction.</span> </strong>Traditional agricultural production systems prevail in the southern region of Nariño, however, the area harvested from transitory potato, corn and beans crops has been decreased. To address this problem, pea planting has been strengthened, which is marketed in local and regional markets. The department of Nariño is the first pea producer in Colombia, and in 2018, 9425 ha were reported, with an average yield of 1.19 t ha<span class="CharOverride-3">-1</span>. The farmers in the study area are traditional and show technical limitations of production and commercialization.&nbsp;<strong><span class="CharOverride-2">Objective.</span></strong> The objective of the investigation was to analyze the production and commercialization of peas in the department of Nariño. <strong><span class="CharOverride-2">Materials and methods. </span></strong>The research was descriptive and allowed to establish costs, production volumes, planting times, product characteristics, prices, and marketing during 2012. The target population included producers, municipal intermediaries, wholesalers and retailers, and association leaders located in the pea-producing municipalities. <strong><span class="CharOverride-2">Results. </span></strong>The Andean variety was the most sown, the post-harvest losses were 52 %, the prices vary due to the seasonality of production, and the greater volume of production was channeled through intermediaries. <span class="CharOverride-2"><strong>Conclusions.</strong> </span>The production and commercialization of peas in Nariño presents difficulties that requiere sowing planning to balance production volumes, access development credit, train and organize farmers, and foster strategic alliances to guarantee conditions in the value chain.</p> <p>Keywords: productivity, competitiveness, value generation, production flow.</p> Francisco Javier Torres-Martínez Carlos Nelson Rivadeneira-Miranda Álvaro José Castillo-Marín ##submission.copyrightStatement## 2020-01-01 2020-01-01 129 140 10.15517/am.v31i1.36776