https://revistas.ucr.ac.cr/index.php/agromeso/issue/feed Agronomía Mesoamericana 2021-06-10T10:36:32-06:00 Nancy León Ulate pccmca@gmail.com Open Journal Systems <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="https://revistas.ucr.ac.cr/index.php/agromeso/oai">https://revistas.ucr.ac.cr/index.php/agromeso/oai</a></p> https://revistas.ucr.ac.cr/index.php/agromeso/article/view/42862 Production and quality of forage of Sambucus nigra in living fences, high Colombian tropics 2021-06-10T10:35:36-06:00 Alexander Navas Panadero anavas@unisalle.edu.co Juan David Hernández Larrota juandhernandez00@unisalle.edu.co Juan Carlos Velásquez Mosquera jcvelasquez@unisalle.edu.co <p><strong>Introduction.</strong> Livestock feeding in Colombian high tropic livestock systems is based on monoculture grass grazing of low quality and low biomass during drought periods, which affects the productive performance of the animals. <strong>Objective.</strong> To evaluate the production and nutritional quality of forage of Sambucus nigra L., established&nbsp;as a silvopastoral live fence arrangement. <strong>Materials and methods.</strong> The research was carried out at the San Joaquin farm, located in Paipa, Colombia; the samplings were done between January 2019 and March 2020. In a live fence arrangement, a 226 m linear transect was selected, in which 17 trees were randomly selected. The green forage and dry matter production of the complete plant and its fractions (leaves and stems), the leaf - stem ratio and the nutritional quality (NIRS) of the complete plant and of each fraction were evaluated. A randomized design was carried out, descriptive statistics and analysis of non parametric variance (Kruskal Wallis test) were performed for forage production and leaf-stem relationship, the data analysis was done using the Infostat® program. <strong>Results.&nbsp;</strong>The production of green forage and dry matter was 19, t km-1 year-1 and 3,9 t km-1 year-1, respectively. There were differences (p&lt;0.0001) in nutritional quality, the leaves were of higher quality, the forage had a high crude protein content, metabolizable energy and digestibility, low percentage of neutral detergent fiber and acid detergent fiber, the leaf-stem ratio was 0.8: 1, although there were differences between samplings (p&lt;0.0001). <strong>Conclusions.</strong>&nbsp; The living fences of S. nigra produced high production of edible biomass per kilometer per year, the forage of the complete plant and its fractions had good nutritional quality, crude protein, energy, and digestibility.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/40628 Applied biotechnology to the study of the boar semen motility 2021-06-10T10:35:55-06:00 Anthony Valverde anvalverde@itcr.ac.cr Vinicio Barquero vinicio119@gmail.com Vanesa Carvajal vcarvajal@tec.ac.cr <p><strong>Introduction.</strong> The use of reproductive biotechnologies has meant an important improvement of the efficiency and profitability in the swine industry. <strong>Objective.</strong> To determine the state of the art in which the applied biotechnology to semen study and their implementation; in pig farms; of assisted reproductive techniques such as artificial insemination. <strong>Development.</strong> In the swine industry, the fertility of boars (Sus scrofa domestica) has a significant effect&nbsp;on the overall efficiency of herd reproduction. Although there are objective methods of accurate assessment of the boar’s semen variables, many farms still carry out subjectively assessments. The biochemical concepts that determine the functionality of the spermatozoa are molecularly complex, however, the general aspects of functionality can be known, and semen management methods can be developed that allow the maintenance of the optimal conditions of the semen doses used in artificial insemination (AI). Within the sperm functionality, classical parameters of volume, concentration, and motility are involved, which are fundamental for the optimization of the seminal doses produced by boar. The CASA (Computer-assisted semen analysis) systems are a biotechnological application that displaces the traditional subjective semen analysis and provides a large data that have allowed us to explore in greater detail the boar ejaculates. <strong>Conclusions.</strong> Biotechnological semen processes are a tool for assessing seminal quality and optimizing seminal doses on farms that use artificial insemination.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/41437 Protein hydrolyzed from byproducts of the fishery industry: Obtaining and functionality 2021-06-10T10:35:52-06:00 Manuel Montero Barrantes manuel.montero@ucr.ac.cr <p><strong>Introduction.</strong> By-products from the fishing industry represent more than 50% of the raw material and are usually used to generate low value-added products. However, these by-products present components with high commercial value such as omega-3 rich oils, proteins of high nutritional value, collagen, enzymes, and bioactive peptides. <strong>Objective.</strong> To present the current state of research on the functionality and the process of obtaining protein hydrolysates and bioactive peptides of fishing origin.&nbsp;<strong>Development.</strong> This work was carried out in Costa Rica between&nbsp;January 2017 and September 2019, it describes the generation and use of by-products from the fishing industry, the process of obtaining hydrolysates and peptides, from the preliminary stages to their fractionation and purification, ends with the applications and functional properties of these compounds such as their nutritional value, water retention, emulsifying, and foaming capacity, and their antioxidant and antihypertensive activity.&nbsp;<strong>Conclusion.</strong> Protein hydrolysates and peptides of fishing origin are a good source for the production of new ingredients with applications in the food and pharmaceutical industry, especially due to their antioxidant and antihypertensive activity, properties that depend on the fractionation and purification of bioactive peptides, which is why the technologies that allow these processes must be developed and optimized to be carried out at an industrial level and at an adequate cost.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/41630 Tree composition of cocoa associated species: Lacandon jungle and agroforestry systems, Chiapas, Mexico 2021-06-10T10:35:47-06:00 Carlos Hugo Avendaño Arrazate avendano.carlos@inifap.gob.mx Gicli Manuel Suárez Venero glici@cug.co.cu Alexander Mendoza López amenlo@hotmail.com Misael Martínez Bolaños martinez.misael@inifap.gob.mx Jorge Reyes Reyes jorge.reyes@unach.mx Saúl Espinosa Zaragoza samuelez1@gmail.com <p><strong>Introduction.</strong> The tree composition associated with creole cocoa and that developed in cocoa production systems is different. This information is important to adopt future strategies in conservation and improvement programs.&nbsp;<strong>Objective.</strong> Contribute to the knowledge about the tree composition of species associated with creole cacao in Mexico.&nbsp;<strong>Materials and methods.</strong> The data analyzed in this study included variables of the horizontal and vertical structure, in addition to the diversity of tree species associated with cocoa under different conditions. This study was carried out during May to September 2018, in plots where creole cacao trees were found in their natural habitat in the Lacandona jungle and in cacao plantations in three locations in Soconusco, in Chiapas, Mexico. In them, the tree species were counted and taxonomically classified. <strong>Results.</strong> Associated with the creole cacao in the Lacandon jungle, twenty-one species were registered, which were grouped into nineteen genera and thirteen families, whose abundance, richness and density was greater than that registered in cocoa production systems in the Soconusco region, which contributed to a difference between both ecosystems with only two shared species.<strong> Conclusion.</strong> The abundance, richness, and density of tree species associated with creole cocoa was higher than that registered in the production systems, with dissimilarity in their conditions. Differences were recorded in the location of the cocoa crop within the vertical structure of both scenarios studied.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/43794 Prevalence, incidence and risk factors of subclinical mastitis in specialized dairies in Colombia 2021-06-10T10:35:24-06:00 Catalina Medrano-Galarza cata.medrano@outlook.com Diego Germán Ahumada Beltrán dahumada@agrosavia.co Juan José Romero Zúñiga juan.romero.zuniga@una.ac.cr Pilar Donado Godoy pidonado@agrosavia.co <p><strong>Introduction.</strong> Subclinical mastitis (SCM) is one of the main diseases in cattle; studying its epidemiology is essential to implement health programs.<strong> Objective.</strong> To determine the prevalence, incidence, and factors associated with subclinical mastitis in specialized dairies in Cundinamarca, Colombia. <strong>Materials and methods.</strong> An observational-analytical, prospective-cohort study was performed. Fifteen farms were visited three times every 56 days (September-2019 to February-2020). At each visit, the California test (CMT) was performed and dirtiness of udders and hind limbs of milking cows was evaluated; likewise, milking routine was evaluated. One milk sample per farm was collected to determine somatic cell counts (SCC) and bacteria count (BC). Logistic regression mixed models were used to determine factors associated with having or acquiring SCM, and generalized linear models to determine factors associated with the probability of a greater prevalence of SCM and BC. 960 CMT were performed on 454 cows.&nbsp;<strong>Results.</strong> A total of 960 CMT were performed on 454 cows. The median herd-level prevalence of SCM was 50 % and it was directly associated with SCC and BC. The median cumulative herd-level incidence of developing a new and a chronic infection of SCM was 42 % and 75 %, respectively. Factors associated with having SCM were: multiparous cows (Odds Ratio, OR≥2.35), late lactation (OR=3.39), no pre-dipping (OR=1.74), and over-milking (OR=1.96). Factors that reduced the risk of acquiring SCM were: having &lt;3 lactations (OR≤0.29), early-mid lactation (OR≤0.32), segregating cows (OR=0.37), and pre-sealing (OR=0.27). Factors associated with the probability of a greater prevalence of SCM were: not segregating (OR=2.42) and not pre-dipping (OR=2.50). Factors associated with increased BC were: dirty udders, pre-sealer action time less than 30 s, and having more than one milker.&nbsp;<strong>Conclusion.</strong> Multiparous cows, late lactation (&gt;180 days in production), not segregating, not pre-sealing, and over-milking, were factors associated with acquiring and having subclinical mastitis, therefore, they are key factors to consider in prevention and control measures.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/41265 Adaptation of fodder mixtures at different levels of amendment and irrigation in Nariño, Colombia 2021-06-10T10:35:53-06:00 Paola Andrea Portillo López pportillo@agrosavia.co Diego Hernán Meneses Buitrago dmeneses@agrosavia.co Elizabeth Lagos Burbano elizalagosb@hotmail.com María E. Duter Nisivoccia latinlincuru@gmail.com Edwin Castro Rincón ecastro@agrosavia.co <p><strong>Introduction.</strong> Specialized dairy farming in the high tropics of Nariño faces with different limitations, such as the variability and seasonality of the fodder supply. <strong>Objective.</strong> To evaluate six mixtures of perennial, annual, and leguminous fodder, three levels of amendment and two levels of irrigation in the high tropic of Nariño. <strong>Materials&nbsp;</strong><strong>and methods.</strong> The study was developed between December 2017 and November 2018 at the Obonuco research center of the Colombian Agricultural Research Corporation. A complete randomized block design was used, with an arrangement of subdivided plots. It was measured: vigor, height, coverage, number of leaves, incidence of pests, incidence and severity of diseases, nutritional deficiencies, and dry matter (MS). Software R V.3.6.0 was used for the analysis. <strong>Results.</strong> The association (gramineous and leguminous) generated a direct effect on the yield of MS, cover, and number of leaves, being the best mixture the one composed by Dactylis glomerata, Trifolium repens L., and Trifolium pratense L. For the variable height, the highest values were presented in the Tetrablend 260 mixture. Most of the treatments were kept on scales without damage and slight damage for the variables incidence of pests, severity of diseases and nutritional deficiencies. <strong>Conclusion.</strong> The mixtures of grasses and legumes showed comparative advantages over pure grass monoculture in terms of MS yield and agronomic variables. In general, all the treatments were kept in minimum and light damage thresholds for the phytosanitary variables.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/43207 Nutritive value of forage mixtures in the dry and rainy seasons in Nariño, Colombia 2021-06-10T10:35:33-06:00 Paola Andrea Portillo López pportillo@agrosavia.co Diego Hernán Meneses Buitrago dmeneses@agrosavia.co Elizabeth Lagos Burbano elizalagosb@hotmail.com María E. Duter Nisivoccia latincuru@gmail.com Edwin Castro Rincón ecastro@agrosavia.co <p><strong>Introduction.</strong> The use of associations of grasses and legumes allows to have greater nutritional value and dry matter yield. <strong>Objective.</strong> To evaluate six mixtures of perennial, annual and legume forages in the dry and rainy season&nbsp;in Nariño, Colombia. <strong>Materials and methods.</strong> The study was conducted between December 2017 and November 2018 at the Obonuco Research Center of the Colombian Agricultural Research Corporation (AGROSAVIA). A randomized complete block design was used, with an arrangement of sub-divided plots. The following were determined: PC (crude protein), FDN (neutral detergent fiber), FDA (acid detergent fiber), D (digestibility), ENL (net energy of lactation) and TC (growth rate of the species). The software R V.3.6.0 was used for the analysis.&nbsp;<strong>Results.&nbsp;</strong>The nutritional value of the mixtures for the season of high and low rainfall presented significant differences (p&lt;0.05) at the age of 28, 35 and 42 days, where the mixture made up of Dactylis glomerata yielded the best results except for the PC at the age of 28 days. The best values for this mixture occurred in dry season. <strong>Conclusion.</strong> Mix 4 (Trifolium repens + Trifolium pratense + Dactylis glomerata) presented the highest growth rate and accumulation of CP at the age of 35 and 42 days in the two evaluated seasons. Therefore, it could be evaluated commercially as a food alternative for livestock systems in the high tropics of Nariño.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/43179 Detection of IHHNV in Litopenaeus vannamei farms in Costa Rica 2021-06-10T10:35:34-06:00 Jose Francisco Parajeles Mora jfparajeles@gmail.com Nelson Peña Navarro npena@utn.ac.cr Anthony Solorzano Morales anthony.solorzano.morales@una.ac.cr Gaby Dolz gaby.dolz.wiedner@una.ac.cr <p><strong>Introduction.</strong> The infectious hypodermal and haematopoietic necrosis virus (IHHNV) produces cuticular deformities and growth reduction of white shrimp (Litopenaeus vannamei) causing losses due to a lower harvest&nbsp;weight and lower market prices. Although different pathogenic and non-pathogenic genotypes of IHHNV have been described, it is unknown whether these are present in the country. <strong>Objective.</strong> To characterize the IHHNV lineages present in white shrimp farms in Costa Rica. <strong>Materials and methods.</strong> Between 2017 and 2018, a total of 15 shrimp farms distributed in the Gulf of Nicoya, Guanacaste, Costa Rica were investigated. Water, postlarvae, and juvenile shrimp samples were collected during a production cycle of three months, additionally, physicochemical parameters of the water in the ponds were measured and a survey was applied to the producers, to know if they had knowledge about the disease and if they suspected the presence of the agent in their establishments. The collected samples were analyzed by Polymerase Chain Reaction (PCR) and sequencing. <strong>Results.</strong> The presence of IHHNV was determined in 86.6 % (13/15) of the farms analyzed, the sequencing of the amplified products determined the presence of IHHNV lineage III, with 99.2 %-100.0 % (386-389/389 bp) similarity with the sequence isolated from L. vannamei in Venezuela (KM485615.1). Poor physicochemical parameters of the water were determined. A total of 53.3 % of producers had not heard of IHHNV, while the remaining producers suspected having the virus on their farms. <strong>Conclusion.</strong> IHHNV pathogenic lineage III was present in most of the farms. It is recommended to train producers and establish welfare, management, and biosecurity protocols in order to improve the productive parameters of their farms.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/42079 Resistance of eggplant (Solanum melongena L.) cultivars to Tetranychus ludeni Zacher (Acari:Tetranychidae) 2021-06-10T10:35:41-06:00 Janeth Alexandra Sierra-Monroy jaalexandrasierramonroy@gmail.com Oscar Burbano-Figueroa burbano.figueroa1@gmail.com Liliana María Grandett-Martínez lgrandett@agrosavia.co Maria del Valle Rodriguez-Pinto mariadelvalle-02@hotmail.com Lilibet Tordecilla-Zumaqué lilytordecilla@hotmail.com José Antonio Rubiano-Rodríguez jrubiano@agrosavia.co <p><strong>Introduction.</strong> Eggplant (Solanum melongena L. (Solanales: Solanaceae), one of the major vegetable crops<br>in the Colombian Caribbean, is attacked by spider mites (Tetranychus ludeni (Acari: Tetranychidae) causing<br>notable reductions in yield. Besides the substancial economic losses related to yield reduction, its control provokes environmental contamination due to excessive use of acaricide affecting the health of farmers and their families.&nbsp;<strong>Objective.</strong> The purpose of this study is to assess the resistance of seven eggplant cultivars to T. ludeni on field and greenhouse assays. <strong>Materials and methods.</strong> Eggplant landraces (Buelvas and Gonzalez), cultivars (C029 and C015), and breeding lines (C036, C025, C049) were assessed for resistance to T. ludeni. Field and greenhouse resistance assays were conducted in a randomized complete block design on field and greenhouse conditions (four replications for each accession). <strong>Results.</strong> Field assays showed significant differences in mite population density between eggplant cultivars (F=4.42; p&lt;0.0004). C025 presented the highest mite population density while Buelvas had the lowest density. In the greenhouse assays, Buelvas showed lower mite density in comparison with the density observed in cultivar C036.&nbsp;<strong>Conclusions.</strong> Buelvas and Gonzalez exhibited resistance against T. ludeni providing evidence of the<br>occurrence of field resistance in eggplant landraces from the Colombian Caribbean. The greenhouse assays, performed at high levels of mite density, offered greater discriminatory power and they are suitable for inclusion in the early phase of germplasm screening. We recommend the inclusion of cv. Buelvas as resistant reference genotype, and C036 as susceptible reference genotype in future screening trials. Cultivar Buelvas is recommended as reference genotype due to its reliable resistance level in field and greenhouse assays and its high yield.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/43632 New records of host plants of Raoiella indica Hirst in Colombia 2021-06-10T10:35:26-06:00 Guillermo A. León Martínez gleon@agrosavia.co Juan Carlos Campos Pinzón jcampos@agrosavia.co Janeth Alexandra Sierra Monroy jaalexandrasierramonroy@gmail.com <p><strong>Introduction.</strong> The red palm mite Raoiella indica Hirst (Acari: Tenuipalpidae) is recognized as a quarantine pest on coconut palm leaves, reported since 2004 in the American continent. In Colombia its presence was recorded in 2010 and it’s spread along the Atlantic coast has been rapid. In 2013 it was reported in the departments of Atlántico, Bolívar, Córdoba, Guajira, Magdalena, Norte de Santander, and Sucre, in coconut (Cocos nucifera), banana (Musa&nbsp;acuminata), heliconias, and plantain (Musa paradisiaca) plants. <strong>Objective.</strong> To know new host plants and the dispersal of the mite R. indica in three departments of Colombia. <strong>Materials and methods.</strong> During the years 2019 to 2020, in the Colombian departments of Meta (municipalities of Villavicencio, Guamal, San Carlos de Guaroa, and Granada), Casanare (municipality of Yopal) and Tolima (municipality of Guamo), plants of the families Arecaceae, Musaceae and Heliconiaceae, which could be hosts of the mite R. indica, were checked.&nbsp;<strong>Results.</strong> Of the twenty plant taxa sampled, sixteen were found to be hosts of R. indica and one of them was a new host. The presence of R. indica was recorded for the first time in the three departments, mainly on coconut palms and several alternate host plants including palms, mosses and Heliconia psittacorum. <strong>Conclusions.</strong> The red mite R. indica was reported officially for the first time in the Colombian departments of Meta, Casanare, and Tolima, and the seje palm, Oenocarpus bataua Burret, is reported as a new host plant species for R. indica in Colombia.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/44042 Agronomic and nutritional evaluation of genotypes of Chloris gayana for the Colombian livestock 2021-06-10T10:35:23-06:00 Julian Roberto Mejía Salazar julianmejia58@gmail.com David Felipe Nieto Sierra dnieto@agrosavia.co Sergio Luis Mejía Kerguelen smejia@agrosavia.co Miguel Arango marangoa@agrosavia.co Esteban Burbano Erazo eburbano@agrosavia.co Iván De Jesús Higuita Corrales ihiguita@agrosavia.co <p><strong>Introduction.</strong> Grazing forages are the main feed source for livestock. Climatic variation challenges producers to maintain a constant supply of food, so it is necessary to explore other forage alternatives. <strong>Objective.</strong> To evaluate the performance of twenty genotypes of Chloris gayana for livestock farms. <strong>Materials and methods.</strong> The work was carried out at the El Nus Research Center of the Corporacion Colombiana de Investigacion Agropecuaria (AGROSAVIA), San José del Nus, Antioquia, Colombia. A randomized complete block design, three repetitions, and twenty treatments (Chloris gayana genotypes) was used. The analysis used a mixed model repeated measures over time, with the GLIMMIX procedure, whose time effect was represented by cut-off age. The cutting frequencies used were 21, 28, 35, and 42 days, between August 2017 and October 2019 in low and high rainfall seasons. Vigor, species cover, plant height, pests, and pathogen incidence, flowering, dry matter yield (MS), crude protein (PC), fiber in neutral and acid detergent (FDN, FDA), lignin (LIG), digestibility (DIG), hemicellulose (HEM), and net lactation energy (ENL) were evaluated. <strong>Results.</strong> The characters that contributed the greatest variability corresponded to MS, PC, FDN, FDA, and DIG; an association was observed between DIG, HEM, and ENL. There were differences between seasons and between genotypes for most of the variables, except for PC. Lignin was the only variable that showed a difference in the triple interaction (genotype*season*cutting days). The genotype*season interaction showed differences for FDA and LIG. Genotype 13103 obtained the highest MS yield (3032.2 kg DM ha-1). B. decumbens had the lowest content of FDA and LIG; but the highest of digestibility. <strong>Conclusions.</strong> The experimental genotypes presented similar or even better productivity and nutritional characteristics than the controls.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/43297 Allometric response of two sugarcane cultivars for panela to foliar fertilization in the nursery 2021-06-10T10:35:30-06:00 Leidy Yibeth Deantonio-Florido leidydeflo@gmail.com Luis Gabriel Bautista Montealegre lbautista@agrosavia.co Juan Carlos Lesmes Suáres jlesmes@agrosavia.co William Andrés Cardona wcardona@agrosavia.co <p><strong>Introduction.</strong> In Colombia, the panela agribusiness stands out for its social, economic, and food security contributions; however it demands technological improvements in the management of the fertilization of sugarcane cultivars. <strong>Objective.</strong> To determine the effect of foliar fertilization in the nursery stage on the growth parameters of two sugarcane cultivars for the production of panela. <strong>Materials and methods.</strong> The experiment was carried out in 2018 at the Corporacion Colombiana de Investigacion Agropecuria (AGROSAVIA) Cimpa headquarters. A completely randomized experimental design was established to evaluate in cultivars CC 93-7510 and CC 93-7711 the growth of plants exposed to three foliar fertilization treatments: (1) nitrogen source, (2) source with macro and micronutrients (complete), (3) mixture of sources, and an absolute control. Allometric variables (height, diameter, number of leaves, and root dry weight) and growth indices were recorded over time; with the former, generalized linear mixed models and Poisson models were constructed, and with the indices, a uni and multivariate analysis of variance. <strong>Results.</strong> The evaluation factors (fertilization and time) presented significant effects (p≤0.05) on the allometric variables in the two cultivars compared to the control (without fertilization); while the growth indices presented statistically significant differences due to the effect of the fertilization sources. The CC 93-7510 sugarcane plants fertilized with the mixture of complete and nitrogen sources presented greater height and diameter of the stems, number of leaves, and dry weight of roots. As for the CC 93-7711 sugarcane plants fertilized with the complete source, they showed greater diameter of the stem and accumulation of dry weight of roots.&nbsp;<strong>Conclusions.</strong> Foliar fertilization in sugarcane plants of both cultivars allowed greater allometric development in less time.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/42066 Categorization of the water status of rice inoculated with arbuscular mycorrhizae and with water deficit 2021-06-10T10:35:43-06:00 Michel Ruiz Sánchez mich762016@gmail.com Juan Adriano Cabrera Rodríguez nani@inca.edu.cu José M. Del'Anico Rodríguez josemdellamico@gmail.com Yaumara Muñoz Hernández yaumara@upr.edu.cu Ricardo Aroca Álvarez raroca@eez.csic.es Juan M. Ruiz Lozano juanmanuel.ruiz@eez.csic.es <p><strong>Introduction.</strong> The water deficit negatively affects rice plants and limits their productivity. Arbuscular mycorrhizal symbiosis has been shown to improve rice productivity in drought conditions. <strong>Objective.</strong> To propose a new categorization for the state of water stress of rice plants inoculated (AM) or not with arbuscular mycorrhizal fungi (nonAM) and exposed to water deficit (D) during the vegetative phase. <strong>Materials and methods.</strong> The experiment was carried out under controlled greenhouse conditions during the years 2009 and 2010 at the Zaidín Experimental Station, Granada, Spain. The rice transplantation was carried out fourteen days after germination to pots with a 5 cm water sheet and at 30, 40, or 50 days after transplantation (DAT) they were subjected to water deficit during a period of 15 days, at which time the water sheet was restored. The control treatment was maintained throughout the cycle under flood conditions (ww). Evaluations were performed at 45, 55, 65 DAT and after recovery at 122 DAT. The harvest was carried out at 147 DAT. <strong>Results.</strong> The reduction in water supply demonstrated water stress in the plants, manifested by the decrease in the water potential of the leaves. Arbuscular mycorrhizal symbiosis always favored the water status of the plant. Four categories of water status of plants were proposed taking into account water potentials and agricultural yield: no stress (≥-0.67 MPa); light stress (&lt;-0.67 to -1.20 MPa); moderate stress (&lt;-1.20 to -1.60 MPa), and severe stress (&lt;-1.60 MPa). <strong>Conclusion.</strong> The categorization of stress due to the water deficit is a tool of high scientific value for the specific case of rice, since this plant has the capacity to adapt to tolerate the presence of a sheet of water throughout its biological cycle and is highly susceptible to water deficit.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/44057 Relationship among diseases and grain yield in soybean 2021-06-10T10:35:21-06:00 M. Lavilla miguellavillapergamino@gmail.com A. Ivancovich ajivancovich@comunidad.unnoba.edu.ar <p><strong>Introduction.</strong> Vascular and foliage diseases are among the most relevant factors affecting soybean production. <strong>Objective.</strong> To quantify the damage of vascular and foliage diseases on the yield of soybean (Glycine max) crops. <strong>Materials and methods.</strong> This study was carried out for two consecutive years (2018 and 2019) in the town of Pergamino Buenos Aires, Argentina. In the case of vascular diseases, the sampling was carried out on 40 lots from the town of Pergamino. In each batch, 30 pairs of plants were collected by relieved disease. Each pair of plants was harvested by hand quantifying the number of grains per plant (NGP) and the yield per plant (RP). For the&nbsp;quantification of yield losses due to foliage diseases, tests were carried out with and without foliar fungicide. In each treatment the yield (kg ha-1) and its main components were determined. <strong>Results.</strong> The wet rot of the stem caused by Sclerotinia sclerotiorum was the disease that generated the greatest damage losses in the NGP and RP. Vascular diseases can cause damage losses in the crop yield per plant, greater than 50 % and this must be associated with the percentage of incidence of the disease or diseases present in the soybean lot to determine the total damage losses. Foliage diseases in soybean can significantly reduce the yield between 11 % to 20 %, if they are not controlled in time with foliar fungicides.<strong> Conclusion.</strong> The vascular and foliage diseases diagnosed in this study significantly reduced the yield and its components in the soybean crop.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/43359 Evaluation of leaf blight and purple seed stain in soybean in Argentina 2021-06-10T10:35:27-06:00 M. Lavilla miguellavillapergamino@gmail.com A. Ivancovich ajivancovich@comunidad.unnoba.edu.ar A. Díaz Paleo diazpaleoo.antonio@inta.gob.ar <p><strong>Introduction.</strong> The Cercospora leaf blight and the purple seed stain are endemic diseases of soy in Argentina. <strong>Objective.</strong> To evaluate the prevalence, incidence and severity of Cercospora leaf blight and the purple seed stain in Argentina during two consecutive years, 2015 and 2016. <strong>Materials and methods.</strong> Samples were taken from a total of 132 lots. The evaluation of the prevalence, incidence, and severity of Cercospora leaf blight were carried out in the field&nbsp;in R<sub>6</sub>. The evaluation of the prevalence and incidence of purple seed stain was carried out in the laboratory. <strong>Results.&nbsp;</strong>Cercospora leaf blight and purple seed stain were found to be widespread throughout the soybean region of Argentina, with a prevalence of 100 %. In 2015 and 2016, the severity of the leaf blight by Cercospora was statistically lower in the southern pampa region compared to the other regions. The northern region presented the highest severity levels of the Cercospora leaf blight. The incidence of purple seed stain did not have statistical differences between regions and years evaluated. No association was found between the pathometric variables of both diseases. There was no quantitative relationship between the severity of symptoms of Cercospora leaf blight on leaf with the incidence of purple seed stain.&nbsp;<strong>Conclusion.</strong> Both diseases under study were found widespread in all soybean-producing regions of Argentina.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/39720 Antifungal activity of Bacillus amyloliquefaciens against Fusarium oxysporum f. sp. cubense race 1 2021-06-10T10:35:56-06:00 Mileidy Cruz Martín mileidy@ibp.co.cu Liliana Leyva lilianalr89@nauta.cu Mayra Acosta Suárez mayra@ibp.co.cu Tatiana Pichardo tatiana@ibp.co.cu Idalmis Bermúdez Caraballoso idalmis@ibp.co.cu Yelenys Alvarado Capó yelenys@ibp.co.cu <p class="western" lang="es-CR" style="margin-bottom: 0cm; line-height: 150%;" align="justify"><strong>Introduction.</strong> Due to the absence of totally effective either economically viable chemical agents for the control of Fusarium wilt, the use of antagonistic microorganisms is of great interest since it could represent a more economically and ecologically sustainable alternative. <strong>Objective.</strong> To analyze the antifungal effect of the Bacillus amyloliquefaciens CCIBP-A5 strain against Fusarium oxysporum. <strong>Materials and methods.</strong> The work was carried out in the Laboratory of Applied Microbiology of the Instituto de Biotecnología de las Plantas, Cuba, between September 2017 and June, 2018. The in vitro and in vivo antifungal activity of its culture filtrate and cell against F. oxysporum has been assayed. <strong>Results.&nbsp;</strong>The results indicated that the metabolites present in the culture filtrate of B. amyloliquefaciens CCIBP-A5 significantly influenced the growth and morphology of the mycelium and the conidia. They also caused oxidative damage to the lipid molecules of F. oxysporum. In addition, this strain showed inhibitory effects on the development of the disease under controlled conditions. These aspects are key when selecting a bacterial candidate as a biological control agent.&nbsp;<strong>Conclusions.</strong> The results showed that the B. amyloliquefaciens CCIBP-A5 strain, isolated from Musa sp., had an in vitro antifungal effect against the vegetative and reproductive structures of Foc race 1 as well as on the Musa spp.-F. oxysporum interaction. This strain is suggested for the development of a bioproduct for Fusarium wilt management.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/42182 Multilocus typing sequences in Lactobacillus casei isolates from pineapple peels silages 2021-06-10T10:35:39-06:00 Rodolfo WingChing Jones rodolfo.wingching@ucr.ac.cr Mauricio Redondo Solano mauricio.redondosolano@ucr.ac.cr Jessie Usaga jessie.usaga@ucr.ac.cr Lidieth Uribe lidieth.uribe@ucr.ac.cr Natalia Barboza natalia.barboza@ucr.ac.cr <p><strong>Introduction.</strong> Lactobacillus casei is characterized by adapting to the environment during the fermentation process. <strong>Objective.</strong> To characterize with multilocus typing sequences (MTLS) isolates of L. casei present in pineapple peel silage with increasing levels of urea. <strong>Materials and methods.</strong> During 2017 and using an unrestricted random design, twenty silos (2 kg) were prepared. Every five bags, 0, 0.5, 1 and 1.5 % urea (w/w on fresh basis) were added. After thirty days, a sample was taken from each repetition for bromatological analysis. Dry matter (DM), crude protein (PC), non-fibrous carbohydrates, fiber in acid detergent (ADF), fiber in neutral detergent (NDF), in vitro digestibility of dry matter (IVDDM), hemicellulose, ethereal extract (EE), ashes, ammonia nitrogen, and pH. The Lactic Acid Bacteria (LAB) count was determined for each one of the treatments. Identification of LABs was carried out using the 16S rRNA sequence. The isolates of L. casei were analyzed using MTLS. <strong>Results.</strong> The four evaluated treatments did not present significant differences in DM (12.10 to 12.86 %), ADF (31.44 to 32.18 %), NDF (58.46 to 58.56 %), hemicellulose (26.36 to 27.02 %), EE (2.45 to 2.96 %), ash (4.96 to 5.12 %), ammonia nitrogen (0.45 to 0.49 %) and pH (3.36 at 3.48). Not so, in CP (6.94 to 9.12 %), and IVDDMS (82.84 to 84.72 %). The addition of urea was associated with changes in the BAL populations (6.56 to 6.90 CFU). Seven isolates of L. casei were identified and typed with five different genes. Between two (polA) and five (nrdD, pgm, mutL) alleles were found. This allowed the identification of a total of six different type sequences (ST) in the Costa Rican isolates. <strong>Conclusion.</strong> The L. casei isolates were found to be related to bacteria from the gastrointestinal tract in humans.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/42487 Sex Link Black and Rhode Island Red hens with access to grazing: Productivity and behavior 2021-06-10T10:35:38-06:00 Ana Cruz Bermúdez ancruzber@hotmail.com Rodolfo WingChing Jones rodolfo.wingching@ucr.ac.cr Rebeca Zamora Sanabria rebeca.zamora@ucr.ac.cr <p><strong>Introduction.</strong> Learning about the productive and behavior indicators of poultry allows optimizing the pasture access system.<strong> Objective.</strong> Describe performance, pasture management, and behavior of Rhode Island Red (RIR) and Sex Link Black (SLB) hens in a lodging system on a floor with pasture access. <strong>Materials and methods.</strong> The research took place in Turrialba, in the province of Cartago, between October 2016 and January 2018, with 210 SLB and 180 RIR hens, aged from 13 to 80 weeks. Body weight, uniformity, mortality, discard, and weekly production percentage, hen housed egg production, feed conversion, feed intake, natural behavior, egg weight and egg mass, were obtained. Pasture management in pasture areas, forage availability, leaf/stem ratio, and the behavior of the poultry in the parks were described. <strong>Results.</strong> Lower production performance of the SLB and RIR were observed when compared to the Isa Brown genetic line, only the weight of the egg was higher for the RIR hens. Food waste was observed in both groups of birds, the main cause of death was the discard of subordinate birds, pecking, and cannibalism. The most commonly observed behaviors were scratching, pecking, and sand baths. When SLB and RIR poultry entered the parks, fodder production of 5033 and 3460 kg MF GM ha-1 was recorded, respectively. A leaf/stem ratio of &gt;1 was obtained, which reflected a higher preference of the hens for the leaves when grazing.&nbsp;<strong>Conclusion.</strong> In the flat housing system with access to grazing, the assessed birds displayed low production performance, stress from the heat, loss of feathers due to pecking, cannibalism, and food waste. The production system with access to pasture under the conditions studied was not optimal for the hens used.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/39673 Egg production feasibility in laying hen with access to grazing 2021-06-10T10:35:58-06:00 Ana Cruz Bermúdez ancruzber@hotmail.com Rodolfo WingChing Jones rodolfo.wingching@ucr.ac.cr Rebeca Zamora Sanabria rebeca.zamora@ucr.ac.cr <p><strong>Introduction.</strong> The production of hens with access to grazing integrates bird, fodder, and marketing management. <strong>Objective.</strong> To describe laying hens’ production systems with grazing access in Costa Rica and determine the feasibility of implementing aproduction model. <strong>Materials and methods.</strong> During the years 2017 and 2018, information on the&nbsp;production, health, grazing, and egg management was collected and analyzed in six farms with laying birds that have access to grazing. To determine the feasibility of the proposed production model, a cash flow (ten years) was prepared, which included the investments to develop the system, and an inflation rate of 10% through the years. The costs of investment, operation, and income from the sale of the eggs, discarded hens, and poultry litter were analyzed. The NPV, IRR, C/B ratio, and break-even point were calculated. <strong>Results.</strong> Sixty six percent of the systems use specialized birds, densities between 5 to 12, and 1 to 3 birds m-2 in the shed and grazing area, respectively. Grazing began at 22 and 32 weeks, with 2-10 h day-1. Five systems did not substitute feed for fodder; they consider it as an added value. The proposal is demanding in facilities, plot, and work equipment. Feeds represent 41% of the operational costs, followed by labor (22 %), and bird purchase (17 %). It is profitable, by obtaining a positive NPV ($31 455.39) and IRR of 21.48 % and the C/B ratio&gt;1, and the investment will be recovered after six years. <strong>Conclusions.</strong> Farms with laying hens with access to grazing evaluated in this work could improve in nutritional aspects and forage cultivation. In addition, they are production systems that present economic indicators that favor their implementation.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/41606 High quality DNA isolation in Psidium guajava L. for genomic studies 2021-06-10T10:35:50-06:00 Elodia Sánchez elodia.sanchez@ucr.ac.cr Eric Mora Newcomer eric.mora@ucr.ac.cr Walter Barrantes Santamaría walter.barrantes@ucr.ac.cr <p><strong>Introduction.</strong> Guava is one of the main fruit trees of the Myrtaceae family for its high nutritional value. It is originally from tropical America and the main producing countries are: Mexico, India, Brazil, and Thailand. The interest generated in recent years by the genetic improvement of this crop, has led to the use of molecular tools that allow determining genetic variability and selecting genes of agronomic interest in a fast and reliable way. However, the isolation of high-purity DNA is a prerequisite for the use of state-of-the-art molecular techniques for genetic analysis.&nbsp;<strong>Objective.</strong>&nbsp; Isolate high-quality genomic DNA (gDNA) from guava, in adequate quantity and integrity. <strong>Materials and&nbsp;</strong><strong>methods.</strong> The experiment was carried out in the Molecular Biology Laboratory of the Estacion Experimental Agricola Fabio Baudrit Moreno, between January and December 2019. Three different methods for isolating DNA were compared: Promega (ReliaPrep™ gDNA Tissue Miniprep Kit), Qiagen (DNeasy Plant Mini Kit), and CTAB (Doyle and Doyle, 1990) with modifications. For the gDNA extraction, fresh and lyophilized of young leaves of guava (Psidium guajava L; 2n = 22) were used. To determine the best method, the quality, quantity, and integrity of the gDNA were measured for each method. <strong>Results.</strong> The gDNA was obtained with the three evaluated methods. The best results in terms of gDNA quantity (ng μl-1) were obtained with the lyophilized material and with the CTAB method (Doyle and Doyle). The CTAB (Doyle and Doyle) and Qiagen methods showed a higher degree of purity (A260 / 280 ratios with optimal values) compared to the Promega method. <strong>Conclusion.</strong> The gDNA was obtained in adequate quantity, quality, and integrity. This was achieved based on extractions in lyophilized young leaf tissue and with the extraction method of the Qiagen kit.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/43281 High population density in arracacha (Arracacia xanthorrhiza Bancroft) increase radiation interception, yield, and profitability 2021-06-10T10:35:32-06:00 Yeison Mauricio Quevedo Amaya yquevedo@agrosavia.co Jorge Enrique Villamil Carvajal jvillamil@agrosavia.co Joanna Paola Garnica Montaña jgarnicam@agrosavia.co Omar Montenegro Ramos omontenegro@agrosavia.co Eduardo Barragán Quijano ebarragan@agrosavia.co <p><strong>Introduction.</strong> Arracacha (Arracacia xanthorrhiza Bancroft) a promising crop due to its nutritional and gastronomic relevance. Population density is an agronomic practice that increases water and radiation use efficiencies, maximizes the yield, and crop profitability. However, the selection of the optimal population density based on physiological, agronomic, and economic criteria for arracacha has not been studied. <strong>Objective.</strong> To describe the effect of different population densities on the physiology, yield, and profitability of arracacha. <strong>Materials and methods.</strong> The experiment was conducted in Cajamarca, Colombia in 2019. There, the soil water potential, relative chlorophyll content, photosynthesis, stomatal conductance, water use efficiency, leaf temperature depression, photosynthetic reflectance index, leaf area index, the fraction of light interception, light extinction coefficient, cracking index, yield, and profitability were evaluated. <strong>Results.</strong> The results showed that high population densities did not generate water deficit because there were no significant differences for the soil water potential, leaf temperature depression, and photosynthetic reflectance index. Furthermore, no nutritional deficiencies were evidenced because the relative chlorophyll content (&lt;32 SPAD) was higher at the critical level. Due to this, no limitations were observed in leaf gas exchange processes. However, the densities of 25,000 and 30,000 plants ha-1 showed a higher fraction of light interception due to the increase in the leaf area index; this allowed to obtain a higher yield at these densities. <strong>Conclusion.</strong> The maximum yield (41.96 t ha-1) and profitability (US$ 15,333.06 ha-1) were reached with a population density of 22,222 plants ha-1.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/42041 Chickpea in western Cuba: Agrodiversity fairs contributions 2021-06-10T10:35:46-06:00 Regla María Cárdenas Travieso rmaria@inca.edu.cu Rodobaldo Ortiz Pérez rortiz@inca.edu.cu Dania Vargas Blandino dania@inca.edu.cu <p><strong>Introduction.</strong> The Cuban government has attached importance to the national production of chickpea, with the purpose of substituting imports, meeting market demands and contributing to food security and sovereignty.&nbsp;<strong>Objective.</strong> To present the contributions of the agro-diversity fairs in the selection of new chickpea (Cicer arietinum) genotypes in western Cuba. <strong>Materials and methods.</strong> The work was developed during the period 2000-2018. The selection of chickpea materials from six nurseries introduced by the National Institute of Agricultural Sciences (INCA) from the International Center for Agricultural Research in Dry Areas (ICARDA) and nine commercial&nbsp;varieties donated by the Institute for Fundamental Research in Tropical Agriculture (INIFAT) were analyzed. They were planted in three locations in the western region of Cuba. Agro-diversity fairs were held to select the genotypes with the best agricultural production performance. <strong>Results.</strong> The comparison between the international nurseries did not show significant agro- productive differences between them. The variables with the greatest weight in the agroproductive characterization were: days to maturation, days to flowering, number of branches, plant height, and yield. The largest number of genotypes selected in the agro-diversity fairs corresponded to the Elite International nursery for Latin American. The average yield of the selected materials was above 1.00 t ha-1. <strong>Conclusions.</strong> The holding of chickpea agro-diversity fairs has provided 17 new materials with suitable productive and culinary behavior and adaptability to the edaphoclimatic conditions of different locations in western Cuba.</p> 2021-05-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/43420 Irrigation on coffee plantations and its effect on residual water from fruit processing 2021-06-10T10:35:59-06:00 Walter Danilo Maradiaga Rodriguez, Dr maradiagawd@gmail.com Adão Wagner Pêgo Evangelista, Dr awpego@pq.cnpq.br Luiz Antônio Lima, Dr lalimas@ufla.br José Alves Júnior, Dr josealvesufg@yahoo.com.br <p><strong>Introduction.</strong> In the coffee beneficiation process, nutrient-rich by-products with a high organic load are generated, which in most cases they are underused and deposited, without prior treatment in the water bodies.&nbsp;<strong>Objective.</strong> To evaluate the influence of irrigation, on the chemical compounds of the residual water obtained from the coffee fruits of the “Rubi” variety, irrigated by central pivot. <strong>Materials and methods.</strong> The experiment was developed at the Federal University of Lavras, Brazil, during 2018. The statistical delineation used was in random blocks, with three repetitions. The treatments corresponded to five irrigation sheets (0, 60, 80, 100, 120, and 140 % of the sheet of water evaporated from the Class A tank). The sowing spacing used per plot was 3.5 m X 0.80 m, in an area of 1.6 ha-1, subdivided into eighteen plots with approximately 888 m2. The cherry fruits of the coffee were harvested from each treatment and mixed in water, in a ratio of 2 L of water: 1 L coffee fruit and then pulped in an industrial blender. The residual water obtained was analyzed through the standard method for the analysis of residual water.<strong> Results.</strong> The irrigation sheets caused a significant effect on the evaluated chemical parameters, the irrigated plants based on 57 % of the evaporated water from the Class A tank, resulted in chemical compounds within the established patterns, for the disposal of residual water in Brazil. The content of Mg, S, Mn, P, Zn, Cu, and Fe, was higher than the plots that did not receive irrigation.<strong> Conclusions.</strong> The use of irrigation in coffee, produce significant effects on the concentration of chemical compounds in the residual water of the coffee fruits of the “Rubí” variety.</p> 2021-03-18T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/42001 Effect of Azofert®-F on the stomatal response of beans to water deficit 2021-06-10T10:36:01-06:00 Wilfredo - Estrada Prado estrada@dimitrov.cu Licet Chávez Suáres licet@dimitrov.cu Yariuska Caridad Maceo Ramos yariuska@dimitrov.cu Eduardo Jerez Mompie ejerez@inca.edu.cu María Caridad Nápoles García tere@inca.edu.cu <p><strong>Introduction.</strong> Water deficit is the abiotic stress with the highest incidence on the growth and yield of bean plants. For this reason, alternatives are being sought to mitigate its adverse effects, such as the use of biofertilizers based on the microbial biodiversity existing in the soil.<strong> Objective.</strong> The effect of Azofert®-F inoculant on the stomatal index (IE) of bean plants was evaluated under water stress conditions. <strong>Materials and methods.</strong> The experiment was carried out in the period 2016-2017 in a room with fluorescent lamps of the Department of Plant Physiology and Biochemistry of the National Institute of Agricultural Sciences, San José de las Lajas, Mayabeque, Cuba. For the anatomical study, the leaf epidermis was observed with an optical light microscope (Motic) and photographed with a coupled camera. Stomatal variables were measured using the ImageJ morphometric program and processed with the SPSS Version 22.0 statistical package. A completely randomized design was used. Ten plants were randomly selected for each treatment to evaluate density and stomatal index. <strong>Results.</strong> Azofert®-F increased the IE of the studied cultivars. The structure of the epidermal cells was altered in both leaf surfaces when the humidity in the soil decreased; the stomatal density was modified with the presence of the product. On the abaxial surface, the occlusive cells were narrower, which showed that the leaves with the highest IE had smaller stomata. The Azofert®-F caused the stomata to remain semi-closed when there was a water deficiency in the plants, because these bacteria helped to alleviate the water deficit by producing hormones and other enzymes that regulate the loss of water through transpiration. <strong>Conclusion.&nbsp;</strong>The application of Azofert®-F increased the density and stomatal index of bean plants under conditions of water stress.</p> 2021-03-18T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/39822 Nitrogen and potassium fertilization in corn in an Alfisol of Guanacaste, Costa Rica 2021-06-10T10:36:32-06:00 Gabriel Garbanzo-León juan.garbanzo@ucr.ac.cr Alfredo Alvarado-Hernández alfredo.alvarado@ucr.ac.cr Jorge Claudio Vargas-Rojas jorgeclaudio.vargas@ucr.ac.cr Gilberto Cabalceta-Aguilar gilberto@cabalceta.com Edgar V. Vega-Villalobos edgar.vega@ucr.ac.cr <p><strong><span class="CharOverride-2">Introduction.</span></strong>&nbsp;In Guanacaste, Costa Rica, corn (<span class="CharOverride-5">Zea mays</span>) has been a cultural crop for consumption since pre-Colombian times. Many farmers have set aside areas for its planting in association with other crops. However, the varieties used require fertilization and plant nutrition studies to improve ear quality and postharvest life.&nbsp;<span class="CharOverride-2"><strong>Objective.</strong>&nbsp;</span>To evaluate the effect of increasing doses of nitrogen and potassium in the J-Saenz maize variety, in combination with three sowing densities.&nbsp;<strong><span class="CharOverride-2">Materials and methods.</span></strong>&nbsp;The study was conducted at the Santa Cruz Experimental Farm, Universidad de Costa Rica, in 2018. Three doses of N (100, 200, 300 kg ha<span class="CharOverride-4">-1</span>&nbsp;with a base of 160 kg ha<span class="CharOverride-4">-1</span>&nbsp;of K<span class="CharOverride-6">2</span>O) and K<span class="CharOverride-6">2</span>O (100, 160 and 200 kg ha<span class="CharOverride-4">-1</span>&nbsp;with a base of 300 kg N ha<span class="CharOverride-4">-1</span>) were evaluated with three sowing densities (50 000, 57 143, and 66 667 plants ha<span class="CharOverride-4">-1</span>) with the J-Sáenz variety. The crop yield, the percentage of exposed ear, and the accumulation of nutrients in the phenological R5 stage were evaluated. The data were subjected to analysis of variance with a factorial structure and generalized linear models with DGS tests of means separation.<span class="CharOverride-2">&nbsp;<strong>Results.</strong></span>&nbsp;There was a significant increase in grain production by increasing the sowing density from 50 000 to 66 667 plants ha<span class="CharOverride-4">-1</span>. The highest efficiency in the N and K use was achieved with the application of 100 kg ha<span class="CharOverride-4">-1</span>&nbsp;of each element at a density of 57 000 plants ha<span class="CharOverride-4">-1</span>. The exposed ear variable was not related to nutrient doses. Corn increased absorption with increasing doses of N but not K.&nbsp;<strong><span class="CharOverride-2">Conclusion.</span>&nbsp;</strong>The planting density of 57 143 plants ha<span class="CharOverride-4">-1</span>&nbsp;showed the best yield at doses of 100 kg of N ha<span class="CharOverride-4">-1</span>&nbsp;and 100 kg of K<span class="CharOverride-6">2</span>O ha<span class="CharOverride-4">-1</span>.</p> 2021-01-01T00:00:00-06:00 ##submission.copyrightStatement## https://revistas.ucr.ac.cr/index.php/agromeso/article/view/40439 Protein quality in lines and experimental hybrids of QPM. Central Highlands, Mexico 2021-06-10T10:36:27-06:00 José Luis Arellano-Vázquez arellano.jose@inifap.gob.mx Germán Fernando Gutiérrez-Hernández gfgutierrez@ipn.mx Estela Flores-Gómez esfloresg@ipn.mx Daniel Eduardo López-Martínez d.lopez.m@outlook.com <p><strong><span class="CharOverride-2">Introduction.</span></strong>&nbsp;Currently, maize is the most cultivated grain in the world and it is feasible to improve the nutrition of its consumers through the development of quality protein maize (QPM), whose basis is the expression of the&nbsp;<span class="CharOverride-4">opaque2</span>&nbsp;gene, which increases the contents of lysine and tryptophan in the grain.&nbsp;<strong><span class="CharOverride-2">Objective.</span>&nbsp;</strong>To analyze chemically the protein of the grain of lines and experimental simple hybrids of QPM and to know the relationships between the genotype and the evaluated variables of protein quality.<strong>&nbsp;</strong><span class="CharOverride-2"><strong>Materials and methods.</strong>&nbsp;</span>The experiments were carried out during 2017 in the Interdisciplinary Professional Unit of Biotechnology of the Instituto Politecnico Nacional (Mexico City). Whole grains of parental lines (P1 to P6) and direct simple hybrids were used. Lysine, tryptophan, and protein quantity and quality were estimated. A completely randomized design with three replications was used. Analysis of variance, comparison of means, and principal component analysis were performed.<strong>&nbsp;<span class="CharOverride-2">Results.</span>&nbsp;</strong>Lines P<span class="CharOverride-5">2</span>, P<span class="CharOverride-5">3</span>, and P<span class="CharOverride-5">6</span>, and hybrids P<span class="CharOverride-5">2</span>&nbsp;x P<span class="CharOverride-5">4</span>&nbsp;and P<span class="CharOverride-5">2</span>&nbsp;x P<span class="CharOverride-5">6</span>&nbsp;were identified as significant (p ≤ 0.05) QPM. The protein quality index was correlated with tryptophan (r = 0.9 *) and with lysine (r = 0.7 *) but not with total protein.<span class="CharOverride-2">&nbsp;<strong>Conclusions.&nbsp;</strong></span>The fundamental factor for developing the QPM were the essential amino acids and the limiting factor for increasing their nutritional value was the quality of the protein.</p> <p>&nbsp;</p> 2021-01-01T00:00:00-06:00 ##submission.copyrightStatement##