Agronomía Mesoamericana

Typification of cocoa-producing farms (Theobroma cacao L.) in Montes de María and La Mojana, Colombia

Mon, 13 Nov 2023 00:00:00 -0600

Introduction. The cocoa production system is part of the agriculture of the subregions of Montes de María and La Mojana in the department of Sucre, when reviewing the literature there is no evidence of a study of characterization and typification of the production system.

Objective. Analyze the socioeconomic and technological aspects of cacao cultivation for the subregion of Montes de María and La Mojana and define homogeneous groups of producers who share the same characteristics that serve as a recommendation domain. Materials and methods. Surveys were designed and applied to farmers in the Montes de María and La Mojana region during 2019, selected by deterministic sampling of twenty-two farmers. The analysis consisted of typifying the farmers by Ward's method of distances and hierarchical grouping. Results. Three different farmer groups were obtained. The GI group with a low technological level, the farmers' schooling is incomplete primary, production presents low yields (420 kg/ha). The GII Group farmers with incomplete secondary, yields higher than those of the GI (491 kg/ha), incorporate practices such as training and maintenance pruning. The GIII group with the highest level of schooling, use of technological options such as better planting materials and crop management techniques and obtain the highest yields among all farmers 550 kg/ha. Conclusion. The typified farms showed differences between the groups, concluding that the G3 group obtained higher yields per hectare, which is attributed to the fact that they use different technologies from the conventional one.

Predictive model of the severity of leaf blight by Cercospora kikuchii using meteorological variables

M. Lavilla, M. Martínez, A. Ivancovich, A. Díaz-Paleo — Fri, 14 Jul 2023 00:00:00 -0600

Introduction. In integrated disease management, it is important to incorporate elements such as economic
damage thresholds, monitoring, and risk forecasting systems, which constitute tools to define disease control strategies. Objective. Develop a predictive model of the severity of Cercospora leaf blight (TFC) using meteorological variables for the north of the province of Buenos Aires, Argentina. Materials and methods. There were data on the incidence
and severity of TFC corresponding to five relevant Pergamino, Buenos Aires, soybean production cycles (2013-2017) in different reproductive stages R1 to R7. The dependent variable was the probability of occurrences of categorized levels of the rate of increase (TI) of the severity of TFC caused by C. kikuchii. The elements and meteorological variables used were daily records of maximum and minimum temperature, precipitation, and relative humidity. The
nonparametric Kendall Tau-b coefficient TI of connection between the TI binary categorized levels of TFC severity and the weather variables was calculated. Results. The meteorological variables with the greatest consequences in relation to the TI of the TFC were those related to relative humidity (DHR, MOJRO, DHRT). The inclusion of a thermal variable (GDTmax) was important for the adjustment of the predictive model. Conclusion. It was possible to develop a TFC severity prediction model that included two meteorological variables, one related to relative humidity
days and another thermal related to a maximum temperature limit for the development of the disease. To validate and strengthen the proposed model, it is necessary to have more severity data over the years.

Allelopathy of Panicum maximum Jacq. on Euphorbia heterophylla L. and Amaranthus dubius Mart. in laboratory

Lisette Alonso Sánchez, Leónides Castellanos González, Isabel Ortega Meseguer — Mon, 13 Nov 2023 00:00:00 -0600

Introduction. Deepening the allopathic effects of weeds on agricultural crops and other weeds is of great importance to establish management estrategies. Objective. To evaluate the allelopathic effect of rhizome residues of Panicum maximum Jacq. on Euphorbia heterophylla L. and Amaranthus dubius Mart. in pre and post emergency. Materials and methods. Four trials were carried out in completely randomized 5x5 designs at the Plant Health Laboratory of Cienfuegos, Cuba in the year 2020. The allelopathic capacity of rhizome residues of the P. maximum plant was evaluated against E. heterophylla and A. dubius in applications prior to emergence or germination (pre-emergence) and after emergence (post-emergence). Five treatments 0, 40, 60, 80 and 100 g of divided rhizomes of P. maximum plants per 2 kg of soil with five repetitions (plastic pots) were evaluated. To obtain the rhizomes, plants were taken in the flowering and fruiting phase at three months of age. Twelve days after the treatment, the percentage of emergence and/or survival, the length of the radicle and the hypocotyl were evaluated. Analysis of variances were performed and the means were compared with Tukey’s test (p≤ 0.05) using SPSS (vers. 15). Results. When comparing the effect of the treatments against E. heterophylla, a significant reduction in emergence was observed in pre-emergence and a significant decrease in survival percentage and hypocotyl length in post-emergence, while against A. dubius there was a reduction in emergence and survival and a significant decrease in radicle and hypocotyl length pre- and post-emergence. Conclusions. The negative allelopathic effect (P<0.05) of P. maximum residues on E. heterophylla and A. dubius was verified.

Soil cover on nutrient concentration in an agroecosystem in Napo, Ecuador

Fri, 25 Aug 2023 00:00:00 -0600

Introduction. Nutrient loss in different soil cover generates a decrease in productivity in agroforestry systems in tropical forests. Objective. To determine the effect of soil cover over a two-year period on nutrient concentrations in the agroecosystem of the Amazonian Research and Production Experimental Center. Materials and methods. This study was conducted at the Amazonian Research and Production Experimental Center in Napo, Ecuador. Two plots of primary forest were established with the following soil covers: a) guava (Inga sp.) and b) melastomataceae. Two random soil samplings were conducted, one in 2019 (four samples per cover) and another in 2021 (six samples per cover). Concentrations of nitrogen, phosphorus, potassium, calcium, and organic matter were analyzed. An analysis of variance was applied to determine significant differences between the soil coverages and sampling periods. Pearson correlation analysis was performed to determine relationships between the concentrations of different nutrients. Results. Significant differences (p<0.05) were observed for soil covers in concentrations of organic matter and phosphorus, which were higher in the melastomataceae plot. In 2021, significant differences were observed for potassium, phosphorus, and nitrogen concentrations. The year x cover interaction in guava cover showed an increase in nutrient concentrations after two years. Significant correlations were found between potassium concentrations and the other nutrients, as well as between organic matter and nitrogen concentrations. Conclusion. Soil cover influenced nutrient concentrations, which varied between years. The primary forest exhibited the highest nutrient loss, and the Inga cover showed an increase in nutrient concentrations over time.

Oligogalacturonides as an alternative to increase nitrogenous nutrition and growth in common bean (Phaseolus vulgaris L.)

Fri, 25 Aug 2023 00:00:00 -0600

Introduction. Bean production is limited by the availability of nitrogen in the soil and its low efficiency in biological nitrogen fixation. The application of a bio-stimulant based on oligogalacturonides (Pectimorf®) is considered an alternative to improve nitrogen nutrition in early stages of growth, but its effectiveness in later stages of cultivation is unknown. Objective. To determine the effect of Pectimorf® on indicators related to biological nitrogen fixation and the growth of common bean plants bio-fertilized with Azofert®-F during the R5 growth stage (pre-flowering). Materials and methods. The research was carried out at the Genomic Sciences Center of the Universidad Nacional Autónoma de México (October 2018-March 2019) and at the Instituto Nacional de Ciencias Agrícolas en Cuba (November-December 2019). Experiments were carried out under controlled and semi-controlled conditions, evaluating the application of 10 mg L^-1of Pectimorf® to seeds along with Azofert®-F and foliar spraying at 5 and 100 mg L^-1on bio-fertilized plants. Plants treated only with Azofert® were used as a control. Nodulation, indicators of biological nitrogen fixation, and plant growth were evaluated. Results. Under controlled conditions, Pectimorf® stimulated nodulation, root development, and increased nitrogenase activity. In the semi-controlled conditions, it favored nodulation and growth, with the seed treatment and foliar spraying (100 mg L^-1) standing out. Pectimorf® also increased the ureides synthesis in the nodules and the nitrogen content in the leaves. This product showed more than a 15 % effectiveness in relation to bio-fertilization. Conclusions. The application of Pectimorf® improved biological nitrogen fixation and growth during pre-flowering stage of common bean.

Damage and population dynamics of the armyworm (Spodoptera frugiperda) in elite maize lines

Fri, 25 Aug 2023 00:00:00 -0600

Introduction. Spodoptera frugiperda has the capacity to form large populations and its high rate of dissemination make this species a pest with an economic impact. Losses due to pests and diseases are estimated at 37 % of world agricultural production, with 13 % due to insects. Objective. Evaluate the attack and population dynamics of fall armyworm caterpillars in maize lines. Materials and methods. The study was carried out in the laboratory and greenhouse of the National Institute of Agricultural and Livestock Forestry Research and at the Roque Technological Institute, located in Celaya, Guanajuato in 2019. Manual sowing was established and when the seedlings reached (V4) at twenty-five days after sowing they were infested with stage IV larvae. To measure the population dynamics, samples were taken from day twenty-six covering the entire life cycle (eggs, larva I, larva II, larva III, larva IV, larva V, pupa and adult). A completely randomized experimental design with ten genotypes and ten repetitions was used. Results. The stages of S. frugiperda that generated the greatest variability in the maize lines were larvae IV and V. The population dynamics show differences between tolerant genotypes with an accumulated population of four to seven caterpillars in stage IV and V, while the susceptible presented seven to twenty-one IV larvae and fourteen to twenty-one V instar larvae. The protruding lines had a cumulative two to six IV larvae and four to five V instar caterpillars per plant. Conclusion. The variability was greater in larval stages IV and V that occurred between 26 and 54 days after sowing. In the tolerant genotypes, up to seven larvae per plant were found, while in the susceptible ones there were twenty-one caterpillars.

Mycorrhizal inoculants on sweet potato (Ipomoea batata) in Eutric Cambisol soils of Cuba

Fri, 25 Aug 2023 00:00:00 -0600

Introduction. The effective use of mycorrhizal inoculants poses a challenge for Cuban agriculture. Sweet potato is an important crop for human and animal nutrition, being a mycorrhizal crop with a successful breeding program. Objective. To determine whether all sweet potato cultivars respond to inoculation and if the effectiveness of inoculants varies among cultivars and planting seasons. Materials and methods. Two experiments were conducted during 2010 - 2012 in Eutric Cambisols in Villa Clara, Cuba, one for each planting season and repeated twice. Seventeen cultivars were evaluated for their response to the application of three inoculants, in the presence of a half the fertilization dose, and three non-inoculated treatments with fertilization levels of 0, 50, and 100 % of the nitrogen, phosphorus, and potassium dose (100 % NPK). A split plot design was used. Root yields, colonization frequency, and mycorrizal spore production were evaluated as response variables. Results. Cultivars responded positively to inoculation and fertilization, showing differences in yields. However, the highest yields were obtained when inoculated with Rhizoglomus irregulare/ INCAM-11, surpassing (p≤0.05) those obtained with only 50 % of the NPK dose. In the rainy season with higher yields, the differentiation between inoculants was more pronounced, and in thirteen and nine of the cultivars, yields obtained with INCAM-11 were higher (p≤0.05) to those obtained with Glomus cubense/ INCAM-4 and 100 % NPK, respectively. In the dry season, no significant differences were found between yields obtained by inoculating INCAM-11 or INCAM-4 or applying 100 % NPK. In both seasons, inoculation with Funneliformis mosseae/ INCAM-2 was consistently lower. Colonization frequencies and spore production were always higher (p≤0.05) when INCAM-11 was inoculated. Conclusion. Under these soil conditions evaluated, inoculation with INCAM-11 showed higher effectiviveness for all cultivars and planting seasons, resulting in a higher yields and mycorrhizal performance indicators.

Potential use of porcine zoogenetic resources (sus scrofa domestica) in silvopastoral systems

Mon, 13 Nov 2023 00:00:00 -0600

Introduction. In Colombia, there has been an increase of over 100 % in the consumption of pork meat in the last decade, placing it as the protein of animal origin that has grown in greater proportion in the country, which has driven the pork sector to develop as a sustainable and competitive industry, nationally and internationally. This productive progress has been possible through high technology and improvement processes that allow meeting the current supply demands of the market. However, access to these modernization processes and improvement practices by family systems of animal husbandry is more limited. Objective. Analyze technical strategies for productive, economic, and environmental sustainability in family animal husbandry systems focused on raising and fattening pigs. Development. 61 documents were collected and analyzed using key terms and search formulas, addressing central topics such as the characteristics of porcine animal genetic resources, emphasizing the Colombian creole breed of San Pedreño pigs, forage, and bush alternatives for the nutritional supplementation of pigs in silvopastoral systems, animal welfare criteria, and development opportunities in the production of creole pigs. Conclusion. This review considers the social importance of contextualizing family animal husbandry systems, with alternatives that lead to greater productive, environmental, and economic sustainability, as well as the improvement of the competitiveness and recognition of their products, due to the optimal management of natural, food and animal genetic resources of each region. Therefore, value-added products from sustainable production systems are generated, and the food security of the family nucleus that implements these alternatives is safeguarded. Research is needed that leads to the evaluation of potential animal genetic and feeding alternatives.

Yield, morphological characteristics, and quality of Sweet Pepper (Capsicum annuum L.) under two planting densities and pruning methods

Kevin Carrillo-Montoya, Jorge Claudio Vargas-Rojas — Fri, 25 Aug 2023 00:00:00 -0600

Introduction. Sweet Bell pepper is one of the most consumed vegetables, but in warm climate areas, there is a need for more research on agronomic management practices to increase fruit production and quality. Objective. To evaluate the effect of two planting densities and two pruning methods on the yield, morphological characteristics, and fruit quality of Sweet Bell peppers. Materials and methods. The research was conducted in a greenhouse in Guanacaste, Costa Rica, from July 2015 to March 2016. Two planting densities were evaluated: 20 800 and 41 700 plants/ha, along with two pruning systems (Dutch and Spanish) and a control without pruning. Fruit weight, Brix degrees, plant height, leaf area index, total yield, and quality category yield were quantified. The data from each variable were subjected to an analysis of variance with factorial treatment structure. Results. Pruning did not affect the yield first-quality fruit, while the higher planting density achieved a higher yield in this category. Spanish pruning produced longer first-quality fruits but had no effect on other variables (width, weight, and Brix degrees). When using any pruning system and a high planting density, the total yield (p>0.05) was similar to non-pruned plants planted at a low density. Conclusion. Increasing planting density increased the yield of first-quality fruits, while pruning had no effect on yield.

Report of Caliothrips phaseoli (Hood) (Thysanoptera: Thripidae: Panchaeothripinae) in onion in Panama

Anovel Amet Barba-Alvarado, Randy Atencio-Valdespino — Fri, 25 Aug 2023 00:00:00 -0600

Introduction. Thrips (Thysanoptera) encompass a variety of phytophagous species that have an impact on the development of agriculturally important plants. Objective. To identify the species and damage caused by thrips associated with onion (Allium cepa L.) cultivation in the Arco Seco region of Panama. Materials and methods. The study was carried out from December 2020 to April 2021 in two onion-producing locations in the Arco Seco region of Panama. Fifty onion plant samples were taken per location. The species of thrips present, the number of thrips specimens captured in each life stage, the percentage of plants with damage and the characteristics of the damage were identified. Results. The species Caliothrips phaseoli (Hood) (Thysanoptera: Thripidae: Panchaeothripinae) caused lacerations, spots, and leaf drying in 80 % of the onion plant samples from El Ejido locality. Among the captured specimens, 47.69 % were female, 46.30 % were immature, and 6.02 % were male. Conclusions. Damage to onions caused by C. phaseoli was recorded for the first time in the Republic of Panama. The knowledge generated represents the initial step for phytosanitary surveillance of this pest in onion cultivation.

Factors that affect the quality of Kikuyu grass (Cenchrus clandestinus) silage

Tue, 11 Jul 2023 00:00:00 -0600

Introduction. The availability of Kikuyu grass silage helps reduce the seasonality of dairy production, but it is necessary to evaluate the factors affecting the ensiling process to maintain a quality similar to that of fresh forage. Objective. To evaluate the effect of regrowth age, chop size, wilting time with the use of additives on the quality of Kikuyu grass silage. Materials and methods. The study was conducted in Mosquera, Colombia, during 2020. The effect of regrowth age (28, 42, and 70 days), chop size (1.5 cm, 3.0 cm and whole plant), wilting time (0 and 6 hours), and the use of additives (crude glycerin and lactic acid bacteria (LAB)) on parameters such as chemical composition, in situ dry matter digestibility (ISDMD), pH dynamics, volatile fatty acid (VFA) profile, dry matter losses, and organoleptic quality was evaluated. The data was analyzed using a completely randomized design with a factorial arrangement. Results. The use of 70-day regrowth Kikuyu grass reduced (p<0.05) crude protein, digestibility, and energy, while increasing cell wall content and dry matter (DM) of the silage. Additive use reduced (p<0.05) the final pH of mature grass. Small chop size or inclusion of crude glycerin in the whole plant increased (p<0.05) ISDMD. Additive use reduced (p<0.05) the final pH of silage made with the whole plant. Pre-ensiling wilting increased (p<0.05) the DM and final pH, but reduced (p<0.05) crude protein and lactic acid. Conclusion. The use of tender forage, small chop size, and fresh bagging improved the quality of Kikuyu grass silage. The use of mature forage requires the application of additives.

Characterization of rabbit meat marinated in mustard and white wine with spices

Fri, 25 Aug 2023 00:00:00 -0600

Introduction. Developing new commercial options can bring benefits to the rabbit meat market. Objective. To evaluate the sensory, physicochemical, and microbiological characteristics of two marinated rabbit meat preparations in mustard and white wine with spices. Materials and methods. The research, conducted in Costa Rica in 2016, involved a refrigeration storage study with two marinated rabbit meat products: one with mustard and the other with wine and spices. A total count of anaerobic psychotrophs, yield, color, pH, texture, and sensory satisfaction was evaluated with a panel of 100 consumers. Results. There were no significant differences (p>0.05) in yield. Lower pH values were obtained than those reported in fresh rabbit meat for the wine preparation, which had lower counts of anaerobic psychotrophs (p>0.05), proving greater stability and allowing storage for up to 28 days without exceeding 106 CFU/g. A high L* value was obtained for both preparations. Significant differences were found in all color parameters according to the preparation method (p<0.05), and for L*, b*, and C, there was an interaction between the factors of time and marination. The texture did not show differences (p>0.05) based on the marination, but there were differences between this method and time for shear force, hardness, chewiness, and elasticity. The preparation did not affect the texture parameters compared to non-marinated rabbit meat. Both preparations had good sensory acceptance. Conclusion. The marinating processes with mustard and wine with spices generated products with high sensory acceptance and desirable physicochemical and microbiological characteristics.

Physiological maturity in maize (Zea mays L.) seeds through morphological markers and moisture content

Tue, 11 Jul 2023 00:00:00 -0600

Introduction. Physiological maturity is the accumulation of the maximum dry matter content, the milk line and the black layer affect the corn seed, as morphological factors of the degree of maturation. The milk line is related to the solidification of starch, and the black layer with the cessation of the translocation of soluble substances from the plant to the grain. The moisture content is related to the physiological maturity and the harvest opportunity associated with the maximum quality of the product. Objective. To determine seeds physiological maturity, through morphological markers and moisture content, and its physiological quality relationship. Materials and methods. The study was carried out at Colegio de Postgraduados, Campus Montecillo during the months of September-October, 2021. By weekly sampling cobs of experimental cv. (Amarillo × V-54A) F6 genotype, seeds from the apex were taken, middle section and basis. In function by its moisture content, the milk line, black layer, and the relationship of these factor with physiological quality (germination and vigor- accelerated aging and cold tests) were determined. Results. Moisture content was below than referred in literature (35 %), also, physiological maturity was defined visually by milk line and black layer; on the other hand, as sampling were done, there was an increase in seed germination with the less moisture content; what vigor refers, a better response was detected by accelerated aging test. Conclusions. As the moisture content decreased, germination increased. The morphological markers allowed to determine the time in which the maize seed reached the physiological maturity and with it, the maximum quality.

Soybean (Glycine max) Purple Syndrome and its relationship with bioclimatic variables

M. Lavilla, A. Ivancovich, A. Díaz Paleo — Fri, 25 Aug 2023 00:00:00 -0600

Introduction. Cercospora leaf blight (TFC) and purple seed stain (MPS) are two endemic soybean (Glycine max) diseases in Argentina. Objective. Select the bioclimatic variables (VB) related to severity values greater than or equal to 90 % of the TFC and/or incidence greater than or equal to 50 % of the MPS in Argentina. Materials and methods. In the soybean region of Argentina during the years 2015 and 2023, 45 VB available in Worldclim (temperatures, precipitations and radiation) were used for modeling with the MaxEnt program. From the maps obtained in the

modeling, the probabilities of a severity (SEV) of TFC ≥ 90 % and/or an incidence (I) of MPS ≥ 50 % were extracted for each geographical point evaluated in this experience, to later use them in the analysis. generation of multiple linear regressions. Results. Of the 45 VB analyzed, the ones that were most related to both diseases were rainfall and temperatures. Radiation was the VB with the least association both with the SEV of the TFC and with the I of the MPS Conclusion. The bioclimatic variables temperatures (between 25 °C and 30 °C) and rainfall between the months of December to April had the greatest associations with severity values greater than or equal to 90 % of the TFC and/or incidence greater than or equal to 50 % of the MPS in Argentina.

Morphoagronomic variability of native quinoa (Chenopodium quinoa Willd.) Chimborazo type in Ecuador

Hugo Alejandro Castro-Albán, Rosa del Pilar Castro-Gómez, Yelenys Alvarado-Capó — Tue, 11 Jul 2023 00:00:00 -0600

Introduction. Quinoa (Chenopodium quinoa Willd.) is a strategic and important crop for food security and sovereignty. It is the only plant-based food that provides all essential amino acids. Its wide varietal diversity constitutes a valuable genetic resource, as it adapts to different agroecological conditions and is tolerant to frost, drought and salinity. Objective. To perform a morpho-agronomic characterization of native Chimborazo-type quinoa in Ecuador. Materials and Methods. The research was conducted in the province of Chimborazo, Colta canton, Sicalpa parish, Ocpote Tablarumi community in Ecuador between January and July 2021. Seeds from an Andean family that had selected and conserved them in all cultivation cycles for generations were used. The crop was established by continuous sowing at a rate of 12 kg/ha in a total plot area of 640 m² (estimate to contain 10,240 plants). After the emergence, 100 randomly selected plants were marked and taken as basic units for the population characterization. Phenotypic descriptors established at international level were used, evaluating both qualitative (16) and quantitative (12) traits. Results. The results revealed phenotypic variability. Stem and streak color, panicle diameter, panicle length, and days to harvest were the characteristics that most contributed to the observed variability. Conclusions. The population of native Chimborazo-type quinoa evaluated through 100 individuals showed phenotypic variability in both quantitative and qualitative traits, with greater frequency observed in panicle diameter, panicle length, petiole length, plant height, leaf width, yield, and stem and streak color.

Farmers of the southern Caribbean of Costa Rica: Socioeconomic, productive, and commercial characterization

Marianita Harvey-Chavarría, Raciel Javier Estrada-León — Fri, 14 Jul 2023 00:00:00 -0600

Introduction. In Costa Rica, the agricultural sector is one of the most diverse, it presents, a high socioeconomic variability. The canton of Talamanca harbors a strong economic lag and it is necessary the generation of productive alternatives. Objective. To characterize the socioeconomic, productive, and commercial level of the South Caribbean farmers. Materials and methods. An exploratory and descriptive study was carried out in the districts of Cahuita, Bratsi, and Sixaola of Talamanca from 2019 to 2021. A sample size was determined with a confidence level of 95%. A structured questionnaire with twenty-seven questions was designed for farmers, and eight for heads of government institutions in the area. Surveys were applied to 155 farmers and 33 representatives of institutions and organizations. Farmers were classified through hierarchical cluster analysis and discriminant analysis, continuous quantitative socioeconomic variables were used. Results. Four types of farmers were identified, 1) subsistence farmers (ATS, 7.10 %), 2) small (ATP, 23.23 %), 3) medium (ATM, 41.29 %), and 4) large (ATG, 28.39 %), with significant statistical differences (p<0.05, χ2<0.05) between their study variables. Regarding agro-industry, it was identified that 77.91 % did not industrialize their products, due to lack of market (14.68 %) and lack of resources (14.37 %) as the main reasons. Conclusion. The agricultural activity is characterized by family farming. Plantain, cocoa, and bananas are produced; however, the diversity of crops and fruit trees represents a high potential for the development of agro-industry.

Fertilization type and regrowth age on ruminal parameters of Tithonia diversifolia

Tue, 11 Jul 2023 00:00:00 -0600

Introduction. Forages in the tropics have low digestibility, which is why alternative feed option such as Tithonia diversifolia (Hemsl.) are sought to improve the quality of the offered diet. Objective. To evaluate the effect of fertilizer type and the regrowth age of Tithonia diversifolia forage on rumimal parameters. Materials and methods. The study was conducted in 2020 at the Santa Lucía Experimental Farm of the Universidad Nacional, Costa Rica. A completely randomized split-plot design was used with fertilizer type as the main plot and regrowth age as subplot, with three replications per treatment. The fertilizer types were: vermicompost (L), chemical (Q), and control (C) without fertilizer use. The evaluated regrowth ages were 30, 50, and 70 days, resulting in a total of nine treatments. The variables assessed were: in situ dry matter degradability kinetics (DISMS), pH, ammoniacal nitrogen (NH₃), in vitro gas, and methane production (CH₄). An ANOVA was carried out for divided plots. Results.The highest DISMS was found in C30 (92.84 %) and the lowest in Q70 (64.21 %). The type of fertilization influenced NH₃ contents, with the highest value observed in chemical fertilizer treatments (275.88 mg NH₃/L rumen fluid). C70 produced the highest amount of gas (79.59 mL/g), whereas Q30 had the lowest average (28.38 mL/g). Methane production did not show significant differences, with values ranging from 3.42 to 8.67 mL CH₄/g DM. Conclusion. Fertilization and regrowth age modified in situ and in vitro ruminal parameters. The obtained results suggest that this forage resource can be considered a supplement to grazing grasses in the tropics, where positive effects are generated on DM digestibility, gas, and CH₄ production.

Fertilization and regrowth age on yield and bromatological composition of Tithonia diversifolia

Tue, 13 Jun 2023 00:00:00 -0600

Introduction. Tithonia diversifolia (Hemsl.) A. Gray is a plant with high potential for ruminant feeding, but there is limited research comparing the effects of chemical or organic fertilization at different regrowth ages on its yield and nutritional composition. Objective. To evaluate the effect of the type of fertilizer and the age of regrowth on the yield and nutritional composition of Tithonia diversifolia forage. Materials and methods. The work was conducted in 2020 at the Finca Experimental Santa Lucía of the Universidad Nacional de Costa Rica. A completely randomized divided plot design was employed, with fertilizer type as the main plot and regrowth age as the subplot, with three replicates per treatment. The fertilizer types tested were vermicompost, urea, and a control without fertilizer, with a nitrogen application rate of 150 kg/ha/year. The regrowth ages evaluated were 30, 50, and 70 days for a total of nine treatments. The variables evaluated were biomass production, leaf/stem relation, and nutritional composition. A split plot ANOVA was performed to analyze the data. Results. Among the treatments, the urea treatment with 70 days of regrowth exhibited the highest biomass production (77.18 t/ha of green matter and 7.10 t/ha of dry matter [MS]), while the control treatment with 30 days of regrowth yielded the highest leaf/stem relation (1.77). The type of fertilizer had a significant effect on the variables of MS, crude protein (PC), neutral detergent fiber, and non-fibrous carbohydrates (CNF), whereas regrowth age alone did not significantly affect digestible neutral detergent fiber and CNF. The highest PC content was observed in the urea treatment with 30 days of regrowth (27.61 % PC). Conclusion. Fertilization and regrowth age influenced the yield and bromatological composition of T. diversifolia. These findings contribute to our understanding of optimizing T. diversifolia production for ruminant feeding.

Production of edible insects: challenges, opportunities, and perspectives for Costa Rica

Ileana Maricruz Bermúdez-Serrano, Ana María Quirós-Blanco, Óscar Acosta-Montoya — Fri, 25 Aug 2023 00:00:00 -0600

Introduction. Edible insects emerge as an alternative source of protein generated with environmentally sustainable production practices and high nutritional value. The production of insect-based food products has increased globally in recent years and it is expected to continue growing. Costa Rica has a small number of edible insect producers, which has led to growing interest from academia and government entities in promoting the sector. Objective. To present the current market, opportunities, challenges, and perspectives of edible insect production, processing, and marketing internationally and in Costa Rica. Development. The current global market for edible insects is described, the main challenges, and opportunities in their production, processing, and marketing, as well as the sector’s development in Costa Rica. Conclusion. Globally, key challenges in edible insect production include low consumer acceptance, lack of insect production technologies, and inadequate regulatory framework. In Costa Rica, collaborative efforts from academia, the public, and private sectors have established a basic regulatory framework allowing the production of three insect species for human consumption. Costa Ricans are willing to include insects in their diet, but there is still a need to develop better production methods to facilitate the sector growth.

Genetic resistance to Ceratocystis fimbriata in elite genotypes of Gmelina arborea

Thu, 13 Jul 2023 00:00:00 -0600

Introduction. In Costa Rica, an incidence of nearly 40 % has been reported for a disease caused by Ceratocystis fimbriata in commercial plantations of Gmelina arborea (melina), which is the second most widely planted forest tree species in the country. Consequently, there is a pressing need to explore genetic material that exhibit resistance to this pathogen. Objective. To evaluate two methods of C. fimbriata inoculation and their effect on elite genotypes of melina, for their use within the melina genetic improvement program at the international forest genetic improvement cooperative GENFORES. Materials and methods. A pathogenicity test was established using the CIF 001 isolate of C. fimbriata under greenhouse conditions, in Santa Clara, San Carlos, Costa Rica. Two inoculation methods were evaluated in five elite genotypes from October 2019 to January 2020. The effect of the pathogen was evaluated by measuring total height development, basal diameter, number of leaves, incidence, and internal injury within the plant. The assessment was conducted at 30, 60, 90, and 120 days. Results. Mortality was observed from day 38 and reached an incidence of 26.7 % at 120 days. The treatment using solid medium displayed the highest incidence percentage. Genotypes 15N and 58 exhibited high susceptibility to the CIF 001 isolate, whereas genotypes 1 and 57 exhibited high tolerance. Based on the results, it was determined that the pathogenicity test of C. fimbriata on melina can be evaluated at 90 days. Conclusion. Solid medium was the most effective method for inoculating melina with C. fimbriata (isolate CIF 001). Evaluations showed the need to assess results at least 90 days after inoculation. Based on the analysis of the internal lesion, genotype 1 was identified as highly resistant to the effect of the pathogen. The inclusion of this genotype as an evaluation technique will substantially enhance the protocol for assessing tolerance to the pathogen.

Isochoric freezing: advantages and research opportunities in the food industry

José Chaves-Quesada, Oscar Acosta-Montoya — Tue, 13 Jun 2023 00:00:00 -0600

Introduction. Isochoric freezing (at constant volume) is a novel technology that has been evaluated in different studies to demonstrate the possible benefits for the food industry. Objective. To present an overall summary about the frozen food market, the freezing technologies currently used, as well as the emerging ones, and delve into the fundamental theories of isochoric freezing and the advantages in the food industry compared to traditional freezing systems and to show the possible fields of research related to this technology. Development. This work was carried out in Costa Rica between February 2022 and June 2022, it describes the general context of the frozen food market, the technologies used in the industry, the thermodynamic principles of the isochoric technology, the physicochemical, microbiological and energetical advantages, and ends with the possible fields of research and disadvantages recently found. Conclusion. Isochoric freezing presents important advantages compared to the current freezing processes in the food industry, however, it is necessary to perform more research related to microbiological aspects, as well as to optimize the process parameters and equipment to generate a change in the global food freezing system.

Potential use of two herbaceous forage (Axonopus catarinensis and Smallanthus sonchifolius) crops in the silvopastoral systems in the tropical highlands of Colombia

Fri, 14 Jul 2023 00:00:00 -0600

Introduction. Specialized dairy farming in Colombia highlands entails high production costs, methane emissions, nitrogen pollution in soil and water, the use of pesticides in pastures, and milk production that has not yet reached high-quality standards. All of these factors necessitate a structural change in the production model with a sustainability focus. In addition to other aspects, sustainable livestock farming requires greater complementarity and diversity of forage, shrub, and tree species adapted to high-altitude tropical conditions. Objective. To gather information through participatory action and rural innovation by producers and research advancements on the species Axonopus catarinensis and Smallanthus sonchifolius, herbaceous forage species with potential production and environmental benefits (in preliminary stage), for their integration into silvopastoral systems in the Colombian highlands. Development. A. catarinensis and S. sonchifolius are species that could be used in basic diet and energy supplementation, respectively, of dairy cows in the Colombian highlands. While there is no scientific information available for these conditions, some producers’ experiences suggest that these species may improve milk production and quality with positive effects on family economics. Additionally, they can contribute to the generation of dairy products with beneficial functional attributes that impact human health. Conclusion. A. catarinensis and S. sonchifolius are species that may have forage and nutritional potential to be included in silvopastoral dairy production systems in the Colombian highlands.

Microbiology of carrot, tomato and cabbage from organic and conventional agriculture in Costa Rica

Thu, 27 Apr 2023 00:00:00 -0600

Introduction. Interest in consuming fresh products such as vegetables has been increasing over the years. Different cultivation methods to produce vegetables such as carrots, tomatoes, and cabbages are available. Conventional and organic farming systems are the most common. Objective. To compare the microbiology of carrot, tomato and cabbage from farms with organic or conventional agricultural production systems in Costa Rica. Materials and methods. Sampling was carried out in Cartago, Heredia and Alajuela, Costa Rica, from September 2020 to November 2021, during the rainy season in all cases. Vegetables from model farms of carrot, tomato and cabbage, one of organic production and three of conventional production, were sampled. Microbial counts of total aerobic mesophilic, total coliforms, Escherichia coli, yeasts and molds, and the absence/presence of Listeria monocytogenes were determined. Results. Total aerobic, yeast and mold and total coliform counts for conventionally and organically grown carrots, cabbages, and tomatoes did not differ from each other. In the vegetables studied, E. coli counts were <1 log CFU/g and Listeria monocytogenes was absent. Presence of Listeria sp. in carrot samples from conventional cultivation was found in contrast to its absence in carrots from organic cultivation. Conclusions. L. monocytogenes was absent in the vegetables studied, which in general had acceptable microbial loads according to regulations and similar to studies reported worldwide. Under controlled conditions, when compared to those obtained from conventional production systems, it is possible to obtain vegetables from organic farming without detriment to their microbiological quality and with the derived benefits for the health of the consumer and the environment.

Agricultural experiments with repeated measures over time: analysis strategies comparison

Jorge Claudio Vargas-Rojas, Alejandro Vargas-Martínez, Eduardo Corrales-Brenes — Thu, 27 Apr 2023 00:00:00 -0600

Introduction. Several modeling techniques have been used to analyze experiments with repeated measures over time; however, some of these are no longer relevant. Objective. To compare four analysis strategies that are used to analyze agricultural experiments with evaluations over time. Materials and methods. Data from an experiment in which the effect of different nitrogen fertilizer sources on chlorophyll content in a forage grass at different harvest ages was used. These data were analyzed using four strategies: the area under the curve index (AUC), multivariate analysis of variance (MANOVA), random effect of the experimental unit, and temporal correlation modeling. The lasts two strategies were performed under the theory of mixed linear models; in these different models were fitted, all with the same fixed effects structure, but with different random effects, residual correlation structure, or residual variance structure. Using penalized likelihood criteria [Akaike information criterion (AIC) and Bayesian information criterion (BIC)], the best fitting model was chosen, with which inferences were made about the means of the significant fixed effects, and compared with the results obtained from the AUC and MANOVA strategies. Results. The best fitting mixed linear had a compound symmetry correlation structure and heteroscedastic variances. This model allowed for the analysis of the treatment × time interaction; on the other hand, both the MANOVA and the AUC allowed for the analysis of temporal trends of the treatments. Conclusion. The best fitting mixed linear model made it possible to select the best treatment based on the evaluation time. On the other hand, both the MANOVA and the AUC led to the selection of treatments that were not the best at all evaluation times.

Antioxidant substances in different phenological phases of Psidium guajava L.

Mon, 27 Mar 2023 00:00:00 -0600

Introduction. There is worldwide interest in determining the content of plant-based antioxidant substances, and the relationship of the phenological phases of the plant with the production of secondary metabolites. Objective. To determine the effect of phenological phases on the content of antioxidant substances of guava (Psidium guajava L.). Materials and methods. A population sample of 10 % of guava plants from the germplasm bank of CESID-Frutícola y Apícola-CORPOZULIA, located in the municipality of Mara, Zulia state, Venezuela, was evaluated. The content of total phenols (FeT), total flavonoids (FlT), and antioxidant capacity (CA) were determined in dry leaves samples at different phenological phases of the plant, recorded from October 2012 to September 2013. Extraction of the FeT was performed by ultrasound with 0.5 g of dry sample and a methanol: water mixture (80:20 % v/v). For quantification by UV-VIS absorption spectrophotometry, gallic acid for FeT and catechin for FlT were used as standard. The AC was determined by the cation-radical ABTS▪+. Non-parametric statistics were used using SPSS statistical software. Results. The three phenological phases (flowering, fruiting, vegetative sprouting) occurred in guava plants, the reproductive phase prevailed with 38.99 % of flowers and fruits; with higher average presence of vegetative shoots that occurred during the rainy season and the alternation between flowers and fruits production. Intra-population variability was observed in the content of antioxidant substances, FeT content, compared to CA and FlT, was higher in fruiting and in the absence of precipitation. Conclusion. The phenological phases had an effect on the content of antioxidant substances of guava. The fruiting phase had the highest content of total phenols. The contents of total phenols and flavonoids were related to antioxidant capacity.

The effect of extender, age, and bovine sexual status on the sperm kinematics

Ignacio Araya-Zúñiga, Francisco Sevilla, Vinicio Barquero, Anthony Valverde — Wed, 12 Jul 2023 00:00:00 -0600

Introduction. The kinematic patterns of semen are influenced by individual variation and/or environmental effects, determined by the handling after sample collection. Objective. To evaluate the effect of two commercial extenders, bull age, and sexual status on the motility and kinetics parameters of fresh bovine semen. Materials and methods. The study was conducted on the livestock farms “La Vega,” San Carlos, and “La Balsa”, San Ramón, Costa Rica, between March and August 2021. Donated semen from thirteen Brahman bulls was used, extracted through electroejaculation. A total of 45 ejaculates were collected, with a minimum of two and a maximum of five per animal. The semen was diluted with two commercial extenders, Optixcell^®and Bioxcell^®, at a temperature of 37 °C. The samples were analyzed using the Computer-Assisted Semen Analysis (CASA)-Mot ISAS^®v1 system and a reusable Spermtrack^®counting chamber (20 μm). Results. Differences (p<0.05) were observed in sperm motility and kinematics, as well as sperm kinetic parameters, depending to the extender used. Bioxcell^® showed higher progressive motility (64.03±2.01 %) compared to Optixcell^®. Ejaculates diluted with Bioxcell^®exhibited a more linear and progressive kinematic pattern than those diluted with Optixcell^®, which had lower average velocity (VAP=106.67±0.24 μm s-1) and straightness index (STR=79.35±0.10%). Age did not show differences in total motility, but progressive motility was higher in animals >48 months (62.27±1.87 %). An effect of sexual status was observed with higher linearity, velocity, and sperm oscillation during mating compared to sexual rest. Conclusion. Age, sexual status, and the extender used for semen preservation influenced the sperm quality of bovine ejaculates.