Agronomía Mesoamericana

Plant growth and nutrients uptake in dragon fruit (Hylocereus costaricensis and H. monocanthus ) in Costa Rica

Gabriel Garbanzo-León, Jorge Claudio Vargas-Rojas, Edgar Vidal Vega-Villalobos — Thu, 11 Apr 2024 00:00:00 -0600

Introduction. The cultivation of pitahaya (Hylocereus costaricensis and H. monocanthus) is increasing in Costa Rica, but there is a knowledge gap in terms of technical information. This primarily includes nutrient requirements, the timing of fertilization, and the patterns of growth. Objective. To quantify and model the growth and nutrient uptake of pitahaya (H. costaricensis and H. monocanthus) under the conditions of the seasonally dry tropics of Costa Rica. Materials and Methods. The research was conducted during the period from 2017 to 2020 in Guanacaste, Costa Rica. Plants were sampled at 76, 165, 308, 450, 607, 903, 1249, and 1706 days after planting (DDS) and 205 fruits. Dry matter was quantified, and the absorption of N, P, Ca, Mg, K, S, Fe, Cu, Zn, Mn, and B was calculated. Two logistic models were fitted to determine nutrient absorption, and linear regressions were calibrated for fresh fruit. Results. The nutritional requirements of the crop were (kg ha^-1): 137 N, 32 P, 327 K, 63 Mg, 32 S, 1,60 Zn, and 0,21 B per 3000 plants/ha. The best-fitting logistic model (RMSE = 0,09) accurately estimated the absorption of N, P, Ca, S, Zn, and B. The linear regression model had high predictive capacity (R² > 0,85) for the requirements of N, P, K, Mg, S in fruit.. Conclusion. The logistic models demonstrated high precision in deterministically modeling nutrient absorption in dragon fruit plants. Additionally, the nutritional behavior of dragon fruit plants in the seasonal dry tropics of Costa Rica was efficiently quantified and modeled, providing essential information for the crop fertilization programs.

Soil microorganisms, and its relationship with coffee beverage quality: A review

Thu, 11 Apr 2024 00:00:00 -0600

Introduction. Coffee (Coffea spp.) is the second most traded product globally and is cultivated in over eighty countries. This crop is complex due to its belonging to an ecosystem where abiotic and biotic factors have dynamics under different agronomic management conditions. To understand the plant's development and its influence on the sensory quality of the product, it is necessary to understand the intricate interaction between the coffee plant and its indigenous microorganisms. Objective. To describe the role of soil microbiota in coffee, including bacteria and fungi, and how it can contribute to the final quality of the beverage. Development. Soil is one of the most diverse and least studied ecosystems, in which various ecological functions important for plant growth and development occur. The identification of soil microbial components and their interactions with other organisms are important from an agronomic perspective. Soil microbiota can favor plant physiology, and thus, this compilation of information seeks to associate how the sensory attributes of coffee beverage can be benefited by soil microbiota. Articles from ScienceDirect, Scopus, Web of Science, and Google Scholar were reviewed between 2011 and 2023. The data show the diversity of plant growth-promoting rhizobacteria (PGPR), nitrogen-fixing bacteria (NFB), and arbuscular mycorrhizal fungi (AMF) associated with coffee cultivation. There are also microbial compounds that play an important role in shaping sensory attributes and are related to coffee cup quality. Conclusion. The microbial diversity of soil and fruit can synthesize or degrade compounds that influence the sensory profile of the beverage, which could have implications for sustainability and quality.

Factors influencing the adoption of sustainable practices in rice cultivation: The case of Costa Rica

Thu, 11 Apr 2024 00:00:00 -0600

Introduction. Sustainable practices are essential as tools for mitigating and adapting to climate change, so it is timely to understand what factors influence the decisions of rice farmers to adopt a conservation practice in their production system. Objective. To determine the causal relationships among the variables that allow understanding the adoption of conservation practices in rice cultivation by rice farmers. Materials and methods. Between July and September 2021, a study was conducted on the rice production systems in Costa Rica with producers in the rice-producing regions of Costa Rica, Brunca, Chorotega, Huetar, and Central Pacific through quota sampling. A total of 67 rice producers were surveyed. The quantitative research identified degrees of adoption of conservation practices, groupings through clusters, and an ordered probit model was used to analyze the factors that influence the intensity of conservation technologies or practices in these production systems. Results. Greater adoption of conservation practices in rice production systems is influenced by the level of schooling of the producer, membership or affiliation to rice organizations, and land tenure. Conclusions. This research highlights that the design of conservation practice strategies in rice cultivation benefits from a better understanding of the relationships between socioeconomic, productive, and environmental variables, increasing the probability that a producer implements and maintains these conservation practices over time.

Analysis of the competitive forces of cocoa farmer in San José de Cúcuta

Miller Eduardo Otero-Gómez, César Villamizar-Quiñonez, Susan Cancino — Thu, 11 Apr 2024 00:00:00 -0600

Introduction. Competitiveness measures the ability of a company or organization to produce and market a good or product more efficiently and effectively compared to other competitors. Objective. Analyze the competitive forces related to the productivity and marketing of cocoa beans by cocoa farmers in San José de Cúcuta and to provide information for future research aimed at improving the cocoa sector. Materials and Methods. The research was conducted in the municipality of San José de Cúcuta in the rural areas of Guaramito, Matecaña, La Floresta, Banco de Arena, and Palmarito, Colombia, during the year 2022. The study population, consisted of cocoa producers residing in the rural area of the municipality. The sampling was non-probabilistic in nature, representing a convenience sample, and a total of 86 cocoa producers who were willing to respond to the survey were identified. The approach was observational with a quantitative nature. Descriptive and inferential statistical methods were applied for data analysis. Results. Regarding producers’ negotiation capacity on bean prices, 34.88 % considered it to be very low. In the case of access to cultivation technology, 47.67 % expressed it as low. Concerning production costs, 45.35 % responded that they are high. As for substitute products, 84.88 % of the respondents perceive a threat ranging from medium to very high. Conclusions. In the municipality of San José de Cúcuta, cocoa production is an activity of productive and socioeconomic importance. Regarding the power of marketers, cocoa farmers do not have any positive effect on the prices of the beans produced in the study area; on the contrary, they must submit to what is imposed by the large industries in the country.

Use of RPAS for precision evapotranspiration in rice fields to reduce water consumption

Thu, 11 Apr 2024 00:00:00 -0600

Introduction. The estimation of crop evapotranspiration (ETc) allows knowing the water requirements of the crop, which helps to propose water-saving irrigation techniques. Aim. Use Remotely Piloted Aircraft System (RPAs) for greater precision of evapotranspiration in rice fields to reduce water consumption, Materials and methods. The distribution of plots followed a completely randomized block design with a factorial structure of two experiments, flooded irrigation (E1) and controlled dry irrigation (E2), with three varieties of rice (IR43, IR71706, Sahod Ulan 12) in the Area. Experimental Irrigation (AER) of the Unalm. Eight flights of an RPAS were carried out, distributed between the tillering and cotton knitting stages, in January and February 2019. Results. The combined analysis of treatments with analysis of variance and Duncan's test with p < 0.05 revealed a significant difference in ETc between E1 and E2; However, no significant difference was found between rice varieties. Maximum values of ETc and yield were obtained for E1 of 4.50 (mm/d), 10389 (Kg/ha) and for E2 of 3.7 (mm/d), 9710 Kg/ha), respectively. Conclusions. The use of a remotely piloted aircraft system allowed for improved temporal and spatial resolution of multispectral and thermal images to achieve greater precision in crop evapotranspiration (ETc) under two irrigation regimes. A 24% reduction in ETc was achieved under deficit irrigation, resulting in a water saving of 855 m3/ha.

Germination and growt of Porcelia mediocriss y Compsneura Trianae in Arosemena Tola, Napo, Ecuador

Thu, 11 Apr 2024 00:00:00 -0600

Introduction. Wild species are important in the ecosystem, these require the development of techniques that allow their preservation. Objective. Determine the characteristics of in situ and ex situ germination and field growth of the species Porcelia mediocris N.A. Murray and Compsoneura trianae Warb. in Arosemena Tola, Napo, Ecuador. Materials and methods. The study was carried out between 2019 and 2020, seeds were collected in the primary forest of P. mediocris and C. trianae. Germination tests were developed in a greenhouse and in primary forest, seed emergence and tray growth were measured and an analysis of variance was applied between the test sites. The seedlings were transplanted in three different soil covers at the Amazon Teaching, Research and Productivity Center, measurements of growth in height, stem diameter, number of leaves and survival were taken, growth curves were prepared and an analysis of variance in the final growth measurements between the different coverages. Results. In P. mediocris, the plants grown in the greenhouse reported fewer days to the emergency (67.6), but the plants grown in the guabas coverage had a greater height (19.45 cm) and germination percentage (70 %) at end of the test. In C. trianae, the plants developed at the collection site had greater height (13.38 cm) and number of leaves at the end of the evaluation. In field growth, no differences were reported between the different coverages, reaching a survival of 47 % in P mediocriss and 75 % in C. trianae. Conclusions. In germination, P. mediocris reported better germination percentages in the guabas coverage and C. trianae had greater growth in the primary forest, without the germination site influencing the growth after transplantation in both species.

Endophytic fungi associated to Vitis vinifera with antibiosis capacity against Botrytis cinerea

Thu, 11 Apr 2024 00:00:00 -0600

Introduction. Endophytic fungi (EF) in grapevines (Vitis vinifera) hold significant potential for agricultural applications and could serve as potential biological control agents for vineyards. Objective. To isolate and identify endophytic fungi (EF) from grapevine plants capable of displaying antibiosis towards Botrytis cinerea. Materials and methods. Young and mature branches were collected from forty healthy grapevine plants across seven production lots in the Cañete province, Lima, Peru, between March and May 2022. EF isolation was carried out from 702 disinfected tissue sections on potato dextrose agar (PDA) medium, with genus-level identification. Secondary metabolites were extracted from twenty-eight EF strains to determine their inhibition of the pathogen’s mycelium growth. Analysis of variance (ANOVA) was conducted using the Minitab statistical software for evaluated parameters. Results. A total of 129 EF strains were isolated from leaves and stems of young and mature grapevine branches, encompassing seven genera (Trichoderma, Aspergillus, Alternaria, Cladosporium, Fusarium, Nigrospora, and Stemphylium). The highest frequency occurred in leaves and mature branches; Trichoderma and Alternaria were the most prevalent genera, constituting 22.48% and 21.71% of total isolates, respectively. Metabolites derived from the EFVH-01 strain of the Cladosporium genus, as well as EF-99 and EF-70 strains of the Alternaria genus, displayed the greatest impact on inhibiting the pathogen’s mycelium growth. Conclusions. Strains of endophytic fungi of the genus Cladosporium and Alternaria showed antibiosis capacity towards Botrytis cinerea at the laboratory scale and could potentially serve as biocontrols, offering an alternative to chemical disease management in grapevines.

Rhizobium pusense associated to chickpea (Cicer arietinum L.), in Cuba.

Tue, 09 Jan 2024 00:00:00 -0600

Introduction. Chickpea has been considered a restricted host species for nodulation, although recent studies describe a greater bacterial diversity associated with the crop, which can enhance our understanding of this symbiosis to obtain efficient isolates in its contribution. Objective. To characterize and identify an isolate obtained from chickpea nodules and evaluate its effectiveness under field conditions. Materials and methods. The research was conducted in the laboratories of two centers: the Institute of Fundamental Research in Tropical Agriculture "Alejandro de Humboldt," Cuba, and the National Center for Genetic Resources, Mexico, as well as under field conditions in two campaigns to demonstrate its effectiveness in crop interaction in the first center during the years 2018 and 2020. The isolate R3 showed morpho-physiological and biochemical characteristics similar to rizobia and it was taxonomically identified through the sequencing of four genes. For laboratory experiments, a completely randomized design was used, while plant trials were conducted under a randomized block design. The results were subjected to analysis of variance, and means were compared using the Tukey test (p<0.05). Results. The isolate R3 showed variability in terms of its morpho-physiological-biochemical characteristics. Furthermore, it exhibited significant differences compared to the other treatments in the growth and yield indicators evaluated in chickpea. Conclusions. Rhizobium pusense associated with chickpea nodules was identified for the first time in Cuba. The strain demonstrates positive growth at pH levels between 5.5 and 9.0 and temperature ranges from 29 °C to 38 °C, indicating its tolerance to these factors. Its inoculation in chickpea stimulates nodule formation and increased yield-related variables.

Fermentation of Trichoderma for biological control using local inputs in Costa Rica

Patrick Becker, Paul Esker, Gerardina Umaña Rojas — Tue, 09 Jan 2024 00:00:00 -0600

Introduction. Supply chain issues have driven up raw material costs and reduced the availability of materials for producing biological control agents. These delays in application could result in increased disease pressure and reduced farm yields. Objective. To determine the effect of different amounts of starch and the use of local ingredients for small and commercial-scale fermentation processes for Trichoderma harzianum. Materials and methods. All trials took place in San José, Costa Rica, between 2016 and 2018. Flask trials were executed to investigate the potential reduction or elimination of starch in commercial fermentation media. Additionally, fermentation vessel trials were conducted to assess the effectiveness of an alternative local medium, encompassing three treatments: 1) Commercial medium as a control, 2) 10% molasses medium, and 3) 10% molasses mediaum with 0.5% yeast extract. Viable spore counts were performed to determine colony forming units (CFU/mL). Results. Reducing starch to 10% of the original medium had no impact on CFU/mL. However, the absence of starch led to uneven growth during fermentation, resulting in solid mycelium accumulations. Molasses medium yielded roughly half the CFU/mL compared to the commercial medium, but it still exceeded the 107 CFU/mL threshold commonly used in studies for biological plant pathogen control. Results from a commercial-scale fermenter mirrored those from pilot-scale fermentation. Conclusion. While reducing starch content in the commercial medium didn't affect growth, the absence of starch caused solid mycelium accumulations, potentially posing issues in commercial production. Employing locally sourced molasses medium on a commercial scale appears feasible while maintaining a viable spore count meeting the minimum field-use specifications. Overall, these findings support the use of these media for Trichoderma production in biological control applications.

Ocañera onion (Allium cepa L.)cultivars under protected and open field conditions.

Thu, 11 Apr 2024 00:00:00 -0600

Introduction. Given its importance in food in different countries, the reduction of its genetic diversity, the loss of its beneficial traits, together with its resistance to diseases and pests; it is important to evaluate onion (Allium cepa) cultivars in different environments to know their adaptation. Objective. To evaluate the agronomic performance of onion cultivars under different environments to identify the best in adaptation, yield and interaction. Materials and methods. At the La Selva Research Center of the Colombian Agricultural Research Corporation (AGROSAVIA), Rionegro, Antioquia, Colombia, 21 cultivars plus two controls: Peruana of the Aggregatum group and Yellow Granex of the Cepa, were evaluated under open field conditions and protected with plastic cover, using multilocation trials with a randomized complete block design and four replications. The bulb weight, number, length and diameter were evaluated by categories, together with the interaction of cultivars with these environments. Results. In open field, the highest yields of bulb weight and number of bulbs were obtained because temperatures were lower than those recorded under protected conditions. In protected environments, the cultivars of the Aggregatum group behaved as if they were of the Cepa group, producing a few large bulbs. The adaptation of the cultivars was different in the environments: in the open field, cultivars L55 and L63 presented the best yields while, under protected conditions, RPT20 and RPT11 were the best adapted. Conclusion. Environments significantly influenced the performance of the cultivars of the Aggregatum group with higher production of extra-large bulbs. The high and low-temperature contrasts that occurred in the environments protected with a plastic cover affected the yields of the cultivars, while the environmental conditions in the open field were favorable.

Physiological response of Solanum phureja under water deficit

Tue, 09 Jan 2024 00:00:00 -0600

Introduction. The parameters of physiological response to drought stress are the conjugation of a series of attributes of slow or fast action. The gas exchange variables are classified as fast-acting, and their level of occurrence or affection depends on the interaction between factors such as genotype, duration and intensity, and the phenological stage of occurrence of the stress. Objective. To identify the levels of physiological response of Solanum phureja under progressive water deficit stress. Materials and methods. The experiment was conducted between 2019 and 2020, under semi-controlled conditions at the Obonuco Research Center of the Colombian Agricultural Research Corporation, where four potato cultivars were planted, half of the trial was maintained with irrigation at field capacity and the other part was suspended to induce water deficit stress for 15 days, then rehydrated; variables of gas exchange, chlorophyll and photosynthetic efficiency were evaluated every three days. Results. Statistically significant differences were presented, with the maximum values of gas exchange in plants of the control treatment with 16.67 µmol m^-2 s^-1 photosynthesis rate (A); 0.34 mol m^-2 s^-1 stomatal conductance (gs) 5.5 mmol m^-2 s^-1 transpiration (E) and in stress 1.17 µmol m^-2 s^-1 (A); 0.013 mol m^-2 s^-1 (gs); 0.29 mmol m^-2 s^-1 (E). As for chlorophyll content, values between 451.7 and 474.69 m^-2 s^-1 were presented with irrigation and without irrigation, respectively. Conclusions. Stomatic closure was the earliest response to water deficit, and potato plants showed recovery of gas exchange values after the supply of irrigation following stress. Finally, three levels of physiological response were identified: mild, moderate and severe stress according to the intensity and duration of stress, which is useful for future studies and irrigation schedules.

Biocontrol of Penicillium digitatum with secondary metabolites of endophytic fungi in mandarin fruits

Thu, 11 Apr 2024 00:00:00 -0600

Introduction. "Green mold," caused by Penicillium digitatum, is one of the phytosanitary problems limiting citrus production. Synthetic fungicides are used to control it, but over time, they have lost their effectiveness due to resistance developed by the fungus. An alternative to chemical control is the use of endophytic fungi with biocontrol action. Objective. To evaluate the effect of secondary metabolites (SM) from endophytic fungi (EF) on the mycelial inhibition of Penicillium digitatum and the disease control efficacy in post-harvest mandarins Citrus reticulata). Materials and methods. The study was conducted under a completely randomized experimental design in the Plant Health laboratory of Universidad Nacional de Cañete (UNDC), Lima, Perú. For the antibiosis test, secondary metabolites were extracted from ten strains of EF from the genera Trichoderma sp., Fusarium sp., and Aspergillus sp., and the mycelial inhibition of the pathogen (%) was evaluated. The SM were sprayed at a concentration of 15 % (v/v) on fruits that were disinfected and then inoculated with the pathogen by spraying (1x 10⁵ CFU/mL). Commercial biocontrol, vegetable oil, and fungicide were added to the treatments. After six and nine days, disease incidence (%) and severity index (0, 1, 2, 3) were evaluated. Data were analyzed using the InfoStat statistical program. Results. The secondary metabolites from the HEA-111 (Aspergillus), HEA-109 (Fusarium), and HSA-1 (Trichoderma) strains showed the highest mycelial inhibition with 95.05 %, 87.51 %, and 47.47 %, respectively. The fruits mandarins treated with SM from the HEA-109 and HSA-1 strains there were t control e at 80 % and 55 %, respectively. Conclusions. The SM from HE have effect in the mycelial inhibition of P. digitatum and reduces theprogression disease in fruits.

Sensitivity of the corn (Zea mays) crop to different periods of controlled water deficit

Tue, 09 Jan 2024 00:00:00 -0600

Introduction. Corn is one of the oldest food grains. With climate change, frequent and severe droughts, available water in the soil will be greatly reduced. Water deficit affects corn crop development to varying degrees, the sensitivity to this stress varies at different stages of development. Objective. To identify the phenological stages most sensitive to water deficit in corn. Materials and methods. This experiment was conducted during two cycles 2020 and 2021 in El Ejido, Los Santos province, Republic of Panama, under semi-controlled conditions in the grow house greenhouse of the Coronel Segundo de Villarreal Institute. The commercial corn hybrid ADV-9293 was used. Agronomic management was carried out according to the technology generated by the Panama Institute for Agricultural Innovation (IDIAP). Variables such as plant height, leaf length and width, stalk diameter, biomass and yield components such as number of rows per ear, number of kernels per row and mass of 100 kernels were determined throughout the crop cycle. Soil moisture was also determined by the gravimetric method. Water deficit at different stages was generated through drought simulation. Results. The control grain yields exceeded the different treatments evaluated with 12.83 t ha^-1, followed by the treatment with grain filling stress with 10.31 t ha^-1. Two periods were determined to be more sensitive to water deficit; these are the stages from 20 to 35 and 40 to 55 days after sowing. Water deficit in the different phenological stages of the crop had a negative impact on the relative chlorophyll content. Conclusion. The pre-flowering and flowering stages were more sensitive to water deficiency in corn.

Commercial microbial inoculants with PGPR on productive and economic variables of common bean (Phaseolus vulgaris L.)

Wed, 10 Jan 2024 00:00:00 -0600

Introduction. In Ecuador, there are few studies on the use of microbial inoculants for sustainable common bean (Phaseolus vulgaris L.) production. Objective. To evaluate the effect of inoculation with plant growth-promoting rhizobacteria (PGPR) on productive and economic variables of P. vulgaris. Materials and methods. The research was conducted at the La Argelia Experimental Station in Loja, Ecuador, from February to July 2022. Using loamy soil, the common bean cultivar "Mantequilla" was employed in a randomized complete block design with seven treatments and four replications each. The treatments were: T1) absolute control, T2) Bacillus subtilis, T3) Rhizobium leguminosarum bv. viciae, T4) Pseudomonas fluorescens + B. subtilis, T5) R. leguminosarum bv. viciae + B. subtilis, T6) R. leguminosarum bv. viciae + P. fluorescens + B. subtilis, and T7) chemical fertilization. The effect of the treatments on growth, development, and yield components in the evaluated cultivar was assessed. Additionally, an economic analysis of the application of beneficial microorganisms versus chemical fertilization was conducted. Results. Treatment T6 (R. leguminosarum bv. viciae + P. fluorescens + B. subtilis) shortened the phenological phases (days), promoted a higher number of nodules, emergence percentage, plant height, leaf area, number of pods per plant, weight of 100 seeds, nitrogen content, and agricultural yield without statistical differences (p<0.05) compared to chemical fertilization (T7). The economic analysis showed that T6 generated higher income and greater profitability compared to chemical fertilization. Conclusion. Inoculation with beneficial microorganisms positively affected the productive and economic variables of common beans and can be a valid alternative to the conventional use of chemical fertilizers.

Biological activity of improved color maize (Zea mays) grown in southern Sonora

Tue, 09 Jan 2024 00:00:00 -0600

Introduction. In Mexico, 85 % of the crops are white maize, 10 % white yellow and 5 % other colours. There are biochemical studies of pigmented native maize, but little information on colour-improved maize. Objective. To evaluate the phytochemical content and antimicrobial capacity of two pigmented maize hybrids grown at the Tecnológico Nacional de México-Valle del Yaqui. Materials and methods. Extraction of biocompounds from a portion of the maize grown in southern Sonora, Mexico, during the summer-winter 2020 cycle was performed on red and purple maize hybrids. A thirty-part solution of ethanol, acetic acid and water was used. Proximal composition, anthocyanin, polyphenol and flavonoid content were determined by standardised methods. Antioxidant capacity was determined by ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) methodologies. In addition, antimicrobial capacity and minimum inhibitory concentration were determined. Results. Purple maize showed higher content of anthocyanins (340.98±5.21 mg/100 g) and polyphenols (173.68±24.23 mg gallic acid/100 g) compared to red maize. Flavonoids are more abundant in purple maize (575.10±27.88 mg quercetin/100 g). Both maize hybrids exhibited more than 50 % antioxidant capacity against ABTS and DPPH radicals. Regarding antimicrobial activity, higher inhibition was observed for Escherichia coli and Salmonella (18 % and 47 %), and lower for Staphylococcus aureus and Shigella (19 % and 34 %) compared to gentamicin. Conclusion. Purple maize showed higher content of anthocyanins, polyphenols and flavonoids. Both hybrids had more than 50 % antioxidant capacity. Antimicrobial activity was higher against E. coli and Salmonella, but lower against S. aureus and Shigella.

Pelletized Mucuna pruriens and Trichoderma harzianum applied to tomato (Solanum lycopersicum L.) as an amendment and biocontrol agent

Arnaldo Martínez-Alfaro, Andrés Zuñiga-Orozco — Tue, 09 Jan 2024 00:00:00 -0600

Introduction. In organic agriculture, green manure and biocontrollers are used as methods for fertilization and pest control. However, the independent application of these inputs increases production costs. A pelleted formulation is proposed to allow for the simultaneous application of both inputs. Objective. To evaluate the effect of pelletized Mucuna pruriens L. inoculated with Trichoderma harzianum Rifai on nutritional contribution, agricultural yield, and the regulation of Fusarium oxysporum f. sp. lycopersici in tomato (Solanum lycopersicum L.). Materials and methods. The experiment was conducted during the year 2022 in Tablón del Guarco, Cartago (Costa Rica), using a randomized complete block design with seven treatments and seven replicates. Two formulations (A and B) of biopellet (M. pruriens + zeolite + T. harzianum) were applied at three dosages (15, 30, 50 g/plant). T. harzianum was added at a rate of 5 g/kg of biopellet. Applications of each treatment were conducted every 15 days for a total of eight applications. At the time of planting, F. oxysporum was inoculated (100 mL/plant with a concentration of 1 x 10³ CFU). Results. The application of biopellet achieved a yield and weight of high-quality fruits similar to the commercial control. There were no significant differences among treatments for second and third-quality fruits. The technical efficiency in controlling F. oxysporum reached 97.6% with biopellet. This amendment increased the levels of C, N, and organic matter in the soil and affected the nutritional content of the plant foliage in the first 60 days after sowing. Conclusions. The biopellet has the capacity to make chemical and organic contributions to the soil, which improves the nutrition of the tomato crop. Some dosages had a similar performance to the commercial control. It is a biocontrol alternative against F. oxysporum and compatible with T. harzianum. The dosage and composition of this amendment must be studied in depth for the partial or total replacement of chemical fertilization in the crop.

Evaluation and estimation of calibration curves of devices to measure soil moisture

Tue, 09 Jan 2024 00:00:00 -0600

Introduction. Adaptation measures to climate change require informed decision-making. However, small-scale agriculture shows low technology adoption rates due to their cost and lack of connectivity. Objective. To evaluate three low-cost prototypes of small-scale agriculture devices for soil moisture measurement in different soil textures, determine the respective calibration equations, and assess the effects of electrical conductivity and temperature on moisture measurement. Materials and methods. Three measurement and recording prototypes for soil moisture were evaluated in soils with variations in clay/sand content and electrical conductivity in productive plots at Zamorano University in Honduras and a demonstration farm in Popayán, Colombia during the first quarter of 2022. Commercial sensors were used as a reference to compare the performance of the prototypes through regression analysis of hourly sensor readings over 90 days. Electrical conductivity (dS/m) and temperature variables were collected to determine their influence on moisture reading accuracy. Results. The soil moisture measurement devices showed better performance in soils with lower sand content. The measurement from the devices overestimated moisture readings by 0.19 to 0.52 percentage points for each additional degree of soil temperature. Additionally, for each additional dS/m of electrical conductivity, the reading needed adjustment by 8 to 55 percentage points. Conclusions. Prototype A was the most accurate device, while prototype B was the most precise compared to commercial sensors. Soil moisture devices performed best in soils with lower sand content. All three evaluated models performed best in loamy soil with a medium clay content.

Keywords: calibration equations, volumetric content, conductivity, textural differential.

Varroasis and nosemosis in Apis mellifera hives in the municipality of Tomalá, Honduras

Daneri Jasael Pineda Nataren, Elder Leonel Videz, Byron Flores Somarriba — Tue, 09 Jan 2024 00:00:00 -0600

Introduction. Beekeeping in Honduras is an important activity for the livestock sector, threatened by the presence of pests and diseases that affect the development and production of hives. Objective. To determine the parasitic load of Varroa destructor and Vairimorpha (Nosema) spp associated with hygienic behavior, productivity, and presence of other pests in Apis mellifera hives in the municipality of Tomalá, department of Lempira, Honduras. Materials and methods. A descriptive cross-sectional study was carried out on 57 samples of hives from 19 apiaries, analyzed with the screening method to determine the infestation rate of Varroa destructor. To find the average infection rate of Vairimorpha spp spores, the Cantwell method was used. In addition, the association between parasite loads and variables such as yield, use of chemical control, hygienic behavior, and presence of other pests was determined, through a stratified analysis according to the history of the use or not of treatment against Varroa spp. Data were analyzed using measures of central tendency and the Shapiro Wilk test. The determination of associations was performed by means of no parametric Mann Whitney U and Kruskal Wallis tests. Results. The infestation rate for V. destructor in the dispersion and larval phases were 3.48 % and 6.82 % respectively, the history of applying chemical treatment did not show an association with the infestation rate of V. destructor in larvae or in adults (p≥0.05), the presence of the small hive beetles (SHBs) was associated with a greater infestation of V. destructor in larvae (p˂0.007) in hives that had not received treatment. The range of infection of Vairimorpha spp was found within the very light classification with 50,000.00 (IC 50,000.00-260,000.00) spores per sample, the load of Vairimorpha spp did not show an association with the variables (p≥0.05). Conclusion. The results suggest that varroasis is an important disease for in the municipality of Tomalá, department of Lempira, Honduras, associated with hygienic behavior and the presence of SHBs in the hives. butNosemosis presented a very light infection.

Ovulation induction in cows with Kisspeptin-10 in an estrus synchronization protocol

Tue, 09 Jan 2024 00:00:00 -0600

Introduction. In prepubertal heifers, Kisspeptin-10 has stimulated the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and in postpartum lactating cows, it has stimulated LH secretion without evidence of inducing ovulation. Objective. To induce ovulation using Kisspeptin-10 or gonadotropin-releasing hormone (GnRH) in beef-producing cows under subtropical conditions in Mexico. Materials and methods. he study was conducted in the northeastern region of the state of Puebla from 2020 to 2021, involving 252 crossbred Bos taurus x Bos indicus cows. The estrous synchronization protocol involved the insertion of an intravaginal device impregnated with progesterone (1.9 g) and intramuscular injection of 2 mg of estradiol benzoate (day 0). On day seven, the intravaginal device was removed, and cows were immediately intramuscularly injected with 0.150 mg of D-cloprostenol. On the following day (day eight), Kisspeptin-10 was as effective as GnRH in inducing ovulation. 56 hours after the removal of the intravaginal device (day nine), cows were intramuscularly injected with GnRH or Kisspeptin-10. Cows were assigned to four treatments: T1, 100 µg of GnRH (positive control), T2, T3, and T4 with 500 µg, 1000 µg, and 1500 µg of Kisspeptin-10, respectively. Ovulation was detected via ultrasonography four days post-treatment. The response variable evaluated was the ovulation rate. Data were analyzed using generalized linear models with a logit link function. Results. Ovulation rates obtained with T1 and T4 were statistically equal (99.9%; p>0.05) and higher (p<0.05) than those achieved with T2 (98.5%) and T3 (88.4%), with the latter two being statistically equal (p>0.05).Conclusion. Kisspeptin-10 was as effective as GnRH in inducing ovulation.

Perception of farmers on the management of fungal diseases of soybeans (Glycine max x (L.) Merr.) in Paraguay

Tue, 09 Jan 2024 00:00:00 -0600

Introduction. Paraguay is the sixth largest producer and third largest exporter of soybeans (Glycine max x (L.) Merr.) globally, making this crop of paramount socio-economic importance in the country. However, its productivity can be adversely affected by diseases caused by phytopathogenic fungi. Additionally, phytosanitary information regarding soybean cultivation in Paraguay is limited. Objective. To understand farmers' perceptions of the the primary soybean diseases and their management. Materials and methods. Between April and May 2022, we administered a questionnaire in Google Forms format, consisting of both open and closed-ended multiple-choice questions, to 45 soybean producers aged between 30 and 50 years. These producers cultivate areas ranging from 200 to 1000 hectares in the departments of Alto Paraná, Itapúa, and Caaguazú in Paraguay. Results. Among the respondents, 56% considered Asian soybean rust (Phakopsora pachyrhizi) as the most significant phytosanitary issue associated with soybean cultivation, followed by late-season diseases (LSD) such as brown spot (Septoria glycines) and frogeye leaf spot (Cercospora kikuchii). Respondents reported using three to four fungicide applications as a disease control measure, with their choice based on the type of product formulation. A majority of respondents noted that both the cost and frequency of applications increased over time. Additionally, 53% mentioned that biological fungicides are a viable alternative for integrated disease management. Conclusion. The responses obtained in this study provide valuable insights into the disease management tactics perceived by soybean producers in Paraguay, underscoring the significance of Asian soybean rust and late-season diseases. Nevertheless, further research is necessary to explore all aspects of pathogen management thoroughly.

Resilience capacity of coffee agroecosystems in Tezonapa, Veracruz, Mexico

Wed, 10 Jan 2024 00:00:00 -0600

Introduction. Coffee agroecosystems have a great environmental, social, and economic importance in subtropical regions of Mexico, but it is vulnerable to unexpected crisis such as climate change. In recent history, it has been documented that the coffee agroecosystem presents a constant process of self-organization based on adaptation and learning in the face of various adverse scenarios. Objective. Therefore, the aim was to determine the resilience capacity of the coffee agroecosystem in the central region of the Veracruz state. Materials and methods. The research was carried out in Tezonapa, Veracruz, Mexico from December 2017 to November 2018. 52 interviews with coffee farmers were conducted to measure the resilience index, made up of 30 variables corresponding to seven factors (social, economic, technological, infrastructure, communications, institutional and environmental). Resilience was estimated on a scale of 0-1, where values close to zero represent low resilience and close to one, high resilience. Data were analyzed using descriptive statistics and Kruskal-Wallis and, Chi-squared tests. Results. Statistically significant differences (p<0,05) were found for the indicators of the economic (0,06) and technological (0,22) dimensions, with the least contribution to resilience. On the contrary, social (0,78) and environmental (0,74) dimensions had a greater contribution to resilience determined by the altitudinal gradient. Conclusion. The indicators with the greatest contribution to the resilience capacity of the coffee agroecosystem are those of social and environmental dimensions, and with low contribution the economic and technological dimensions capacity.

Effect of macronutrient omission on cadmium uptake in rice seedlings

Wed, 10 Jan 2024 00:00:00 -0600

Introduction. The edaphoclimatic conditions of Ecuador are ideal for growing rice, yields are higher than the world average, but its agronomic management leads to an increase in cadmium in the soil, which can reach the grain by translocation, which affects its safety. Objetive. To evaluate the absorption of cadmium through the omission of macronutrients technique in six soils of Ecuador and its effect on the vegetative development of rice crops. Materials and methods. The trial was carried out at the Pichilingue Tropical Experimental Station of the National Institute of Agricultural Research, Ecuador, during 2018. Nine treatments were studied: 1) Without fertilization and without Cd (control 1), 2) without fertilization and with Cd (Control 2), 3) Complete fertilization and six omission treatments of one nutrient at a time, a completely randomized block design of experiments, divided plots and three repetitions was used. The variables evaluated were those related to the production of dry matter in the root and aerial part. For the comparison between means, the Tukey test was used (p<0.05). Results. The omissions of nutrients (N and P) led to reduced Cd absorption, which decreased dry matter production, particularly in very acidic or alkaline soils such as in Sucumbíos (pH 4) and Guayas (pH 7, 9), respectively. Conclusions. The absorption of cadmium in rice plants was reduced to a greater extent with the omission of the macronutrients N and P, mainly in the soils of Sucumbíos, Los Ríos, El Oro and Manabí, the nutrient omission technique also affecting the production of dry matter and yields, also observing that a pH below 5 or higher than 7.9 affects the absorption of cadmium in the soils studied.

Cattle fattening market in Mexico: A network approach

Nicolás Callejas-Juárez — Mon, 08 Jan 2024 00:00:00 -0600

Introduction. The network of cattle mobilization for fattening in Mexico is complex. The purpose, volume, origin, and destination of the mobilized animals determine the economic structure and market network. Objective. To analyze the market structure of the national network of cattle for fattening in Mexico from 2017 to 2021. Materials and methods. The study considered all heads of cattle mobilized for fattening in 956 municipalities (supply) and 1173 destination municipalities (demand) within Mexico from 2017 to 2021. The market structure was analyzed using economic, density, and centrality measures from Social Network Analysis (SNA). Results. The network of cattle mobilization for fattening was composed of 31 sources and 32 destinations, with an average annual mobilization of of 3.9 million heads of cattle and 73.6 heads of cattle per mobilization. The most important states in cattle mobilization, both in origin and destination, were Chiapas and Durango. In all cattle sources and destinations, there was a high concentration of fattening steers, as they had low centrality and density measures throughout the network. Veracruz and Durango were the most influential both in origin and destination. Conclusions. The cattle fattening market network in Mexico has a structure with high density and low centrality. The degree of specialization, both in sources and destinations, is low. Supply is concentrated in the southeast, while demand is concentrated in the north and center of the country. This information allows the establishment of three networks: sanitary prevention, cattle traceability, and market information.

Alelopathy of Cenchrus clandestinus on common bean (Phaseolus vulgaris L.) germination

Sugey Velasco-Villabona, Enrique Quevedo-García, Amanda Lucía Chaparro-García — Thu, 25 Jan 2024 00:00:00 -0600

Introduction. Weeds are one of the main problems in agricultural productivity due to their interactions with crops, such as alelopatic effects on germination. Objective. To evaluate the allelopathy of kikuyo grass (Cenchrus clandestinus) on the germination of beans (Phaseolus vulgaris L.) variety ICA Cerinza. Materials and methods. The study was conducted at the Quality Control Laboratory of the Universidad de Pamplona, Central Campus, Pamplona, Norte de Santander, Colombia, from May to August 2022. To each experimental unit (Petri dishe) with 12 been seeds, 6 mL of kikuyo aqueous extract (leaf, stem, and root) at three concentrations (1, 2.5, and 5 %), plus a control (0 %), were added, totaling 12 treatments. From day 0 to 12, the number of germinated seeds (NGS) was recorded, and the germination rate index (GRI) and germination index (IG) were calculated. The biomolecular profile of the aqueous extract was determined using the Fourier-transform spectroscopy. A completely randomized experimental design with a factorial arrangement (3x4), with repeated measures in each experimental unit, was employed. The intersuject factors were the organ type and concentration, while the intrasubject factor was the evaluation time (12 days). Results. Significant differences (p<0.001) were observed for NSG among treatments due to the concentration of the aqueous extract, as well as for IG, while GRI depended on the organ (p<0.05) and concentration (p<0.001), both negatively affected as the concentration increased. The infrared spectrum of the extract determined the presence of polyphenols, nitriles, and siloxanes. Conclusión. C. clandestinus affected NGS, GRI, and GI of P. vulgaris, with an allelopathic effect of the leaf aqueous extract at higher concentrations. Polyphenols, nitriles, and siloxanes associated with allelopathic effects were identified in the aqueous extracts.

Herbicide selectivity in sweet potato (Ipomoea batatas (L.) Lam.) Criollo variety

Franklin Herrera-Murillo, Grettel Picado-Arroyo — Mon, 08 Jan 2024 00:00:00 -0600

Introduction. Sweet potato (Ipomoea batatas (L) Lam.) is sensitive to weed competition, and chemical control in Costa Rica is challenging due to limited local information on herbicide selectivity. Objective. To determine the selectivity of six herbicides applied at different stages of development to Criollo sweet potatoes and their effect on coverage, biomass, and crop yield. Materials and methods. Between August and December 2021, three experiments were conducted at the Fabio Baudrit Moreno Agricultural Experimental Station, Universidad de Costa Rica, Alajuela,
Costa Rica. Herbicides were applied (in kg a.i. ha^-1) as follows: a) Experiment 1: 0.36 of metribuzin, 1.50 of
pendimethalin, 0.48 of clomazone, 0.075 of halosulfuron, 1.00 of linuron, and 1.25 of metolachlor, applied six days after planting (dap) in a randomized block design with four repetitions; b) Experiment 2: 1.00 of linuron and 0.36 of metribuzin 0.36, applied at -1, 15 and 30 dap, in a randomized block design with a 2x3 factorial arrangement and three repetitions; and c) Experiment 3: 0.075 of halosulfuron and 0.36 of metribuzin, mixed with 0.125 of fluazifop-p-butyl
in a randomized block design with three repetitions. Weeding was performed at 15 and 30 dap in all cases. Results.
Root yield was not affected in any of the three experiments. Experiment 1: Only halosulfuron caused mild damage to the plants; no herbicide affected above-ground biomass production. Experiment 2: Only linuron and metribuzin applied at 15 and 30 dap caused mild damage. Experiment 3: The mixtures caused temporary damage to the plants. Conclusions. The evaluated herbicides were selective to the Criollo sweet potatoes, and did not affect the yield of
marketable storage roots. Only halosulfuron caused mild damage in all application forms, and metribuzin and linuron
only in late applications.

Zinc oxide supplementation as a substitute to antibiotics in pigs (Sus scrofa domestica)

Cristian Barría, Richard Mudarra, Reggie Guerra — Tue, 09 Jan 2024 00:00:00 -0600

Introduction. There is a high human concern about resistance to antibiotics due to their inappropriate use as growth promoters in animal husbandry. Objective. To evaluate the effect of a high level of zinc as a substitute to antibiotics in nursery pigs. Material and methods. The study was carried out from June to August 2022 in the province of Chiriqui, Panama. The experimental period consisted of three phases with 14 days each. The nursery pigs (n= 54) were distributed to one of three treatments with six replicates per treatment and three pigs per replicate. The treatments were: 1) control diet, which was formulated to meet the nutritional requirements for nursery pigs; 2) similar to treatment 1, plus 200 mg of amoxicillin /kg of feed and 40 mg of florfenicol /kg of feed during phase 1 (P1) and phase 2 (P2), respectively; and 3) similar to treatment 1, plus 2000 ppm and 1600 ppm of zinc during P1 and P2, respectively. In phase 3 (P3), all pigs were fed a common diet. Results. The supplementation of zinc improved the average daily gain in all phases. Pigs fed zinc diet had better F:G ratio in P2 compared to pigs fed antibiotic diet (p<0.05). A higher concentration of hemoglobin and percentage of monocytes was found in pigs fed with higher level of zinc than the other treatments. (p<0.05). Furthermore, Pigs fed the antibiotic, or the control diet had a lower percentage of fecal dry matter compared to those supplemented with zinc. (p<0.05). Conclusion. The supplementation of high levels of zinc exerted improvements, in comparison to the antibiotic, in terms of hemoglobin concentration, incidence of diarrhea and weight gain in pigs during 42 days after weaning.