Agronomía Mesoamericana

Strategies in developing tropical maize hybrids.

S. K. Vasal — 1994-01-01

The strategies in a hybrid development program should be so oriented to achieve short, medium and long term objectives. The germplasm source utilized is quite important and should possess desirable agronomic traits with good plant and ear height characteristics along with good stalk quality to allow development of good progenitors. To achieve these objectives, it is imperative to introduce new strategies and modifications in the conventional systems to obtain higher efficiency. In this presentation various aspects are discussed relating to germplasm source oriented towards hybrids, integration and introduction of new schemes of population improvement parallel to hybrid development, production of vigorous and productive lines using diversified and efficient strategies, precise characterization of lines in inbred-line evaluation trials, combining ability in crosses with testers, identification of new hybrids during various stages of hybrid development, prediction of new hybrids with less number of single crosses, use of inbred lines in forming new populations as well as heterotic groups and synthetics. Options for developing single cross hybrids to add efficiency in the future are discussed.

Some considerations for the organic production of vegetables.

Floribeth Mora — 1994-01-01

This article is based on a Bibliographical Compilation where the ecosystemic problems, generated by the scientific and technological advances in modern agriculture, are analyzed. The basic principles ruling the organic, bilological, alternative or ecological agriculture are defined, emphasizing the importance of maintaining and improving the soil as the basic component of organic production, adducing that a well nourished plant is most resistant to any plague. Diseases, insects, weeds and nematodes are also mentioned, giving emphasis to practices of integrated plague management.

The phytogenetic resources: an option for the agricultural development in the American Tropics.

Jorge A. Morera — 1994-01-01

The Central American agriculture shows a low productivity in most of the cultivated crops, apparently due to a lack of improved varieties and a reduced used of cultural practices. The Central American region has climatic, topographic, edaphic and social characteristics that could allow a more integral development and exploitation of the autochthonous phytogenetic resources. Nonetheless, in spite of the significance that it has to the farmer and the industry, there is little research and information on the use and of cultural practices of some potential species of American origin. A better knowledge of the genetic diversity, seasonal production, quality, supply and demand of the products, will allow for the preparation of a list of the phytogenetic potential which is still preserved. The most important incentive of any crop is its economic profitability. On this way, the economic factor promotes the basis for developing an increased production, improve quality and open new alternatives to the farmer and the industry. If a new crop is not profitable, it is rejected inmediately; but on the other hand, if a crop is highly profitable, it is almost imposible to restrain its diffusion. The recognition and conscience drawn by the reasonable use of the "genetic resources" on the national, regional and world level, as an essential base for a dynamic and rational agriculture, by far justifies the programs of the countries in the American Tropics to join their efforts in the preservation and promotion of the genetic diversity.

Aerobiology: a new research area.

Jesús Loera — 1994-01-01

A workshop to address the science of aerobiology was held at Michigan State University‘s Kellog Biological Station on October 10-13, 1992. The purpose of the workshop was to bring together scientistis and to our-reach specialists from diverse disciplines to advance the understanding of aerobiology and improve the capability to predict the atmospheric movement of biota. Biota important to agriculture, forestry, human health and the envirommental move in predictable atmospheric transport events. The workshop participants discussed the principles of long-distance atmospheric transport of biota, formulated strategies to share diagnostic technologies and information systems, and concluded that science is positioned to make major advances in forecasting the movement of arthropods, plant viruses, fungi, and bacteria; birds and human allergens. A North American alliance for aerobiology research is being accelerate research advances in the important area of science. Approximately 70 nationally and internationally recognized scientists from agriculture, medicine, engineering, physics, eviromental science, and systems science participated in the workshop. The workshop generated (1) a set of generic foci and scientific hypotheses that will serve as guidelines to conceptualize and direct research in aerobiology, (2) recommendations for networking biological, atmospheric, and other environmental monitoring networks for in forecasting aerobiological transport events, (3) recommendations for utilizing existing electronic networks to link scientistis with agencies and institutions with and tools, (4) recommendations for developing an information database on an electronic comunications network to facilitate access to aerobioogical information, and (5) the establishment of an organizational, structure for the Alliance for Aerobiological Research (AFAR)with a governing board to serve the membership.

Biotechnology and the agricultural field.

Susana Azpíroz — 1994-01-01

This article summarizes how the modern biotechnology techniques can be used as a tool to make the traditional animal and plant breeding methodologies more efficient. The advantages and disadvantages of using these techniques were analyzed at each stage of the selection process of the breeding program. We compared the ease of handling and time saving obtained when the biotechnology component is integrated in the process used by the breeder. The new techniques analyzed were: a- Tissue and organ culture; b- Genetic transformation; c- Molecular genetic markers. Likewise, the current interest of multinational corporations on the potential of the agriculture modified by the biotechnology and the further concentration of knowledge and intellectual rights was analyzed. The importance for the Latin American countries to rule as a group and to share a common criteria in order to legislate in favor of the intellectual rights and biosafty was also emphasized. This legislation would allow a harmonic development of biotechnology among our countries.

Application of zinc nitrate plus chitosan favors carbon assimilation and bean (Phaseolus vulgaris L.) yield

Bryan S. Valencia-Vázquez — 2024-06-13

Introduction. A novel alternative to increase productivity and nutrient utilization is the use of biostimulants such as chitosan, which is a product derived from the exoskeleton of crustaceans and has properties that promote growth and nutrition in crops. Objective. To evaluate the application of zinc nitrate (NZN) plus chitosan on biomass, yield, photosynthetic activity and photosynthetic pigments in green bean plants (Phaseolus vulgaris L.) for consumption of the fresh pod. Materials and methods. The experiment was conducted in a shade house located at the Centro de Investigación en Alimentación y Desarrollo (CIAD), located in Delicias, Chihuahua, Mexico; during the months of August to October 2021. A completely randomized design with eight treatments and four replications was used, where zinc nitrate was applied via foliar at doses of 0, 25, 50 and 100 ppm with and without chitosan at a dose of 50 ppm. Biomass accumulation, yield, in vivo nitrate reductase enzyme activity, photosynthetic activity using Licor 6400 equipment, photosynthetic pigment content, and foliar and fruit zinc concentration were evaluated. Results. The results obtained indicate increases for the biomass variable when applying doses of 50 ppm NZN and 25 and 50 ppm NZN plus chitosan of 37.76 %, 42.39 % and 40.61 % respectively in relation to the control without application, while for yield an increase of 45.22 % was obtained when NZN plus chitosan was applied at a dose of 25 ppm. The application of chitosan individually did not show statistical differences. Conclusions. The application of zinc nitrate plus chitosan increased total biomass production, yield and Zn content in fruit. It also favored photosynthetic activity and parameters related to photosynthetic pigments.

Effect of oil palm compost and sandy soil on the growth of cacao (Theobroma cacao L.) seedlings

Oscar A. Tuesta — 2024-06-13

Introduction. Low-fertility soils and high logistics costs for seedling production characterize the Peruvian Amazon. Objective. To evaluate the effect of a combination of sandy soil and oil palm compost on substrate, growth, and nutrition of cocoa seedlings under greenhouse conditions. Materials and methods. The experiment was conducted for 90 days in Yurimaguas-Loreto using a completely randomized design in a 5x5 matrix, with five doses of Oil Palm Compost and Sandy Soil to determine the best combination for cocoa growth and nutrition. Height (cm), diameter (mm), leaf area (cm2), dry weight of stem and root were measured; soil chemical analysis and plant analysis (macro and micronutrients) were also conducted. Results. Sandy soil showed no significant effect on cocoa seedlings, while treatments with oil palm compost promoted shoot and root biomass. Additionally, this compost favored conditions for seedling growth by promoting higher organic matter, available phosphorus, exchangeable calcium, potassium, and higher cation exchange capacity. Regarding cocoa nutrition, it promoted greater absorption of macro and micronutrients in cocoa seedlings. Conclusions. These results indicate that the best treatment was the one composed entirely of oil palm compost, as it promotes growth and nutrition by improving substrate conditions.

Soil macrofauna in agroecosystems of Coffea arabica L., in Tepec-Xomolth, Nicaragua

Juan Carlos Morán Centeno — 2024-06-13

Introduction. The coffee tree is an item of great importance worldwide, having a direct impact on the economies of countries. In Nicaragua, it represents 25 % of exports. The coffee plant production agroecosystem is made up of components that are found above and below the soil surface. Objective. To estimate the populations of soil macrofauna in productive coffee plantation agroecosystems and their relationship with soil fertility and management practices. Materials and methods. The research was conducted from May to August 2023 in fourteen coffee plantation production systems in the Tepec-Xomolth La Patasta nature reserve. Soil monoliths measuring 25 x 25 x 20 cm were extracted, and three transects were established in each system, separated by 50 m. Specimens collected were identified at the family level. The data were analyzed using descriptive statistics, generalized linear models, hypothesis tests, and diversity indices. Results. Significant statistical differences (p<0.5) were found for rural communities and practices. Soil fertility varied according to the altitude of the farms, with abundant macrofauna in the Nueva Esperanza community (20,672 individuals) and shade management (23,632 individuals). Fifteen orders and 38 families were identified, with the insect class and the trophic group of predators predominating. Diversity was high and stable, a result of the management practices employed by the producers. Conclusions. Taxonomic richness and abundance of macrofauna were similar in the evaluated systems, specifically in the orders Haplotaxida, Coleoptera, Hymenoptera, and Isopoda, where detritivores, omnivores and predators stand out. The study revealed that crop management directly affects soil diversity, indicating that the soils are minimally disturbed and there is ecological balance.

Impact evaluation combining ability of tomato hybrids and lines for production and fruit quality traits

Bassim Almass Essa — 2024-06-13

Introduction. The selection of pure lines followed by crosses to create superior hybrids is one of the oldest strategies in crop breeding. Combining ability studies provide reliable information for selection of parents for hybrid combination by revealing the nature and magnitude of gene actions involved in expression of quantitative traits. Objective. To estimate the General and Specific Combining Ability (GCA and SCA) values for yield in cherry tomatoes and select F1 hybrids combining high yield and fruit quality traits. Materials and methods. The half-diallel design, following method 2 of Griffing was used to define the best breeding method. Five lines were crossed to produce 10 hybrid combinations using a half diallel design involving the parents. Crosses and evaluations were conducted in a greenhouse in the Experimental Station at the University of Diyala, Baqubah, Iraq, in the winter of 2022-2023. Results. Based on GCA effects, lines 'LA353', 'LA3899' and 'IQ2' could be potential donor parents in breeding. Based on average performance, heterosis manifested and SCA effects, crosses IQ2×LA4013, LA3899×LA353 and IQ2×LA3899 were best in respect to yield and fruit quality. Conclusion. The general and specific combining ability values for the majority of the traits supported the material's great variety. The magnitude of heterosis was improved compared to parental lines. The high-yielding parent lines 'LA3899' and 'IQ2' could be used for breeding cherry tomatoes under greenhouse conditions.

Gene expression in Longissimus dorsi and liver in two stages of growth in pigs

Clemente Lemus-Flores — 2024-06-13

Introduction. It is said that genetic expression varies in relation to the physiological stage of the pig and the nutritional source, it is different in muscle and liver. Objective. Identify the genes that present differential genetic expression, through transcriptome analysis in Longissimus dorsi and liver, during growth and final fattening, differentiating them into two stages of pig fattening, growth group (55 ± 1.05 kg) and final group (101 ± 7.8kg). Materials and methods. 12 total samples were considered, three from Longissimus dorsi muscle and three from liver per stage for RNA extraction and sequencing. With the DESeq2 method, the gene expression of the Log2FC was obtained differentially for the Growth Group vs final fattening of Longissimus dorsi and Liver and the biological function of the DEG genes was identified. Results. The largest number of genes with DEG were identified in the liver and on chromosome 6 in Longissimus dorsi and liver. In Longissimus dorsi from the growth group with high expression, the genes FUT1, SESN2 and FGF21 associated with growth and with low expression, NR4A3, PDK4, PER1 and PTPRO involved in immune system processes and circadian rhythm were identified. In the liver of the Growth Group, with high expression, the IHH and MYL7 genes were identified, and with low expression, the genes MFSD2A, LIPG, THBS1, TGFB2, LTF and APOA4 were identified as those most involved in biological processes. Conclusions. In Longissimus dorsi from the growth group the genes were related to growth and in final fattening with immunity, growth and meat quality. In the liver of the growth group the genes were related to growth and in the final fattening group with immunity, growth, nutrient and lipid metabolism, lipoproteins and detoxification.

Influence of mycorrhizal fungi on growth and cadmium adsorption in sunflower (Helianthus annuus L.)

Omar Enrique Cartaya-Rubio — 2024-06-13

Introduction. Heavy metals can accumulate in the soil and affect plant growth. The symbiosis established between plants and arbuscular mycorrhiza-forming fungi (AMF) improves the tolerance of plants to heavy metal toxicity, being considered an alternative for the management of plants grown in soils affected by heavy metals. Objective.To evaluate the effect of different arbuscular mycorrhizal-forming fungi on cadmium absorption and vegetative growth of sunflower (Helianthus annuus L.). Materials and methods. The research was carried out in the years 2021-2023, at the National Institute of Agricultural Sciences (INCA), San José de las Lajas, Mayabeque, Cuba. Sunflower seeds were inoculated with the strains INCAM-4 (Glomus cubense) and INCAM-11 (Rhizoglomus intraradices), at a rate of 45 spores/g, in a soil with high levels of Cd. After 60 days, the plant height, dry weight, chlorophyll content, percentage of mycorrhization and viability of fungal structures and the effect of AMF on cadmium partitioning in sunflower plants. Results. Sunflower plants showed a beneficial response to inoculation with strains of arbuscular mycorrhizal fungi, with a differentiated behavior between the strains and with the greatest effects obtained in growth, biomass production and in the phytoextraction process with the INCAM- strain. 11, by increasing the concentration of metal in the plants to 8.01 mg kg-1 and an infection percentage of 60% and visual density 5.01. Conclusions. Arbuscular mycorrhizae increased cadmium absorption and vegetative growth of sunflower.

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

Gabriel Garbanzo-León — 2024-04-11

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.

Molecular identification of microorganisms in agriculture, ornamental and forest crops in Costa Rica, 2009-2018. Part 2

Mónica Blanco-Meneses — 2024-06-13

Introduction. The identification and detection of microorganisms using molecular techniques has become a very helpful tool for the disease diagnosis, and other microorganisms present in crops. Pathogenic, non-pathogenic organisms, biological controllers, and other microorganisms used as competitors, antagonists, or mutualists can be isolated from agriculture, ornamental, and forest crops. Objective. Taxonomically identify, using molecular techniques, pathogenic and non-pathogenic bacteria and yeast isolated in agriculture, ornamental, and forest crops in Costa Rica and preserve the material in a DNA bank. Materials and methods. Between 2009 and 2018, the Molecular Techniques Laboratory, at the Plant Protection Research Center, Universidad de Costa Rica, received a total of 181 isolates of bacteria and yeast for detection by end-time and real-time PCR; and identification through sequencing of specific regions. Results. Of the total samples, 94.2 % were analyzed by sequencing and 5.8 % by PCR. Using PCR, bacteria species were identified in rice, such as Burkholderia spp., Acidovorax avenae, and Pseudomonas fuscovaginae. Through sequencing of the partial 16S region, 172 samples of bacterial species were identified, and five samples of yeast species with the ITS region of the 18S ribosomal RNA. Microorganisms isolated from eighteen species of agricultural, ornamental, and forest plants were identified. The genera most identified were Pseudomonas, Bacillus, and Enterobacter, and in the case of yeast Candida, Pichia, and Wickerthamomyces. Conclusion. This research allowed us to taxonomically identify bacteria and yeast from crops in Costa Rica. In addition, a consultation input is developed, and the possibility of future use of the microorganisms that are preserved at the DNA bank.

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

José Andrés Rojas-Chacón — 2024-04-11

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.

A theoretical approach to energy requirements in guinea pigs (Cavia porcellus)

William Armando Tapie — 2024-04-23

Introduction. In some countries of the Andean region, interest in guinea pig breeding (Cavia porcellus) is growing due to the potential that the meat of this species has to contribute to food security. With the genetic improvement that has been carried out in guinea pigs, animals with high productive yields have been obtained. However, these achievements have not been accompanied by studies on the net energy requirements of guinea pigs. Objective. To make a theoretical estimation of the energy requirements for maintenance and weight gain in guinea pigs. Development. Using bibliographic information on energy nutrition in rabbits and guinea pigs, an approximate calculation of energy requirements for weight gain and maintenance in guinea pigs was established. For this, an animal with an initial weight of 0.3 and a final weight of 1.2 kg with an average gain of 13 g/day was considered. It was found that studies on energy in guinea pigs for meat production are given in energy densities, mostly in digestible energy (DE) in kilocalories per kilogram of dry matter of food, whose values were between 2700 and 3000 kcal/kg and to a lesser extent of metabolizable energy. According to theoretical calculations, for an animal weighing 0.75 kg on average, the requirements for DE for maintenance and gain were 92.8 and 49.34 kcal/day, respectively. With a diet of 3000 kcal of DE in the food, the animal must consume 47.38 g of dry matter to meet its total requirements. Conclusion. The energy requirements found from theoretical calculations were coherent for guinea pigs bred for meat production from a biological point of view.

Weeds or segetal vegetation? A concept proposal for their agroecological management

Robin Gómez-Gómez — 2024-06-13

Introduction. The perception that native vegetation in crop fields are plants that do not contribute to production in cropping systems, and therefore must be eliminated in their entirety, has caused multiple agronomic, environmental, and social problems in agroecosystems around the world, such as selection of herbicide-resistant plants, contamination of water bodies, loss of biodiversity, increase in pest insect populations, and impact on the health of agricultural workers due to the intensive use of herbicides. Objective. To provide basic information on the origin of weeds in agriculture, the biological characteristics that make them harmful to human activities, and their ecological functions in the agroecosystem, as well as to propose the application of the concept of functional biodiversity for the agroecological management of weeds in crop fields. Development. At this time of change towards agricultural production with less use of pesticides, weed management continues to be a great challenge. To ensure that integrated weed management advances towards agroecological strategies that allow a reduction in the use of herbicides, it is necessary to promote the beneficial biotic interactions that naturally regulate weeds. The study and application of functional biodiversity in agroecosystems then emerges as a need to manage vegetation in such a way that the negative effects of weeds on crops are minimized and the agroecosystem services of weeds are maximized. Conclusion. The differentiation between weeds and segetal vegetation as part of an agroecological management of cropping systems would make it possible to maintain a positive productivity-biodiversity balance in the agroecosystems.

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

Luz Barrantes-Aguilar — 2024-04-11

Introduction. Sustainable practices are important tools for mitigating and adapting to climate change, making it essential to understand the factors influencing rice producers’ decisions to adopt conservation practices in their production system. Objective. To determine the causal relationships between variables that explain the adoption of conservation practices by rice producers. Materials and methods. A study was conducted between July and September 2021 in rice production systems in Costa Rica, involving producers from the Brunca, Chorotega, Huetar, and Central Pacific regions through quota sampling. A survey was administered to a total of 67 rice producers. The research was quantitative, identifying degrees of adoption of conservation practices, performing cluster groupings, and using an ordered probit model was to analyze the factors influencing the intensity of adoption of conservation technologies or practices in these production systems. Results. Greater adoption of conservation practices in rice production systems was influenced by the producer’s level of education, membership or affiliation with organizations in rice sector, and land ownership. Conclusions. The design of strategies for conservation practice in rice cultivation benefits from a better understanding of the relationships between socioeconomic, productive, and environmental variables, which can increase the likelihood that a producer will implement and maintain these conservation practices over time.

Bioformulated to maintain the viability of rhizobacteria and their application in Theobroma cacao L. CCN-51

Hayron Fabricio Canchignia Martínez — 2024-06-13

Introduction. The use of bioformulated plant growth-promoting rhizobacteria is an alternative to reduce the dependence on pesticides in agriculture, due to their pathogen biocontrol and nutrient solubilizing action. Objective. To evaluate the effect of bioformulates on the cell viability of rhizobacteria and their effect on T. cacao L. Materials and methods. The research was developed out from January to December 2020 in the laboratories Microbiology and Molecular Biology of the State Technical University of Quevedo and in the farm "Ignolia", La Maná, Ecuador. The potential characteristics to be considered as a rhizobacteria were evaluated; identification of the chiA gene by Polymerase Chain Reaction; the effect of bioformulates on the cell viability of rhizobacteria and their application in the field to evaluate productivity and phytosanitary status of T. cacao. Results. Rhizobacteria had the capacity to solubilize of nutrients, producers of hydrolytic and biofilm-generating enzymes. Eighty percent of the strains presented the chiA gene, with antifungal activity against pathogenic fungi. The BIOQPGPRs bioformulated with A. calcoaceticus, E. asburiae, S. marcescens, P. protegens and P. veronii showed greater cell persistence (1.83E+5, 1.80E+5, 1.63E+5 and 1.63E+5) during the 26 days. Its edaphic application and injection in the rainy season increased leaf emissions with 100 and 108, and reduce the incidence of Phytophtora spp. and its edaphic application of the bacterial consortium improve dry grain yield (1270.6 kg/ha). Conclusions. BIOQPGPRs preserved rhizobacteria with cell viability for 26 days. Its field application increased the number of foliar emissions, the reduction of Phytophthora spp. incidence on pods and crop yield.

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

Miller Eduardo Otero-Gómez — 2024-04-11

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.

Ethnobotanical knowledge, potential and geographical distribution of the mortiño (Vaccinium floribundum Kunth) in the high Andean paramo, Colombia

Johanna Nataly Oliva Burbano — 2024-04-23

Introduction. The mortiño (Vaccinium floribundum Kunth) faces significant genetic erosion due to anthropogenic pressure in the páramos, leading to the gradual loss of traditional knowledge about species in these ecosystems. In Colombia, the lack of specific records has hindered the identification of associated species, as well as the understanding of the distribution and living conditions of this plant in the territory. Objective. To build a model of geographical and potential distribution of the mortiño, quantify plant diversity, analyze associated species, and explore the uses and importance of the species in its life context. Materials and methods. A participatory action research methodology was implemented, using surveys, interviews, field trips with the community, and participatory workshops. ArcGIS 10.5 and MaxEnt 3.4.4 were employed to develop distribution maps. Biological diversity indices, such as Shannon-Weiner and Simpson, along with the importance value, were determined to assess species richness. The study was conducted in the El Encano district, Nariño-Colombia, during the year 2021. Results. The community emphasizes the use of mortiño in traditional food and medicine. Twenty-one associated species were identified, with the fern (Blechnum loxense (Kunth)) being the most significant. The distribution of V. floribundum is primarily attributed to favorable climatic conditions, with temperatures between 8 and 16 °C and an altitudinal gradient of 2800 to 3200 m above sea level. Conclusions. The study reveals two ecosystems conducive to mortiño: the high Andean forest and the páramo. The importance value index highlights the fern as the most representative species associated with mortiño, providing valuable information for the conservation and sustainable management of these ecosystems in the region.

Use of RPAS for precision evapotranspiration in rice fields and water consumption reduction

David Junior Quispe-Tito — 2024-04-11

Introduction. Estimating crop evapotranspiration (ETc) helps determine water requirements, enabling the proposal of irrigation techniques that save water. Objective. To use remotely piloted aircraft system (RPAs) for greater precision in measuring evapotranspiration in rice fields, aiming to reduce water consumption. Materials and methods. The study utilized a randomized complete block design with a factorial structure of two experiments: flooded irrigation (E1) and irrigation with controlled drying (E2), and three rice varieties (IR43, IR71706, Sahod Ulan 12). The study was conducted at the Experimental Irrigation Area (AER) of the Universidad Nacional Agraria La Molina, Peru. Eight RPAS flights were carried out between January and February 2019, distributed between the tillering and cotton point stages. Results. The combined analysis of treatments using analysis of variance (ANOVA) 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 the rice varieties. Maximum values of ETc and yield were obtained for E1 at 4.50 mm/ day and 10389 kg/ha, and for E2 at 3.7 mm/day and 9710 kg/ha, respectively. Conclusions. The use of a remotely piloted aircraft system improved the temporal and spatial resolution of multispectral and thermal images, providing greater accuracy in crop evapotranspiration (ETc) under two irrigation regimes. Controlled drying irrigation resulted in a A 24% reduction in ETc, allowing for a water saving of 855 m³/ha.

Genotype/environment interaction and yield stability in advanced lines of Topito pepper

Julio Ernesto Muñoz-Falcon — 2024-06-13

Introduction. The Topito type sweet pepper (Capsicum chinense Jacq, sinense Murray) is a traditional crop from the Caribbean region of Colombia, which occupies third place among the vegetables cultivated in this area of the country. Objective. To evaluate the genotype x environment interaction and yield stability in nine advanced lines of Topito type sweet pepper obtained within the vegetable breeding program of the Colombian Agricultural Research Corporation (AGROSAVIA) Materials and Methods. In the year 2020, four agronomic evaluation trials were established in the localities of San Pelayo, Córdoba; Sincelejo, Sucre; Suan, Atlántico and Zona Bananera, Magdalena, all located in the Caribbean region of Colombia. For the experiments, a design of complete blocks at random with four repetitions was carried out. As variables for the answer, the yield, the number of fruits per plant, the fresh weight of the fruit and the length of the fruit are considered. Analysis of phenotypic performance stability will be carried out using the methods proposed by Eberhart and Russell and Lin and Binns. Results. The results demonstrated the existence of a significant genotype-environment interaction for variables associated with fruit yield. Through the analysis of the productive behavior of materials in different environments, it was possible to identify the advanced lines L61 and L7 as outstanding genotypes with statistically superior yields (p≤0.05) in the regional test used and with fruit characteristics according to the requirements of the regional fresh consumption market. Conclusions. The L61 and L7 genotypes were the ones that presented the best adaptation to the different environments evaluated and the greatest productive potential, with the Banana Zone environment where the highest yields were achieved with 59.11 t ha^-1 for L61 and with 55.05 t ha^-1 for line 7.

Germination and growth of Porcelia mediocris and Compsoneura trianae in Arosemena Tola, Napo, Ecuador

Ricardo Vinicio Abril-Saltos — 2024-04-11

Introduction. Wild species are important in the ecosystem, and their preservation requires the development of effective techniques. Objective. To determine the in situ and ex situ germination characteristics and field growth of 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, with seeds collected from the primary forest of P. mediocris and C. trianae. Germination tests were conducted in a greenhouse and in the primary forest, measuring seed emergence, tray growth, and performing an analysis of variance between the testing sites. Seedlings were transplanted into three different soil covers at the Amazon Center for Teaching, Research, and Productivity, with measurements taken for height, stem diameter, number of leaves, and survival. Growth curves were created, and an analysis of variance was performed on the final growth measurements among the different soil covers. Results. For P. mediocris, greenhouse-grown plants showed fewer days to the emergence (67.6), but those grown under guabas cover had a greater height (19.45 cm) and germination percentage (70 %) at end of the trial. For C. trianae, plants grown at the collection site had greater height (13.38 cm) and number of leaves at the end of the evaluation. Field growth did not show differences between soil covers, with survival rate of 47 % for P. mediocris and 75 % for C. trianae. Conclusions. P. mediocris showed better germination percentages under guabas cover, while C. trianae exhibited greater growth in the primary forest, with the germination site not affecting post-transplant growth for either species.

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

Betsabe León-Ttacca — 2024-04-11

Introduction. Endophytic fungi (EF) in grapevines (Vitis vinifera) have great potential for agricultural applications and may represent possible biological control agents for vineyards. Objective. To isolate and identify endophytic fungi (EF) from grapevine plants with antibiosis capacity against Botrytis cinerea. Materials and methods. Young and mature branches from forty healthy grapevine plants were collected from seven production lots in the Cañete province, Lima, Peru, during March to May 2022. EF isolation was performed on 702 sections of disinfected tissues using potato dextrose agar (PDA) culture medium, and identification was carried out at the genus level. Secondary metabolites were extracted from twenty-eight EF strains to determine the mycelial inhibition of the pathogen. An analysis of variance (ANOVA) was conducted on the evaluated parameters using the Minitab statistical program. 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 was found in leaves and mature branches. Trichoderma and Alternaria were the most frecuent genera in grapevine plants, with 22.48 % and 21.71%, respectively. Metabolites obtained from the EFVH-01 strain of the genus Cladosporium, and EF-99 and EF-70 strains of the genus Alternaria, had the greatest effect on mycelial inhibition of the pathogen. Conclusions. Strains of endophytic fungi from the genera Cladosporium
and Alternaria showed antibiosis capacity against Botrytis cinerea at the laboratory scale, which could potential biocontrol agents of pathogens in grapevine cultivation.

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

Marisel Ortega-García — 2024-01-09

Introduction. Chickpea has been considered a restricted host species for nodulation, although recent studies describe a greater bacterial diversity associated with the crop to increase the knowledge about this symbiosis in orden to obtain efficient isolates in its contribution. Objective. To characterize and identify an isolate obtained from chickpea plant 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 during the years 2018 and 2020 to demonstrate its effectiveness in crop interaction in the first center. The isolate R3 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 and 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 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 — 2024-01-09

Introduction. Supply chain issues have increased the costs of raw material and reduced the availability of materials for the production of biological control agents. This can result in greater disease pressure and lower yields on farms. Objective. To determine the effect of different amounts of starch and the use of local ingredients in small- and large-scale fermentation processes for Trichoderma harzianum. Materials and methods. The study was conducted in San José, Costa Rica, between 2016 and 2018. Flask experiments were performed to investigate the reduction or elimination of starch in commercial fermentation media. Fermentation vessel trials were conducted to evaluate the effectiveness of an alternative local medium, which included three treatments: 1) commercial medium as a control, 2) 10 % molasses medium, and 3) 10 % molasses 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 resulted in uneven growth during fermentation. Molasses produced approximately half the CFU/mL compared to the commercial medium but exceeded the threshold of 107 CFU/mL used in studies for the biological control of plant pathogens. Results obtained in a commercial-scale fermenter were similar to those of pilot-scale fermentation. Conclusion. Reducing starch content in the commercial medium did not affect growth, but the absence of starch led to solid mycelium clumps. The use of a local molasses-based medium on a commercial scale feasible as long as the required viable spore count for field use is maintained.