The University of Córdoba, the Faculty of Agricultural Sciences and IBAC have once again fulfilled their mission of disseminating scientific knowledge and contributing to the development of the agricultural sector. The proceedings of these papers will be published in volume 27 of the journal Temas Agrarios, the natural organ of dissemination of the Symposium. Likewise, participation in the III International Symposium and IV National Symposium on Agronomic Sciences, to be held Agronomic Sciences, which will be held in 2023. | La Universidad de Córdoba, la Facultad de Ciencias Agrícolas y el IBAC, han cumplido nuevamente con su misión de difundir el conocimiento científico y contribuir con el desarrollo del sector agrícola. Las memorias de estos trabajos se publicarán en el volumen 27 de la revista Temas Agrarios, órgano natural de difusión del Simposio. Así mismo, se invita a la participación del III Simposio Internacional y IV Simposio Nacional de Ciencias Agronómicas, que realizaremos en el 2023.

The reproduction process of Apis mellifera L. (Hymenoptera: Apidae) occurs in defined congregation areas where natural mating occurs and males and unfertilized queen bees from different colonies converge. This work focused on the identification and characterization of a congregation drone zone in a biogeographic region of the low montane dry forest corridor, in the upper Andean valley of Sugamuxi-Tundama, for the density of bee colonies established there, considering the climatic factors of the environment and the description of biometric characters of bees and drones collected, and which constitutes the first report of a congregation zone for Colombia. In the study area, dry summer periods predominate alternating with short winter, cloudy days, and intense cold, with thermal sensations between 8 to 19°C. The drone movement route was established with an unmanned flight vehicle, through the interaction between the vehicle and bee specimens. The path of movement of drones was established operated between 10 and 60 m in North-South direction. Specimens of worker bees were collected identifying African, European, or Eastern European lines and drones of two types, yellow and black, evaluating biometric parameters and estimating the discriminant factor. The activity of the drones, occurs in two periods of 10:00 to 12:00 hours and 15:00 to 17:00 hours, flying regularly between round trips up to a 1 km radius. This work describes a methodology for monitoring congregation areas and consolidates itself as a tool for beekeepers for the conservation of regional ecotypes through bee reproductive planning.

The medicinal Cannabis crop is one of the main growing agricultural activities in Colombia. However, the increase in production areas and the intensification of crops brings a greater predisposition to pests and diseases incidence. The objective of this research was to identify the main diseases associated with a high-density commercial Cannabis crop in a greenhouse. Samples of disease symptoms present in the crop during a round year of production were characterized. Samples were taken in different phenological phases and areas of the farm such as: propagation areas, field production and post-harvest. A total of 43 samples were collected among diseased tissue, soil, compost, substrates, and water. "Damping off" was present in the highest percentage of samples collected from cuttings (28%), followed by samples affected with leaf spot chlorotic halo symptoms (19%). 26 pure isolates of phytopathogenic fungi were obtained, and morphologically and molecularly characterized causing diseases in the crop. They were consistent with Botrytis cinerea (8%), Sclerotinia sclerotiorum (15%), Fusarium sp. (46%), Bipolaris sp. (12%), Rhizoctonia solani (8%) and Corynespora casiicola (8%). Symptoms associated with "Damping off" or wilt tissues revealed the presence of Rhizoctonia solani causing strangulation and cutting rot at the base. Three species of Fusarium were reported: Fusarium fujikuroi, Fusarium oxysporum and Fusarium graminearum, the latter associated with stem end rot. Leaf spot associated with Bipolaris sp. and Corynespora casiicola was present at a high incidence.

The crop of medicinal cannabis has developed great importance in recent years in Colombia and other Latin American countries. Considering the production characteristics of the crop, which is fundamentally based on organic models, it is important to know the microorganisms that accompany the production system and their possible implications for management. In this research were isolated and characterized the microorganisms in the different phases of production of a high-density cannabis crop: planting, or propagation areas, production areas, and postharvest areas (flower pre-drying). In each area samples of soil, substrates and water were taken and the microorganisms present were identified by direct sowing in culture media, using microscopic identification and molecular characterization. A high diversity was found in all production areas, and it was evidenced that beneficial microorganisms (Trichoderma spp. and Bacillus spp.) applied to the production system regulate the populations of microorganisms in the soil and in the substrates. It was identified that perlite and coconut fiber allow the development of populations of phosphorus solubilizing and nitrogen fixing microorganisms and that the production of compost using crop waste is safe at a sanitary level. No populations of pathogens were identified in any of the samples evaluated at levels that could explain the presence of diseases in the crop.

A greenhouse experiment was carried out to evaluate the mycorrhizal response of seedlings of cocoa (Theobroma cacao variedad FSV-094) to the application of different mycorrhizal inoculum. A complete randomized experimental design was used, with four treatments: three commercial mycorrhizal multispore inoculum, Ab (Glomus spp, Scuttellospora spp y Entrophospora spp), Bs (Glomus spp, Acaulospora spp, Entrophospora spp, y Scutellospora spp) y Bl (Rhizophagus irregularis, R. clarus, R. aggregatus, R. proliferum y Claroideoglomus etunicatum), and the negative control (without inoculation), each treatment was established in the same soil that was adjusted 0.02 mg L-1 of phosphorus (P). Shoot and root dry weight (SDW & RDW), mycorrhizal colonization, leaf P content, and mycorrhizal response were measured. The results indicated that all the inoculum showed colonization, the best treatments were Ab and Bs with values of 27 and 28% respectively. Although there were no significant differences, the Ab and Bs treatments always had higher values in terms of SDW (3,4 y 3,7 g) and leaf P (0,25 y 0,2%). Regarding to mycorrhizal response, it was found that when inoculated with Bs and Ab the response was moderate (25 - 50%), and with Bl marginal (≤ 24%). The use of commercial AMF can lead to a differential response to T. cacao variety FSV-094. Therefore, it is suggested to carry out an evaluation of the mycorrhizal inoculum in relation to the genotype before massively using it to produce cocoa seedlings under greenhouse.

Mango production presents challenges, such as the maturation of the mango branches, which, combined with good nutrition and biochemicals involved in this process, such as carbohydrate and starch favor the development of the plant. Therefore, the use of non-destructive, fast techniques to determine the levels of these components in the plant, such as spectroscopy, can optimize the analysis of these components. Therefore, this work aimed to develop predictive models for determination of starch and carbohydrate contents in “Palmer” mango leaves using vis-nir spectroscopy subjected to different potassium sources. The work was carried out in the region of San Francisco Valley, using the following steps: (1) leaf sampling; (2) spectral analysis; (3) lab determination of carbohydrate and starch contents; and (4) development of predictive regression and classification models. The predictive regression models used were Principal Components Regression (PCR) and Partial Least Squares Regression (PLSR). Supervised discriminant models were also developed to classify mango leaves according to different potassium sources used, using linear discriminant analysis (LDA). Vis-NIR spectroscopy showed low values for the non-destructive evaluation of “Palmer” mango leaves using PCR and PLSR for carbohydrate and starch prediction with R2 of 0.58 lower than the models considered excellent (R2 >0.90); The development of classification models did not allow the discrimination of different sources of potassium in “Palmer” mango leaves with an accuracy of 64.2%.

Grown in different regions of Brazil, mango is of great importance at the national level. However, mango cultivation is directly related to physiological factors such as photosynthesis, stomatal conductance and chlorophyll. Physiological factors are related to the nutritional balance of the plant. Among the nutrients, potassium (K) can be highlighted, which, despite not being a structural element for the plant, stimulates, or is part of several physiological plant processes. Therefore, an experiment was carried out with the purpose of evaluating, in the vegetative period of 'Palmer' mango, the effect of different sources of K to accelerate the maturation stage of mango branches and verify their influence on physiological indexes and chlorophyll. Treatments consisted of three ripeners and a control, which were applied directly to the branches and leaves of “Palmer” mango trees. The variables analyzed were chlorophyll A, B and Total indexes; Internal concentration of CO2; Stomatal conductance; transpiration rate; Net photosynthesis; Instantaneous Carboxylation Efficiency and Water Use Efficiency. After collecting, and analyzing the data, it was concluded that the vegetative period of the “Palmer” mango tree, in relation to the different evaluation dates, was not influenced by potassium sources. The use of T4 treatment (SpeedFol® induction mango) can provide a greater increment of chlorophyll A, B and Total than KCl and K2SO4.

The goldenberry, Physalis peruviana L., is an important fruit in Colombia due to its export value and nutritional quality. However, commercial crops face challenges of fruit heterogeneity and the presence of diseases that reduce fruit yield and quality. These drawbacks could be handled through different breeding methods to develop uniform cultivars, for example, through anther culture, which is used to rapidly produce homozygous lines. However, the ploidy level may change when using this technique. Therefore, in this study, the level of ploidy of parental and the plants obtained by anther culture was determined by cytogenetics, flow cytometry, and single-simple repeat or microsatellites (SSR).Additionally, the homozygous condition of obtained plants and the degree of heterozygosity of parental plants were evaluated using SSR. Cytogenetic analysis showed parental plants with 48 chromosomes and anther culture generated plants with 24, 32 and 48 chromosomes, and mixoploids and average nuclear DNA content between 5.04 and 20.08 pg. Diploid, tetraploid, hexaploidy, and octoploid plants were identified by flow cytometry; the highest levels of ploidy (6x and 8x) correspond to mixoploid plants found by cytogenetics. The SSRs did not allow identifying ploidy due to the lack of a particular band pattern, however, they showed heterozygosity in most of the plants obtained by anther culture. It was concluded that the anther culture modified the ploidy level with respect to the parental plants, and that flow cytometry is efficient, precise, and less laborious, compared to cytogenetics, to determine the ploidy level of goldenberry in the laboratory.

The biotic interaction between plants and endophytic fungi strengthens the adaptive capacity of the hosts against environmental disturbances, and confers nutrition and protection benefits to the associated microorganisms. Studies associated with endophytic fungi report their presence in the greatest diversity of existing plants. In hosts such as Cannabis, the interaction with endophytic fungi favors the production of secondary metabolites and phytohormones that participate in obtaining organoleptic properties such as flavors and aromas. However, the research carried out in the Vanilla genus is scarce, making it difficult to understand the functions that these microorganisms can perform for the benefit of the host. In relation to Vanilla, the fruits of species within the aromatic clade are distinguished by the presence of aromatic compounds, which increase their content during ripening. Some studies have shown that in the fruits of this orchid there are endophytic fungi possibly associated with the ripening process that is accelerated by curing, but few of these studies have evaluated the activity of these fungi related to the natural ripening of the fruit. In this review, scientific literature related to the knowledge of fungal endophyte communities and their possible contribution to the ripening and production of aromatic compounds in vanilla fruits is compiled. Research opportunities are identified to develop future studies on the role of fungal microorganisms in obtaining metabolites and aromatic precursors from the fruits of Vanilla species, both in wild conditions and in commercial crops.

The high biodiversity can make it difficult to select dendrometric models for each ecosystem. In order to contribute to these models, a relict tropical dry forest of approximately 100 hectares was selected in the valley of the Magdalena River, located in the central region of Colombia. This forest relict is in the municipality of Venadillo, department of Tolima. A sample of 36 trees of different species with a normal diameter greater than 10 centimeters were randomly selected. All trees were measured using a non-destructive method. Diameters with bark were measured on the trunks of the standing trees at different heights from the base of the tree to its commercial height using Field Map equipment and technology. With the information collected, a tree form factor was determined to be used as a forestry decision tool or as an element of comparison with similar ecosystems. The form factor for the calculated commercial volume was 0.8.