Abstract:Disease detection and classification in crops is crucial for the development and growth of the agricultural sector. Traditional techniques and the low technical level applied to crop control generate significant losses for farmers. Computer vision offers solutions in this field; however, current research focuses on using convolutional neural networks (CNNs), which cannot accurately locate the most relevant features in an image. To overcome these limitations, this study proposes a deep learning model based on the Vision Transformers (ViT) architecture to detect and classify early and late blight diseases in potato leaves. This research demonstrates how data augmentation, fine-tuning, and transfer learning techniques can improve the model's performance. The dataset for training and testing was taken from the PlantVillage platform. The report of the proposed model's evaluation metrics reaches an accuracy of 99.18% and an F1 score of 98.7%. The results demonstrate a high level of prediction in potato foliar diseases and evidence of the efficiency of attention mechanisms. It is concluded that the model is an innovative and functional tool for farmers.

Resumen:La detección y clasificación de enfermedades en cultivos es crucial para el desarrollo y crecimiento del sector agrícola. El uso de técnicas tradicionales y el bajo nivel técnico aplicado al control de los sembríos generan grandes pérdidas para los agricultores. La visión por computadora aporta soluciones en este campo, no obstante, las investigaciones actuales se centran en el uso de redes neuronales convolucionales (Convolutional Neural Networks, CNNs), las cuales tienen una limitada capacidad para ubicar de forma precisa las características de mayor relevancia en una imagen. Para superar estas limitaciones, nuestro estudio propone un modelo de aprendizaje profundo basado en la arquitectura de Transformadores de Visión (Vision Transformers, ViT) para detectar y clasificar las enfermedades tizón temprano y tizón tardío en las hojas de papa. En esta investigación se evidencia cómo las técnicas de aumento de datos, ajuste fino y aprendizaje por transferencia permiten mejorar el rendimiento del modelo. El conjunto de datos para entrenamiento y prueba fue tomado de la plataforma PlantVillage. El reporte de métricas de evaluación del modelo propuesto alcanza una exactitud de 99.18% y un puntaje F1 de 98.7%. Los resultados demuestran un alto nivel de predicción en las enfermedades foliares de papa y evidencian la eficiencia de los mecanismos de atención. Se concluye que el modelo se consolida como una herramienta innovadora y funcional para los agricultores.

Abstract Expansion of avocado production areas in Colombia has led to an increased demand for plant propagation material. However, this expansion has exacerbated phytosanitary challenges, particularly root rot disease mainly associated with Phytophthora spp. Therefore, this study aimed to identify Phytophthora species associated with root rot in avocado seedlings within nurseries. Avocado plants exhibiting wilting symptoms were collected from nurseries in the departments of Quindío, Risaralda, and Valle del Cauca (Colombia). Segments of diseased roots were selected, cut, and surface-disinfected, before being planted on Potato Dextrose Agar (PDA) supplemented with antibiotics and fungicides. Microorganism identification was conducted using taxonomic keys and confirmed by molecular techniques employing the identification based on phylogenetic hypothesis, using ITS1-5.8s-ITS2 region encoding for rRNA. Isolates obtained from necrotic avocado roots were identified as P. cinnamomi and P. heveae. The pathogenicity of the isolates was confirmed in avocado seedlings through inoculation, resulting in symptom reproduction. Consequently, this study identified P. cinnamomi and P. heveae as causal agents of root rot in avocado during the nursery stage.

RESUMO: A batata (Solanum tuberosum L.) é uma fonte cada vez mais importante de alimento, de emprego rural e de aumento de renda, contribuindo para a estabilização social do meio rural, principalmente nos países em desenvolvimento. Entretanto, trata-se de uma cultura bastante sensível às doenças, as quais afetam drasticamente a produtividade, além da necessidade de controle elevar o custo de produção e o risco de contaminação ambiental. O objetivo do trabalho foi avaliar o controle da requeima (Phytophthora infestans) da batata cv. Ágata com base no sistema de previsão de doenças Blitecast e sua produtividade de tubérculos em duas safras. Os experimentos foram conduzidos na primavera de 2022 e no outono de 2023, no município de Passo Fundo. Diferentes valores de severidade (VS) acumulada, calculados pelo modelo Blitecast, constituíram os tratamentos VS 18, VS 24 e VS 30, acrescentando o tratamento semanal e a testemunha, sem aplicação. O delineamento foi em blocos casualizados com quatro repetições, sendo cada parcela composta de cinco fileiras de plantas com 3 metros de comprimento. Foram avaliadas a severidade da requeima e a produtividade final de tubérculos. A utilização do sistema de previsão Blitecast para o controle da requeima da batata, permite reduzir o número de aplicações de fungicidas sem afetar a produtividade final de tubérculos. O sistema de previsão deve ser utilizado como ferramenta para o manejo integrado de doenças da batata. RESUMO Solanum L. L alimento renda desenvolvimento Entretanto tratase trata se ambiental Phytophthora infestans cv safras 202 2023 Fundo (VS acumulada 18 2 30 testemunha aplicação repetições comprimento 20 1

ABSTRACT: Potato (Solanum tuberosum L.) is an increasingly important source of food, rural employment, and financial income, contributing to the social stabilization of rural areas, especially in developing countries. However, this crop is very sensitive to diseases, which drastically affect yield, in addition to increasing production costs for their control and the risk of environmental contamination. This study evaluated the control of late blight (Phytophthora infestans) in potato cv. Ágata based on the Blitecast disease forecast system and tuber yield in two growing seasons. The experiments were conducted in the spring of 2022 and autumn of 2023 in the municipality of Passo Fundo. Different accumulated severity values (SV) were calculated by the Blitecast model, which constituted the treatments SV 18, SV 24 and SV 30, in addition to a weekly treatment and a control without application. The experimental design consisted of randomized blocks with four replications, in which each plot had five rows of plants measuring 3 m in length. Late blight severity and the final tuber yield were evaluated. The use of the Blitecast forecast system to control potato late blight allows for a reduction in the number of fungicide applications without affecting the final tuber yield. The forecast system should be used as a tool for the integrated management of potato diseases. ABSTRACT Solanum L. L food employment income areas countries However diseases contamination Phytophthora infestans cv seasons 202 Fundo (SV model 18 2 30 application replications length 20 1

RESUMO A batata-doce é uma raiz alimentar vital, rica em vitaminas, minerais e compostos bioativos. Genótipos que atendam a essas demandas nutricionais são essenciais para combater deficiências de nutrientes e promover a saúde humana. Assim, pressupõe-se a hipótese de que os genótipos de batata-doce diferem na qualidade físico-química e nos compostos bioativos quando avaliados sob as mesmas condições ambientais. Deste modo, este estudo tem como objetivo avaliar a qualidade físico-química e os compostos bioativos em genótipos de batata-doce de polpa alaranjada. O experimento foi conduzido de abril de 2022 a agosto de 2022, na área experimental de Engenharia Agronômica, localizada na Unidade Acadêmica Especializada em Ciências Agrárias (UAECA) - UFRN, em Macaíba, RN, Brasil. Os tratamentos foram compostos por oito genótipos, sendo duas cultivares (BRS Amélia e Beauregard) e seis acessos (Macaíba I, Macaíba II, Macaíba III, Macaíba IV, Ceará-Mirim e Natal I) de batata-doce de polpa alaranjada da coleção didática da UAECA. Após a colheita, foram avaliadas as seguintes características: firmeza, elasticidade, potencial hidrogeniônico (pH), acidez titulável (AT), sólidos solúveis (SS), razão (SS/AT), vitamina C e os compostos bioativos: antocianinas, flavonoides e carotenoides totais. Os genótipos de batata-doce de polpa alaranjada apresentaram características distintas para as variáveis físico-químicas e os compostos bioativos. Devido ao aumento do pH da polpa, as antocianinas foram reduzidas nos genótipos Ceará-Mirim, Macaíba III e Macaíba IV. Os genótipos Macaíba II e Natal I se destacaram quanto à relação SS/AT, flavonoides e antocianinas. Em contrapartida, o genótipo Macaíba III apresentou o maior teor de carotenoides e grande potencial bioativo. batatadoce batata doce vital vitaminas humana Assim pressupõese pressupõe físicoquímica físico química ambientais modo 202 Agronômica UAECA (UAECA UFRN RN Brasil BRS Beauregard IV CearáMirim Ceará Mirim colheita firmeza elasticidade pH, , (pH) AT, AT (AT) SS, SS (SS) SSAT SS/AT (SS/AT) totais físicoquímicas químicas CearáMirim, Mirim, contrapartida bioativo 20 (pH (AT (SS (SS/AT 2

ABSTRACT Sweet potato is a vital food root, rich in vitamins, minerals, and bioactive compounds. Genotypes that meet these nutritional demands are essential to combat nutrient deficiencies and promote human health. Thus, it presupposes the hypothesis that sweet potato genotypes differ in physicochemical quality and bioactive compounds when evaluated under the same environmental conditions. Thus, this study aims to evaluate the physicochemical quality and bioactive compounds in genotypes of orange-fleshed sweet potato. The experiment was conducted from April 2022 to August 2022 in the experimental area of Agronomic Engineering, located at the Academic Unit Specialized in Agricultural Sciences (UAECA) - UFRN, in Macaíba, RN, Brazil. The treatments were composed of eight genotypes, being two cultivars (BRS Amélia and Beauregard) and six accessions (Macaíba I, Macaíba II, Macaíba III, Macaíba IV, Ceará-Mirim, and Natal I) of orange-fleshed sweet potato from the UAECA teaching collection. After harvest, the following characteristics were evaluated: firmness, elasticity, hydrogen potential (pH), titratable acidity (TA), soluble solids (SS), ratio (SS/TA), Vitamin C, and the bioactive compounds: anthocyanins, flavonoids, and total carotenoids. The orange-fleshed sweet potato genotypes showed distinct characteristics for the physicochemical variables and the bioactive compounds. Due to increased pulp pH, anthocyanins were reduced in the Ceará-Mirim, Macaíba III, and Macaíba IV genotypes. The Macaíba II and Natal I genotypes stood out regarding the SS/TA ratio, flavonoids, and anthocyanins. In contrast, the Macaíba III genotype had the highest carotenoid content and great bioactive potential. root vitamins minerals health Thus conditions orangefleshed orange fleshed 202 Engineering (UAECA UFRN RN Brazil BRS Beauregard CearáMirim, CearáMirim Ceará Mirim, Mirim Ceará-Mirim collection harvest firmness elasticity pH , (pH) TA, TA (TA) SS, SS (SS) SS/TA, SSTA (SS/TA) C flavonoids carotenoids contrast 20 (pH (TA (SS (SS/TA 2

RESUMO: A batata-doce é uma cultura importante para a segurança alimentar com mercado mundial em ascensão. Com base nas alterações fisiológicas das plantas em resposta às condições climáticas e à fertilização, este estudo avaliou os efeitos da época de cultivo (período chuvoso e seco) e de doses de P2O5 (0, 50, 100, 200 e 400 kg ha-1) na produtividade total e por classes comerciais, bem como, a composição química das raízes de armazenamento de duas cultivares de batata-doce. A produtividade de raízes tuberosas foi maior na estação chuvosa. As doses ótimas agronômica e econômica foram de 128 e 95 kg ha-1 de P2O5 para a cultivar Canadense. A cultivar Uruguaiana não respondeu a adubação fosfatada, mas suas raízes tiveram maiores teores de matéria seca, lipídios, fibras, açúcares totais e redutores e amido. O cultivo de batata-doce no período chuvoso com doses de até 100 kg ha-1 de P2O5 aumenta a produtividade de raízes em classes de maior valor econômico e com maiores teores de carboidratos. Estes resultados ajudam os produtores a planejarem o plantio e a colheita da batata-doce ao longo do ano e contribui para a gestão da aplicação de fertilizantes fosfatados. RESUMO batatadoce batata doce ascensão fertilização seco PO P P2O 0, 0 (0 50 20 40 ha1 ha 1 comerciais como batatadoce. doce. chuvosa 12 9 ha- Canadense fosfatada seca lipídios fibras amido 10 carboidratos fosfatados ( 5 2 4

ABSTRACT: Sweet potato is an important food security crop, and the world market for this root is on the rise. Based on the physiological changes in plants in response to climatic conditions and fertilization, this study evaluated the effects of the growing season (rainy and dry season) and P2O5 doses (0, 50, 100, 200 and 400 kg ha-1) on total yield, marketable classes yields, as well as chemical composition of storage roots of two sweet potato cultivars. The storage roots yield was greater in the rainy season. The optimum agronomic and economic doses were 128 and 95 kg ha-1 P2O5 for the cultivar Canadense. Cultivar Uruguaiana did not respond to phosphate fertilization, but its storage roots had higher contents of dry matter, lipids, fibers, total and reducing sugars, and starch. Sweet potato cultivation in the rainy season with doses up to 100 kg ha-1 P2O5 increase root yield in marketable size classes in higher economic value and with higher carbohydrate contents. The results can help producers schedule the planting and harvesting of sweet potatoes throughout the year and contribute to the seasonal management of phosphate fertilizer application. ABSTRACT crop rise fertilization PO P O P2O 0, 0 (0 50 20 40 ha1 ha 1 yields cultivars 12 9 ha- Canadense matter lipids fibers sugars starch 10 application ( 5 2 4

RESUMO O presente estudo visou investigar a força de atrito durante o processo de separação da batata do solo, bem como os fatores e padrões que influenciam essa força, além de estabelecer um sistema de teste para medir a força de atrito das batatas. Verificou-se que a massa da batata, a velocidade da manivela e a inclinação da peneira têm um impacto significativo na força de atrito ao longo da superfície da peneira. A interação entre a massa da batata e a velocidade da manivela tem o maior impacto na força de atrito ao longo da superfície da peneira. Além disso, sob os mesmos fatores - massa da batata entre 200-400 g, velocidade da manivela em 200 r min-1 e ângulo inclinado da peneira em 14.7°, a força de atrito das batatas ao longo da superfície com o solo é muito maior do que ao longo da superfície sem solo, variando entre 2,32 e 4,85. Verificouse Verificou se disso 200400 400 200-40 g 20 min1 min 1 min- 147 14 7 14.7° 232 2 32 2,3 485 4 85 4,85 20040 40 200-4 14.7 23 3 2, 48 8 4,8 2004 200- 14. 4,

ABSTRACT This study aimed to explore the friction force on potatoes in the process of potato-soil separation, its influencing factors and laws, and establish a testing system of potato-friction force. It was verified that the potato mass, crank speed, and sieve inclination significantly affected the potato’s friction force along the sieve surface. The interaction of potato mass and crank speed had the greatest effect on the friction force on the potato along the sieve surface. In addition, under the same factors of potato mass of 200~400 g, crank speed of 200 r min-1, and sieve inclination of 14.7°, the friction force of potato along the sieve surface with soil was much greater than that along the sieve surface without soil, ranging between 2.32 and 4.85. potatosoil separation laws potatofriction potatos s addition 200400 400 200~40 g 20 min1, min1 min 1, 1 min-1 147 14 7 14.7° 232 2 32 2.3 485 4 85 4.85 20040 40 200~4 min- 14.7 23 3 2. 48 8 4.8 2004 200~ 14. 4.

Resumen La presente investigación pretende determinar la influencia del corcho granulado en las propiedades físicas, térmicas y mecánicas del bloque de concreto. Se realizaron ensayos de absorción, densidad, contenido de humedad, resistencia a la compresión y conductividad térmica a bloques de concreto elaborados artesanalmente, con sustitución de arena por corcho granulado en 3 % y 5 % en dos grupos experimentales, junto con un grupo patrón. Para el caso de las propiedades físicas, la absorción presentó valores promedio de 9.47 %, 8.23 % y 9.37 % para el grupo patrón (BP) y grupos experimentales (BC3 y BC5), respectivamente. Los valores de densidad aumentaron a medida que se incrementó el porcentaje de corcho, con una densidad de 2088.77 kg/m3 para el grupo con 5 % de corcho. En cuanto al contenido de humedad, los valores fueron disminuyendo desde 13.67 % del BP, 11.87 % para BC3 y, finalmente, 9.23 % para BC5. La propiedad mecánica de resistencia a la compresión presentó variaciones de aumento y disminución con valores de 19.53 kg/cm2 para el grupo BP, 23.10 kg/cm2 para el grupo BC3 y 16.21 kg/cm2 para el grupo BC5. Por último, para el ensayo de conductividad térmica, los resultados disminuyeron según lo esperado, con valores de 0.387 W/mK, 0.3164 W/mK y 0.3036 W/mK para los grupos BP, BC3 y BC5, respectivamente. Estos datos procesados con las pruebas estadísticas mostraron que la incorporación de corcho granulado en el bloque de concreto tiene una influencia significativa en sus propiedades físicas, térmicas y mecánicas.

Abstract This research intends to determine the influence of granulated cork on the physical, thermal and mechanical properties of the concrete block. Absorption, density, moisture content, compressive strength and thermal conductivity tests were carried out on concrete blocks produced in a traditional way, with a substitution of sand by granulated cork at 3 % and 5 % in two experimental groups, in addition to one standard group. In the case of the physical properties, absorption presented average values of 9.47 %, 8.23 %, and 9.37 % for the standard group (BP) and experimental groups (BC3 and BC5) respectively. Density values showed an increase as the percentage of cork grew, reaching a density of 2088.77 kg/m3 for the group with 5 % cork. Respecting moisture content, its values decreased from 13.67 % for BP, 11.87 % for BC3, and finally 9.23 % for BC5. The mechanical property of compressive strength showed variations of increase and decrease with values of 19.53 kg/cm2 for the BP group, 23.10 kg/cm2 for the BC3 group, and 16.21 kg/cm2 for the BC5 group. Lastly, for the thermal conductivity test, the results decreased as expected with values of 0.387 W/mK, 0.3164 W/mK, and 0.3036 W/mK for the BP, BC3 and BC5 groups respectively. These data processed with statistical tests showed that the incorporation of granulated cork in the concrete block has a significant influence on its physical, thermal and mechanical properties.

Resumen Introducción. La producción de banano es una de las actividades económicas más significativas para el país. Sin embargo, enfrenta serios desafíos debido a la presencia de diversos patógenos, entre los más significativos se encuentran los nematodos fitoparásitos que afectan el rendimiento y la calidad del cultivo. El uso de hongos nematófagos (HN) para el control biológico de nematodos es una alternativa para reducir la aplicación de productos químicos en cultivos agrícolas. En Costa Rica existe gran variedad de hongos debido a la diversidad de los suelos, por lo que el aislamiento y la correcta identificación de estos hongos es crucial para determinar su potencial antagonista. Objetivo. Aislar e identificar potenciales hongos nematófagos (PHN) presentes en muestras de suelo de plantaciones de banano de la región Huetar Atlántica. Materiales y métodos. Se analizaron seis muestras de suelo provenientes de cinco cantones de la región Huetar Atlántica de Costa Rica mediante el método de espolvoreado en placas con agar-agua en búsqueda de PHN. Para la selección y purificación de los PHN se utilizaron placas Petri con papa dextrosa agar (PDA), identificando las estructuras morfológicas para el diagnóstico a nivel de género. Los hongos identificados morfológicamente se replicaron y se conservaron en viales con PDA y en aceite mineral a 4°C. Se extrajo ADN de los PHN y mediante amplificación por PCR (Reacción de Cadena de la Polimerasa) y secuenciación de diferentes regiones del genoma (ITS, tef 1-alfa, rpb2 y β-tubulina), se identificaron molecularmente. Resultados. Se aislaron e identificaron doce hongos, entre ellos Trichoderma asperellum, Penicillium steckii, Purpureocillium lilacinum, Fusarium oxysporum, Fusarium sp., Fusarium pseudocircinatum, y Talaromyces sp. Conclusión. El descubrimiento e identificación correcta de PHN subraya la importancia de investigar su aplicación en programas de manejo integrado de plagas, así como la necesidad de evaluar su eficacia y seguridad en diferentes condiciones agroecológicas para maximizar su impacto positivo en la agricultura.

Abstract Introduction. Banana production is one of the most significant economic activities for the country. However, it faces serious challenges due to the presence of various pathogens, among the most significant are plant-parasitic nematodes that affect crop yield and quality. The use of nematophagous fungi (NF) for biological control of nematodes is an alternative to reduce the application of synthetic chemicals in agricultural crops. In Costa Rica there is a great variety of fungi due to the diversity of soils. Therefore, the isolation and correct identification of these fungi is crucial to determine their antagonistic potential. Objective. To isolate and identify the potential nematophagous fungi (PNF) present in soil samples from banana plantations at the Huetar Atlantic region. Materials and methods. Six soil samples from the Huetar Atlantic region of Costa Rica were analyzed by the agar-water sprinkling plates method in search of PNF. For PNF selection and purification, Petri dishes with potato dextrose agar (PDA) were used, identifying morphological structures for diagnosis at genus level. Morphologically identified fungi were replicated and preserved in vials with PDA and in mineral oil at 4°C. DNA was extracted from the isolated PNF and through PCR amplification (Polymerase Chain Reaction) and sequencing of different regions of the genome (ITS, tef 1-alpha, rpb2 and β-tubulin), they were molecularly identified. Results. Twelve fungi were isolated and identified, including Trichoderma asperellum, Penicillium steckii, Purpureocillium lilacinum, Fusarium oxysporum, Fusarium sp., Fusarium pseudocircinatum, and Talaromyces sp. Conclusion. The correct discovery and identification of PNF underscores the importance of investigating its application in integrated pest management programs, as well as the need to evaluate its efficacy and safety under different agroecological conditions to maximize its positive impact on agriculture.

Resumen Introducción. El cultivo de la papa representa una actividad fundamental en la economía costarricense. Desde el 2015, la variedad Elbe-UCR está disponible en la agrocadena de papa, y es considerada como promisoria debido a su alta tolerancia a patógenos, plagas insectiles y condiciones de sequía, así como sus elevados rendimientos (mayores a 40 t ha-1). Pese a lo anterior, no se tienen estudios sobre crecimiento y acumulación de nutrimentos que permitan una mejor planificación de la fertilización del cultivo, con miras a una producción más sostenible. Objetivo. Desarrollar y validar las curvas de acumulación de nutrimentos en la variedad de papa Elbe-UCR, cultivada en la Zona Norte de Cartago. Materiales y métodos. Se recolectaron muestras de la biomasa de la planta cada 15 días después de la siembra (dds), las cuales se separaron en parte aérea, tubérculo y raíz, para determinar su masa fresca y seca, así como su concentración de nutrimentos. Resultados y discusión. La variedad Elbe-UCR acumuló un valor promedio de materia seca de 12016 kg ha-1 a los 135 dds, de los cuales el 70% correspondió a la biomasa del tubérculo. Para un rendimiento de 40 t ha-1, esta variedad acumuló un total de 195, 20, 312, 54, 16, y 20 kg ha-1 de N, P, K, Ca, Mg y S, respectivamente. También, acumuló un total de 336, 123, 6250, 337, y 213 g ha-1 de Zn, Cu, Fe, Mn y B, respectivamente. Conclusión. La variedad Elbe-UCR presentó una gran capacidad de acumulación de Ca y K, y no requiere los niveles altos de N que aplican regularmente los productores en Costa Rica. Los resultados obtenidos en el presente trabajo se consideran básicos para el manejo correcto de la fertilización y desarrollo de formulaciones comerciales para esta variedad, con miras a una producción más sostenible.

Abstract Introduction. Potato crop represents a fundamental activity within the Costa Rican economy. Since 2015, the Elbe-UCR variety has been available in the potato agrifood chain, being considered as promising due to its high tolerance to pathogens, insect pests, and drought conditions, as well as its high yields (greater than 40 t ha-1). Despite this, there are no studies about growth and nutrient accumulation that would allow a better fertilization planning for this potato variety, aiming to attain sustainable production. Objective. To develop and validate nutrient accumulation curves for the Elbe-UCR potato variety, cultivated in the Northern Zone of Cartago. Materials and methods. Biomass samples were collected every 15 days after planting (dap), which were separated into aboveground biomass, tuber, and root, to determine their fresh and dry mass, as well as their nutrient concentration. Results and discussion. The Elbe-UCR variety accumulated an average dry matter value of 12016 kg ha-1 at 135 dap, of which 70% corresponded to the tuber biomass. For a yield of 40 t ha-1, this variety accumulated a total of 195, 20, 312, 54, 16, and 20 kg ha-1 of N, P, K, Ca, Mg, and S, respectively. It also accumulated a total of 336, 123, 6250, 337, y 213 g ha-1 of Fe, Cu, Zn, Mn, and B, respectively. Conclusion. The Elbe-UCR variety showed a great capacity for Ca and K accumulation and does not require the high levels of N regularly applied by producers in Costa Rica. The results obtained in this study are considered fundamental for the management of fertilization and the development of commercial formulations for this variety, aiming for a more sustainable production.

Resumen Introducción. Los parámetros de respuesta fisiológica al estrés por sequía son la conjugación de una serie de atributos de acción lenta o rápida. Las variables de intercambio gaseoso son catalogadas como de respuesta rápida, su nivel de aparición o afección dependen de la interacción entre factores como el genotipo y duración, intensidad y etapa fenológica de ocurrencia del estrés. Objetivo. Identificar los niveles de respuesta fisiológica que presenta Solanum phureja bajo el estrés progresivo por déficit hídrico. Materiales y métodos. El experimento se realizó entre 2019 y 2020, bajo condiciones semi-controladas en el Centro de Investigación Obonuco de la Corporación Colombiana de Investigación Agropecuaria. Se sembraron cuatro cultivares de papa, la mitad del ensayo se mantuvo con riego a capacidad de campo y a la otra parte se le suspendió para inducir estrés por déficit hídrico durante 15 días, luego se rehidrataron; se evaluaron variables de intercambio gaseoso, clorofila y eficiencia fotosintética cada tres días. Resultados. Se presentaron diferencias significativas con los valores máximos de intercambio gaseoso en plantas del tratamiento control con 16,67 µmol m-2 s-1 tasa de fotosíntesis (A); 0,34 mol m-2 s-1 conductancia estomática (gs) 5,5 mmol m-2 s-1 transpiración (E) y en estrés 1,17 µmol m-2 s-1 (A); 0,013 mol m-2 s-1 (gs); 0,29 mmol m-2 s-1 (E). En cuanto al contenido de clorofila, se presentaron valores entre 451,7 y 474,69 mg m-2 con riego y sin riego, respectivamente. Conclusiones. El cierre estomático fue la respuesta más temprana al déficit hídrico, además, las plantas de papa presentaron recuperación de los valores de intercambio gaseoso después del suministro de riego posterior al estrés. Finalmente, se identificaron tres niveles de respuesta fisiológica, estrés leve, moderado y severo, según la intensidad y duración del estrés, lo cual es de utilidad para futuros estudios y planteamientos de calendarios de riego.

Abstract Introduction. The parameters of physiological response to drought stress are the result of a combination of slow- or fast-acting attributes. Gas exchange variables are classified as fast-acting and their level of occurrence or impact depends on the interaction between factors such as genotype and the duration, intensity, and phenological stage of stress occurrence. Objective. To identify the levels of physiological response exhibited by 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 Corporación Colombiana de Investigación Agropecuaria. Four potato cultivars were planted, with half of the trial was maintained at field capacity and the other half subjected to water deficit stress by withholding irrigation for 15 days, followed by rehydration. Gas exchange variables, chlorophyll content, and photosynthetic efficiency were evaluated every three days. Results. Significant differences were observed, with maximum gas exchange values in control plants showing 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 under 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). Chlorophyll content values ranged between 451.7 and 474.69 mg m-2 with and without irrigation, respectively. Conclusions. Stomatic closure was the earliest response to water deficit, and potato plants showed recovery in gas exchange values after rehydration following stress. Finally, three levels of physiological response were identified: mild, moderate, and severe stress, depending on the intensity and duration of stress, which is useful for future studies and the development of irrigation schedules.

Resumen Introducción. Los hongos endófitos (HE) de la vid (Vitis vinifera) tienen un gran potencial de aplicación en la agricultura y pueden representar posibles agentes de control biológico de los viñedos. Objetivo. Aislar e identificar los hongos endófitos (HE) de plantas de vid con capacidad de antibiosis hacia Botrytis cinerea. Materiales y métodos. Se colectaron ramas jóvenes y maduras de cuarenta plantas sanas de vid de siete lotes de producción en la provincia de Cañete, Lima, Perú, durante los meses de marzo a mayo 2022. El aislamiento de HE se realizó de 702 secciones de tejidos desinfectados en medio de cultivo papa dextrosa agar (PDA) y la identificación fue a nivel de género. Se extrajeron metabolitos secundarios de veintiocho cepas de HE para determinar la inhibición micelial del patógeno. Se llevó a cabo un análisis de varianza (ANDEVA) de los parámetros evaluados con el programa estadístico Minitab. Resultados. Se aislaron un total de 129 cepas de HE de hojas y tallos de ramas jóvenes y maduras de vid, que correspondieron a siete géneros (Trichoderma, Aspergillus, Alternaria, Cladosporium, Fusarium, Nigrospora y Stemphylium). La mayor frecuencia se presentó en las hojas y rama madura. Trichoderma y Alternaria fueron los géneros más frecuentes en las plantas de vid con 22,48 % y 21,71 %, respectivamente. Los metabolitos obtenidos de las cepas HEVH-01 del género Cladosporium, HEV-99 y HEV-70 del género Alternaria, tuvieron mayor efecto en la inhibición micelial del patógeno. Conclusiones. Cepas de hongos endofitos del género Cladosporium y Alternaria mostraron capacidad de antibiosis hacia Botrytis cinerea a escala de laboratorio, los cuales podrían ser potenciales biocontroladores de patógenos en el cultivo de vid.

Abstract 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.

RESUMEN El objetivo fue caracterizar genotipos y obtener datos sobre la diversidad genética de batata. El diseño fue en BCA con 26 tratamientos y tres repeticiones. Fueron evaluadas productividad total, rendimiento comercial y no comercial de raíz (t ha-1), número de raíces por planta, biomasa aérea, forma y color de la raíz. La diversidad genética fue obtenida por la medida de disimilaridad media similares y para delimitación de grupos se utilizó el método de dendrograma UPGMA. Como medida de proximidad de distancias se utilizó la medida de disimilitud Euclidiana Cuadrática. La cantidad de clusters fue por el Criterio de Mojena. El mayor número de accesiones fue agrupado en el cluster III, con nueve accesiones, cluster II con seis accesiones, cluster IV, con seis accesiones, cluster VII con dos accesiones y cluster I, V y VII con una accesión cada una. La mayor distancia genética fue entre Morotí Guazú (6) e Ib-019 (23) con 40.443 y los más similares resultaron Morado (3) y Pyta guazú (9) con un valor de 1098. La productividad de raíces es la variable de mayor importancia para la distancia genética. El color predominante de la piel de la colección es crema y color de carne amarillo pálido.

ABSTRACT The objective was to characterize the genotypes and obtain data on the genetic diversity of sweet potatoes. The experimental design was an RCBD with 26 treatments and three replications. It was evaluated total productivity, commercial and non-commercial root yield, number of roots per plant, biomass, root shape, and root color. The estimation of genetic diversity was obtained by the similar mean dissimilarity measure and, the delimitation group by the UPGMA dendogram. As a measure of proximity distances, the Euclidian Quadratic dissimilarity measure was used. and the number of clusters was determined using the Mojena Criterion. The collection was grouped into seven clusters. The highest number of accessions was grouped in cluster III, with nine accessions, cluster II with six accessions, cluster IV, with six accessions, cluster VII with two accessions and cluster I, V, and VII with one accession each. The greatest genetic distance was found between Morotí Guazú and Ib-019 with 40,443 and the most similar were Morado and Pyta guazú with a Euclidean dissimilarity measure value of 1098. Root productivity is the most important variable for genetic distance. The predominant skin color of the collection is cream and pale yellow flesh color.

Abstract Dry rot represents the most destructive disease of cocoyam (Xanthosoma violaceum). The isolation of Pythium myriotylum requires the use of fresh root samples, so specific isolation techniques and selective growth media must be developed. The objective of this study was to evaluate techniques for the isolation of Pythium myriotylum and to determine the pathogenicity of microorganisms associated with dry rot in cocoyam. The efficacy of three isolation methods was assessed: a) soil dilutions, b) roots exhibiting symptoms of dry rot, and c) cocoyam leaves as baits [HQC]. The isolates were placed in different culture media, namely a) potato dextrose agar, b) water agar + streptomycin sulfate, c) V8 + Pimaricin, Ampicillin, Rifampicin and Benomyl [PARB]; and d) tetrazolium chloride medium, for bacteria. The isolated microorganisms were identified using taxonomic keys. The pathogenicity of the isolates was evaluated in a greenhouse setting using with vitroplants of cocoyam Lila. This was done by inoculating the isolates obtained, alone and in combination, to a sterile substrate and a control treatment without inoculation. The Pythium spp. demonstrated mycelial growth with an abundance of fruiting structures when the HQC method and V8-PARB culture media were employed. The pathogenicity test revealed that the combined treatments with P. myriotylum resulted in the manifestation of symptoms indicative of root damage. The combination of soil isolation with cocoyam leaves, and the V8-PARB culture media was the most effective method for the isolation of Pythium myriotylum. This approach resulted in the growth of abundant mycelium that facilitated morphometric identification. P. myriotylum was observed to indice symptoms consistent with dry rot in vitroplants of cocoyam. Inoculation of plants with F. solani and R. solanacearum, either individually or in combination, did not result in the manifestation of symptoms characteristic of dry rot.

Resumen El mal seco es la enfermedad más destructiva del quequisque (Xanthosoma violaceum). El aislamiento de Pythium myriotylum requiere de muestras de raíces frescas; por lo que se deben desarrollar técnicas de aislamiento específicas y medios selectivos. En este estudio, se evaluaron técnicas para el aislamiento de Pythium myriotylum y se determinó la patogenicidad de microorganismos asociados a mal seco en quequisque. Se evaluaron tres métodos de aislamiento: a) diluciones de suelo, b) raíces con síntomas de mal seco, y c) hojas de quequisque como cebos [HQC]. Se colocaron los aislados en diferentes medios de cultivo a) papa dextrosa agar, b) agar agua + sulfato de estreptomicina, c) V8 + Pimaricina, Ampicilina, Rifampicina y Benomil [PARB]; y d) el medio cloruro de tetrazolio, para bacterias. Se utilizaron claves taxonómicas para la identificación de los microorganismos aislados. La patogenicidad se evaluó en invernadero con vitroplantas de quequisque Lila al inocular los aislados obtenidos, solos y su combinación, al sustrato estéril y un tratamiento testigo sin inoculación. Agentes patógenos como P. myriotylum, F. solani y R. solanacearum, fueron aislados. Pythium spp. tuvo un crecimiento micelial con estructuras fructíferas abundantes con el método HQC en V8-PARB. En la prueba de patogenicidad, los tratamientos combinados con P. myriotylum mostraron síntomas de afectación en las raíces. El método de aislamiento de Pythium myriotylum a partir de suelo, con hojas de quequisque y combinado con el medio de cultivo V8-PARB fue el más efectivo, obteniéndose aislados con micelio abundante que facilitaron su identificación morfométrica. P. myriotylum provocó síntomas característicos de mal seco en las vitroplantas de quequisque lila. Las plantas inoculadas con F. solani y R. solanacearum, solos o combinados, no presentaron síntomas de mal seco.

Abstract Endophytic fungi [EF] are microorganisms that reside within plant tissues without causing apparent damage. They play a role in synthesizing growth-regulating substances, nitrogen fixation, protection against pathogens, and other benefits for plants. In this study, we evaluated the capacity of Indole Acetic Acid [IAA] production and phosphate solubilization in four strains of EF isolated from roots of Araucaria Araucana, and assessed their effect on the growth promotion of Nicotiana tabacum, as a model plant. Fungi were identified as Phialocephala fortinii (strain E-1), Penicillium melinii (strain E-13), Umbelopsis dimorpha (strain E-14), and Preussia cymatomera (strain E-36). The concentration of IAA was determined using the Salkowski method using potato dextrose broth [PDB] supplemented with 10 mg L-1 L-tryptophan, as a precursor for IAA synthesis. The yield was expressed in mg L-1. The capacity of phosphate solubilization was determined in Pikovskaya solid medium through the evaluation of halos formed in the medium and calculating the relative solubilization efficiency ratio [RSE]. Finally, we evaluated the effect of EF in a co-culture with N. tabacum seedlings under in vitro conditions measuring aerial and root biomass of the seedlings. The highest values for IAA and RSE were observed in the case of U. dimorpha (52.29 and 3.36 mg L-1, respectively). All fungi used promoted the growth of both aerial and root biomass of N. tabacum plants under in vitro conditions, obtaining the highest production of total dry biomass (aerial and root) with U. dimorpha, with a value of 188.5 mg, which was significantly higher (p < 0,01) than that of control plants (8.85 mg). Our findings suggest that EF isolated from A. araucana has the potential to promote plant growth and provide benefits to plants through the production of phytohormones.

Resumen Los hongos endófitos [HE] son microorganismos que viven dentro de las plantas sin causar daño aparente, y colaboran en la síntesis de sustancias reguladoras del crecimiento, fijación de nitrógeno, protección contra patógenos, entre otros beneficios para las plantas. En este estudio se determinó la capacidad de producción de ácido indol acético [AIA] y de solubilización de fosfato, en cuatro cepas de HE aislados desde raíces de Araucaria araucana y se evaluó su efecto sobre la promoción del crecimiento en Nicotiana tabacum, utilizada como planta modelo. Los hongos fueron identificados como Phialocephala fortinii (cepa E-1), Penicillium melinii (cepa E-13), Umbelopsis dimorpha (cepa E-14) y Preussia cymatomera (cepa E-36). El AIA fue determinado utilizando el método de Salkowski, usando caldo de papa dextrosa [CPD] suplementado con 10 mg L-1 de L-triptófano, como precursor para la síntesis de AIA, y la producción fue expresada en mg L-1. La solubilización de fosfato fue determinada en medio sólido Pikovskaya, evaluando los halos formados en el medio y calculando el índice de eficiencia relativa de solubilización [ERS]. Finalmente, la estimulación del crecimiento vegetal por los HE en un co-cultivo con las plántulas de N. tabacum, en condiciones in vitro, fue evaluada a través de la producción de biomasa aérea y radicular de las plántulas. Los mayores valores de AIA y ERS fueron obtenidos con U. dimorpha (52,29 y 3,36 mg L-1, respectivamente). Los hongos utilizados promovieron el crecimiento de la biomasa aérea y radicular de las plantas de N. tabacum en condiciones in vitro, obteniéndose la mayor producción de biomasa seca total (aérea y radicular) con U. dimorpha, con 188,5 mg, valor significativamente mayor (p < 0,01) que el de las plantas control (8,85 mg). A través de este estudio se infiere que los HE aislados de A. araucana promueven el crecimiento vegetal y brindan beneficios para las plantas mediante la producción de fitohormonas.

Abstract Chimborazo province is one of Ecuador's main potato (Solanum tuberosum L.) production areas, where crop nutrition management is a key factor limiting yield. This study aimed to determine the Nitrogen Use Efficiency (UEN) and the Nitrogen (N) rates needed to achieve yield goals for the Superchola and INIAP-Natividad potato varieties. Field experiments were conducted using a split-plot design with three replicates in two potato growing areas (Cortijo Bajo and Chañag) of Chimborazo province in Ecuador, from May to November 2016. The variables evaluated were total plant N recovery and total tuber yields, which were used to calculate Nitrogen Agronomic Efficiency (AEN) and the N fertilizer rates needed to reach the yield goals for these potato varieties. Results indicated that the increase in potato yield consistently diminished as N fertilizer rates increased, with a clear quadratic function response for the two varieties. The AEN for the Superchola variety ranged from 130 to 160 kg of tuber kg-1 of applied N, while the AEN for the INIAP-Natividad variety ranged from 120 to 150 kg of tuber kg-1 of applied N. These values determined the N fertilizer rates required to achieve the yield goals in the following potato production cycle for the fertilizer recommendation domain: 120 kg-1 N ha-1 and 80 kg-1 N ha-1 for Superchola, and 80 and 110 kg-1 N ha-1 for INIAP-Natividad in Cortijo Bajo and Chañag, respectively. The study concluded that calculating the AENeffectively adjusts N fertilization recommendations for potato crops under the soil and climatic conditions studied.

Resumen La provincia de Chimborazo es una de las zonas de mayor producción de papa (Solanum tuberosum L.) en el Ecuador y el manejo de la nutrición del cultivo es uno de los limitantes para alcanzar altos rendimientos. El objetivo de la presente investigación fue determinar la eficiencia de uso del nitrógeno (EU.) y las dosis de nitrógeno (N) necesarias para llegar a la meta de rendimiento de las variedades de papa Superchola e INIAP-Natividad. Los experimentos se implementaron bajo un Diseño de Parcela Dividida con tres repeticiones en dos localidades paperas (Cortijo Bajo y Chañag) de la provincia de Chimborazo-Ecuador, desde mayo a noviembre del año 2016. Las variables evaluadas fueron extracción de N y rendimiento total de tubérculos, con las cuales se calcularon la eficiencia agronómica de N (EA.) y las dosis de fertilización nitrogenada necesarias para las dos variedades de papa evaluadas. Los resultados indicaron que el aumento en rendimiento del cultivo de papa fue consistentemente menor a medida que se incrementaron las dosis de N con una clara respuesta cuadrática para las dos variedades. La EA. de la variedad Superchola varió entre 130 y 160, mientras que la EA. de la variedad INIAP-Natividad entre 120 y 150 kg de papa kg-1 de N aplicado; estos valores de EA. permitieron determinar la dosis de fertilización nitrogenada (120 kg-1 N ha-1 y 80 kg-1 N ha-1 para Superchola y 80 y 110 kg-1 N ha-1 para INIAP-Natividad en Cortijo Bajo y Chañag, respectivamente) que serán necesarias para lograr la meta de rendimiento en el siguiente ciclo de siembra de papa en el correspondiente dominio de recomendación de fertilización. Se concluye que el cálculo de la EA. permite ajustar efectivamente las recomendaciones de fertilización nitrogenada para el cultivo de papa bajo las condiciones edafo-climáticas estudiadas.