Efecto de la actividad microbiana sobre la nitrifiación en suelos cultivados con Brachiaria humidicola (Rendle) Schweicerdt en Cereté, Córdoba

Nitrogen fertilizers used in agriculture have increased the emissions of nitrogen oxides to the atmosphere. This study evaluated the production of NO2 - (nitrite) and N03 - (nitrate) by soilborne bacteria during the dry and the rainy seasons in The Reseach Center Turipaná, Corpoica, (Cereté, Colombia). A split plot desing with three accessions of Brachiaria humidicola (CIAT 16888, CIAT 26159 and CIAT 679), three levels of nitrogen (0, 150 and 300 kg ha-1) and two time of applications (rainy and dry season) were used. Unplanted plots were used as a control. The Most Probably Number (MPN) of bacterial colonies (Log NMP/10g of soil) was assessed in the rainy and dry season. In addition, the speed of nitrite and nitrate production (mg N-NO2- kg-1 day- 1 ) by soilborne bacteria was determined at the beginning (May) and the end of the rainy season (September). The results showed that the number of bacterial colonies were directly proportional to the nitrogen levels. Consequently, the highest number of MPN of bacterial colonies was observed at the highest level of nitrogen (300 kg ha-1). The nitrite and nitrate production was higher in planted plots compared to unplanted plots. However, the higher production of oxides of nitrogen was observed at the beginning of the rainy season. B. humidicola CIAT 26159 showed the highest production of nitrite at the level of 300 kg of N ha-1 compared to the other two B. humidicola accessions and the control in May. In contrast, B. humidicola CIAT679 was more efficient in the nitrite production compared to the other treatments.Los fertilizantes nitrogenados en la agricultura han incrementado las emisiones de óxidos de Nitrógeno a la atmósfera. En este trabajo se evaluó la producción de NO2- (nitrito) y NO3- (nitrato) de microorganismos del suelo durante la época seca y de lluvias, en el Centro Investigación Turipaná de Corpoica, Cereté, Colombia. Se utilizó un diseño de parcelas divididas con bloques completamente al azar, con tres accesiones de Brachiaria humidicola (CIAT 16888, CIAT 26159 y CIAT 679), tres dosis de nitrógeno (0, 150 y 300 kg ha-1), dos épocas de aplicación y tres repeticiones por tratamiento. Parcelas sin cobertura vegetal fueron usadas como control. Se determinó el número más probable (NMP) de colonias de bacterias productoras de nitrito y nitrato en la época seca y lluviosa, se evaluó la velocidad de producción de nitritos, nitratos y nitratos totales (nitritos + nitratos) en la época lluviosa, al inicio (Mayo) y al fial (Septiembre) de la fertilización nitrogenada. El mayor NMP se encontró a 300 kg ha-1 de N y la más alta producción de nitritos y nitratos se encontró en las parcelas sin cobertura. Las accesiones CIAT 16888 y CIAT 279 presentaron las menores producciones de nitratos y nitratos en todos los tratamientos en ambos muestreos. Las accesiones de B. humidicola utilizadas en este estudio redujeron la producción de nitritos y nitratos en condiciones de campo, por lo que constituyen una pastura importante en las estrategias de reducción de emisiones de óxidos nitrosos a la atmósfera

Nematodos fitoparasitos asociados al cultivo de papaya (Carica papaya L.) en Córdoba

The main objective of the present research was to identify phytoparasitic nematodes associated to papaya’s crops in the Córdoba department and link their presence with soil characteristic. Soil and root samples were taken from Tierralta, Valencia, Montelíbano, Montería and Lorica. the samples were evaluated with respect to pH, EC, OM and texture, and morphological and morphometric variables were evaluated to identify nematode genus and species. The genus found were Paratylenchus, Xiphinema, Helicotylenchus, Pratylenchus, Tylenchus, Ditylenchus, Trophurus, Aphelenchus, Psilenchus, Tylenchorhynchus, Criconemella , Hoplolaimus and Meloidogyne , and the species were Meloidogyne javanica , M. incognita y M. arenaria. The pH ranged between 4.6 to 6.9, the CE between 0.097 and 1.4 dS m- 1 , OM between 1.2 and 3,1% and texture was found to be sandy, mixed and sandy-mixed. Sand ranged between 45 and 86%, clay between 3 and 22% and mud between 10.9 and 47%. The correlation analysis found that while sand content favors pH, EC and OM affect negatively the number of phytoparasitic nematodes in the Cordoba department. The results showed for first time the simultaneous presence of M. incognita, M javanica y M. arenaria affecting papaya crops in the Colombian Northern Coast.El presente trabajo tuvo como objetivo identificar los nematodos fitoparasitos asociados al cultivo de papaya ( Carica papaya L) en el departamento de Córdoba y correlacionar las características edafológicas con la presencia de los mismos. Se tomaron muestras de raíces y suelo rizosférico en los municipios de Tierralta, Valencia, Montelíbano, Montería y Lorica, de las que se obtuvieron los diferentes estadíos. De las muestras de suelo se evaluaron el pH, CE, MO y textura. Se evaluaron variables morfológicas y morfométricas para determinar los géneros y las especies. Se encontraron los géneros Paratylenchus , Xiphinema, Helicotylenchus, Pratylenchus, Tylenchus, Ditylenchus, Trophurus, Aphelenchus, Psilenchus, Tylenchorhynchus, Criconemella, Hoplolaimus y Meloidogyne , con las especies; Meloidogyne javanica , M. incognita y M. arenaria. El pH de los suelos varió de 4.86 a 6.9; la CE de 0.097 a 1.4 dS m- 1; la MO de 1.2 a 3.1% y la textura del suelo fue arenosa, franca y franco arenosa. Las arenas oscilan del 45 al 86%, arcilla del 3 al 22% y limo del 10.9 al 47%. El análisis de correlación mostró que el contenido de arena esta correlacionado positivamente; mientras que el pH, la CE y la MO están correlacionados negativamente con la riqueza y el número de individuos de los nematodos fitoparasitos en el departamento de Córdoba. Los resultados permiten el reporte por primera vez de M. incognita, M javanica y M. arenaria afectando conjuntamente el cultivo de papaya en la Costa Caribe Colombiana

Meloidogyne incognita (Kofoid and White, 1919) Chitwood 1949 y Meloidogyne arenaria (Neal 1889) Chitwood 1949: Nematodos de las nudosidades radiculares en Guayaba (Psidium guajava L.) c.v manzana en Montería, Córdoba

The objective of the present research was to identify at the species level and using morphological and morphometric parameters the root-knot nematode present in guava’s crop in Monteria. Samples from roots and ryzospheric soil were taken and the female, male and second stage juvenile larvae (J2) were obtained using the acid sodium hypochlorite-fuscine, mesh centrifuge and egg mass eclossion, respectively. Two types of perineal patterns were observed: the first one with high square dorsal arch, stilettos with 14 to 16 µm, flat and wide nodules and DGO distance of 2 to 4 µm. The males showed a rounded lip disc and centrally concave stilettos with 22 to 25 µm, flat and rounded nodules and a DGO distance of 2 to 4.5 µm, a typical fact of the M. incognita species. The second patterns has low and rounded dorsal arch. The strives form a shoulder, stilettos with 13 to 17 µm, wide and rounded nodules in the posterior zone, the DGO distance was 3 to 6 µm. All this characteristics are typical of the M. arenaria species. The results showed for first time the simultaneous presence of M. incognita and M. arenaria attacking guava’s crop in the Colombian Caribbean Coast.El presente trabajo tubo como objetivo identificar los nematodos agalladores asociados al cultivo de Guayaba ( Psidium guajava L.) en Montería, Córdoba. Se tomaron muestras de raíces y suelo rizosférico. Las hembras, machos y juveniles de segundo estadío larval (J2) se obtuvieron mediante los métodos de hipoclorito de sodio-fuscina ácida, tamizado centrifugado y eclosión de masas de huevecillos, respectivamente. Se evaluaron variables morfológicas y morfométricas para determinar la especie. Se encontraron dos tipos de patrones perineales: El primer patrón con arco dorsal alto y cuadrado. El estilete de 14 μm a 16 μm, los nódulos anchos y planos. La distancia DGO de 2 μm a 4 μm. Los machos presentaron el disco labial redondeado y cóncavo centralmente. El estilete de 22 μm a 25 μm; nódulos planos y redondeados. La distancia DGO de 2 μm a 4.5 μm. Lo cual es típico de la especie M. incognita . En el segundo tipo de patrón, el arco dorsal es bajo, redondeado. Las estrías se curvan ligeramente hacia las líneas laterales y forman una ondulación, conocida como “hombrera”. El estilete midió de 13 μm a 17 μm, los nódulos son anchos y redondeados en su parte posterior. La distancia DGO de 3 μm a 6 μm. Estas características coinciden con las descritas para M. arenaria . Los resultados permiten el reporte por primera vez de M. incognita y M. arenaria afectando conjuntamente el cultivo de guayaba en la Costa Caribe Colombiana

Interannual Variation in Gas Exchange and Leaf Anatomy in <i>Cenostigma pyramidale</i> Is Exacerbated through El Niño and La Niña Climate Events

This study sheds light on the remarkable physiological adaptations that the Cenostigma pyramidale makes, particularly during periods of extreme water scarcity, and their remarkable ability to rebound when a new rainy season arrives. C. pyramidale employs a survival strategy to mitigate the adverse effects of water shortage and then endures challenging environmental conditions and sustaining vital functions. Previously, this species was classified as deciduous since it retained at least 40% of its leaves to sustain basal gas exchange rates. The discrepancy in classification arises from differences in study methodologies, with this research being conducted in the field under natural conditions. This study demonstrates a negative correlation between rainfall and specific leaf area (SLA), highlighting that plants with smaller SLA are more drought-tolerant. Changes in leaf anatomy, including an increase in palisade parenchyma and reduction in spongy tissue, serve as adaptive strategies to enhance photosynthesis under water stress conditions. Hydraulic conductance plays a crucial role in plant adaptation to water scarcity. An intricate interplay between leaf anatomy and hydraulic conductance is observed, with adjustments in xylem characteristics influencing leaf gas exchange. The phenotypic plasticity is high in C. pyramidale, demonstrating the species’ ability to adapt to changing environmental conditions. In summary, this study illuminates the multifaceted strategies employed by plants to cope with water scarcity, from leaf shedding to anatomical and physiological adaptations, highlighting the resilience of native species in arid environments. These findings offer valuable insights into plant responses to environmental stress and their ability to thrive in challenging conditions