Search

Resumen El éxito de un bioproducto a base de microorganismos depende de que la formulación sea adecuada para su uso y estable en condiciones de almacenamiento. En este contexto, se evaluó la estabilidad de cuatro sistemas de liberación para la formulación de conidios del hongo antagonista Trichoderma asperellum Samuels, Lieckfeldt & Nirenberg (polvo mojable, gránulo cubierto, gránulo dispersable y concentrado emulsionable). La estabilidad de los prototipos almacenados a 4 °C y 30 °C fue evaluada durante seis meses mediante la determinación de características microbiológicas y fisicoquímicas. Los productos almacenados a 4 °C fueron más estables que los almacenados a 30 °C; presentando estos últimos una pérdida total de la germinación después de seis meses de almacenamiento, con excepción del polvo mojable (WP) que mantuvo su germinación por encima del 80%. Dentro de los sistemas de entrega, el polvo mojable fue el prototipo más estable, manteniendo una germinación de conidios mayor al 85% y una viabilidad de 1x108 unidades formadoras de colonias por gramo (UFC/g). Esta formulación además mantuvo las propiedades fisicoquímicas dentro de los estándares de calidad cuando fue almacenada bajo condiciones de refrigeración. Abstract The success of a microorganism-based bio product depends on an appropriate formulation for use, stable under storage conditions. In this context, four delivery systems were evaluated for the formulation of conidia of the antagonist fungus Trichoderma asperellum (wettable powder, coated granule, dispersible granule and emulsifiable concentrate). The stability of the prototypes stored at 4ºC and 30ºC was assessed for six months by determining microbiological and physicochemical characteristics. The products stored at 4ºC were more stable than those stored at 30ºC, the latter presenting a total loss of germination except for the wettable powder (WP), which presented a germination of over 80% after six months of storage. Within delivery systems, wettable powder was the most stable prototype, maintaining conidia germination above 85% and viability in 1x108 colony forming units per gram (UFC/g). This formulation also maintained all physicochemical properties within quality standards, when stored under refrigeration.

Se evaluó el efecto de 3 enmiendas líquidas en la fertilidad de un Ultisol, cultivado con maíz bajo condiciones de invernadero. El estudio se realizó en macetas de 1,0 y 0,5 l de suelo proveniente de Orosí, Cartago, con acidez intercambiable de 4,64 cmol.l-1, a partir de enmiendas líquidas de Cal 56 (C56) y Surkal (SK) y el carbonato de calcio en polvo mojable Surflow Calcio (SC), diluidas en agua y aplicadas en 2 dosis cada una. Se realizaron análisis de pH y acidez intercambiable en diferentes momentos durante un período de 61 días después de aplicadas (dda) las enmiendas, en macetas sin plantas. También se realizaron análisis de fertilidad a los 45 días después de la siembra, y se llevaron a cabo mediciones de altura de las plantas, largo de las raíces y peso seco de la biomasa del maíz, en macetas con plantas. La aplicación de las enmiendas C56 y SK disminuyó la acidez intercambiable y elevó el pH en forma proporcional a la dosis durante los primeros 14 dda. A partir de los 27 días la acidez empezó a subir y el pH a bajar. Con el SC la acidez se mantuvo baja y el pH alto durante todo el período de evaluación debido que se aplicó una dosis mayor que las enmiendas líquidas. La fertilidad del suelo mejoró con la aplicación de enmiendas, principalmente en los tratamientos de SC. La aplicación de enmiendas incrementó la altura de las plantas, longitud de las raíces y el peso seco de la biomasa del maíz. El SK produjo mayor acumulación de materia seca aérea, sin embargo, con el producto C56 se determinó una mayor densidad longitudinal de raíces. Se concluye que las cales en presentación líquida pueden disminuir la acidez del suelo de manera rápida con un efecto residual superior a los 61 días, siendo una alternativa potencial para etapas fenológicas críticas bajo condiciones de invernadero. The effect of 3 liquid amendments on ultisol fertility, cultivated with corn under greenhouse conditions was evaluated. The study was conducted in 1.0 and 0.5 l pots containing soil from Orosi, Cartago, with exchangeable acidity of 4.64 cmol.l-1, using liquid amendments Cal 56 (C56) and surkal (SK), and calcium carbonate in wettable powder Surflow calcium (SC), diluted in water and applied in 2 doses each. Soil pH and exchangeable acidity analyses were made at different times over a 61-days period after lime application (daa), in pots with no plants soil fertility analyses were also done at 45 days after planting, and measurements of plant height, root length, and dry corn biomass weight were taken in pots with plants. The application of SK and C56 amendments decreased exchangeable acidity and increased pH in proportion to the dose during the first 14 daa. Soil acidity began to rise and pH started to drop at 27 daa. Soil acidity was low and pH was high throughout the evaluation period with SC treatment because this lime was applied at a higher dose than liquid amendments. Soil fertility improved with liming application, mainly with the SC treatments. Amendment application increased plant height, root length, and dry corn biomass weight. SK produced higher aerial dry matter accumulation; however, with C56 a greater longitudinal root density was determined. It is concluded that liquid lime can reduce soil acidity rapidly with more than 61 days residual effect, being a potential alternative for critical growth stages in crops under greenhouse conditions. UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro de Investigaciones Agronómicas (CIA) UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Agronomía

Wettable powder formulations by microencapsulation of viral occlusion bodies (OBs) of both Spodoptera frugiperda multiple nucleopolyhedrovirus from Colombia (SfCOL) and a genotypic variant (SfCOL-A) were evaluated for controlling the fall armyworm S. frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in maize crops. Microencapsulation preserved OBs activity after three months of storage at 35ºC, where insecticidal activity loss was not greater than 12%. Additionally, the formulation protected the OBs against inactivation caused by UV-B radiation, retaining its insecticidal activity after 6 hours of UV laboratory exposure, in contrast to unformulated viral suspensions, which presented an Original Activity Remaining (OAR) between 12.1 and 50%. Under greenhouse conditions, the insect mortality was greater than 80% with microencapsulated viruses. In field trials, treatments reduced the percentage of damaged plants to levels below the economic injury level (35%) when the formulated and unformulated virus were applied at 8x1011 OBs/ha (800g/ha) dose, while the damage in the control treatment was close to 60%. Microencapsulation of SfCOL and SfCOL-A OBs provides useful advantages related to half-life and photostability of both viruses, which showed the same efficacy under field conditions. Wettable powder formulations by microencapsulation of viral occlusion bodies (OBs) of both Spodoptera frugiperda multiple nucleopolyhedrovirus from Colombia (SfCOL) and a genotypic variant (SfCOL-A) were evaluated for controlling the fall armyworm S. frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in maize crops. Microencapsulation preserved OBs activity after three months of storage at 35ºC, where insecticidal activity loss was not greater than 12%. Additionally, the formulation protected the OBs against inactivation caused by UV-B radiation, retaining its insecticidal activity after 6 hours of UV laboratory exposure, in contrast to unformulated viral suspensions, which presented an Original Activity Remaining (OAR) between 12.1 and 50%. Under greenhouse conditions, the insect mortality was greater than 80% with microencapsulated viruses. In field trials, treatments reduced the percentage of damaged plants to levels below the economic injury level (35%) when the formulated and unformulated virus were applied at 8x1011 OBs/ha (800g/ha) dose, while the damage in the control treatment was close to 60%. Microencapsulation of SfCOL and SfCOL-A OBs provides useful advantages related to half-life and photostability.