Abstract Yerba mate (Ilex paraguariensis St. Hil.) is a species native to the subtropical regions of South America. Despite being an important crop for the region, there are few studies on the use of microorganisms to improve the growth of seedlings in the nursery stage. The objective of this study was to isolate spore-forming endophytic bacteria with plant growth promoting properties associated with yerba mate seedlings and determine their phytobeneficial effect under controlled laboratory conditions. Isolates were selected based on their sporulation capacity and evaluated for in vitro plant growth promoting properties (nitrogen fixation, phosphate solubilization, production of siderophores and synthesis of indolic compounds). Yerba mate seedlings were inoculated with the most promising isolates, which were identified via analyses of the sequence of their 16S rDNA gene as Bacillus circulans (12RS3) and Bacillus altitudinis (19RS3, T5S-T4). After 120 days plants showed higher root dry weight when inoculated with isolate 19RS3 and higher shoot dry weight with 19RS3 and T5S-T4. In conclusion, further studies to determine the ability of these isolates to adapt to the climatic conditions and to survive amidst the native soil microflora in yerba mate cultivated native soils, will be crucial for developing such strains as biofertilizer.

The aim of this research was to isolate and characterize Tríchoderma native strains from Misiones (Argentina) exploring their antagonistic capacities to phytopatogens fungi and their mass multiplication using different agricultural wastes. Fifteen native strains of Tríchoderma spp. were isolated from soil samples. These isolates were characterized via morphological observations and molecular phylogenetic analysis based on DNA sequences of the rDNA internal transcribed spacer region. The Tríchoderma native strains were identified as T. koningiopsis, T. harzianum, T. pleuroticola and T. brevicompactum. All strains showed antagonistic activities in vitro against Alternaría sp., Fusaríum sp. and Botrytis sp. T. koningiopsis LBM 090, LBM 091, LBM 092, and LBM 098 strains, T. pleuroticola LBM 097 and T. harzianum LBM 096 presented radial mycelial growth inhibition higher than 50% and antagonism index between 3 and 4 against the phytopathogens assayed. Among the different substrate sources evaluated, rice husk and rice polishing were the most suitable combination for mass multiplication of T. harzianum LBM 096.

El objetivo de esta investigación fue aislar y caracterizar cepas de Tríchoderma nativas de Misiones (Argentina) explorando sus capacidades antagónicas y su multiplicación masiva utilizando diferentes residuos agroindustriales. Quince cepas nativas de Tríchoderma spp. fueron aisladas de muestras de suelo. Estos aislamientos se caracterizaron mediante observaciones morfológicas y moleculares basados en secuencias de ADN de la región espaciadora transcrita interna del ADNr. Las cepas de Tríchoderma spp. fueron identificadas como T. koningiopsis, T. harzianum, T. pleuroticola y T. brevicompactum. Estas cepas mostraron actividades antagónicas in vitro contra Alternaría sp., Fusaríum sp. y Botrytis sp.. T. koningiopsis LBM 090, LBM 091, LBM 092 y LBM 098, T. pleuroticola LBM 097 y T. harzianum LBM 096 presentaron una inhibición del crecimiento micelial mayor del 50% y un índice de antagonismo entre 3 y 4 contra los fitopatógenos ensayados. La cáscara de arroz y el pulido del arroz fueron las combinaciones más adecuadas para la multiplicación de T. harzianum LBM 096.

This study presents a germination chamber built for a water hydroponic system provided with a fuzzy logic based controller. The system was built based on an Arduino electronics platform where the fuzzy control program and telemetry systems lie. Also, all data from sensors are stored for future studies. The telemetry system sends the data obtained by the embedded system to two computers, one conected via a USB (Universal Serial Bus) and the other conected via BT (Bluetooth). In both cases data are stored in virtual disks. The results show that the germination chamber built has better performance than the conventional floating root system.

Este estudio presenta una cámara de germinación construida para un sistema hidropónico de agua provisto de un controlador basado en lógica difusa. El sistema fue construido sobre la base de una plataforma electrónica Arduino, donde residen los sistemas de programas de control y telemetría difusos. Además, todos los datos de los sensores se almacenan para futuros estudios. El sistema de telemetría envía los datos obtenidos por el sistema a dos ordenadores, uno a través de un USB (Universal Serial Bas) y el otro a través de BT (Bluetooth). Todos los datos se almacenan en discos virtuales. Los resultados muestran que la cámara de germinación construida tiene mejor rendimiento que el sistema de raíz flotante convencional.