Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The cultivation of maize is important in the Argentine subtropics. The Subtropical Corn Improvement Programs of the IIACS-CIAP-INTA, seeks the improvement of yield and other characters of interest, seeking more efficient methods. The objective was to evaluate the potential of the "cryptic hybrids" method, determining the genetic gains of first cycle hybrids (HC1), through yield analysis (RTO), prolificacy (PRO), weight thousand seeds (P1000), stalk broken (QUE%), stalk lodging (AC%), anthesis-silking interval (ASI), ear height (EH) and plant height (PH). Two experiments were carried out, the first with cycle 0 hybrids and cycle 1 hybrids (HC1), determining the gains achieved, these were high for RTO (1,841.3 kg.ha-1), QUE% and EH. The second experiment evaluated the HC1 in four environments, from the IIACS-CIAP-INTA in the department Leales Tucumán (LE), Finca El Manantial de la FAZ-UNT Tucumán (MA), Los Altos, Catamarca (LA) and El Palomar, Santiago del Estero (PA), in which the HC116 stood out for RTO and stability, in addition other hybrids with specific site adaptation were found. This methodology was found to have good potential for use in breeding programs.

Air temperature is a key variable in a wide range of environmental applications, including land–atmosphere interaction, climate change research and hydrology and crop growth models, among others. The objective of this study was to estimate daily maximum (Tmax) and minimum (Tmin) temperatures, based on MODIS AQUA/TERRA land surface temperature (LST), NDVI, extraterrestrial solar radiation and precipitation data. Artificial neural networks (ANN) and random forests (RF) models were developed to predict these temperatures covering weather stations in Córdoba (Argentina) for 2018-2020. The results show that RF and ANN machine learning algorithms are capable of modeling non-linear relationships between registered temperatures and LST MODIS data, in a very robust way. The validation of the models confirms that Tmax and Tmin can be accurately estimated using, jointly or separately, AQUA and TERRA LST. The best models present determination coefficients equal to 0.81/0.91 and root mean square error of 2.7/2.1 ºC for Tmax/Tmin, when using AQUA LST day/night satellite overpass time data, respectively. The robustness and confidence of the models developed, and the ease and free accessibility of input data at a global scale, suggest that these methodologies have the potential to be applied to other regions.

El objetivo del estudio fue analizar el aporte ambiental hacia la calidad del río Torres considerando la remoción de contaminantes fisicoquímicos y microbiológicos de la planta de tratamiento de aguas residuales (PTAR) Los Tajos. Se realizó el análisis de datos fisicoquímicos y microbiológicos de las aguas de afluente y efluente de la PTAR (DBO, DQO, SST, STT, N-NH4+, P-PO43-, GyA, SAAM y coliformes fecales principalmente) y se analizó la variación en concentración de contaminantes en el río Torres previo y posterior a la construcción de la PTAR, que realiza un tratamiento primario a las aguas, todo asociado a la estacionalidad. Los datos se analizaron en R versión 3.6.1. Según la metodología del índice holandés, el río Torres se clasificó severamente contaminado previo a la construcción de la PTAR, y actualmente aumenta su grado de contaminación después de la descarga de la PTAR, principalmente en época lluviosa. La PTAR presenta remoción significativa para siete de los ocho parámetros analizados, los porcentajes de remoción más representativos son: SST (68.5 %), DBO (49.8 %) y GyA (54.7 %). Se demostró el aporte cuantitativo de la PTAR al río Torres removiendo toneladas de contaminantes de las aguas residuales desde el 2015 hasta el 2020, principalmente DQO (26,791.8 Mg), SST (24,162.6 Mg), DBO (12,290.0 Mg) y STT (30,267.7 Mg). Finalmente se dejó en evidencia la necesidad de construir las siguientes etapas de la PTAR que incluyen tratamiento secundario, que mejoraría la remoción de materia orgánica, surfactantes y nutrientes.

Among the main limitations for the production of amaranth, various species of phytophagous insects are pointed out. The objective of this study was to contribute to the knowledge of the herbivore species and its natural enemies associated with this crop, determining density, times of appearance and their relationship with the phenological stages. To obtain specimens of phytophagous and predators, weekly samplings were carried out, from emergence to physiological maturity of the crop in experimental plots of Amaranthus hypochondriacus located in the School Field of the Faculty of Agricultural Sciences, National University of Córdoba in the agricultural campaigns of the years 2016, 2017 and 2019. Parasitoids were obtained from Lepidoptera larvae. The insect community consisted of 5 orders, 21 families and 40 species. Coleoptera showed the highest abundance of specimens. The importance of the defoliating caterpillars Achyra similalis and the two species of borers Conotrachelus histrio and Aerenea quadriplagiata was highlighted due to their presence and abundance in the reproductive stage of the crop. From Lepidoptera larvae, six species of parasitoids (Hymenoptera and Diptera) were obtained. Mainly associated with small caterpillars and colonies of aphids, six species of predators were also recorded (Coleoptera, Hemiptera and Diptera).

Large amounts of lignocellulosic residual biomass are generated annually in La Rioja province (Argentina). We have performed a survey to identify crop residues and agro-industrial by-products in the province, which could be suitable for oyster mushroom culture. We characterized their morphological composition and estimated a proxy of the mass that is generated annually by each of them. We have also evaluated the availability of the biomass by assessing the processing, distribution, seasonality, cost and other common uses that may compete with its application as substrate. Eight residual crops and eight agro-industrial by-products were identified, being olive and grape pomace the most abundant, followed by grape pruning, and olive and jojoba litter. These last two in addition to Prosopis bran and olive pits, did not register use as a substrate for the production of oyster mushrooms. In biological efficiency (BE) assays with commercial strains of Pleurotus species we recorded BE ranging from 28% to 72% depending on the substrate and fungal species. In a context of high quality food production deficit and nutritional problems related to it, this province has an interesting potential to introduce the production and consumption of oyster mushrooms as a feasible solution for food supply regional.

The aim of this work was to identify genetic resistance to charcoal rot (Macrophomina phaseolina) in soybean germplasm from the National Breeding Program of the Instituto Paraguayo de Tecnología Agraria (Paraguayan Institute of Agricultural Technology). During two seasons, 51 commercial and experimental lines from the local breeding program were field evaluated in Itapúa-Paraguay. The lines were planted in single rows previously infested, using a completely randomized block design with four repetitions. The charcoal rot severity was evaluated in the stems and roots at the physiological maturity stage. On a Root and Stem Severity index scale of 1-5, the median severity for the 34 early maturity genotypes was 1.5 and 1 in 2017/2018 and 2018/2019, respectively. Nine genotypes (AG-6525 xi, SP14041, SP14222, SP14583, SP15013, SP15133, SP15218, SP16020, and SPB-14146) were rated as resistant (1) in both evaluations. The median severity for the 15 semi-early genotypes was 2 and 1 in 2017/2018 and 2018/2019, respectively. This study allowed us to identify previously unreported sources of resistance to charcoal rot in maturity group IV, V and VI. We believe that germplasm screening under field conditions is a viable alternative to identify breeding lines which are less sensitive to charcoal rot.

This work assessed the difference between daily reference evapotranspiration rate (ETo) calculated by the Penman-Monteith method (PM) with the complete set of meteorological variables and that obtained using only thermal records and a constant surface velocity (u2) of 2 m s-1 (PMxn),employing meteorological data from the weather stations Río Cuarto Aero (RC), Marcos Juárez Aero (MJ), Pilar Observatorio (PI) and Villa Dolores Aero (VD) between 1968 and 2018. The difference between ETo rates resulting from PM and PMxn increases linearly with the increase in u2, so that the use of PMxn should be restricted only to places and days with lower u2. The annual ETo values obtained with both procedures show a fluctuation between 1968 and 2018, with decreasing values until the 1990s, when rainfall shows maximum records in the region, and increasing since then. While the thermal amplitude (AT) in PI, MJ and RC shows a fluctuation analogous to ETo, in MJ u2also exhibits a fluctuation in phase with ETo and in VD only u2 presents the long-term variation concurrent to ETo. Solely RC showed an increasing linear trend of ETo.

This study aimed to analyze the chemical composition and the antioxidant and antimicrobial activities of Laurus nobilis L. essential oil (LEO) and its fractions obtained by short-path molecular distillation. According to the chemical composition, it can be said that LEO and its fractions proved to have antioxidant activity sinceboth have a high content of total phenolic content (TPC). Short-path molecular distillation was used to separate essential oil fractions with superiorantioxidant activity. Laurel residue (LR) exhibited the greatest antioxidant activity, with higher values of trolox equivalent antioxidant capacity with ABTS radical cation (TEAC-ABTS) assay and TPC. In addition, LR had the lowest value of IC50-DPPH. For antimicrobial activity, all natural products tested had an effect on all foodborne pathogenic microorganisms. LEO, as well as its fractions, showed antimicrobial, bacteriostatic, or bactericidal activity against Gram-positive and Gram-negative bacteria. The LEO and its fractions obtained by molecular distillation can be used as antimicrobials and as food preservatives to prevent oxidation. Also, consumers considered the addition of LEO or its fractions in food products as positive.

In Argentina, current regulations establish four years of yield evaluation for any new commercial bread wheat cultivar. The objective of this work was to determine the optimum number of years of evaluation in comparative yield trials of bread wheat cultivars, conditioning this optimum to the quality group, growth cycle and phytosanitary management. Variance components (REML) were estimated from the data of the bread wheat cultivar evaluation network of Argentina (RET), corresponding to ten experimental sites. The three quality groups (GC1, GC2 and GC3), the first and third sowing season (E1 and E3), and management with and without fungicide (CF and SF) were considered. The results show that three years of trials are required to evaluate the performance of the different quality groups and growth cycles managed CF. For SF, four years are required, except for GC1 in E3 and GC2 in E1, which demand three and more than five years, respectively. These results indicate that the current standard is appropriate for most cases; it could even be reduced to three CF, to improve trial quality and increase the number of repetitions.

The expansion of the agricultural frontier causes losses of biodiversity and native genetic resources, affecting the sustainability of the ecosystem. The presence and diversity of cyanobacteria are considered to be bioindicators sensitive to land use change. The objective of this work was to characterize the communities of cyanobacteria present in the soils in the northeast of the province of Córdoba, comparing soils with implanted pastures and in pristine conditions. Soil samples were taken in three locations, in environments with different levels of salinity: mild, moderateand saline. The samples were cultured in Watanabe medium, under controlled conditions to promote the growth of cyanobacteria. An Olympus BX 50 optical microscope was used for taxonomic identification. It was possible to identify the species of cyanobacteria present at each site, observing a dominance of heterocyst nitrogen fixators in soils with higher salinity. In turn, in the three native forest present at each site, greater species richness was observed. The most sensitive to the change in land use being Oscillatoria limosa and Phormidium constricta. Cyanobacteria constitute a future line of research related to the restoration and productive recovery of saline environments, under the focus of sustaining biodiversity.