Revista de la Facultad de Ciencias Agrarias
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Estrategias de manejo para la transición hacia viñedos sostenibles en Mendoza
Get PDFIn fragile irrigated agro-ecosystems like those in Mendoza, with low fertility soils, scarce rainfall and high summer evapotranspiration, climate change will have a significant impact. Agricultural practices with tillage and intensive use of agrochemicals generate serious ecological imbalances. This problem requires the redesign of these systems and a reconsideration of its practices. The Agricultural Experimental Station of INTA Mendoza worked on the transition to vineyard management systems with an agroecological approach. In a demonstrative and experimental vineyard plot, biological corridors and diverse cover crops were established, studying different methodologies of elaboration of compost, compost tea, bio-slurry and their periodic application to the crop. We evaluated alternative technologies for weed control and phytosanitary programs with lower environmental impact. The proposed practices allowed increasing biodiversity of species in the vineyard, improving soil fertility and achieving productive levels close to those of conventional management. In the course of nine agricultural seasons, the sanitary conditions of the vineyard were satisfactorily maintained. Finally, operating costs were close to those of conventional management.En agro-ecosistemas de regadío frágiles como los de Mendoza, con suelos de baja ferti¬lidad, escasas precipitaciones y elevada evapotranspiración estival, el cambio climático tendrá un impacto significativo. Las prácticas vitícolas convencionales mediante labranza y uso intensivo de agroquímicos, profundizan los desequilibrios ecológicos generando serios riesgos ambientales. La problemática requiere de un rediseño de estos sistemas y el replanteo de sus prácticas actuales. En la Estación Experimental Mendoza del INTA se trabajó en la transición hacia sistemas de manejo del viñedo con enfoque agroecológico. En una parcela demostrativa y experimental de vid, se establecieron corredores biológicos y diversos cultivos de cobertura, se estudiaron diferentes metodologías de compostaje y obtención de té de compost, bioles y su aplicación periódica al cultivo. Se ensayaron tecnologías alternativas para controlar malezas y programas preventivos de menor impacto para el control de plagas y enfermedades. Las prácticas propuestas permitieron aumentar la diversidad de especies en el viñedo, mejorar la fertilidad del suelo y alcanzar niveles productivos cercanos al manejo convencional. En el transcurso de nueve temporadas agrícolas, se logró mantener satisfactoriamente las condiciones fitosanitarias. Por último, los costos operativos se aproximaron a los de un manejo convencional
Temperaturas de germinación y dormición de semillas de dos especies de Larrea (Zygophyllaceae) del desierto del Monte, Argentina
Get PDFThe genus Larrea includes five species of desert shrubs distributed along the American Continent. These species produce dormant mature seeds, but the type of dormancy and the factors that produce it have been poorly assessed. The objective of this work was to determine the optimum germination temperatures of L. cuneifolia and L. nitida, to analyze the response to pre-germination treatments, and to evaluate the type of seed dormancy these species have. Seeds were incubated at five constant tempera¬tures and were subjected to mechanical scarification and rinsed with running water to break dormancy. Seed coat permeability and the presence of water-soluble germi¬nation inhibitors were also assessed. The optimum germination temperature range was between 15-40ºC for both species. A positive response to all pre-germination treatments was observed in L. cuneifolia (37-47%), while L. nitida showed higher germination percentage only with mechanical scarification (73%). Both species presented water-permeable seed coats, ruling out the occurrence of a physical dormancy. The inhibitory test of seed-coat extracts was positive for L. cuneifolia, suggesting the possible presence of a chemical dormancy. These results are valuable for conservation purposes and directly contribute to improving production of seedlings required for restoration projects.El género Larrea incluye cinco especies de arbustos desérticos distribuidos a lo largo del Continente Americano. Estas especies producen semillas en estado de dormición, pero el tipo de latencia y los factores que la producen han sido poco estudiados. El objetivo de este trabajo fue determinar las temperaturas óptimas de germinación de dos especies de Larrea, analizar la respuesta a los tratamientos pre-germinativos y evaluar el tipo de dormición de las semillas. Las mismas se incubaron a cinco temperaturas, se sometieron a escarificación mecánica y se lavaron con agua corriente para romper dormición. También se evaluó permeabilidad de coberturas seminales y presencia de inhibidores de la germinación solubles en agua. El rango óptimo de temperaturas estuvo entre 15-40ºC para ambas especies. Se observó una respuesta positiva a todos los tratamientos pre-germinativos en L. cuneifolia (37-47%), mientras que L. nitida mostró un mayor porcentaje de germinación solo con escarificación (73%). Ambas especies presentan semillas permeables al agua, lo que descartó la existencia de una dormición física. El test de inhibidores fue positivo para L. cuneifolia, sugiriendo la presencia de una dormición química. Estos resultados son valiosos para la conservación y contribuyen a mejorar la producción de plantines en proyectos de restauración
Current knowledge and future prospects of lima bean (Phaseolus lunatus)-rhizobia symbiosis
Get PDFLima bean (Phaseolus lunatus) is an important species of the genus Phaseolus for human consumption in tropical regions. The seeds are important source of protein for people from South America, Africa and Mexico. In addition, as a legume plant, lima bean presents the ability to perform the biological nitrogen fixation (BNF) through the symbiosis with nitrogen-fixing bacteria. The studies about diversity and efficiency of lima bean-rhizobia symbiosis have increased worldwide, mainly in Latin America. These studies have shown Bradyrhizobium and Rhizobium as the main symbionts, although Sinorhizobium, Mesorhizobium and Allorhizobium have been found associated with lima bean. Also, there is a large variation in the efficiency of N fixation by the current isolates of rhizobia and some rhizobia have presented high capability for fixing N. This review aims to explore the studies about diversity and efficiency of rhizobia in symbiosis with lima bean.Lima bean (Phaseolus lunatus) is an important species of the genus Phaseolus for human consumption in tropical regions. The seeds are important source of protein for people from South America, Africa and Mexico. In addition, as a legume plant, lima bean presents the ability to perform the biological nitrogen fixation (BNF) through the symbiosis with nitrogen-fixing bacteria. The studies about diversity and efficiency of lima bean-rhizobia symbiosis have increased worldwide, mainly in Latin America. These studies have shown Bradyrhizobium and Rhizobium as the main symbionts, although Sinorhizobium, Mesorhizobium and Allorhizobium have been found associated with lima bean. Also, there is a large variation in the efficiency of N fixation by the current isolates of rhizobia and some rhizobia have presented high capability for fixing N. This review aims to explore the studies about diversity and efficiency of rhizobia in symbiosis with lima bean
Evaluación participativa de la sustentabilidad entre un sistema campesino bajo manejo convencional y uno agroecológico de una comunidad Mapuche de la Región de la Araucanía (Chile)
Get PDFThe purpose of the present study is to assesment the sustainability levels of two peasant agrarian systems (conventional and agroecological) identifying the aspects (factors) that limit and enhance their sustainability. The methodological scheme used corresponded to the MESMIS and the instruments for information recollection were survey and field measurements, direct observations using field records, transects and open dialogues supported by scripts. The definition of indicators and assessment ranges were performed jointly with the peasants (men and women) through various participative methodologies. Results for the agroecological system point out a greater diversity of crops, higher percentage of crop diversity and seed self-production, higher total revenues and less seasonality of such incomes, less dependence on external inputs, higher percentage of recycling/reuse of on-farm resources/waste, greater application of own knowledge and abilities, increased application of agro-ecological technologies and greater participation in decision-making by women. It is concluded that the agroecological system has better levels of sustainability and socioecological performance than the conventional one.El objetivo del trabajo es evaluar la sustentabilidad de dos sistemas agrarios campesinos (convencional y agroecológico) identificando los aspectos que limitan y potencian su sustentabilidad. El esquema metodológico utilizado correspondió al MESMIS y los instrumentos de recolección de la información fueron levantamiento y mediciones en terreno, observaciones directas con ayuda de registros de campo, transectos y diálogos abiertos apoyados con guión. La definición de indicadores y los rangos de valoración se realizó de manera conjunta con las y los agricultores, mediante diversas metodologías participativas. Los resultados señalan, para el sistema agroecológico -en relación con el convencional- una mayor diversidad de cultivos, mayor porcentaje de autoproducción de semilla y material vegetal, mayor ingresos totales y menor estacionalidad de dichos ingresos, menor dependencia de insumos externos, mayor porcentaje de reciclaje y/o reutilización de recursos/ residuos intraprediales, mayor aplicación de conocimiento y habilidades propias, mayor aplicación de tecnologías agroecológicas y una mayor participación en la toma de decisiones por parte de la mujer. Se concluye que el sistema agroecológico presenta mejores niveles de sustentabilidad, por tanto, un mejor desempeño socioecológico que el sistema convencional
Chemical composition and in situ ruminal disappearance of sorghum silages grown in the mexican humid tropic
Get PDFThe purpose was to evaluate the chemical composition and in situ ruminal dry matter disappearance of four types of grain sorghum silages, one brown midrib sorghum (bmr) and, a corn silage, grown under rainfed conditions in a humid tropical region of Mexico. The crops were established at three sites. At harvest, three minisilos per treatment were filled with forage previously chopped. Minisilos opened at 55 days and samples of silage taken to dry and ground to 1 mm to determine the chemical composition and in situ ruminal dry matter disappearance. The crude protein was higher (p<0.05) in sorghum silages than corn silage. In sorghum silages, bmr sorghum had the lowest (p0.05) in ADF and ADL to corn silage. The degradation parameters (a, b, c ) was higher (p0.05) in bmr sorghum and corn silages. In the humid tropics, bmr sorghum silages are a good alternative to corn silage, especially in the dry season.The purpose was to evaluate the chemical composition and in situ ruminal dry matter disappearance of four types of grain sorghum silages, one brown midrib sorghum (bmr) and, a corn silage, grown under rainfed conditions in a humid tropical region of Mexico. The crops were established at three sites. At harvest, three minisilos per treatment were filled with forage previously chopped. Minisilos opened at 55 days and samples of silage taken to dry and ground to 1 mm to determine the chemical composition and in situ ruminal dry matter disappearance. The crude protein was higher (p<0.05) in sorghum silages than corn silage. In sorghum silages, bmr sorghum had the lowest (p0.05) in ADF and ADL to corn silage. The degradation parameters (a, b, c ) was higher (p0.05) in bmr sorghum and corn silages. In the humid tropics, bmr sorghum silages are a good alternative to corn silage, especially in the dry season.
 
Effect of cold stress at cellular and foliar level and regrowth capacity of three Cenchrus ciliaris L. cultivars: Americana, Biloela and Texas 4464
Get PDFBuffelgrass (Cenchrus ciliaris L.) a native pasture species of Africa is widely used in arid regions because of its forage productivity and quality. It could become serious invasive species, not only for crops but also in natural vegetation. Buffelgrass is highly affected by low temperatures at all stages of its life cycle. The objective was to determine the behavior of three buffelgrass cultivars (Americana, Biloela, Texas 4464) under cold stress and define the critical temperatures. To determine the effect of cold stress on the plasma membrane, foliage damage and survival (regrowth), it was evaluated relative electrical conductivity (ECr) of leaves, percentage of foliar damage and the ability of regrowth after exposure to 2 temperatures (-5ºC and -10ºC) with 2 exposure times (4 and 7 hours). The results showed a higher percentage of foliar damage and greater ECr as temperature decreased and hours of exposure increased. A similar response was observed when survival (regrowth) was evaluated. There were no significant differences among cultivars in both temperature treatments and time when the regrowth was evaluated.Buffelgrass (Cenchrus ciliaris L.) a native pasture species of Africa is widely used in arid regions because of its forage productivity and quality. It could become serious invasive species, not only for crops but also in natural vegetation. Buffelgrass is highly affected by low temperatures at all stages of its life cycle. The objective was to determine the behavior of three buffelgrass cultivars (Americana, Biloela, Texas 4464) under cold stress and define the critical temperatures. To determine the effect of cold stress on the plasma membrane, foliage damage and survival (regrowth), it was evaluated relative electrical conductivity (ECr) of leaves, percentage of foliar damage and the ability of regrowth after exposure to 2 temperatures (-5ºC and -10ºC) with 2 exposure times (4 and 7 hours). The results showed a higher percentage of foliar damage and greater ECr as temperature decreased and hours of exposure increased. A similar response was observed when survival (regrowth) was evaluated. There were no significant differences among cultivars in both temperature treatments and time when the regrowth was evaluated.
 
Potencialidades, desafíos y limitaciones de la investigación agroecológica como un nuevo paradigma en las ciencias agrarias
Get PDFThe scientific research applied to the agrarian sciences in the last 50-60 years has generated a highly productive and profitable agriculture, but with great environmental and social consequences. The predominance of a short-term and reductionist approach, which does not take into account social and environmental costs, has resulted in this unsustainable model. A new paradigm in agrarian sciences is required that contemplates and minimizes long-term environmental and social impacts and generates more inclusive agriculture. This new paradigm has 3 interrelated components: a) sustainability, b) complexity and c) uncertainty. Agroecology emerges as that new paradigm and conception of research. From this new paradigm this article reflects on the topics to be investigated, the profile and training of the researchers and the characteristics of the Institutions and if they serve the methodologies designed and commonly used by research and extension.La investigación científica aplicada a las ciencias agrarias en los últimos 50-60 años ha generado una agricultura altamente productiva y rentable, pero con grandes consecuencias ambientales y sociales. El predominio de un enfoque cortoplacista y reduccionista, que no tiene en cuenta los costos sociales y ambientales ha dado, como resultado previsible, este modelo insustentable. Se requiere un nuevo paradigma en las ciencias agrarias que contemple y minimice los impactos ambientales y sociales a largo plazo y genere una agricultura más inclusiva. Este nuevo paradigma tiene 3 componentes interrelacionados: a) la sustentabilidad, b) la complejidad y c) la incertidumbre. La Agroecología surge como ese nuevo paradigma y concepción de la investigación. Desde este nuevo paradigma este artículo reflexiona sobre los temas a investigar, el perfil y formación de los investigadores y las características de las Instituciones y si sirven las metodologías diseñadas y utilizadas comúnmente por la investigación y la extensión
Vineyard zoning of cv Bonarda argentine (Vitis vinífera L.), from Sentinel satellite images and three vegetation indexes
Get PDFThis study describes the results and conclusions obtained from vineyard zoning in Mendoza by using three vegetation indexes (NDVI, EVI and SAVI). Such indexes were calculated from spectral signals received by the Sentinel- A satellite in the days close to the 2017 harvest. With this information, maps from the plot of land with the zoning given by each index were obtained. Based on the NDVI zoning, a stratified sampling was carried out. On each stratum, 14 plants were marked and the production variables total weight of grape per plant, number of grape bunchs per plant and the weight of 50 berries were measured. The results showed that NDVI and SAVI led to similar classifications in terms of vineyard zones (strata), while EVI captures high vigor levels with less sensitivity. There was a correspondence between the production variables and the strata of high, medium and low vigor. The three indexes clearly showed two different vineyard areas in terms of production. Consequently, these indexes may contribute to rationalize viticulture practices, adjusting the intensity of such practices to the characteristics and needs of each of these vineyard areas.This study describes the results and conclusions obtained from vineyard zoning in Mendoza by using three vegetation indexes (NDVI, EVI and SAVI). Such indexes were calculated from spectral signals received by the Sentinel- A satellite in the days close to the 2017 harvest. With this information, maps from the plot of land with the zoning given by each index were obtained. Based on the NDVI zoning, a stratified sampling was carried out. On each stratum, 14 plants were marked and the production variables total weight of grape per plant, number of grape bunchs per plant and the weight of 50 berries were measured. The results showed that NDVI and SAVI led to similar classifications in terms of vineyard zones (strata), while EVI captures high vigor levels with less sensitivity. There was a correspondence between the production variables and the strata of high, medium and low vigor. The three indexes clearly showed two different vineyard areas in terms of production. Consequently, these indexes may contribute to rationalize viticulture practices, adjusting the intensity of such practices to the characteristics and needs of each of these vineyard areas
Effect of environmental factors on bee activity and onion (Allium cepa L.) seed yield
Get PDFPollinators are required to produce onion seeds. This specie is one of the main vegetable crops. Two types of onion varieties are mainly grown worldwide: hybrids and open pollination (OP) cultivars. Although hybrids offer advantages to bulb growers, seed yields of hybrids are lower than OP cultivars and that is a significant problem. The influence of environmental factors (temperature, radiation, rainfall, relative humidity (RH) and wind speed) was determined, as well as bee attraction and seed production in three locations of the main onion seed production area in Argentina. Nine male sterile lines (MSL) and one OP were used. The results obtained showed a marked variability in the attraction of bees and seed production between the OP and MSL and within MLS. In addition, environmental factors such as minimun temperature or RH were determinant to modify bee foraging behavior, where values lower than 9ºC and 22%, respectively, caused that bees stop their activity.Pollinators are required to produce onion seeds. This specie is one of the main vegetable crops. Two types of onion varieties are mainly grown worldwide: hybrids and open pollination (OP) cultivars. Although hybrids offer advantages to bulb growers, seed yields of hybrids are lower than OP cultivars and that is a significant problem. The influence of environmental factors (temperature, radiation, rainfall, relative humidity (RH) and wind speed) was determined, as well as bee attraction and seed production in three locations of the main onion seed production area in Argentina. Nine male sterile lines (MSL) and one OP were used. The results obtained showed a marked variability in the attraction of bees and seed production between the OP and MSL and within MLS. In addition, environmental factors such as minimun temperature or RH were determinant to modify bee foraging behavior, where values lower than 9ºC and 22%, respectively, caused that bees stop their activity
Effects of salt stress on germination, seedling growth, osmotic adjustment, and chlorophyll fluorescence in Prosopis alba G.
Get PDFProsopis alba G. is a species of high forest importance in the phytogeographical region of Western Chaco. Although P. alba has been considered as salinity tolerant, its salinity thresholds for germination and seedling growth are unknown, as well as the physiological mechanisms involved in them. The aim of this study was to elucidate the mechanisms of tolerance of P. alba to salt stress. Seed germination, seedling growth, osmotic adjustment, and chlorophyll fluorescence were- analyzed. Germination was more tolerant to salinity than seedling growth, with thresholds of 600 mM and 500 mM, respectively. The species showed a high capability of osmotic adjustment, with values near to those observed in halophytes. The photochemical phase of photosynthesis was highly tolerant to saline stress, showing photoinhibition from 400 mM NaCl, as indicated by the fluorescence variables of chlorophyll. This behavior was associated to an increase in anthocyanin concentrations in the leaves.Prosopis alba G. is a species of high forest importance in the phytogeographical region of Western Chaco. Although P. alba has been considered as salinity tolerant, its salinity thresholds for germination and seedling growth are unknown, as well as the physiological mechanisms involved in them. The aim of this study was to elucidate the mechanisms of tolerance of P. alba to salt stress. Seed germination, seedling growth, osmotic adjustment, and chlorophyll fluorescence were- analyzed. Germination was more tolerant to salinity than seedling growth, with thresholds of 600 mM and 500 mM, respectively. The species showed a high capability of osmotic adjustment, with values near to those observed in halophytes. The photochemical phase of photosynthesis was highly tolerant to saline stress, showing photoinhibition from 400 mM NaCl, as indicated by the fluorescence variables of chlorophyll. This behavior was associated to an increase in anthocyanin concentrations in the leaves