Efecto de la salinidad sobre el establecimiento de plántulas de dos especies arbóreas dominantes en un "quebrachal" de Schinopsis balansae ENGL. (ARGENTINA).
Fecha
2004
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Schinopsis balansae (Quebracho colorado) y Prosopis nigra (Algarrobo negro) son especies dominantes en la cuña boscosa santafesina. La primera de ellas ocupa los sitios mas elevados del gradiente topográfico, mientras que la segunda los más bajos e inundables. Aunque existe evidencia que esta distribución está asociada a dos factores: humedad y salinidad, aún no se dispone de datos experimentales que permitan determinar con certeza la influencia de la sal en el establecimiento definitivo de las plántulas. Con el objeto de aumentar el conocimiento acerca del efecto de la concentración salina en la germinación y establecimiento de las plántulas, que es el estado más vulnerable en el ciclo de vida de las mismas, se realizaron experimentos de germinación y el establecimiento de plántulas de Quebracho colorado y de Algarrobo negro. Para ello se estudió el efecto de distintas concentraciones de cloruro de sodio (ClNa): 0.2, 0.3, 0.4, y 0.6 molal (m), además de un testigo con agua destilada. Las semillas se incubaron en bandejas con arena saturada con la solución salina correspondiente, a 25 ºC con fotoperíodo de 12 horas, durante 34 días. Se determinó el Índice de velocidad de germinación (IVG) y el Tiempo medio de germinación máxima (TMG). Los resultados se analizaron usando análisis de la varianza. En ambas especies no hubo germinación a las mayores concentraciones de ClNa (0.4 y 0.6 m). Aún en las semillas que germinaron, sus plántulas presentaron anormalidades y luego murieron. Los resultados obtenidos sugieren que las variaciones espacio-temporales en las concentraciones de ClNa por encima de 0.2 m que se presume ocurren en la región estudiada, podrían estar influyendo en la distribución de las especies en este tipo de bosque, según se ha observado en relevamientos sucesivos.
Schinopsis balansae (Quebracho colorado) and Prosopis nigra (Algarrobo negro) are two dominant species in the santafesinian woody wedge.The first one occupies the higher places of the gradient, and the second one, the lower and waterlogged. This distribution is associated to humidity and salinity gradients. Although some evidence indicates that this distribution is correlated to two factors humidity and salinity- there is still lacking experimental data to determine the salinity on the successful establishment of seedlings. With the purpose of increase the knowledge on the effect of saline concentration on seed germinaton and seedling establishment, which the most vulnerable stage in the plants life cycle, experiments were made for the two species Quebracho blanco and Algarrobo. We studied the effect of a range of sodium chloride concentrations 0.2, 0.3, 0.4, y 0.6 molal (m) plus a test with distilled water. Seeds were incubated in trays filled with sand saturated with the corresponding saline solution. Trays were incubated at 25 ºC, photoperiod of 12 horas, during 34 days.The rate of germination index (RGI) and the average time for maximum germination (TMG) were determined. In both cases there was no germination in the higher salt concentrations (0.4 and 0.6m) and even on the germinated seeds with lower concentration (0.3m) the seedlings showed abnormalities and then died. We postulate that spatial & temporal sodium chloride concentrations beyorn 0.2 m, could be strongly influencing the distribution of species in this forest, has it has been in several surveys.
Schinopsis balansae (Quebracho colorado) and Prosopis nigra (Algarrobo negro) are two dominant species in the santafesinian woody wedge.The first one occupies the higher places of the gradient, and the second one, the lower and waterlogged. This distribution is associated to humidity and salinity gradients. Although some evidence indicates that this distribution is correlated to two factors humidity and salinity- there is still lacking experimental data to determine the salinity on the successful establishment of seedlings. With the purpose of increase the knowledge on the effect of saline concentration on seed germinaton and seedling establishment, which the most vulnerable stage in the plants life cycle, experiments were made for the two species Quebracho blanco and Algarrobo. We studied the effect of a range of sodium chloride concentrations 0.2, 0.3, 0.4, y 0.6 molal (m) plus a test with distilled water. Seeds were incubated in trays filled with sand saturated with the corresponding saline solution. Trays were incubated at 25 ºC, photoperiod of 12 horas, during 34 days.The rate of germination index (RGI) and the average time for maximum germination (TMG) were determined. In both cases there was no germination in the higher salt concentrations (0.4 and 0.6m) and even on the germinated seeds with lower concentration (0.3m) the seedlings showed abnormalities and then died. We postulate that spatial & temporal sodium chloride concentrations beyorn 0.2 m, could be strongly influencing the distribution of species in this forest, has it has been in several surveys.
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Cuña Boscosa, Chaco Oriental, emergencia, germinación, quebrachal, salinidad, vigor, emergency, germination, salinity, Wedge Forest