Installation of silvopastoral systems with poplar in the Delta of the Paraná River, Argentina

The establishment of silvopastoral systems (SSP) in poplar (Populus deltoides ‘Australiano 106/60’) plantations requires specific management strategies. In this context, the combination of the type of tree multiplication material and its palatability may determine the success of SSP establishment. We proposed to create a new technology for the establishment of a SSP with poplar for cattle and multiple uses such as wood production. The first objective was to assess changes in size and morphological characteristics for poplar pole cuttings grown at different densities in a nursery to test suitable multiplication materials for SSP establishment. The second objective was to determine the effect of pole cutting size (or age) on tree growth and sensitivity to damage caused by cattle browsing. In nursery, results showed that the production of multiplication material from larger spacing resulted in better 1-, 2- and 3-year-old pole cuttings, with higher diameter at breast height (DBH), total height, aerial biomass, straightness, conicity and shaft stability. In the poplar SSP, it was determined that the use of pole cuttings with a DBH equal or greater than 6 cm allowed the entry of cattle after the first years of plantation. Poplar leaves and tender branches obtained after spring pruning provided a good supplement to animal diet due to its higher values of crude protein, P and K content and digestibility. It was concluded that the use of poplar pole cuttings as multiplication material promotes the growth of natural pastures and early beef production in poplar SSP on the Lower Delta of the Paraná River.EEA Delta del ParanáFil: Casaubón, Edgardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Cornaglia, Patricia Susana. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina. Universidad Nacional de la Patagonia Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A strategy of Ca2+ alleviating Na+ toxicity in salt-treated Cyclocarya paliurus seedlings: photosynthetic and nutritional responses

Cyclocarya paliurus seedlings were subjected to 85 mM NaCl and 0, 6, 12 or 18 mM Ca(NO3)2 treatments to study changes in plant growth, photosynthetic parameters and distribution and/or accumulation of organic and inorganic solutes. Na+ toxicity symptoms were observed in plants non-treated with Ca(NO3)2, while 12 mM Ca(NO3)2 supplementation produced a significant promotion of shoot growth; meanwhile chlorophyll content, photosynthetic rate and optimum quantum yield of photosystem II (PSII), represented by the Fv/Fm ratio and pigments content as well as proline and soluble sugars, significantly increased. Ca(NO3)2 supply increased K+ and Ca2+ concentration, whereas the Na+ transport to the shoot was inhibited. There was a strong increase in the K+/Na+ ratio in shoot of Ca(NO3)2-treated plants. X-Ray microanalysis of roots showed that K+, Ca2+ and Na+ accumulated mainly in the epidermal cells and cortical cells of roots with 12 mM Ca(NO3)2 supply, and low accumulation was observed in stelar parenchyma, indicating exogenous Ca2+ possibly induced or strengthened effects of Casparian bands on ion transport. These results suggest that Ca(NO3)2 supplement increased inorganic and organic solutes accumulation in shoot and leaf, and restricted Na+ transport to the shoot by reinforcing barrier effects for attenuating salt injuries in plants, which could be a strategy of Ca2+ alleviating Na+ toxicity in C. paliurus seedlings subjected to salt stress