Requerimientos ambientales para la germinación de sphaeralcea bonariensis

AUTOR(ES)
FONTE

Planta daninha

DATA DE PUBLICAÇÃO

2014-09

RESUMO

S. bonariensis (white mallow), tolerant to glyphosate, is important for the practice of direct sowing in Argentina. The germinating behavior of the species at different temperature conditions (namely 5, 10, 15, 20, 25, 30, 35, 40, 20/10, 25/15, and 30/20°C in a 12 hour photoperiod of light); saline stress (0, 30, 50, 70, 90, 130, and 150 mM of sodium chloride solutions); and water stress (0, -0.2, -0.4, -0.6, -0.8, -1.0MPa of polyethylene glycol solutions) were determined in the laboratory. The experiment was entirely randomized with four replicates. Temperature was analyzed using generalized digital models, and the DGC test was used to find mean differences. Both water and saline stresses were analyzed by non-lineal regression. At steady temperature, maximum germination occurred at 15 and 20°C (77 and 76% respectively), at 25°C, it lowered to 49%, at 30 and 35 °C, values equal or lower to 5-30% were recorded, and germination did not occur at 5 and 40°C. Significant differences among germination rates were not noted under thermal alternation; all of them were above 50%. Germination rates decreased exponentially with increased sodium chloride concentrations. Control provided 66% of germination, which lowered to 10% at 130mM, and was inhibited at 150mM. When water stress was increased from 0 to -0.6MPa, germination rate decreased from 64% to 8%, and was inhibited at -0.8 MPa. Seeds will be able to germinate in warm-temperate regions, being tolerant to salinity and moderately tolerant to water stress.

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