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Water stress effect on germination and initial growth of three Leguminosae species

Seeds of Senna macranthera, S. multijuga e Mimosa bimucronata were submitted to different osmotic potentials using PEG 6000 (0; -0.15; -0.49 and -1.03MPa). The objective of this study was to evaluate the effect of osmotic stress on germinability and initial growth of seedlings. Water stress of -0.15 and -0.49MPa increased the time required for germination in 12, 24 and 48 hours for M.bimucronata, S. multijuga and S. macranthera, respectively. All species showed a reduced germinability in the Ψ = -1.03MPa. Such results suggest a limit of tolerance between the osmotic potentials of -0.49 and -1.03MPa. Senna macranthera seedlings were more sensitive to osmotic stress, reducing shoot and radicle elongation when levels of external water stress were increased. Senna multijuga and M. bimucronata increased the radicle lenght at Ψ = -0.15MPa. Reduction of fresh weight was observed for all levels of osmotic stress in all species.

water stress; PEG 6000; germination; Leguminosae; seedlings


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