Resumo

RODRIGUEZ RIVERA, MF et al. Effects of water stress at different temperatures on germination of Bulnesia retama seeds (Gill. ex. Hook.) Griseb. -Zigofiláceas- in San Luis, Argentina. Phyton (B. Aires) [online]. 2007, vol.76, pp.5-17. ISSN 1851-5657.

We studied the germination capacity of Bulnesia retama seeds to conditions of water stress simulated by PEG6000 at different temperatures. We also evaluated their recovery to water stress conditions. Seeds were collected in San Luis city, Argentina. They were placed in polyethylene bags with different concentrations of PEG6000 to simulate water potentials of 0 (control); -0.25; -0.5; -0.75; -1; -1.25 and -1.5 MPa. Seeds were placed in culture oven without light to three temperatures: 18º, 25º and 32 ºC. Non-germinated seeds were washed and placed again to germinate in distilled water to 25 ºC. We registered the percentage and the rate of germination. Approximately 75% of seeds germinated under all temperatures in the control treatment. At 18 ºC, germination percentages and rates were affected by all water stress treatments, whereas at 25 ºC, these parameters were affected at water potentials lower than -1 MPa. At 32 ºC, germination was not affected by water potentials higher than -1 MPa during the first 48 hours. Germination percentages and rates were similar in the recovery and the original control treatments, indicating that seed germination have thresholds of water and temperature conditions. These results may be the result of the species adaptation to the regional environmental conditions.

Palavras-chave : Bulnesia retama; Germination; Water stress.

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