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Jaouadi W.,Institute National Of Recherches En Genie Rural | Hamrouni L.,Institute National Of Recherches En Genie Rural | Souayeh N.,Institute Superieur Des Science Biologiques Et Appliquees Of Tunis | Khouja M.L.,Institute National Of Recherches En Genie Rural
Biotechnology, Agronomy and Society and Environment | Year: 2010

Since Tunisian acacia populations are threatened by regression, we analyzed as a preliminary study the germination behavior of the species in order to plan subsequently for a preservation and rehabilitation program. In this context and to optimize acacia seed germination and to overcome and remove the obstacle of tegumentary inhibition, we have in a first attempt tested several physical (scarification, boiled water) and chemical (sulfuric acid) pretreatments under different temperatures. Thus, we could determine the optimal germination conditions that have been used afterwards for evaluating the germination capacity of the species under different osmotic constraints. Several concentrations of NaCl (0 to 22 g.1-1) and PEG (0 to -8 bars) were applied on seeds. Parameters related to germination capacity and kinetic were assessed and analyzed. Thus, soaking seeds in concentrated sulfuric acid for one hour allowed us to improve the germination rate and its speed. When studying the effect of the temperature on the germination process, we showed that 25°C could improve the rate and average time of germination. Under osmotic stress, we found a highly significant treatment effect (PEG concentrations) on the germination rate and average time of germination, and the species did not display a high drought tolerance behavior (since germination is totally inhibited under -8 bars). Moreover, the study of the effect of salt stress on germination revealed a highly significant effect of NaCl concentrations on the germination rate and average time of germination, and a good level of salt tolerance since it succeeded to germinate under high salt concentrations (21% of germination rate under 22 g.1-1NaCl). In conclusion, our study clearly showed that germination capacity of Acacia tortilis under the environmental constraints and factors is sufficiently assured to consider this species for a reforestation program and to extend consequently its area of distribution.


Lamia H.,Institute National Of Recherches En Genie Rural | Naoufel S.,Institute Superieur Des Science Biologiques Et Appliquees Of Tunis | Larbi K.M.,Institute National Of Recherches En Genie Rural | Nejib R.M.,Institute National Of Recherches En Genie Rural
Biologia | Year: 2012

The effects of water potential on germination were studied in four provenances of Myrtus from different bioclimatic zones in Tunisia. Water potential between 0 and -10 bars were obtained using polyethylene glycol 6000 (PEG-6000) solutions. Seeds were planted in Petri dishes full of sterile perlite, and kept for one month under 1500 lux light with 16h photoperiod and at 25°C. A low water potential induced a reduction in germination percentage and germination speed. Significant variations between the provenances were found even under control conditions, especially at the speed germination level. The provenances from humid regions were the most susceptible to water stress, and their germination percentage showed significant reductions at -8 bars. These differences in germination ability of provenances might be attributed to intraspecific variations resulting from the effects of natural selection and genetic pool background. © 2011 Versita Warsaw and Springer-Verlag Wien.

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