Abstract
Impaired germination is common among halophyte seeds exposed to salt stress, partly resulting from the salt-induced reduction of the growth regulator contents in seeds. Thus, the understanding of hormonal regulation during the germination process is a main key: (i) to overcome the mechanisms by which NaCl-salinity inhibit germination; and (ii) to improve the germination of these species when challenged with NaCl. In the present investigation, the effects of ABA, GA(3), NO3- and NH4+ on the germination of the oilseed halophyte Crithmum maritimum (Apiaceae) were assessed under NaCl-salinity (up to 200 mM NaCl). Seeds were collected from Tabarka rocky coasts (N-W of Tunisia). The exogenous application of GA(3), nitrate (either as NaNO3 or KNO3), and NH4Cl enhanced germination under NaCl salinity. The beneficial impact of KNO3 on germination upon seed exposure to NaCl salinity was rather due to NO3- than to K+, since KCl failed to significantly stimulate germination. Under optimal conditions for germination (0 mM NaCl), ABA inhibited germination over time in a dose dependent manner, but KNO3 completely restored the germination parameters. Under NaCl salinity, the application of fluridone (FLU) an inhibitor of ABA biosynthesis, stimulated substantially seed germination. Taken together, our results point out that NO3- and GA(3) mitigate the NaCl-induced reduction of seed germination, and that NO3- counteracts the inhibitory effect of ABA on germination of C maritimum. To cite this article: A. Atia et al., C R. Biologies 332 (2009). (C) 2009 Published by Elsevier Masson SAS on behalf of Academie des sciences.