Response of seed germination of Tunisian Allium ampeloprasum to temperature and salt stresses

High salinity and temperature are major problems inhibiting seeds germination and threatening plant cover in arid environment such as the conditions in some regions in Tunisia. Thus, the use of adapted species to rehabilitate these regions could be an alternative to overcome these environmental constraints. In the present study, we intended to evaluate the effect of salt and temperature on seed germination of the wild leek (A. ampeloprasum L.) from two different Tunisian islands (Kneiss & Djerba). Three temperatures (15° C, 23° C & 30° C) and four salinity levels (0, 75, 150 & 225 mM NaCl) were tested in a 14 h dark:10 h light photoperiod. The two studied populations snowed a similar behaviour. The optimum temperature for seed germination was 15° C. Germination was inhibited by an increase in both temperature and salinity. Salt stress decreased both the final germination rate and the final germination percentage (PG%). Delay of germination (T₀) and the time to half of germination (F₅₀) significantly (p < 0.05) increased in response to salt and temperature increasing. An interaction between salinity and temperature completely inhibited germination in 225 mM NaCl at 30° C. Seeds transferred from salt solution to distilled water showed a recovery percentage (R%) varying from 0 to 40.6%. Viability test showed that all non-germinated seeds were alive proving that A. ampeloprasum adopted a strategy of temporal inhibition of germination to survive under salt and temperatures increasing. As such it could be classified as a moderately salt tolerant species.