Agro-physiological responses of Moroccan alfalfa (Medicago sativa L.) populations to salt stress during germination and early seedling stages

摘要

To assess the effect of NaCl on seed germination and early seedling growth of four Moroccan alfalfa (Medicago sativa L.) populations, five salt treatments (0, 50, 100, 150 and 200 mM) were applied during germination in Petri dishes at 25 degrees C +/- 1 for 8 days. Germination (To) and germination velocity index were progressively inhibited as NaCl concentration increased with significant differences between populations. Thus, Tafilalet 1 population was less tolerant to NaCl but Tata population was more tolerant. The use of isotonic mannitol solutions indicated that salinity effect on seed germination occurred by both an osmotic and an additional ion toxicity specific effect which caused an inhibition of seed reserve mobilization. Agro-physiological parameters were also assessed in the seedling. A salt treatment (0, 100 and 200 mM NaCl) was applied 14 days after seeds were sown in pots in a peat/sand mix and assessments of seedlings were taken 15 days later. Seedlings showed a reduction in growth parameters, and accumulation of praline, soluble sugars and inorganic ions with a clear difference between the populations particularly at the highest NaCl concentration. This higher accumulation of solutes during salt stress was related to salt tolerance.