Résumé:
In arid and semi-arid areas, particularly around the Mediterranean Basin, soil salinisation is
one of the major abiotic factors which reduce the yield of several cultures. The introduction of
tolerant plants to salinity is one of the techniques most used to improve the quality of soil in
these areas. Chenopodiaceae constitute a very important family of halophyts, of which are genus
Atriplex and Spinacia.
To highlight the potentialities of adaptation to the salinity of Atriplex halimus L, Atriplex
canescens L and two varieties of spinach: Spinacia oleracea L., a saline stress was induced by
the application of various NaCl doses (0g/l, 6g/l, 12g/l, 18g/l and 24g/l), in semi-controlled
conditions.
The tolerance of these genotypes was studied by the capacity of growth and output. Indeed,
the average height of the stems, the length of roots and the dry weight at the end of the
experiment vary according to the level of saline stress. The two species of Atriplex showed a
great resistance to the salinity expressed by their development of important shoots and roots. The
two varieties of spinach present a growth adapted to the saline stress, but the introduced variety
(Linda) is shown to be more sensitive than the local variety (GSN).The study of the growth of
the plants was supplemented by DNA dosage and chlorophylls (A), (b) and (a+b); these two
parameters reflect the mitotic and photosynthetic activities respectively.
The accumulation of osmoregulators varies from one species another, namely the free
proline and soluble sugars. Atriplex and spinach accumulate proline in shoots and roots. As for
soluble sugars, they are accumulated according to salinity only at the two species of Atriplex.
The comparison of the SDS-PAGE profiles of the protein leaves reveals 7 proteins which
appear in stress, of a molecular weight of 190, 185, 158, 136, 127.5, 27 and 12 KDa, whose
presence and degree of accumulation vary from one genotype to another.
