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Medicago arborea L. is a
Mediterranean leguminous fodder shrub, regarded as a promising species
in arid and semi-arid lands where it can play an important role in the
elaboration of a durable pastoral system.
The aim of this paper is to investigate and characterize the response
of M. arborea plants to water
and salt stress at the early growth stage. Seedlings of the species
derived from seeds collected in the Djelfa province, Algeria, were
grown in pots under greenhouse conditions and separately submitted to
water stress, restoring 20%,40%,60%,80% and 100% of substrate field
capacity, and salt stress, supplying irrigation water with 0, 50, 100,
150 and 200 meql-1 of NaCl+CaCl2.
Stress effects were determined on fresh and dry-matter biomass,
relative water content, leaf pigment content (chlorophyll and
carotenoids), proline and total soluble sugars amount.
Results showed that both water and salt stress affected seedlings
growth. In particular, the lowest water regime (20% of field capacity)
significantly reduced fresh and dry-biomass and relative water content,
whereas seedlings under salinity maintained a good water content
(>70%).Chlorophyll a and b, and carotenoids content did not show
significant differences among treatments, while proline and total
soluble sugars amounts, major osmolytes involved in osmotic adjustment,
significantly increased according to salt and water stress intensity.
The findings highlight that M.
arborea has a remarkable potential of tolerance to water deficit
and salinity, involving a range of physiological strategies to cope
with stress by regulating metabolism activity and maintaining cell
turgor.
