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Science et changements planétaires / Sécheresse

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Analyse d’ouvrages Volume 1, numéro 2, Juin 1990

  • Page(s) : 152-3
  • Année de parution : 1990

This study concerns the behaviour of certain autochtonous species of the arid Tunisian region with respect to water, when they are set up alone or in combinations in lysimetric compartments and in experimental plots. The measurements and observations made bear mainly on the life cycle of the species, and on the moisture potentials in the soil and in the plant. The results show that in the Mediterranean climate, Cenchrus ciliairis L. and Digitaria commutata Sch. ssp. nodosa (Parl.) Maire, species of tropical origin, present two periods of growth and two periods of rest, in winter and in summer. However, Stipa lagascae R. and Sch. ssp. normalis Maire, Plantago albicans L. ssp. albicans, and Argyrolobium uniflorum (D.C.) Jaub and Spach., species of Mediterranean origin, can grow even at low temperatures (winter). It is confirmed that the water use efficiency is greater for the C4 than for the C3 species. The differences in life cycle and in root system structure observed in these species make it possible to explain certain aspects of competition and complementarity in the sharing of resources among species when they are planted in combination.