« Action combinée de la bentonite et de la salinité sur les paramètres hydriques, biochimiques et minérales chez le Radis (Raphanus sativus L.) »

Abstract

In arid and semi-arid regions, soil salinity is a major environmental stress. Conversely halophytic tolerant salts, most plant species are classified in the group of glycophytes, whose physiological and biochemical processes are assigned in the presence of salt. Soils rich in sodium chloride are characterized by an abundance of Na+ and Cl-ions. The Na+ ions disturb absorption of cations (Na+, K+, Mg2+ and Ca2+), so that excessive accumulation of chlorine decreases absorption of anions, essential for the growth and development of plant particularly nitrates, nitrites and sulfates. The impact of salinity on the development and yield of plants are numerous and difficult to prioritize. The sodium and chloride ions enter the plants via the roots and are conveyed by the conductive tissues. These mechanisms of tolerance or sensitivity are experimentally investigated on radish, grown under increasing salt diet (50 et 100 meq.gl- 1 NaCl) on a sandy soil with 07 % and 10 % bentonite. The salinity causes an increased accumulation of proline. The levels of this amino acid increases gradually as the salt concentration increases and also as the member and the stage of growth. Thus the production of proline is more marked as the intensity of treatment is important and that the leaves are young ie under conditions of intense cell multiplication. Changes in proline content evolve in a greater or less weak according to different soil types and the station studied. The data show that the exposure of seedlings (Raphanus sativus L.), salinity resulted in a fall in growth especially of the aerial part, but with an amended soil bentonite, seedlings of three stations show great adaptability. The effect of salinity is not uniform for all organs. This depressive effect on growth was accompanied by cationic modifications. The accumulation of compatible solutes also induces a decrease in the water potential and thereby allows the absorption of water from the environment.