Effet combiné de la bentonite et de la salinite sur les propriétés biochimiques, minérales et hydriques chez l’haricot « Phaseolus vulgaris.L ».

Abstract

Soil salinization is a major limiting factor in agricultural productivity, especially in arid and semi-arid region. The presence of soluble salts at high concentrations in the soil, affect physiological mechanisms of the plant and is a major limiting factor of the vegetable production. Thus, tolerance of cultivated plant is remained, given the complexity of the mechanisms involved in tolerance to salt plants. The objective of our work is to study the influence of some bentonite doses associated with abiotic stresses of salinity on water, biochemical and mineral behavior, of leguminous species very sensitive to salinity commonly grown in Algeria ; the bean “Phaseolus vulgaris L”. The tests were carried out in pots of vegetation in semi-controlled conditions in the greenhouse. Mostaganem bentonite is added at 00, 07 and 10% by weight of the substrate (sand / peat).The mixture thus obtained is used for culturing a variety of bean Phaseolus vulgaris , called El Djadida subjected to salt stress using NaC1 solution with 03 concentrations (0, 50 and 100 meq/l). Interest in physiological and mineralogical characteristics us in adaptation environmental constraints required study of water balance, the accumulation of chlorophyll pigments and proline and the effect on the absorption of some cations: Na + , K + and Ca2 + for mineralogical approach. Salinity effects are manifested by a decrease in water content and chlorophyll pigments. However, we observed an increase in proline content and the disturbance in the distributing of Na+, K + and Ca2+ ions in the leaves and roots (The Na+ content increasing inhibits the absorption of Ca2 + and K+ ions) .These effects is depending to the intensity of the stress. The addition of bentonite in the substrates cultures and in the absence of salt treatment improve significantly the plant growth parameters. It is observed that the doses of 07% for bentonite applied and combined to the salt concentrations are most appropriate that contribute to the osmotic adjustment and provide a balanced mineral nutrition of the three cations in the leaves and roots of the bean and improve the other physiological parameters such as water content and the photosynthesis process.