Influence of the ionic form of mineral salts on growth of faba bean and rhizobium leguminosarum

ABSTRACT

A pot experiment was performed to study the nodulation and growth of Faba bean plants [Vicia faba cultivar Giza 2] [2 months age] in an alluvial clay soil [pH 7.9] as affected by the anionic and cationic component of inorganic salts, i.e. Chlorides, carbonates, and sulphates of Na, K, Ca, and Mg. Each was added at a single concentration 20 meq 100 g-1 soil. Tolerance of Rhizobium leguminosarum biovar viceae [Strain F-15] grown on pure culture medium salinized with the same salts was also tested. Salts applied were generally inhibitory to both the macro-and micro-symbionts. Number and characteristics of plant-root nodules, dry weight of plants [Shoots and roots], N content in plants, and bacterial colony count were decreased. Chlorides reduced these parameters to the greatest degree, while sulfate exhibited the lowest effect. Sodium among cations, showed the greatest inhibition, whereas Mg++ was the least detrmintal; K+ and Ca++ occupied intermediate positions. Formation of effective nodules on roots of the plants grown in the salinized soil was very poor, but R. Leguminosarum showed possible tolerance when grown on salinized pure culture medium