الفهرس 
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Abstract
Colonization of silicate bacteria in soil and root systems
of wheat, broad bean, clover, lentil, squash, tomato and maize was examined at vegetative stage of growth. The amounts of soluble potas.sium released from orthoclase by purified 37 long sporulated and 28 short non-sporulated rod shaped isolates of silicate bacteria were evaluated in liquid culture. The most ef fective four isolates were identified by API system and some other complementary tests adopted from Bergy’s Manual of Determinative Bacteriology, 1984, 1986 and 1994. The effects of two selected and identified strains of silicate bacteria on K mobilization from orthoclase and muscovite, culture pH, total acidity as well as the densities of the two strains were moni tored for 8 weeks under laboratory conditions. The responses of potato, wheat and broad bean to inoculation with these strains in conjugation with N2-fixing bacteria were also re corded under net house and field conditions. Data of this in vestigation showed that higher counts of total microbial flora and silicate bacteria were generally encountered in the rhi zosphere than in root free soil. This finding was particularly observed with wheat, squash and tomato. Among the 65 puri fied isolates of silicate bacteria, the Tal, Zml of the long sporulated rods and the Tal and Zm3 of the short non sporulated rod shaped isolates were the most effective in mo bilizing K. These isolates were found to represent 4 strains belonging to Bacillus circulans (Tal and Zml), Enterobacter sakazakii (Tal) and Pseudomonas mendocina (Zm3). With the
the 2 strains representing B. circulans (Tal) and Pseudo monas mendocina (Zm3), the pH values of cultures supple mented with orthoclase were generally lower and accom pained with higher levels of total acidity than those reported for muscovite. Although, the rate of decrease in pH and that of increase in total acidity was greater in Ps. mendo cina Zm3 than that of B. circulans Tal, the latter strain was more effctive in releasing K from the 2 tested sources. In oculation of potato with B. circulans Tal induced better ef fects, compared with uninoculated control, on the number and fresh weight of tubers specially when conjugated with ortho clase amendment. These effects were also reflected on N,P and K contents of the tubers. The positive responses to inocu lation with B. circulans Tal, Ps. mendocina Zm3 or their mixture in conjugation with Azotobacter chroococcum Uf5 for wheat or with Rhizobium leguminosarum bv. vicieae 602 for broad-bean were also shown in growth, nitrogenase activ ity, yield as well as N,P and K contents. In many cases of dual inoculation treatment; no significant differences were ob served between the effects of B. circulans Tal and those of Ps. mendocina Zm3. Exceptions were always in favour of B. circulans Tal. However, the triple inoculation treatment combined with orthoclase application induced the most sig nificant effects.