Assessment of faba bean (Vicia faba) response to inoculation with Rhizobium leguminosarum in clay loam Nile Delta soil.

A field experiment was conducted to assess the response to inoculation with rhizobia in a clay loam soil of the Nile Delta using faba bean (Vicia faba) for two successive winter seasons (1985/6 and 1986/7). Three selected strains of Rhizobium leguminosarum, TAL 634, NRC 65 and TAL 1400, were used singly or in combination as peat-based inocula in 1985/6 winter season. Strain TAL 1400 was replaced by strain F9 in the 1986/7 winter season. A significant seed yield response was obtained only with strain TAL 1400, in the 1985/6 season. In the 1986/7 season, no significant yield response was observed with any of the strains. The serotyping of nodules collected in the 1985/6 season showed that strain TAL 1400 was more competitive than either the indigenous rhizobia or the two inoculant strains. However, the majority of nodules formed in the 1986/7 season were formed from strains other than the inoculant ones.

Kinetics and properties of L-glutaminase and L-asparaginase activities of Pseudomonas ovalis.

Pseudomonas ovalis produces L-glutaminase and L-asparaginase activities simultaneously upon induction by L-glutamine or L-asparagin in the growth medium. Both activities are confined to the cell during active growth and are not released into the medium. The apparent Km values are 1.4 X 10(-2) M and 6 X 10(-3) M for L-glutamine and L-asparagine substrates, respectively. Induction of both activities is substantially favoured in media with initial pH values higher than 7. In buffered yeast extract L-asparagine medium, significant amounts of L-glutaminase and L-asparaginase activities appeared towards the end of the exponential phase and along the stationary phase. The process of enzyme formation showed a firm link to the cell active growth, as evidenced by the use of growth inhibitors.

Characterization and microbiological evaluation of the red compounds, associated with red rot idsease of sugar cane.

The red coloured compounds, isolated from sugar cane tissues infected with red rot, were phenolic and included a mixture of flavonoid compounds. Two of these compounds were purified and partially characterized. Neither the mixture of the coloured compounds nor any of its individual compounds exhibited in vitro activity against the causal organism Physalospora tucumanensis. One of the purified compounds showed in vitro activity against Bacillus subtilis. The role of the red coloured compounds in the mechanism of disease resistance is discussed.