ABSTRACT. Inoculation of different plant wastes with microorganisms resulted in a release of maximum reducing sugars (33 %) from sugar-cane leaves when subjected to Penicillium oxalicun,. Maximum protein was formed from sugar-cane bagasse inoculated with Aspergillus fumigatus. Association of sugar-cane leaves with P. oxalicurn showed the highest digestibility. The use of such microorganisms may help to provide additional and valuable proteins ultimately for human use.

Abstract This study was performed to evaluate the ability of cellulolytic fungi and wheat straw incorporation to improve the nodulation, growth and nitrogen status of fenugreek grown in saline soils. NaCl addition to the growth medium at rates of 0.5 and 1% strongly decreased the enzymatic activity of the ten tested moulds. Three of these fungi, Aspergillus niger, Chaetomium globosum and Trichoderma harzianum, showed the highest enzymatic activity. The three moulds have the ability to degrade straw in the presence of NaCl and T. harzianum was the best straw degrader. Inoculating the plants with Rhizobium meliloti strain TAL 1373 and cellulolytic fungi slightly promoted nodulation, growth and nitrogen accumulation when plants were grown with the addition of 0.5% NaCl when compared to plants inoculated with R. meliloti alone. However, application of wheat straw with cellulolytic fungi significantly enhanced growth, nodulation and nodule efficiency at 0.5 and 1.0% salinity. The greatest values of nodulation and growth parameters were obtained with a straw-Trichoderma harzianum combination. Cellulolytic fungi and wheat straw increased the concentration of Ca, Mg and K in the shoots and roots of plants. The increase in dry matter production and N content was mainly due to improved N2 fixation reflected by enhanced formation and growth of nodules as well as nitrogenase activity.

ABSTRACT. Survival and nitrogenase efficiency of Nostoc commune and N. austinii were evaluated monthly in four carrier materials (sugarcane bagasse, wheat straw, wheat bran and peat) at 10, 30 and 40 ~ Survival, as well as nitrogenase activity, of both species was much better in peat, followed by wheat bran, sugarcane bagasse than in wheat straw at 10 and 30 ~ up to three months, the activity of N. commune being better than N. austinff. None of the materials tested was found to be superior to peat as carrier of Nostoc species but the results indicated that wheat bran and sugarcane bagasse can be used as inoculant carriers with relative success. Storage of inoculants in these carriers is feasible at 30 ~ up to three months

Abstract Tomato fruits and seed lots were screened for the presence of Xanthomonas vesicatoria and Ralstonia solanacearum. Yellow colonies of Xanthomonas vesicatoria and white colonies of Ralstonia solanacearum were consistently isolated on yeast extract-dextrose-calcium carbonate agar medium (YDC) from diseased fruits and seed samples. This was confirmed by isolation on semiselective medium such as Tween B for Xanthomonas and triphenyltetrazolium salt (TTC) medium for Ralstonia solanacearum followed by biochemical tests. The four isolates belonging to Xanthomonas vesicatoria and Ralstonia solanacearum were used to inoculate a local tomato variety. The isolates were found to cause yellowing and wilting of 2-weeks-old seedlings by 8–14 days after inoculation and by 4 weeks all plants hadwilted and completely died. Bacteria with the same characteristics as those inoculated were reisolated from the infected plants. Uninoculated plants remained healthy.

Common bean seed lots collected from different seed dealers and Malawii agriculture station were screened for the presence of Xanthomonas axonopodis pv. phaseoli. In the laboratory the pathogen was isolated following the routine laboratory assay method, i.e. direct plating method using yeast extract–dextrose– calcium carbonate agar medium (YDC). Yellow, convex, mucoid colonies of Xanthomonas were consistently isolated on YDC from seed samples. The presumptive pathogen was confirmed by isolation on semiselective medium, such as mTBM and MD5A. Further, the pathogen was confirmed by biochemical, physiological and, finally, the pathogenicity tests. Five samples out of seven were positive for Xanthomonas. The isolates were found to cause common blight of 3-week-old common bean plants by 7 d after inoculation. Bacteria with the same characteristics as those inoculated were re-isolated from the infected plants.

ABSTRACT. Twenty-one Rhizobium and Bradyrhizobium strains were tested in vitro against the mycelial growth of three pathogenic fungi on solid and liquid media. All tested rhizobia and bradyrhizobia significantly suppressed the growth of the three soil-borne root-infecting fungi (Fusarium solani, Macrophominia phasolina and Rhizoctonia solani) either in the absence or presence of iron. This indicates that the siderophore played a minor role in the biocontrol potential of Rhizobium and Bradyrhizobiura against pathogenic fungi. Pot experiments revealed that the numbers of propagules causing disease after 4 weeks of planting varied with species and host plant. The three most active Rhizobium and Bradyrhizobium strains (/L leguminosarum bv.phaseoli TAL 182, B. japonicum TAL 377 and Bradyrhizobium sp. (lupin) WPBS 3211 D) tested under greenhouse conditions for their ability to protect one leguminous (soybean) and two non-leguminous (sunflower and okra) seedlings from root rot caused by Fusarium solani, Macrophominia phaseolina and Rlu'zoctonia solani provided significant suppression of disease severity compared vath nonbacterized control in both leguminous and non-leguminous seedlings. Bradyrhizobium sp. (iupin) WPBS 3211 D provided the lowest degree of resistance against all the tested pathogens with all host plants.

Pesticides (Brominal, Cuprosan and Fenvalerate) at 10 and 50 ppm suppressed growth, respiration and nitrogenase activity of Azotobacter chroococcum, AzospiriIIum brasilense and Azospirillum ]ipos The inhibitory effect on respiration of Asm. Iipoferum was most pronounced after 3 and 4 days.

ABSTRACr. In soil salinized with different concentrations of sodium chloride, the total counts of soil fungi were significantly decreased during 11 weeks of incubation. Similarly, the total count of bacteria and actinomycetes were severely depressed by increasing salinity level above 5 %. Invertase and urease activities were severely decreased as NaCi concentration increase during the incubation. Also, the effect on nitrate reductase was inhibitory with most treatments.

ABSTRACT. The ability of Rhizobium and Bradyrhizobium strains to solubilize phosphate from hydroxyapatite was determined in a medium containing NH4CI or KNO3. The presence of NH4 + in the medium resulted in higher solubilization of phosphate as compared to the presence of KNO3, with the exception of R. leguminosarium by. viceae strain TAL 1236 and 1402 which soluhilized comparable amounts of phosphate in a medium containing either KNO3 or NH4Ci. These results suggest that the strains employ two different mechanisms for phosphate solubilization, one depending on the presence of NH4 +, the other not requiring its presence. Temperature and aeration (02 demand) optima were 30 *C and 4.2 Hz (shaking frequency), respectively. In nonsterile soil the tested strain (R. meliloti TAL 1236) was very effective in solubilizing rock phosphate.