Afifi, M.M.I, El-Sayed, G.A.M, Manal, A.H. El-Gamal and Massoud, O.N.( 2014). Synergistic Effect Of Biofertilizers Containing N-Fixer, P And K Solubilizers And Humic Substances On Sorghum Bicolor ProductivityMiddle East Journal of Applied Sciences, 4(4): 1065-1074, ISSN: 2077-4613
Abstract: A field experiment was conducted at Ismailia Agricultural Research Station, Agric. Res. Centre (ARC), Egypt, during summer season of 2012 to study the effect of a symbiotic nitrogen fixer Azospirillum brasilense, phosphate dissolving bacterium Bacillus megaterium and potassium solubilizing bacterium Bacillus circulans in individual, or mixed forms supplemented with either humic or fulvic acids as well as their supernatants on the availability of nitrogen (N), phosphate (P) and potassium (K) and their reflection on some morphological, physiological and yield parameters of sorghum (Sorghum bicolor L.) Dorado cultivar in the presence of 50 % of the recommended dose of mineral NPK. Generally, the application of the microbial cells whether in single or mixed forms was more effective than their supernatants and succeeded to enhance the growth and the yield of treated sorghum plants. Almost values of the tested parameters significantly increased when sorghum plants were treated with viable cells or their supernatants supplemented with humic acid in comparison to the control. Generally, the treatments that possessed bacterial cells and humic acid were recorded the highest population of the bacterial group in
rhizosphere area whether in single or mixed forms. Nitrogenase, dehydrogenase and phosphatase activities, plant height, plant dry weight and number of branches were significantly increased with combined mixture of Azospirillum brasilense, Bacillus megaterium and Bacillus circulans cells plus humic acid after 45 and 75 days
of sowing. Moreover, high content of NPK in sorghum grains as well as crude protein and total carbohydrates (%) were determined with this treatment. The treatment also, exhibited the highest grains yield (3.55 ton/fed) and 1000 grains weight, whereas all other tested treatments including control (full NPK) attained less values. The obtained results clearly revealed that each bacterial stain was succeeded to compensate the half doses of NPK through N-fixation, P and K solubilization processes. Also, the combined inoculation with Azospirillum brasilense, Bacillus megaterium and Bacillus circulans in the presence of humic acid by using seed coating technique was more pronounced in comparison with control and all other tested treatments.
Keywords: (Humic, fulvic, Azospirillum brasilense, Bacillus megaterium, Bacillus circulans, cells, supernatant, sorghum.)
