ENUMERATION OF RHIZOBACTERIA COUNT AND GROWTH CRITERIA OF SUGAR BEET PLANT AS AFFECTED BY BIO FERTILIZATION

Abstract

Two field experiments were carried out at Sakha Agricultural Research Station, Kafer El-Sheikh governorate, Egypt during the two successive winter seasons of 2006/2007 and 2007/2008.Obtained results showed that increasing the applied level of nitrogen significantly increased root length, diameter, leaves and root fresh weight/plant. Using three N-fixing bacterial strains namely Azotobacter chroococcum, Bacillus polymyxa and Azospirillum brasilense recorded the highest values of root length, root diameter, leaves and root fresh weight/plant. Most of mineral nitrogen and N-fixing bacteria insignificantly affected juice impurities. The values of Log number of the tested bacteria at zero time were 3.65, 4.59, 3.7, 2.32 and 3.26, 3.32 for the 1st and 2nd seasons, for Azotobacter spp, Bacillus spp Azospirillum spp, and total bacteria counts, respectively. Results showed that in the first season inoculation with mixed bacteria was the superior treatment in increasing the log numbers of the tested bacteria which presented 6.23, 5.78, 5.45 and 5.63, 5.52, 5.75 after 120 and 180days for Azotobacter chroococcum, Bacillus polymyxa and Azospirillum brasilense, respectively.