Soha S.M. Mostafa, Amal W. Abou El Kheir, Heba S. Shehata( 2013). Effect of plant growth promoting substances from Rhizo- and cyano-bacteria on sugarbeet growth, Yield and yield quality in saline soilINTERNATIONAL JOURNAL of ACADEMIC RESEARCH Vol. 5. No. 6. November, 2013
Abstract: The production of plant growth promotors (indole acetic acid, gibberellic acid and abscissic acid) by rhizobacteria and cyanobacteria has been taken as a main criterion in the selection of the microbial strains used in this study. Two field experiments were conducted at Sahl El-Hussinia station, El-Sharkia Governorate, during the winter seasons of 2010/2011 and 2011/2012 to investigate the effect of rhizobacteria and cyanobacteria either individually or in combination on growth, yield and yield quality of sugarbeet under salinity stress. Soil biological activity in terms of dehydrogenase activity was significantly affected by the biological treatments. The
dehydrogenase recorded its highest value when the combined inoculum of rhizobacteria and cyanobacteria was applied. Inoculation with rhizobacteria and/or cyanobacteria in saline soil alleviated the salinity effects on the sugarbeet and enhanced photosynthesis (leaves chlorophyll content), proline and phenole accumulation in roots, along with, increasing the concentrations of N, P and K and decreasing Na+ concentrations in roots. This physiological positive response of the plant growth promoting rhizobacteria and/or cyanobacteria resulted in significant increases in sugarbeet root yield and yield quality (TSS, sucrose and purity%). Best results were obtained by the combined mixture of bacteria and cyanobacteria followed by the individual treatments of either. This investigation pointed out that plant growth promoting substances secreted by rhizobacteria (PGPR) and cyanobacteria could be used as a good tool to alleviate salinity stress and promote sugarbeet productivity and yield quality as it provides an eco-friendly biological approach under saline soil conditions.
Keywords: (cyanobacteria; bacteri8a; PGPR; sugarbeet, salinity .)
