Evaluation of the potential of two plant growth promoting rhizobacteria [PGPR] on the increase of wheat productivity under different salinity regimes

ABSTRACT

A POT experiments was conducted winter 2007-2008 at the experimental greenhouse of Microbiology Department, Soils, Water and Environment Research Inst., ARC, Giza, Egypt, to evaluate the response of the wheat cultivars, Sakha 93 and Gemiza 7, to be inoculated with Azotobacter sp. and Bacillus sp., under two salinity regimes [NaCl concentration 100 mM and 150 mM, respectively] for improving salinity tolerance in sandy soils. The results showed that dehydrogenase and nitrogenase activities were significantly inhibited by increasing salinity in the rhizosphere of all uninoculated plants. The chlorophyll-a [chl. a], chlorophyll-b [chl. b] and carotenoid contents of 30 days old seedlings were significantly reduced in response to increase of salinity levels in all treatments. Data also revealed that increasing salinity level caused an increased gradual accumulation of proline in the shoots of the stressed wheat plant in both cultivars. Bacterial amendment resulted in a significant increase in all measured yield parameters compared with the un-amended control. The mineral contents [N, P and K] in both wheat cultivars varied as a response to the saliniy regims and presence of Azotobacter sp. and Bacillus sp., N, P and K contents of grains were significantly decreased with increasing salinity in all treatments in both cultivars but most pronounced in Gemiza 7