There is increasing attention to accommodate wheat cultivars to grow
in salinities 0 utside the natural range 0 f tolerance too btain a n appropriate
economic yield. Accordingly, a gnotobiotic experiment was conducted to
study the effect of using different bacterial strains, isolated from saline soils,
i.e. plant growth promoting rhizobacteria (Klebsiella pneumoniae) either alone
or in combination with N₂-fixing (Azospirillum brasilense + Azotobacter
chroococcum) 0 r phosphate dissolving (Bacillus m egatherium) or with both
(composite), as inoculation treatments for one week-old wheat seedlings
(Tn"ticum eestivutn L.) cv, Giza 163 growing under different levels of
seawater, i.e. 0, 3, 6 and 12 csm". In addition, a pot experiment was carried
out using the previous bacterial strains treatments for inoculation of wheat
grains as well as for soil pots of wheat plants (2 and 6 weeks-old) grown
under the same aforementioned levels of seawater. In gnotobiotic experiment, the results of total bacterial counts as well
as of nitrogenase activity indicated that with increasing salinity level, there
were corresponding reductions in total bacterial counts as well as of
nitrogenase activity were detected. Meanwhile, higher values of total bacterial
counts as well as of nitrogenase activity were obtained from wheal plants
inoculated with composite or Klebsiella + Nrfixers inocula as compared
whether with un inoculated or the other inoculation treatments under different
salinity levels. In the pot experiment, the microbiological study revealed that numbers
of total bacterial counts were decreased with increasing salinity level. The
highest total bacterial counts adhering to roots were recorded at nine weeks
of growth period for wheat plants inoculated with composite inocula under
different salinity levels. Inoculation with various bacterial strains as grain
coa~ing treatments increased the germination percentage under different
salinity levels as compared each with uninoculated one. Under different salinity levels, the mean values of germination
percentage of wheat grains as well as different studied growth characters of
wheat plants showed a significant progressive reduction with increasing
salinity levels. Moreover, the mean values of total N, P, K+ and Ca+²
concentrations decreased whereas, Mg+², Na", reducing and total sugar, free
amino acids as well as free proline concentrations increased in roots and
shoots of wheat plants. Also, the endogenous IAA and cytokinins
concentrations decreased, whereas endogenous ABA increased in wheat
shoots under different salinity levels. This was reflected on a significant