Abstract

This study was conducted to determine the effect of plant growth promoting rhizobacteria Azotobacter chroococcum AZ6 isolated from arid soil and osmolytes such as glycine betaine (GB) or proline (P) on the growth of durum wheat varieties under salinity stress. Inoculation by A. chroococcum AZ6 in the presence or absence of P (5 mM) or GB (5 mM) reduced substantially the effect of salt stress on plant growth parameters such as root length, plant height, fresh shoot and root weight and dry shoot and root weight. The differences between the two varieties were low but with a fresh and dry weight higher in Waha. The rate of Na⁺ accumulation in the roots and the shoots was important up to 100 mM and increased at 200 mM. The K⁺ concentration and chlorophyll content decreased but proline and amino acid contents were enhanced with increasing salinity. Treatment by inoculation in the presence or absence of osmolytes improved the chlorophyll (a and total) and the K⁺ concentrations and reduced intracellular proline accumulation and amino acids contents. Also, as result, the use of A. chroococcum AZ6 and osmolytes treatment may provide a means of improving tolerance of durum wheat to salt stress.

Key words: Durum wheat, salinity, osmolytes, Azotobacter chroococcum,