Abstract:
The land areas and crop species adversely impacted by salinity and heavy metals are growing rapidly. Current
research indicates that plant growth-promoting microorganisms offer an environmentally friendly option for
improving physiological and biochemical processes in plants growing under stress conditions. The aim of the
present study was to investigate the potential mitigation of simultaneous salinity and cadmium (Cd) stress in
rapeseed (Brassica campestris cv. BARI Sarisha-17) by the application of pirillum sp. (Az), phosphate solubilizing
bacteria
(PSB),
potassium
mobilizing
bacteria
(KMB),
and
vesicular
arbuscular
mycorrhiza
(VAM).
Seeds
were
treated with PSB or KMB prior to sowing, whereas Az, PSB, KMB, or VAM were added as supplements
during soil preparation. At 21 days after sowing, the plants were treated with a combination of salt (100 mM
NaCl) and Cd (0.25 mM CdCl
), with several applications at 7-day intervals. The combination of salt and Cd
stress decreased plant growth and biomass, relative water content, and photosynthetic pigment levels, while also
increased electrolyte leakage, lipid peroxidation, and the generation of excess reactive oxygen species (ROS). Salt
and Cd stress also impaired plant ion balances of sodium, potassium and nitrate, antioxidant defenses, and
glyoxalase system activity. Application of Az, PSB, or KMB restored these parameters to unstressed levels by
facilitating the scavenging of ROS, maintaining water status, restoring ion balances, enhancing plant antioxidant
defenses, and increasing glyoxalase enzyme activity, while reducing methylglyoxal toxicity and improving
photosynthetic activity. The application of KMB was the most effective; however, all microbe supplementations
showed the ability to alleviate the damage caused by stress in rapeseed. These findings highlight the ability of
soil microorganisms with plant growth-promoting properties to improve the physiological and biochemical
functions of rapeseed under Cd and salt stress.
