Effects of Salinity and Plant Growth Promoting Rhizobacteria on Some Physiological Traits and Grain Yield of Hulled Wheat Compared to Durum Wheat

Scientific data on the hulled wheats is scarce. Therefore, changes in some physiological attributes including carotenoids concentration, antioxidant enzymes activity, malondialdehyde content (MDA), cell membrane stability index (MSI) and grain yield in a hulled tetraploid wheat (i.e. "Joneghan") and  a durum wheat cultivar (i.e. "Yavaroos") in response to salinity and plant growth promoting rhizobacteria (PGPR) were studied using a split-factorial based on randomized complete block design at Research Farm, Isfahan University of Technology, Isfahan, Iran in 2013. Three levels of irrigation water salinity (control, 100 and 200 mM of NaCl) were chosen as main plots and the two tetraploid wheat genotypes and three PGPR strains (550, 57 and UW3) and bacteria-free control were considered as subplots. Salinity led to significant decreases in grain yield/m2 (nearly 30%), activity of the antioxidative enzymes of catalase (CAT), peroxidase (POX) and ascorbate peroxidase (APOX) and carotenoids concentration. Salinity led to a decrease in MSI and an increase in MDA content, indicating salt-induced damages to the cells. Bacterial strains left different effects on the above-mentioned traits. Strain 550 led to 44% increase in grain yield of the two genotypes at the absence of salt, though strain UW3 led to 24% increase in grain yield of the genotypes, when grown at the presence of 200 mM of NaCl. Though, the bacterial strains led to increase in MSI of the salt-treated plants. From the data obtained in the present field study we can conclude that the PGPR efficacy in the mitigating salt stress in tetraploid wheat is genotype-, salt level- and strain-specific. The "Joneghan" hulled tetraploid wheat was out-performed by the "Yavaroos" durum wheat, though its yield penalty due to saline water did not appear to differ from that of the latter genotype.