Effects of super absorbent polymer and plant growth promoting rhizobacteria (PGPR) on yield and oxidative damage of maize under drought stress

This study was carried out to study effects of super absorbent polymer and plant growth promoting rhizobacteria (PGPR) on yield and some physiological traits of maize (double cross 370) in Karaj region/Iran in 2009. Experiment was conducted as a randomized complete block design with 4 replicates and in two separate experiments under drought stress and normal conditions. Seven different treatments studied in this research, including: T₁: Grain inoculation with biofertilizer (Azospirillum lipoferum+Pseudomonas putida), T₂: Applying super absorbent polymer as gel in rows, T₃: Applying super absorbent polymer as powder in rows, T₄: Grain inoculation with biofertilizer (Azospirillum lipoferum +Pseudomonas putida) and applying super absorbent polymer as powder in rows, T₅: Grain inoculation with biofertilizer (Azospirillum lipoferum + Pseudomonas putida) and applying super absorbent polymer as gel in rows, T₆: Mixing biofertilizer (Azospirillum lipoferum+Pseudomonas putida) with super absorbent polymer (as gel) and applying in rows and T₇: Non-application of super absorbent polymer and biofertilizer (control). Results indicated that drought stress decreased ear dry yield. Application of super absorbent polymer (powder or gel) and biofertilizer (Azospirillum lipoferum+Pseudomonas putida) increased ear dry yield in both stress and normal conditions. The highest content of oxidative damage biomarkers Malondialdehyde (MDA), dityrosine achieved in stress condition (T₇). Application of super absorbent polymer (treatments T₂ and T₃) in drought stress condition, decreased content oxidative damage biomarkers (MDA, dityrosine and dihydroxy-guanozine) that indicate the positive effect of this polymer in reducing drought stress effects. Application of biofertilizer alone (T₁) or with super absorbent (T₄, T₅, T₆), decreased the conte- - nt of oxidative damage biomarkers in drought stress condition, but increased the amount of proline. It seems inoculated plants with increasing of proline scavenge produced free radicals under drought stress.