Role of plant growth-promoting rhizobacteria in reducing the harmful effect of water stress on some physiological traits of popcorn

Abstract

A field experiment was conducted in the experimental field of field crops, College of Agriculture, University of Baghdad during the autumn season of 2017. In order to know the role of plant growth-promoting rhizobacteria in improving the physiological traits of popcorn crop under water stress, the split plot design was used with three replicates. The main plots included water stress treatments with three levels of irrigation, which were depletion 50% (Control), 60% and 70% of water availability, which were symbolized by S1, S2 and S3, respectively. The secondary plots included four treatments of bacterial vaccine (Control, Azotobacter, Azospirillum, Azotobacter+Azospirillum) which were symbolized by F0, F1, F2 and F3, respectively. The results showed that the water stress treatment when irrigation by depletion 70% had a significant effect on the decrease in auxin content by 36.44%, gibberellic acid 11.14%, cytokinin 47.55%, chlorophyll 20.07%, relative water content 18.09% and turgor pressure 20.64%. Vaccination with plant growth-promoting rhizobacteria (PGPRs) significantly increased physiological characteristics, Azospirillum treatment gave the highest average of auxin and gibberellic acid content of 66.28 and 43.72 μM sequentially, the mixture treatment of Azotobacter+Azospirillum significantly increased chlorophyll and proline content, relative water content and turgor pressure of the leaves. Vaccination with types of PGPRs achieved the best contribution to a small effect of water stress when treated with Azospirillum and Azotobacter+Azospirillum. Therefore, we suggest that the vaccination of popcorn seeds is used with water stress.