Synergist effects of some PGPR bacteria and sodium nitroprusside in pepper plant

Plant growth promoting rhizobacteria (PGPR) represent promotes plant growth by increasing the supply or availability of nutrients to the host plant. These bacterial applications are environmentally friendly techniques and their use has become widespread recently. Some PGPRs can increase nitrogen (N) fixation and have phosphate (P) solubilizing property. In the current study, we evaluated the synergistic effects of some useful bacteria and sodium nitroprusside (SNP, a nitric oxide donor) in pepper plant. Nitric oxide (NO) acts as a signal molecule in plants and has important role in plant-bacteria symbiosis interaction. Three PGPR strains namely, Enterobacter cloacae (ZE-2), Pseudomonas putida (ZE-12) and Acinetobacter calcoaceticus (ZE-13) were used and the bacteria possess phosphorous-solubilizing and nitrogen-fixing properties. The applications of PGPRs alone and with combination of SNP (0.1 mM) were performed to the plant rhizosphere (the roots) through irrigation two times with two weeks interval starting with seedling planting. End of the study, many morphological parameters including stem diameter, plant height and biomass were improved by all applications compared to control. Root:shoot dry weight ratio decreased by the applications. Stem diameter, plant height and biomass were significantly increased with all treatments compared to control. The yield was found higher in all applications compared to control and the highest increase in the yield was provided by Enterobacter cloacae (ZE-2) application. Dry matter allocation in upper part of the plants provided higher plant yield. The applications significantly affected cell expansion and division. SNP increased the effect of Acinetobacter calcoaceticus (ZE-13) bacteria on cell division in leaf cells and midrib size. Furthermore, Pseudomonas putida (ZE-12) increased the yield combining with SNP compared to alone use. The increase in the plant growth is related with the midrib size. The application of PGPR with SNP could be a promising approach in plant growing.