TOMATO SEEDLING PRODUCTION USING AN INOCULUM PREPARED WITH PLANT GROWTH-PROMOTING RHIZOBACTERIA (PGPR) ISOLATES

A study to attain healthy tomato (Lycopersicon esculentum Mill) seedlings through environment -friendly natural biological products took place from January to March 2022. Determining the effects of the inoculum prepared from five plant growth-promoting rhizobacteria (PGPR) isolates, i.e., Pseudomonas fluorescens, Pseudomonas putida, Lysinibacillus fusiformis, Enterobacter cloacae, and Kineococcus radiotolerans on the production of tomato seedlings, experiments proceeded at the Soil Microbiology Laboratory, Department of Soil Science and Water Resources, College of Agriculture, Tikrit University, Iraq. The isolates underwent screening for their efficiency as a biostimulant to dissolve insoluble phosphate compounds and produce indole acetic acid (IAA) and chelating compounds. The results showed the ability of all the isolates to produce IAA, chelating compounds, and solubility of phosphates. The P. fluorescens isolate showed superior in its phosphate solubilization and IAA production (41.30 mg p-1, 13.00 mg ml-1), followed by P. putida, E. cloacae, L. fusiformis, and K. radiotolerans, respectively, with the production of medium chelating compounds. The results also showed the superiority of the inoculated treatments over the non-inoculated treatments in the percentage and speed of germination, the length of tomato seedlings, the shoot dry weight, the number of leaves per plant, and root weight parts. The treatments with P. fluorescens displayed significant superiority in all studied traits, followed by P. putida, E. cloacae, L. fusiformis, and K. radiotolerans.