The investigation of the effects of endophytic bacteria on plant growth promotion and colonization in cucumber plants

In this study, it was investigated for six endophytic bacteria (EB) strains, which were isolated from the internal tissues of surface disinfected cucumber plants and previously screened according to in vitro plant growth promoting tests, to effects on increasing the plant growth parameters and yield, and the colonization rate in cucumber plants. EB inoculation took place two times; before sowing as seed coating and after transplanting as substrate drenching. In the greenhouse conditions, yield experiments were repeated two times as spring and autumn under soilless cultivation system. In this study, some measurements and analyzes were carried out related with the biomass (fresh and dry weights of root and shoot), yield (total and marketable), and quality of fruits (diameter, length, stiffness, color and so on.). EB isolates increased the plant growth and yield at the rate of 5-28% compared to non treated the negative control. EB strain 56 was determined as the most successful treatment in terms of both biomass and yield. It was recorded that tested EB strains were successfully colonized on root and shoot tissues for a period of 62 days. In this thesis, tested EB strains were identified according to the results of molecular diagnostic test by using 16s rRNA primers and sequence analysis as Pseudomonas punonensis (strains 37 and 56), Ochrobactrum pseudintermedium (strain 80), Pantoea agglomerans (strain 83), Bacillus thuringiensis (strain.99), and Pseudomonas fluorescens (strain 112).