Effects of mycorrhiza and rhizobacteria treatments on growth and quality of petunia (Petunia hybrida L.) grown under drought stress conditions

The study was carried out between 2023 and 2024 in policarbonate greenhouse of Recep Tayyip Erdoğan University Faculty of Agriculture Department of Horticulture to determine the effects of mycorrhiza and rhizobacteria applications against drought stress in Petunia (Petunia hybrida 'Super Cascade White'). Petunia seeds were germinated in peat: perlite: vermiculite (2:1:1) and when they formed 5 true leaves, they were transplanted into pots containing garden soil: peat: perlite (2:1:1). Seedlings were planted by dipping them in solutions containing mycorrhiza (2.5 g/l), rhizobacteria (50 ml/l) and mycorrhiza+rhizobacteria (2.5 g/l+50 ml/l) prior to transplanting. For drought stress, deficit irrigation was applied to the plants at the rates of 100%, 75%, 50% and 25%. The experiment was established according to the split plots experimental design with 3 replications and 5 plants were used in each replication. Measurements and observations were carried out in greenhouse conditions (plant height, number of leaves, number of flowers, petal length, petal width) and in laboratory conditions (plant wet weight, plant dry weight, root wet weight, root dry weight, root length) during the growth period of plants under stress conditions and the statistical relationships between them were investigated. As a result of the analyses, as the amount of water stress increased, there was a negative effect on all parameters examined. This negative effect was reduced when mycorrhiza and rhizobacteria were used separately and combined. The interaction of microorganism treatments and drought stress had a statistically significant effect on all parameters except root dry matter content and showed that they were an important treatment in drought resistance.