INFLUENCE OF INDIGENOUS AND EXOTIC MYCORRHIZA SPECIES ON GEMLİK OLIVE (Olea europaea cv. Gemlik) SEEDLINGS GROWTH UNDER DEFICIT WATER STRESS CONDITIONS

Project no. 23117 · Status: Kapanmış (Yayın bekleniyor) · 2021

Summary

In this project, the aim was to reduce the drought sensitivity of the Gemlik olive variety by enriching and inoculating mycorrhizal spores isolated from the roots and rhizosphere of drought-resistant Ayvalık olive trees into Gemlik seedlings. In this context, the effects of both mixed native mycorrhiza and selected mycorrhiza species Rhizophagus irregularis spores on the growth and drought resistance of Gemlik olive seedlings were investigated, focusing on: 1) identifying natural mycorrhizal species and genera adapted to arid conditions in olive plantations in İzmir province, and 2) evaluating the impact of both mycorrhizal spore applications on the development and drought resistance of Gemlik seedlings.In the first phase of the project, soil and root samples were collected from 11 different olive plantations in the rhizosphere area of İzmir province, where Ayvalık olive trees were grown under non-irrigated, drought conditions. A trap culture experiment was conducted to increase the number of mycorrhizal spores adapted to arid conditions for use in the main experiment. Clover and sorghum plant seeds were used as test plants in the trap plant experiment.In the second phase, the main pot experiment was initiated on April 1, 2022, using Gemlik olive seedlings divided into three groups: a control group without mycorrhizal inoculation (M0), a group inoculated with native and mixed mycorrhiza obtained from olive plant rhizosphere and propagated in the trap culture experiment using soil from Çeşme-Germiyan (M1), and a group inoculated with Glomus intraradices (M2). The experiment was conducted in a split-plot design with three replications, where irrigation levels were applied to the main plots and mycorrhizal inoculations to the subplots. For the first 7 months, all pots were irrigated at 95% of field capacity, after which half of the pots were subjected to limited irrigation conditions. The development of the plants and the decline in photosynthesis rates were monitored, and the water stress period lasted for a total of 14 weeks, conculuding on February 20, 2023, with the pot experiment. Plant and soil samples were analyzed at the 7th month and the end of the experiment.Amplicon Metagenomic Sequencing analysis of the soil from Çeşme-Germiyan, which had the highest mycorrhizal spore count and infection rate from the trap culture experiment, revealed the presence of 1 genus (Glomus sp.) and 2 species (Claroideoglomus lamellosum and Rhizophagus iranicus). The isolated mycorrhizal spores were also morphologically identified, with the dominant group being Glomus and multiple mycorrhizal spore species identified, including Glomus sp. (4 or 5 species) and Acaulospora sp. (at least 3 species).The transition from full to limited irrigation negatively affected all growth parameters of the Gemlik seedlings. Mycorrhizal inoculations were found to have a statistically significant effect only on seedling height. Under full irrigation, mycorrhizal applications increased seedling height by 12% compared to the control, but this increase dropped to 3% under limited irrigation conditions. Mycorrhizal applications significantly enhanced the uptake of N, P, Ca, Mg, Cu, and Zn, with the M1 application showing a more pronounced effect under water-limited conditions, except for Zn.AMF applications increased the chlorophyll content in olive seedlings grown under full irrigation, with the native and mixed mycorrhizal inoculation (M1) being more effective. Water stress reduced chlorophyll content, but M1 applications mitigated this decline. AMF applications also improved the availability of phosphorus, manganese, zinc, nitrogen, potassium, and calcium concentrations in the soil. Although limited irrigation significantly reduced soil microbiological properties, both M1 and M2 applications resulted in higher microbial biomass and enzyme activity compared to the control. Under full irrigation, M2 was more effective in enhancing microbial parameters, while under limited irrigation, M1 showed greater improvement.In conclusion, the native and mixed mycorrhizal species (M1) propagated from the trap plant experiment using soil from Çeşme-Germiyan were found to provide higher resistance to water stress conditions in Gemlik olive seedlings compared to the other mycorrhizal group (M2), demonstrating their potential to mitigate the adverse effects of drought.

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