Gorgan University Of Agricultural Sciences and Natural Resources Journal of Plant Production Research 2322-2050 31 3 2024 10 22 The effect of mycorrhizal fungi inoculation on physiological characteristics and root mass of Paulownia fortunei seedlings under drought stress conditions The effect of mycorrhizal fungi inoculation on physiological characteristics and root mass of Paulownia fortunei seedlings under drought stress conditions 147 164 7049 10.22069/jopp.2023.21823.3079 FA Elham Hasani . Graduate of Forest Science and Engineering, Dept. of Natural Resources, Razi University, Kermanshah, Iran. مرتضی پوررضا Corresponding Author, Assistant Prof., Dept. of Natural Resources, Razi University, Kermanshah, Iran. Saeid Jalali Honarmand Associate Prof., Dept. of Plant Production and Genetic, Razi University, Kermanshah, Iran Ali Beheshti Ale Agha Associate Prof., Dept. of Soil Science Engineering, Razi University, Kermanshah, Iran. Journal Article 2023 10 16 Background and Objectives: Paulownia species is one of the trees introduced for wood production. Developing afforestation in arid and semi-arid areas presents a challenge due to limited water resources. Drought stress is a significant obstacle to the growth and establishment of plantations, making it crucial to implement innovative methods and techniques to reduce water usage for tree irrigation. Using mycorrhizal fungi to coexist with plants saves water consumption and increases tree establishment success. The study aimed to investigate the impact of arbuscular mycorrhiza fungi on the physiological characteristics and root mass of Paulownia fortunei seedlings under drought stress. <br />Materials and Methods: The experiment followed a completely randomized design with two factors and three replications. These factors were drought stress at four levels (80%, 60%, 40%, and 100% of crop capacity) and mycorrhizal fungi at two levels (with and without mycorrhiza). This experiment took measurements for root wet and dry weight, electrolyte leakage, greenness index, photosynthetic gas exchange (including net rate of photosynthesis, intercellular CO2 concentration, transpiration rate, and stomatal conductance), and leaf temperature. Two-way analysis of variance was performed after confirming the normal distribution of data to compare the response of mycorrhizal fungi-inoculated seedlings with those not inoculated under drought stress. <br />Results: The net rate of photosynthesis in the treatment with mycorrhiza at the non-stress level was about 4 times higher than its value in the treatment without mycorrhiza at the severe stress level. Also, the amount of stomatal conductance in the treatment with mycorrhiza at the non-stress level showed an increase of about 10 times compared to its value in the treatment without mycorrhiza at the severe stress level. The rate of transpiration was also showed an increase of about 6 times in the treatment with mycorrhiza in the non-stress level compared to the treatment without mycorrhiza in the severe stress level. The dry weight of the root in the treatment with mycorrhiza at the non-stress level was about 3.5 times higher than its value in the treatment without mycorrhiza at the severe stress level. But the amount of electrolyte leakage in the treatment without mycorrhiza showed an increase of about 7% compared to the amount in the treatment with mycorrhiza. In addition, the greenness index in the treatment without mycorrhiza was about 8% lower than its value in the treatment with mycorrhiza. The concentration of intercellular carbon dioxide also showed an increase of about 13% in the treatment with mycorrhiza compared to its value in the treatment without mycorrhiza.<br /><br />Conclusion: It was concluded that the application of mycorrhizal fungi plays an effective role in photosynthetic gas exchange and membrane stability, ultimately increasing the resistance and survival of Paulownia fortunei seedlings in drought stress. Therefore, the use of mycorrhiza in afforestation with this species in dry areas should be suggested. Background and Objectives: Paulownia species is one of the trees introduced for wood production. Developing afforestation in arid and semi-arid areas presents a challenge due to limited water resources. Drought stress is a significant obstacle to the growth and establishment of plantations, making it crucial to implement innovative methods and techniques to reduce water usage for tree irrigation. Using mycorrhizal fungi to coexist with plants saves water consumption and increases tree establishment success. The study aimed to investigate the impact of arbuscular mycorrhiza fungi on the physiological characteristics and root mass of Paulownia fortunei seedlings under drought stress. <br />Materials and Methods: The experiment followed a completely randomized design with two factors and three replications. These factors were drought stress at four levels (80%, 60%, 40%, and 100% of crop capacity) and mycorrhizal fungi at two levels (with and without mycorrhiza). This experiment took measurements for root wet and dry weight, electrolyte leakage, greenness index, photosynthetic gas exchange (including net rate of photosynthesis, intercellular CO2 concentration, transpiration rate, and stomatal conductance), and leaf temperature. Two-way analysis of variance was performed after confirming the normal distribution of data to compare the response of mycorrhizal fungi-inoculated seedlings with those not inoculated under drought stress. <br />Results: The net rate of photosynthesis in the treatment with mycorrhiza at the non-stress level was about 4 times higher than its value in the treatment without mycorrhiza at the severe stress level. Also, the amount of stomatal conductance in the treatment with mycorrhiza at the non-stress level showed an increase of about 10 times compared to its value in the treatment without mycorrhiza at the severe stress level. The rate of transpiration was also showed an increase of about 6 times in the treatment with mycorrhiza in the non-stress level compared to the treatment without mycorrhiza in the severe stress level. The dry weight of the root in the treatment with mycorrhiza at the non-stress level was about 3.5 times higher than its value in the treatment without mycorrhiza at the severe stress level. But the amount of electrolyte leakage in the treatment without mycorrhiza showed an increase of about 7% compared to the amount in the treatment with mycorrhiza. In addition, the greenness index in the treatment without mycorrhiza was about 8% lower than its value in the treatment with mycorrhiza. The concentration of intercellular carbon dioxide also showed an increase of about 13% in the treatment with mycorrhiza compared to its value in the treatment without mycorrhiza.<br /><br />Conclusion: It was concluded that the application of mycorrhizal fungi plays an effective role in photosynthetic gas exchange and membrane stability, ultimately increasing the resistance and survival of Paulownia fortunei seedlings in drought stress. Therefore, the use of mycorrhiza in afforestation with this species in dry areas should be suggested. https://jopp.gau.ac.ir/article_7049_5965321581c3ba9fcb214c81239efc5f.pdf