AU - Heshmati, Maryam AU - Kowsari, Mojgan AU - Feizi, Hassan TI - Effects of titanium dioxide nanoparticles on germination and growth indices of oak acorns under drought stress PT - JOURNAL ARTICLE TA - flowerjournal JN - flowerjournal VO - 4 VI - 2 IP - 2 4099 - http://flowerjournal.ir/article-1-158-en.html 4100 - http://flowerjournal.ir/article-1-158-en.pdf SO - flowerjournal 2 ABĀ  - The crisis of oak decline in recent years has destroyed big sections of the Zagros forests, and altering the structure of the forest masses. Finding ways to restore deforested forests and increase the ability to deploy new seedlings in the field can help reforest. In this study, the potential of titanium dioxide nanoparticles was used to modify the damaging effects of drought stress on oak seed. Drought stress is one of the most important factors in limiting the seed germination of plants. Treatments consisted of 4 levels of titanium nanoparticles (0, 10, 50 and 100 mg L-1) and 4 levels of drought stress (0, -3, -6 and -9 bar) applied by polyethylene glycol 6000. Zero levels in both treatments were considered as the control treatment. The experiment was conducted as a factorial experiment in a completely randomized design with two factors and three replications. Analysis of variance showed that drought stress had a negative effect on most growth factors, especially at high levels. Drought stress above -6 bar, had a negative effect on root growth and treatment of 50 mg L-1 titanium dioxide with -2 bar of drought stress caused the highest root fresh weight (7228.3 mg) and maximum root length of 127.33 mm. High drought stress levels decreased leaf number and leaf area. Although there were no significant differences between the treatments of nanoparticles on stem length and number of leaves, treatment with 50 mg L-1 nanoparticles had higher numerical value than others. The results showed that the highest germination percentage and seedling emergence were obtained at the concentration of 50 mg L-1 of TiO2 and drought stress in 0 and -3 bar, and the lowest germination percentage was observed at no-treatment and drought stress in -9 bar. The interactions between nanoparticles and drought stress at the 1% level were significant for the crown diameter changes. The concentration of 50 mg L-1 nanoparticles at the drought stress in -6 bar, increased the crown diameter by about 2.63 mm on average. The highest number of lateral roots was obtained at a concentration of 50 mg L-1 and a -3 bar of drought stress. The results showed that when the nanoparticles were treated with drought stress, the plant increased its stress tolerance threshold for better survival under stress conditions. Based on the findings of this study, it can be concluded that a concentration of 50 mg L-1 nanoparticles is the most suitable treatment for improving root characteristics and moderating drought stress effect on oak. The present study is the first study of nanoparticle treatment on vegetative characteristics of oak seed. CP - IRAN IN - LG - eng PB - flowerjournal PG - 87 PT - Research YR - 2020