| چکیده انگلیسی مقاله |
Introduction: Plant growth and development begins with seed germination, afterwards, root growth and seedling performance from the soil as the first signs of growth. Seed evolution and the health of the seed components are necessary for germination. Drought stress, as inanimate and multidimensional stress, has severe effects on plant growth. One of the new solutions in drought stress management is the use of nanoparticles. Nutrient and water uptake can be increased ultimately to improve germination by nanoparticles. The aim of this research to evaluate the effects of titanium dioxide nanoparticles on chickpea plant germination factors to modify the negative effects of drought stress. Materials and Methods: A factorial experiment was conducted in a completely randomized design with four replications on chickpea seeds of Arman cultivar in the Plant Sciences Research Institute of the Ferdowsi University of Mashhad in 1398. Seeds were primed with concentrations of 0, 5, 10, 15, and 20 mg l-1 titanium dioxide for 24 hours. The seeds were cultured in sterilized petri dishes. Drought stress was applied using polyethylene glycol 6000 with 0, -2, -4 and -8 bar osmotic potential. All of the traits related to seedling include root length, mean germination time, seed vigor index, germination percentage, root length, root dry weight in under different level of drought stress were measured. Results: The results showed that germination rate, the number of normal seedlings, seed vigor index, germination index, length of seedling root length, root dry weight decreased by applying stress. Root length by using of the titanium dioxide nanoparticles increased 1.8 times compared to the absence of nanoparticles when seedling under drought treatment -8 bar. Also, in the control treatment, with increasing the concentration of titanium dioxide nanoparticles up to 20 mg l-1, the root dry weight is increased. At the level of drought stress -2 and -4 bar up to 15 mg l-1 titanium dioxide nanoparticles, the dry weight root showed an increasing trend, with increasing the nanoparticle concentration to 20 mg l-1 and also, the germination rate increased by 24% compared to the control in this same situation. The interaction of drought stress levels and different nanoparticle concentrations showed that with increasing nanoparticle concentration in all drought stress levels, germination rate increased. In some traits, titanium dioxide nanoparticles could not show positives effects, so that by increasing the concentration of nanoparticles to 15 mg l-1, the percentage of normal seedlings decreased to a minimum, while the percentage of normal seedlings in control was 18% higher than control. All of the traits related to seedling were encountered under drought stress situation, on the other hand, the presence of titanium dioxide nanoparticles could reduce some negatives impacts on seedling traits. Overall conclusion: The efficiency and effectiveness of nanoparticles at low concentrations comparatively have been proven at the high concentrations, the effects are negative or with signs of toxicity. Based on previous experiments, these nanoparticle levels were selected at low concentrations, at all levels of Drought stress by applied the concentration of titanium dioxide nanoparticles up to 20 mg l-1 in traits such as germination percentage, seed vigor index, increase in root length, and root dry weight significantly increased. Therefore, under drought stress conditions, the application of titanium dioxide nanoparticles up to a concentration of 20 mg l-1 can partially reduce the negative effects of drought stress on the germination characteristics of chickpeas. In general, the role of nanoparticles in the ability to facilitate the entry of water into the shell has been fairly proven. |