The effect of different magnetic field intensities and times on germination and growth characteristics of rice seedlings (Oryza sativa)

Introduction: Rice (Oryza sativa L.), as one of the world's most important cereals, serves as a staple food for more than one-third of the global population.This strategic crop plays a key role in the economies of many countries.Seed priming is a biotechnological tool and a simple, practical, effective, eco-friendly, and cost-efficient approach to enhancing a plant's tolerance to various environmental stresses and improving seed germination.This study was designed and conducted to investigate the germination and physiological responses of two rice cultivars under varying intensities and durations of electromagnetic field exposures.Materials and Methods: A factorial experiment in a completely randomized design with the factors of electromagnetic field intensity at 4 levels, time at 3 levels, and two cultivars (Tarom and Hashemi) in three replications was conducted at the Islamic Azad University, Astara Branch in 2023.Rice seeds were treated in a plastic bag under magnetic fields with intensities (0, 50, 100, and 150 mT) and times (10, 50, and 100 minutes).A plastic tray was used for the second experiment and seedling establishment.Healthy seedlings were transferred to plastic pots containing sand.After 25 days, the desired traits were measured.Results: The analysis of variance results indicated that the effects of the magnetic field, time, cultivar, and their interactions were significant for most traits.The electromagnetic field at 100 mT for 50 minutes led to an increase in germination percentage compared with the control.In contrast, the treatment of 150 mT for 100 minutes caused a significant reduction in all germination-related traits.The highest values were observed under the 100 mT for 50-minute treatment, including germination percentage (98.8%),germination rate (12.5 seeds per day), radicle length (68.1 mm), plumule length (47.5 mm), seedling length (116 mm), radicle dry weight (0.715 mg), plumule dry weight (2.02 mg), seedling dry weight (2.74 mg), seedling length vigor index (11422), seedling weight vigor index (271), chlorophyll-a (0.846 mg g -1 FW), chlorophyll-b (0.96 mg g -1 FW), and carotenoids (0.44 mg g -1 FW). Conclusion:The electromagnetic field had a significant effect on germination-related traits and physiological characteristics, including germination percentage, germination rate, and chlorophyll content, leading to an increase in these indices.In the present study, the 100 mT treatment for 50 minutes improved seedling vigor in terms of both length and weight.Based on these findings, magnetopriming within the studied treatment range enhances germination and improves rice plant establishment by increasing chlorophyll levels.