Iranian Journal of Seed Research

Extended abstract

Introduction: Rice (Oryza sativa L.) is one of the most important cereals in the world and the main source of nutrition for more than one-third of the world's population. Compared to other grains, rice is more sensitive to low-temperature stress. Seed priming is a biotechnological tool and a simple, practical, effective, environmentally friendly and cost-effective approach to improve plant tolerance to various environmental stresses and increase seed germination. This study was designed and conducted with the aim of investigating the germination and physiological responses of of rice seeds under different intensities and durations of electromagnetic fields and temperature stress.

Materials and Methods: An experiment was conducted in 2024 as a factorial in a completely randomized design with the variables of electromagnetic field intensity at four levels, and duration at two levels, and temperature stress at three levels on Hashemi rice cultivar, with three replications, at Islamic Azad University, Astara Branch. Rice seeds were treated in a plastic bag under magnetic fields with intensities of (0, 50, 100, and 150 mT), durations of (30 and 60 minutes), and three levels of temperature stress (10, 15, and 25°C). A plastic tray was used for the second experiment and seedling establishment. Healthy seedlings were transferred to plastic pots containing sand. After 25 days, they were used to measure the desired traits.

Results: Results of the analysis of variance showed that magnetic field intensity, temperature stress, duration, and their interactions had significant effects on most of the evaluated traits. Temperature stress led to a significant increase in proline and malondialdehyde contents and a decrease in chlorophyll a and b. The lowest proline (1.017 µmol g⁻¹ fresh weight) and malondialdehyde (4.403 mmol g⁻¹ fresh weight) contents were observed at 25°C without magnetic field exposure. The highest germination percentage (98.95%), radicle length (69.617 mm), chlorophyll a (0.807 mg g⁻¹ fresh weight), and chlorophyll b (0.993 mg g⁻¹ fresh weight) were recorded under the treatment of 100 mT magnetic field at 25°C. Moreover, the highest germination rate (0.560 day⁻¹), shoot length (58.633 mm), seedling length (130.867 mm), radicle dry weight (3.25 mg), shoot dry weight (2.207 mg), seedling dry weight (5.457 mg), length seedling vigor index (13035.55), and weight seedling vigor index (543.528) were obtained at 100 mT, 25°C, and 30 minutes.

Conclusion: The effects of electromagnetic field treatment on germination traits and physiological parameters, including germination percentage, germination rate, and chlorophyll content, were significant, leading to improvements in these indices. The findings suggest the potential application of electromagnetic field treatment as a strategy to enhance seed germination and certain physiological traits under cold stress conditions.

Highlights:

1. The effect of the magnetic field on germination and physiological traits of rice seeds under temperature stress was investigated.
2. Seed priming with an intensity of 100 mT for 60 minutes under temperature stress of 10°C increased proline and malondialdehyde content.
3. At a temperature stress of 10°C, an increase in field intensity significantly enhanced the germination percentage.