Iranian Journal of Seed Research

The effect of spermidine on seed germination of three different cucumber cultivars under cold stress was studied as a 4×2 factorial experiment by using a completely randomized design with 4 replications. The first factor was 4 concentrations of spermidine consisted of 0 (control), 0.1, 0.5 and 1 mM and the second one was three cucumber cultivars consisted of ‘Emperator’, ‘Amiran’ and ‘Rashid’. For this purpose, 50 seeds of each cultivar were placed on filter papers inside sterilized Petry dishes and spermidine solutions were added to them according to each treatment. All petry dishes were placed at a 13°C temperature of the incubator until end of the experiment and germinated seeds were counted daily. The measured traits were the percentage of germination, plumule length, radicle length, the dry and fresh weight of the plumule and radicle. The results showed that treating seeds of ‘Rashid’ cultivar with 0.1 mM spermidine increased the percentage of germination, plumule and radicle length, fresh and dry weights of radical compared with control. Treating ‘Rashid’ seeds with high concentration (1 mM) of spermidine showed inhibitory effects on all measured characteristics, but in ‘Amiran’ cultivar only decreased the percentage of germination, plumule and radicle length, the fresh and dry weight of radicle.

Extended abstract
Introduction: Rice (Oryza sativa L.), one of the world's most crucial cereals, serves as a primary nutritional source for over one-third of the global population. Compared to other grains, rice exhibits greater sensitivity to low-temperature stress. Seed priming as a biotechnological tool is a simple, practical, cost-effective, and eco-friendly approach to enhance plant stress tolerance and improve seed germination. This study investigated the germination and physiological responses of rice seeds to varying intensities and durations of electromagnetic field (EMF) exposure under cold stress conditions.
Materials and Methods: In 2024, a factorial experiment was conducted in a completely randomized design at Islamic Azad University, Astara Branch. The experiment evaluated four levels of EMF intensity (0, 50, 100, and 150 mT), two exposure durations (30 and 60 minutes), and three cold stress levels (10, 15, and 25°C) on the Hashemi rice cultivar, with three replications. Rice seeds were treated in plastic bags under the specified EMF conditions. For seedling establishment, healthy seedlings were transferred to plastic pots containing sand. After 25 days, physiological traits were measured.
Results: Analysis of variance revealed significant effects of EMF intensity, duration, cold stress, and their interactions on most traits. Cold stress significantly increased proline (1.02 µmol g⁻¹ FW) and malondialdehyde (4.40 mmol g⁻¹ FW) while reducing chlorophyll a and b. The highest germination percentage (98.9%), radicle length (69.6 mm), chlorophyll a (0.807 mg g⁻¹ FW), and chlorophyll b (0.99 mg g⁻¹ FW) were observed under 100 mT at 25°C. Additionally, the highest germination rate (0.560 day⁻¹), shoot length (58.63 mm), seedling length (130.8 mm), radicle dry weight (3.25 mg), shoot dry weight (2.21 mg), seedling dry weight (5.46 mg), length-based vigor index (13035.5), and weight-based vigor index (543.5) were recorded at 100 mT, 25°C, and 30 minutes. While cold stress reduced germination and seedling growth, EMF treatment up to 100 mT counteracted these effects across all temperature levels.
Conclusion: EMF treatment up to 100 mT significantly improved germination traits (e.g., percentage, rate) and physiological parameters (e.g., chlorophyll content) in this rice cultivar. These findings highlight the potential of EMF priming to enhance seed germination and stress resilience under cold conditions.

Highlights:

1. The effect of the magnetic field was investigated on rice seed germination and physiological traits under cold stress.
2. Seed priming with an intensity of 100 mT for 60 minutes under cold stress of 10°C increased proline and malondialdehyde content.
3. Higher EMF intensities (up to 100 mT) significantly improved germination at 10°C.