Iranian Journal of Seed Research

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.

Objective: This study aimed to evaluate the effect of chitosan on germination indicators and the activity of antioxidant enzymes in safflower seedlings under salinity stress.
Method: The experiment was conducted using a factorial arrangement based on a completely randomized design with three replications at the University of Mohaghegh Ardabili in 2024. The experimental treatments included four salinity levels (0, 50, 100, and 150 mM NaCl) and four concentrations of chitosan (0, 0.2, 0.4, and 0.5% w/v), which were dissolved in 1% acetic acid.
Results: The results showed that salinity stress reduced the germination rate, radicle length, plumule length, seedling length, seedling fresh weight, and seedling dry weight. However, priming with different concentrations of chitosan, especially at 0.5%, improved these traits. The highest daily germination rate (0.114) was observed in the control group (distilled water priming) under 150 mM salinity. The activity of catalase and peroxidase enzymes in the control under 150 mM salinity increased by approximately 43% and 70%, respectively, compared to the 0.5% chitosan treatment under non-saline conditions. Similarly, the activity of superoxide dismutase enzyme in the 0.5% chitosan treatment under 150 mM salinity increased by about 67% compared to the control under non-saline conditions. Furthermore, the ascorbate peroxidase enzyme activity in seeds primed with 0.5% chitosan increased by 37% compared to the control (distilled water priming).
Conclusions: The results indicated that seed treatment with different concentrations of chitosan can mitigate the harmful effects of salinity on some traits of safflower seedlings and improve seedling growth. The best results were achieved when 0.5% chitosan was used under salinity conditions.

Highlights

Objective: This study introduces functional analysis of variance as a method for comparing germination trends under different treatments over a given time interval. This approach not only enables the comparison of treatments over the entire time period but also allows for treatment comparisons at each specific moment in time. Moreover, it identifies critical time points at which the maximum significant difference between treatments occurs, which can serve as novel germination indices.
Method: In this study, real experimental data from four germination studies were analyzed: (1) the effect of temperature on Nigella sativa germination, (2) the effect of salinity stress on Zea mays seed germination, (3) the comparison of germination among different Triticum astivum cultivars, and (4) the effect of water stress on Brassica napus germination. Using spline functions, germination data from these experiments were modeled as a function of time. The results of functional analysis were then used to compare treatments in terms of both germination percentage and germination time across the four experiments.
Results: The results of the functional analysis demonstrated its high efficiency in detecting significant or non-significant differences between treatments throughout the germination period. Furthermore, this method enabled comparisons of germination percentages at any given time point, as well as comparisons of germination times at various germination percentiles, providing detailed insights into the nature of differences among treatments. This approach also facilitated the introduction of new germination indices applicable to different seed types.
Conclusions: Overall, the results of this study indicate that the stepwise functional analysis method introduced here is an effective and precise tool for comparing treatments in germination data. This approach not only enhances treatment comparisons but also provides detailed insights into the nature of differences between treatments. Moreover, it overcomes the limitations associated with using conventional germination indices for treatment comparisons.

Highlights

• Functional analysis was applied to compare treatments in germination percentage data.
• The method enabled treatment comparisons in terms of germination percentage at each moment in time, as well as comparisons of germination times at various percentiles.
• Critical germination times and percentiles at which the maximum differences between treatments occur were introduced as novel germination indices.

Objective: This experiment aims to evaluate relative fitness and seed germination indices of tribenuron-methyl sensitive and resistant wild mustard (Sinapis arvensis L.) biotypes under different temperature conditions and gibberellic acid concentrations.
Method: This experiment was conducted in 2023 at the laboratory of the University of Mohaghegh Ardabili. It was performed as a three-factorial arrangement in a completely randomized design (CRD) with three replications. The first factor consisted of two levels (seeds of tribenuron-methyl sensitive and resistant biotypes), the second factor included four levels of gibberellic acid concentration (500, 1000, 1500, and 2000 mg L^-1), and the third factor comprised two temperature regimes: 20/15 °C and 15/10 °C (day/night). The measured parameters included germination percentage, germination rate and uniformity, seed water uptake, and seedling vigor index.
Results: The sensitive biotype of wild mustard exhibited a higher final germination percentage, and germination uniformity. The interactions of temperature × biotype and temperature × gibberellic acid concentration were significant on seed water uptake. Furthermore, the rate of water absorption by seeds was higher under the 10/15 °C temperature regime compared to the 20/15 °C (day/night) regime. The sensitive biotype showed a 1.8-fold higher germination rate and a 38% increase in seedling vigor compared to the resistant biotype.
Conclusions: These findings not only contribute to a deeper understanding of the mechanisms underlying herbicide resistance but also demonstrate that while resistance provides a selective advantage, it may entail a physiological cost in the long term. This fitness cost can be leveraged for sustainable weed management. Specifically, farmers could potentially delay wheat sowing—provided it does not compromise wheat yield—to create suboptimal temperature conditions that suppress the germination of resistant wild mustard biotypes. Furthermore, the slower water uptake observed in the resistant biotype suggests that strategic irrigation management could be employed to further inhibit its germination. Additionally, since the germination of resistant wild mustard is slower at lower temperatures, soil temperature monitoring can be utilized to predict the optimal timing for implementing mechanical control measures or post-emergence herbicide applications.

Highlights

• A simultaneous study of the effects of temperature and gibberellic acid on the germination and growth of herbicide-sensitive and herbicide-resistant wild mustard biotypes.
• Evaluation of the fitness cost in herbicide-resistant biotypes.
• Differential effects of growth-affecting factors on the phenotype of two wild mustard biotypes.