Iranian Journal of Seed Research

Extended abstract
Introduction: A wide range of deteriorative conditions (especially moisture content and temperature) may affect seed quality during storage which may lead to seed aging. As the most important component of the phenylpropanoids pathway, trans-cinnamic acid, found abundantly in plants and its endogenous levels is influenced by stress conditions. The present study was conducted to investigate germination features, seed reserve mobilization, electrolyte leakage and malondialdehyde content in aged cowpea seeds affected by different concentrations of cinnamic acid.
Materials and Methods: The research has been performed in the laboratory of Faculty of Agriculture, Shahrood University of Technology, Iran. The experiment was designed as a factorial (two factors of the experiment included two levels of seed quality including non-aged and aged seeds and five levels of cinnamic acid concentrations including 0, 15, 30, 45 and 60 µM) based on a completely randomized design. Accelerated aging was applied as an efficient method to mimic storage conditions in the presence of accelerating factors. Cowpea (Vigna unguiculata) seeds (Bastam local variety) were incubated in a relative humidity of 95% and a temperature of 43 °C for 72 h to accelerate aging. Both seed lots were treated with 5 different concentrations of cinnamic acid for 6 h followed by standard germination and vigor tests. Data of germination and vigor tests were processed using the GERMINATOR software. Heterotrophic growth, seed reserves mobilization, electrical conductivity and membrane lipid peroxidation were assessed using the available methods.
Results: In this study, cowpea seeds responded to cinnamic acid differently based on their primary quality. In deteriorated seeds, concentrations of 45 µM and 60 µM could successfully enhance seed germination percentage, as compared with the aged seeds (i.e., control). A concentration of 45 µM also improved the vigor of deteriorated seeds. Seed pretreatment of 15, 30 and 45 µM enhanced seed reserves utilization in non-aged seeds. Aging negatively affected area under curve, germination uniformity and seedling dry weight of the deteriorated seeds. Application of 30 µM cinnamic acid improved germination uniformity. The area under the curve was positively affected by 15µM and 30µM. Concentrations of 45 µM and 60 µM enhanced seedling dry weight. Applying 45 µM cinnamic acid decreased electrolyte leakage by 38% and improved efficiency of seed reserves mobilization. Moreover, seed malondialdehyde content, as an indication of membrane lipid peroxidation, showed a sharp decline by applying increased concentrations of cinnamic acid.  
Conclusions: Based on our results, cowpea seeds respond to cinnamic acid differently based on their primary quality. These results imply that seed pretreatment with 45 µM cinnamic acid may successfully invigorate aged cowpea seeds. We also conclude that cinnamic acid application cannot improve physiological traits and can be regarded as a potent antioxidant in the invigoration of the aged seeds.
 
Highlights:

1. This is the first study focusing on the role of cinnamic acid in alleviating deterioration in aged seeds.
2. Cinnamic acid has been introduced as a robust antioxidant, which is effective in reducing the deleterious effects of seed deterioration.

Extended Abstract
 Introduction: Germination is considered the first and most important stage of establishment and consequently, successful competition which is influenced by genetic and environmental factors. Among the environmental factors influencing the germination, temperature and light are the most important ones. Using different models, the germination response of seeds to temperature can be quantified; therefore, this study was performed to investigate the effect of temperature on germination and to quantify the germination response of Buckwheat seed (Fagopyrum esculentum Moenc) to temperature using nonlinear regression models and thermal-time model.
Materials and methods: The seeds were germinated in 4 replications of 25 seeds under 8 constant temperature treatments (5, 10, 15, 20, 25, 30, 35 and 40 ° C). Using a three-parameter logistic model, Buckwheat seed germination was quantified at different temperature levels and the percentage and time to reach 50% germination were obtained. Four nonlinear regression models and a thermal-time model were used to quantify the response of Buckwheat seed germination rate to temperature. To compare the models and determine the most appropriate model, the root mean square error index (RMSE), coefficient of determination (R²), coefficient of variation (CV) and standard error (SE) were used for the observed germination rate versus the predicted germination rate.
Results: The results indicated that temperature affected the seedling length, normal seedling percentage, seed vigor and the germination rate as well as germination percentage. Also, the results showed that germination characteristics increased with increasing temperature up to 20 and 25 °C. Comparison of the three models based on the root mean square error (RMSE) of germination time, the coefficient of determination (R²), CV and SE, the best model to determine the cardinal temperatures of Fagopyrum esculentum was the dent-like model. The results of thermal-time model showed that the base temperature of Fagopyrum esculentum seeds was 4.01 ° C and the thermal-time coefficient was 1242.6 h° C.
Conclusion: Utilization of non-linear regression models (segmented, dent-like and beta) and thermal-time model to quantify the germination response of Fagopyrum esculentum response to different temperatures led to acceptable results. Therefore, germination rate and percentage may be predicted using the outputs of these models at different temperatures.

Highlights:

Extended Abstract
Introduction: Seed aging is a phenomenon that occurs during the life of any seed. Changes that occur during aging affect seed quality. Through the process of aging, seed vigor is the first trait of the seed quality that decreases, followed by a decrease in germination capacity, seedling growth and establishment. Hence, one way to stimulate germination and increase the establishment of seedlings from aging seeds is seed pre-treatment using different materials such as brown seaweed extract. The aim of this study was to investigate the effect of seaweed extract pretreatment on germination traits and heterotrophic growth of un-aged and aged soybean seeds.
Materials and Methods: The experiment was designed and implemented at a laboratory in the faculty of agriculture of Shahrood University of Technology in 2019. Treatments included seed aging at two levels (un-aged seeds and aged seeds) and pretreatment with seaweed extract at seven levels (zero, distilled water, 0.1, 0.2, 0.3, 0.4 and 0.5 %). The experiment was carried out as a factorial in a completely randomized design (CRD) with three replications in the germinator environment. The seeds were aged by being placed at 41°C and 95% relative humidity for 72 hours. Seed pretreatment seaweed extract was done for 6 hours in accordance with the principles of seed aeration.
Results: Aging reduced germination percentage and germination rate, allometric growth ratio, seedling length vigor index, seed reserves use efficiency and seed vigor index. Malondialdehyde content and electrical conductivity of aged seeds were 37.68% and 38.32% higher than un-aged seeds respectively. Seed pretreatment with 0.1, 0.2 and 0.3% of seaweed extract significantly increased germination rate, germination index and seed reserves use efficiency. Slicing interactions of aging and seaweed extract showed that seed pretreatment with 0.1, 0.2 and 0.3% of seaweed extract significantly increased germination rate and germination index in un-age seeds. Pretreatment of aged seeds with 0.1, 0.2 and 0.3% seaweed extract increased germination percentage by 8.73%, 8% and 15% compared to the control (aged seeds without pretreatment), respectively. The use of distilled water and all levels of seaweed extract in this study increased the seed vigor index and decreased the electrical conductivity. The amount of malondialdehyde in aged seeds was reduced by using all levels of seaweed extract. The use of 0.2, 0.3, 0.4 and 0.5% of the extract increased the amount of seed reserves use rate and fraction of seed reserves mobilization in aged seeds.
Conclusions: Finally, in the scope of this research between the concentrations used, the concentration of 0.3% seaweed extract was better than the others. It can also be suggested that the use of seaweed extract as a seed pretreatment improves the effects of seed aging on soybeans.

Highlights:
1-The effect of pretreatment with seaweed extract with concentrations of 0.1 to 0.5% on un-aged and aged soybean seeds was investigated for the first time.
2-Using a concentration of 0.3% seaweed extract for the pretreatment of soybean seeds was introduced as the best concentration.
3- Seaweed extract was introduced as an important antioxidant to improve physiological traits in soybean seeds.

Extended Abstract
Introduction: Safflower is a plant that has been considered due to its high medicinal and nutritional value, especially in the extraction of edible oils in developed countries. Drought is one of the most important harmful factors in arid and semi-arid regions of the world that affects plant production. Modifiers play an important role in plant adaptation to stress conditions. Among these compounds are the hormone gibberellic acid and the antioxidant ascorbic acid, which increase plant tolerance to adverse environmental conditions. The present study investigated the effect of gibberellic acid and ascorbic acid on seed germination parameters and some enzymatic indices of safflower under drought stress.
Materials and Methods: The experiment was conducted as a factorial based on a completely randomized design with three replications in the Agricultural Science Laboratory of Iranshahr University in 2020. Experimental treatments included three levels of control (pretreatment with distilled water), pretreatment with gibberellic acid and ascorbic acid, and four levels of drought stress (0, -3, -6, and -9 bar). Drought stress was applied using polyethylene glycol 6000. Seed germination was carried out inside a germinator at 25 ° ^C for 14 days in darkness. Germination traits and enzymatic indices were measured using standard methods.
Results: The results of variance showed that most germination and growth indices of safflower seedlings decreased with increasing drought stress. Also, drought stress led to changes in the activity of antioxidant enzymes. Seed priming with gibberellic acid and ascorbic acid increased germination indices and seedling growth and improved enzymatic activity, including catalase, peroxidase, and superoxide dismutase in comparison with untreated seeds. Priming with gibberellic acid had a significant advantage. Seed priming in drought stress conditions has increased germination rate, protein content, and catalase, peroxidase, and ascorbic dismutase activity, respectively, compared to the control.
Conclusion: In general, seed priming of safflower using gibberellic acid changed the activity of antioxidant enzymes. These activities ultimately moderated the negative effects of drought stress and increased germination parameters.

Highlights:

1. The role of gibberellic acid and ascorbic acid on safflower seed germination traits was investigated.

The effect of gibberellic acid and ascorbic acid on the activity of antioxidant enzymes and soluble protein during seed germination was investigated.