Iranian Journal of Seed Research

Unfavorable storage conditions, especially relatively high environment humidity and high storage temperature greatly affect the quality of corn seeds. The effects of temperature, environment moisture and length of storage on six maize hybrids were examined. For the purpose of investigating germination traits, total soluble proteins, leakage electrolytes and the activity of antioxidant enzymes in maize hybrids, an experiment was carried out at the Agronomy and Plant Breeding Laboratory of Ilam University in 2016. The study was conducted as two factorial experiments, adopting a completely randomized design with three replications. The first factor comprised six maize hybrids (single crosses: 703, 706, 711, 604, Mobin and 701) that were obtained from Karaj Seed Breeding and Seedling Institute, Iran. The second factor was accelerated aging test in four levels involving non-aging (control treatment), aging for 4, 8 and 12 days under 40°C temperature and 95% humidity. The results showed that mean time to germination and electrolyte leakage significantly increased with aging duration. Mean time to germination and electrolyte leakage of the hybrids 701, Mobin and 711 increased more than the other hybrids. In addition, antioxidant enzyme activity decreased significantly with an increase in the aging period. These results indicated severe damage to cell membranes and enzyme activity in these hybrids. Moreover, there was a significant and positive correlation between germination percentage and the enzyme peroxides, as compared with other antioxidant enzymes. Although antioxidant enzyme activity exhibited a significant reduction in seed deterioration, nonetheless, generally speaking, compared with other varieties, KSC 703 was more tolerant.

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: Priming is one of the most commonly used seed enhancement techniques. Events such as increased synthesis of nucleic acids, activation of repair processes, increased respiratory activity, and improved antioxidant capacity during priming lead to advanced metabolism in seeds. The most important effects of priming include increased percentage, speed and uniformity of germination and emergence. However, the longevity of primed seeds in storage is the major concern for researchers as it restricts widespread use of this technique. Some researchers believe that priming reduces the storage capacity of seeds, while others have reported increased seed shelf life after using priming treatments. Therefore, this study sought to investigate the effects of priming on the storage capacity of the seeds of canola cultivars under different storage conditions.
Material and Methods: In this study, the effects of priming on the shelf life of seeds of three canola cultivars including Dk-xpower, Traper and Hayola50 were investigated. For this purpose, the seeds were first treated with hydropriming and osmopriming methods. Then primed and control seeds with 6, 9, 12 and 15% moisture content were stored for 8 months at 15, 25, 35 and 45 °C. Sampling from different seed treatments was carried out at intervals of 1 to 30 days to assess germination. Finally, by fitting a three-parameter logistic model to cumulative germination data versus the day after storage, the time to germination loss to 50% was calculated and used to compare seed storage behavior between the treatments.
Results: The results showed that the storage behavior of canola seed varies greatly depending on the cultivar, and each cultivar showed a distinct behavior. Priming effects on the shelf life of seeds were different depending on the storage conditions, cultivars and also the priming methods. Comparison of the effects of priming on the seeds’ shelf life under different storage conditions showed that priming treatments were more efficient under higher seed moisture content and storage temperatures than those with lower seed moisture content and storage temperatures. In addition, priming treatments in Dk-xpower cultivar often increased the seeds’ shelf life. However, in the Traper and Hayola 50 cultivars, hydropriming often improved the seeds’ shelf life, and in contrast to osmopriming, it led to a decrease in the shelf life of the seeds.
Conclusion: Based on the results of this study, it was shown that priming effects on canola seed viability can be a function of various factors such as cultivar, storage conditions, and also the type of priming treatment. Moreover, in this study, hydropriming often increased seed longevity whereas osmopriming often increased the deterioration rate and reduced seed longevity.
 
 
Highlights:

1. Seed storage behavior of canola cultivars was compared under natural storage conditions.
2. Priming effects on seed longevity of canola cultivars was investigated under different storage conditions.

Extended Abstract
Introduction: Soybean (Glycine max (L.) Merrill) is the primary source of vegetable oil. Even in desirable conditions, soybean seeds lose their viability in long term storage. Many factors contribute to seed deterioration, including genetic factors, mechanical damage, relative humidity, storage temperature, seed moisture content, existence of microflora, and seed maturity, which reduce seed quality and make seeds unfit for cultivation purposes.
Materials and Methods: In order to investigate the effects of seed deterioration on seed germination and also the effects of salicylic acid and ethylene on the improvement of deteriorated seeds of G. max., accelerated aging test for 0, 6 and 10 days and natural aging test for 6 months were conducted. After aging conditions, seeds were imbibed with 50 µM salicylic acid and 10 µM ACC (precursor of ethylene) for 6 hours at 25 °C. In addition, after natural and accelerated aging tests, a bunch of seeds was used without any hormonal treatment (i.e., dry seeds) as control seeds. The seeds’ germination percentage, total sugar, fructose, and glucose were investigated. Moreover, the gene expression of GAI1 and LOX1 was measured on dry seeds and under imbibition of water, salicylic acid and ACC at 6, 12 hours using Q-RT-PCR method.
Results: The germination results showed that increasing number of aging days led to a decrease in germination. Total sugar content in seeds aged for 6 days did not have a significant difference, as compared with non-aged seeds. However, total sugar content in seeds aged for 10 days was significantly higher than non-aged seeds. Increasing accelerated aging levels from 0 days to 10 days led to increases in glucose and fructose contents in dry seeds. In addition, genes exhibited different expressions in different days and hours. Increasing aging from 0 days to 10 days led to increases in GAI1 gene expression. Moreover, LOX2 expression increased in accelerated aging from 0 to 6 days. LOX2 gene expression in naturally dried aged seeds also increased and was higher than that in non-aged seeds. SA and ACC had different effects on measured values.
Conclusion: In general, it can be concluded that the deterioration of seed quality and vigor result from numerous degradation processes and disruption in seeds’ physiological activity. This study showed that aging is associated with an increase in total sugar, glucose and fructose levels. In addition, the expression of the genes involved in the germination is also affected. Increases in LOX2 gene expression were observed in both accelerated aging and natural aging pathways. GAI1 gene expression increased in accelerated aging. However, in normal aging, it decreased.
 

Highlights:

1. Identifying the role of LOX2 and GAL1 genes in soybean seed deterioration.
2. Investigating seeds’ physiological responses under natural and laboratory aging conditions.

Extended Abstract
Introduction: Providing important and effective elements such as zinc and boron- especially in areas where the soil for some reason cannot meet the needs of the plant- will be a good solution to improve seed and seedling quality and nutrition, and community health status. A considerable part of the wheat producing regions in the country are faced with late season haet during seed development stages. Thus, the present study will investigate the effect of heat stress and mother plant nutrition with zinc and boron micronutrients on seed deterioration and physiological quality of wheat seedlings.
Material and Methods: In a field experiment, wheat seeds were planted on two suitable planting dates (November 20) and late (January 5) to apply late-season heat stress during the seed development stage with three replications in Ramhormoz, Iran. The nutrition of mother plants with zinc and boron elements was done at three levels (nutrient-free and application of zinc and boron) as a foliar application. After harvest, the seeds were transferred to the laboratory and membrane integrity of seed cells was investigated using an electrical conductivity test as an indicator of deterioration. Another part of the seeds was planted in a factorial pot experiment based on RCBD with three replications to evaluate the quality of seeds and seedlings in the greenhouse.
Results: The results showed that exposure of seeds to heat stress during development reduced seed quality as well as seedlings so that the cell membrane in the seeds produced under heat stress conditions was damaged and their electrical conductivity increased by 19%. Also, these seeds showed more sensitivity to deterioration. The percentage of seedling emergence in the stressed seeds decreased by 21.66%. Heat stress also reduced seedling quality indices such as chlorophyll content, shoot dry weight, and root dry weight. Application of zinc and boron on the mother plant not only led to improved quality of seeds and seedlings under normal conditions but also the negative effects of heat stress on seed and seedling quality were reduced. There was a significant negative correlation between the seed electrical conductivity test and qualitative parameters. Therefore, the use of this test is recommended to determine the quality of seeds, especially seeds produced under late-season heat stress conditions.
Conclusion: Noting the negative effect of heat during seed development on seed quality, planting dates should be adjusted as much as possible so that the seed development stage does not coincide with the late-season heat stress. Due to the beneficial effects of using zinc and boron in the mother plant on many traits related to the quality of seeds and seedlings, their application- especially zinc- in soils with deficiency or the possibility of heat stress at the end of the season is recommended.

Highlights:

1. Zinc and boron micronutrients were used to mitigate the harmful effects of heat stress on seed quality.
2.  Physiological characteristics of seedlings obtained from seeds produced in the field under late-season heat stress conditions were investigated.

Extended Abstract
Introduction: Structural and physiological delicacy of soybean seeds is known as an important quality indicator in the cultivation of this plant, but at the same time, the most chronic problems of soybean seed quality are the reduction of seed quality during storage and before sowing. The effect of some nutrients on the quality of soybean seeds under accelerated aging stress was investigated
Materials and Methods: Experiments were conducted for two consecutive years (2019-2020) in the research field of Lorestan University, Faculty of Agriculture in a randomized complete block design. Nutritional treatments included nitrogen and phosphorus application (as soil application) and iron and molybdenum as foliar application. Seeds were harvested at the maturity stage and 1000-grain weight and seed coat resistance to mechanical damage was investigated. Following the exposure of seeds to accelerated aging, leakage from seeds and germination were measured.
Results: The results showed that nutrition had a significant effect on all studied traits. However, the effect of year was only significant on 1000-seed weight and resistance to mechanical damage of seed coat. The highest number of traits related to seed quality was related to complete fertilizer treatment (N-P-Fe-Mo) and accelerated aging had a less negative effect on them.
Conclusion: Among the nutrients, nitrogen and phosphorus had the most effect on germination indices, and iron and molybdenum were in the next ranks. Seeds with strong vigor and treated with fertilizer were less affected by accelerated aging and had better germination. The lower the seed vigor, the more sensitive they were to this stress.

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 seeds are rich in unsaturated fatty acids with a high capacity for peroxidation, which have a high potential to reduce germination and seed vigor during the storage period. Therefore, Introducing appropriate methods to preserve or improve their germplasm during storage would be advantageous. The aim of this study was to investigate the effects of seed priming on germination and vigor of safflower seeds (Sofeh and Sina cultivars).
Materials and Methods: A three-factor experiment was conducted in a completely randomized design with three replications before and after artificial deterioration. The experimental factors included controlled deterioration of seeds at 45°C in six levels (no deterioration, 1, 2, 3, 4, and 6 days) and priming in four levels (no prime, hydropriming, salicylic acid 50 mg/l and sodium chloride 5 percent).
Results: Artificial aging strongly and linearly reduced the germination ability of safflower seeds, and germinability and seed vigor reach zero in a time interval which lasts between 2.5 to 4.5 days (depending on the treatment and the investigated trait). The use of priming prior to artificial aging was more advantageous than priming after artificial aging. In addition, priming with salicylic acid was more useful compared to other priming treatments.
Conclusion: Priming of safflower seeds before storage would result in the extended shelf-life of the stored seeds while also preserving the seed germination potential. 

Highlights:

1. The effect of priming on germination and vigor of safflower seeds before and after artificial deterioration was compared and investigated.
2. The effect of priming before and after artificial deterioration on the improvement of safflower seed quality varied in different cultivars.

Extended abstract
Introduction: This study investigated the effects of storage temperature, humidity, and storage duration on the germination indices of German chamomile seeds. Given the significant impact of storage conditions on seed quality, the primary objective was to standardize optimal storage methods for this medicinal plant. The research aimed to evaluate the influence of seed moisture content, storage temperature, and storage periods on the germination performance of German chamomile seeds.
Materials and Methods: The experiment was conducted in 2019 at the Faculty of Agriculture, Yasouj University. It was designed as a split-split plot arrangement within a completely randomized design, with four storage temperature levels (15, 25, 35, and 45°C), three seed moisture content levels (8, 12, and 16%), and six storage durations (30, 60, 90, 120, 150, and 180 days). Initial seed moisture content was measured, and the desired moisture levels were adjusted using specific formulas. Germination tests and related indices, such as germination percentage and germination rate, were conducted. Data were analyzed using SAS software.
Results: The results from the mean comparison of the interaction between storage duration and seed moisture content at temperatures of 15, 25, 35, and 45°C revealed that germination percentage significantly decreased as storage duration increased. The lowest germination percentage was observed after 180 days of storage at 16% seed moisture content. Similarly, germination rate decreased significantly across all temperatures with prolonged storage. Seedling growth analysis under different storage conditions showed a significant reduction in root, shoot, and seedling length at all temperatures as storage duration increased. The shortest lengths of these components were observed after 180 days of storage at 16% seed moisture content, attributed to seed aging and reduced germination capacity. Increasing seed moisture content from 8% to 12% resulted in an average decrease of 9% in germination percentage and 5% in germination rate. Further increasing moisture content from 8% to 16% led to a more substantial average reduction of 73% in germination percentage and 72% in germination rate. Raising storage temperature from 15°C to 25°C, 35°C, and 45°C resulted in average decreases in germination percentage of 9%, 25%, and 42%, respectively. Similarly, germination rate decreased by 14%, 33%, and 43% at this respective temperature.
Conclusions: Overall, the results indicate a decline in the germination indices of German chamomile seeds with increasing seed moisture content and storage temperature. The optimal seed moisture content of 8% and a storage temperature of 15°C were identified as the most suitable conditions for maintaining seed quality.

Highlights: