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: The longevity of seeds is a crucial aspect of seed quality and a significant concern for the seed industry. The lifespan of a seed, which can extend over several years or even decades, is essential for safeguarding the plant's genetic resources. Storage conditions, including seed moisture level, relative humidity, gases (such as oxygen, nitrogen, carbon dioxide), and temperature, are the primary factors that determine seed lifespan. Among these aging factors, oxygen in dry storage conditions has the most detrimental effect on seed germination, storage metabolic activities, and enzyme activity of dried seeds. Lalemantia iberica and Lallemantia royleana seeds contain high levels of fatty acids, especially linolenic acid (56-67%), which have significant beneficial effects on health. However, a large number of L. iberica and L. royleana seeds deteriorate due to inadequate storage conditions by most farmers. The aim of this study is to investigate the effects of different storage conditions, especially natural aging, controlled aging, aging with oxygen, and nitrogen on germination, chemical activities, metabolic reserves, and enzymatic activities of dry L. iberica and L. royleana seeds.
Materials and Methods: A completely randomized factorial design with four replications was implemented in the seed science laboratory at the Faculty of Agriculture, Shahid University in 2021. The experimental treatments included storage environments (control, natural aging, controlled aging, aging with oxygen and nitrogen pressure) and plant species (Lallemantia iberica and Lallemantia royleana).
Results: The results indicated that aging with oxygen had the most detrimental impact on the germination rate, seed germination, reservoirs content, and the activity of alpha and beta amylase enzymes, compared with controlled aging and natural aging. Conversely, the highest levels of electrical conductivity, hydrogen peroxide, lipid peroxidation, saturated and unsaturated fatty acids were observed in dry seeds stored under oxygen aging conditions. In comparison to artificial aging (controlled aging and oxygen aging), seeds stored under natural aging conditions exhibited the highest germination rate, storage compound content, and amylase enzyme activity. Throughout the storage process, it was observed that the deterioration rate was higher in the dry seeds of L. iberica compared with L. royleana.
Conclusions: Aging with oxygen can be regarded as a rapid artificial aging method for assessing the longevity of dry seeds. Conversely, the use of low temperature and humidity conditions in natural aging can be considered a practical method for preserving the quality and longevity of seeds. Due to their high content of storage compounds (sucrose, starch, and total sugar content), L. royleana seeds can be stored for extended periods.

Highlights: