Seed Pretreatment with Cinnamic Acid Positively Affects Germination, Metabolite Leakage, Malondialdehyde Content and Heterotrophic Growth of Aging Cowpea (Vigna unguiculata) Seeds

Seed Pretreatment with Cinnamic Acid Positively Affects Germination, Metabolite Leakage, Malondialdehyde Content and Heterotrophic Growth of Aging Cowpea (Vigna unguiculata) Seeds Maryam Akbari , Mehdi Baradaran Firouzabadi , Mohammadreza Amerian , Naser Farrokhi 4 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.