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: 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.