Iranian Journal of Seed Research

Micronutrients play a great role in the production of high quality seeds, especially in terms of germination. Therefore, providing seeds with sufficient amounts of these is an important consideration in seed production. The present study was conducted as two separate experiments in the Seed Laboratory of Yasouj University in 2015. In the first experiment, the sesame seeds (cv. Darab 1) obtained from a previous split plot experiment based on RCBD, consisting of three irrigation levels (after 75, 110 and 145 mm evaporation from class A pan) and four foliar applications comprising water, zinc sulfate, boric acid and mixture of zinc sulfate and boric acid, were investigated in germination experiments in the minimum temperature (i.e., 15°C). The second experiment was a factorial based on RCD with three replications. The first factor in the eight levels included seeds soaked in water, ZnSo4, H3Bo3 and ZnSo4 + H3Bo3 and seeds with high contents of Zn (159 m Kg^-1), B (15.3 m Kg^-1) and Zn (139.5 m Kg^-1)+ B (14 m Kg^-1) and dry see as the control. The second factor was accelerated aging periods at three levels (0, 2 and 4 days) at 45°c and RH = 100%. The results showed that with a delay in irrigation time, compared with water foliar application, foliar application of micronutrients (Zn, B, Zn+B), and significantly increased germination traits. The results also suggested that, compared with seeds soaked in nutrients, seeds with high Zn and B contents significantly increased germination indices and antioxidant (catalase and peroxidase) activities, especially under accelerated seed aging.

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.

 Introduction: Stevia is a perennial short day plant, belonging to the Asteraceae family. It is also called sugar leaf. Poor germination of this plant serves as a barrier for its planation on a large scale, which contributes to its scarcity and expensivenss as a medicinal herb. In many plants, seed germination is sensitive to salinity, which determines the survival of the plants in saline soils. High levels of soil salinity can significantly reduce germination and seedling growth due to the effects of high osmotic potential and ion toxicity. Jasmonates represent new plant growth regulators that play an important role in increasing the resistance of plants to environmental stresses, including salinity stress. Therefore, this experiment was conducted to study the effect of pre-treatment of seed with methyl jasmonate on germination indices and biochemical traits of stevia, as a medicinal herb, under salinity stress.

Materials and Methods: They study was conducted, adopting a completely randomized design with three replications in the year 2016 in the Professor Hassabi’s Laboratory of Plant Biology, Islamic Azad University, Islamshahr Branch. The factors were pre-treatment of methyl jasmonate in 5 levels (0, 2.5, 5, 10 and 15 μM) and salinity stress at 4 levels (0, 3, 6 and 9 dS m^-1). At the end of the experiment, germination traits percentage and germination rate, mean germination time, germination value, seedling length, seedling index, total chlorophyll, proline, activity of the enzyme catalase, peroxidase and superoxide dismutase were measured.

Results: The results of the study showed that effects of salinity stress, methyl jasmonate and interaction between salinity and methyl jasmonate were significant on the germination percentage and germination rate, mean germination time, germination value, seedling index, total chlorophyll, proline and catalase enzyme activity. Seed priming with 5 μM methyl jasmonate at salinity level with electrical conductivity of zero ds/m, had the highest germination percentage and rate, germination value, seed vigor index, and total chlorophyll content. Increases in salt stress and methyl jasmonate increased the activity of catalase enzyme. Salinity reduced germination index and seedling stoichiation and increased activity of peroxidase and superoxide dismutase enzymes. However, seed priming with methyl jasmonate improved seed germination through germination percentage, germination rate and seed vigor index and moderated the effects of salt stress.

Conclusions: Given the results of this study, it could be said that methyl jasmonate, as a potent inhibitor, can reduce the negative effects of salinity and by increasing germination indices such as germination percentage and germination rate, it can be effective in improving the growth of Stevia. Of course, further research can produce more definitive results.

Extended Abstract
Introduction: Coneflower herbal medicinal plant is from the Asteraceae family, native to North America. Because of its immune-boosting properties, it is used to treat a variety of pathogens. The seed germination stage is one of the crucial and crucial stages in the growth cycle of plant species that can play an important role in the production process by optimal establishment of seedlings. Seed of Coneflower germinates and grows very slowly and weakly. Therefore, the use of some plant growth regulators, such as the gibberellin hormone, can play an important role in improving seed germination. The aim of this study was investigate the effect of hormone seed priming using gibberellin on seed germination quality of Coneflower.
Material and Methods: A factorial experiment was conducted based on the complete randomized design arranged with three replications. The experiment was conducted at the seed technology laboratory of Agricultural Sciences and Natural Resources University of Khuzestan, 2018. Experimental treatments were different concentrations of gibberellin (0, 50, 100, 200, 400, and 800 mg/l) as the first factor and the durations of seed priming (12, 24, and 48 hour) as the second factor.
Results: Results of in vitro studies showed that the interaction of gibberellin in priming time on percentage, rate and mean germination time, root and shoot length, seed vigor index, peroxidase activity at 1% and Seed soluble protein content was significant at 5% level. Seed germination quality and protein content increased by the application of 200 mg/l gibberellin for the 24 hours, whereas at the concentrations of 400 and 800 mg/l, gibberellin reduced germination quality and antioxidant enzymes activities. Results of stepwise regression models of antioxidant enzymes activity and protein content with germination indices showed that these traits were significantly entered into the prediction model. It was observed that in all traits except for the rate and the mean germination time, the amount of protein entered the prediction equation. In general, stepwise regression models predicted stem length and power index better than other traits and showed the highest coefficients in these traits with values of 0.85 and 0.83. Also, catalase and peroxidase activities were significantly correlated with rate and mean germination time only. The amount of soluble protein had a positive and significant correlation with all studied traits except germination rate and mean germination time. The highest correlation coefficients for protein content were obtained from longitudinal power index with correlation coefficient (r = 0.856).
Conclusion: Based on the obtained results, the best hormone priming treatment was 200 mg/l gibberellin for the durations of 24 hour.
 
Highlights:
1- The role of gibberellin hormone on seed germination traits Coneflower was evaluated
2- The effect of gibberellin hormone on the activity of antioxidant enzymes and soluble proteins during seed germination was investigated.

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.

Extended abstract
Introduction: Due to the high sensitivity of seeds to damage caused by diseases or environmental stresses, germination is considered an important stage in the plant life cycle: Germination, its uniformity and emergence decline during storage due to seed vigor deterioration. Moisture stress is one of the important environmental factors affecting germination, especially during improper storage. Seed priming with gibberellic acid improves seedling characteristics in different plants under different environmental conditions. Therefore, this research aims to investigate the effect of gibberellic acid and seed deterioration on germination indices and antioxidant enzymes of safflower seeds (Carthamus tinctorius L.) under water stress conditions.

Materials and Methods: In order to investigate the effect of gibberellic acid on germination indicators and changes in antioxidant enzymes of aged safflower seeds under osmotic stress conditions, a factorial experiment was conducted in the form of a completely randomized design with four replications. The first factor includes three osmotic stress levels: zero (control), -0.4, and -0.8 MPa, the second factor includes nine aging levels (zero, 1, 2, 3, 4, 5, 6, 7, and 8 days of aging). at a temperature of 41 degrees Celsius) and the third factor included seed priming treatment at three control levels (non-priming), zero (hydro-priming), and priming with 50 mg/l gibberellic acid. A 3-parametric sigmoid model was used to show the changes in germination indices at different levels of seed deterioration.

Results: The effect of osmotic stress, seed deterioration, and seed priming on the measured indices such as germination percentage, germination rate, seedling dry weight, normal seedling percentage, seedling length, seed germ, catalase, and ascorbate peroxidase, as well as seed protein were significant so that the measured indicators decreased with increasing seed deterioration and moisture stress. The results showed that the highest measured germination indices were obtained from seed treatment with 50 mg/l gibberellic acid under normal osmosis and non-deterioration conditions. Also, seed priming with gibberellic acid treatment caused an increase in catalase, ascorbate peroxidase, and protein activity compared to non-primed seeds under deterioration and non-deterioration conditions.

Conclusion: Results showed that the most suitable prime level used was gibberellic acid 50 mg/l, which had acceptable results under both stress conditions and normal conditions and deterioration and non-deterioration in comparison with other treatments. Therefore, the use of gibberellic acid hormone can help to improve germination indices as a result of changes in biochemical activities.

Highlights:

1. The effect of accelerated aging and priming on safflower seed germination under moisture stress conditions was investigated.
2.The effect of priming on catalase and peroxidase activity of aged safflower seeds was investigated.