Iranian Journal of Seed Research

Extended Abstract
Introduction: Catharanthus roseus is regarded as a medicinal ornamental plant. This plant has anti-cancer, anti-hypertensive, anti-diabetes, and antimicrobial properties. Catharanthus has a fairly long vegetative period due to its slow initial growth. The long growth period of the plant is considered one of the limitations in its cultivation on a larger scale. By using plant growth regulators such as salicylic acid (SA) in the imbibition phase and pre-treatment, an increase in seed activity and the seedling growth of many crops is observable. Also, jasmonic acid (JA) plant growth regulators play an important role in seed germination and plant growth. Regarding the long growth period of this plant, the small size of the seed, and poor establishment in the field with semi-heavy and heavy textured soils, the present study aimed to evaluate the effect of seed priming with SA and JA in different concentrations and periods on improving Catharanthus roseus seed germination indices.
Materials and Methods: The studies were conducted as a factorial experiment based on a completely randomized design with three replications at the Laboratory of Seed Science and Technology of Shahed University, Tehran, in 2017. Treatments included five different concentrations of SA (0, 0.01, 0.1, 0.5, and 1 mM), concentrations of JA (0, 1, 10, and 100 µM) and five periods of time (0, 6, 12, 24, and 48 hours). At the end of the experiment (10 days) traits such as germination percentage, germination rate, mean germination time, mean daily germination, germination value, seed length vigor index, seed weight vigor index, seedling dry weight, shoot dry weight, radicle dry weight, radicle length, shoot length, and seedling length were measured.
Results: The results indicated that the effect SA, JA, and time were significant on germination percentage, germination speed, mean germination time, mean daily germination, germination value, seedling length, seedling length vigor index, seedling weight vigor index, and radicle dry weight. The best times for pre-treatment with SA were 24 and 48 hours. Among the applied concentrations of SA, 0.5 and 1 mM concentrations showed the best results. Also, the best time and concentration for pre-treatment with JA were 12 and 24 hours and 10 µM.
Conclusions: The results of this study showed that using SA and JA for seed priming improved seed germination components. In addition to the pre-treatment concentrations of SA and JA, the duration of seed contact with growth regulators is important. It was observed that there was a significant difference among the different priming times, therefore, it can be stated that seed pre-treatment time is one of the important factors of seed priming, and the determination of proper priming time prevented the negative effect of pretreatment on germination and seedling growth in primed seeds.

Highlights:
1- The optimum concentrations of salicylic acid and the priming time of the seed were determined.
2- The appropriate concentrations of jasmonic acid and the optimum time for pretreatment of seed were determined.
3- The effect of growth regulators of salicylic acid and jasmonic acid on seed germination indices was evaluated.

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.

1. The effect of priming Catharanthus roseus seeds with salicylic acid and jasmonic acid phytohormones on the germination characteristics of seeds under drought stress was investigated.
2. Priming Catharanthus roseus seeds with salicylic acid improved the germination percentage and characteristics of seeds under drought stress.

Extended abstract
Introduction: Deterioration reduces the quality of seeds. Oilseeds like Nigella are highly susceptible to seed aging. Seed priming enhances the quality of deteriorated seeds by improving germination indices and increasing the activity of antioxidant enzymes. This research aimed to investigate the extent of damage caused by accelerated aging treatment on the germination characteristics and antioxidant enzyme activity of Nigella seeds and the possibility of mitigating the adverse effects of aging through hormonal priming with cytokinin.
Materials and methods: This research was carried out in the form of a completely random basic design with four replications in the seed technology laboratory of Khuzestan University of Agricultural Sciences and Natural Resources in 2017. The treatments included hormonal priming with cytokinin at five levels (0 (control), 10, 20, 40, and 80 m/l) for two durations (12 and 24 hours), and aging under 100% relative humidity and a temperature of 45 °C at five levels (no aging, 24, 48, 72, and 96 h).
Results: The analysis of variance results indicated that germination indices were only influenced by main and two-way effects at the 5% and 1% probability levels, while the three-way interactions, including aging, hormone concentration, and priming duration, were significant for plant growth and longitudinal and weight indices at the 1% probability level. Furthermore, it was evident that the priming treatment mitigated the negative effects of aging, with the concentration of 10 milligrams per liter of cytokinin for a duration of 12 h having the most significant impact among the hormone concentrations used on the measured traits. The highest germination percentage (88%) and the lowest germination percentage (63.33%) were observed at concentrations of 10 and 80 mg/l, respectively. The use of cytokinin at optimal concentration improved catalase activity and protein levels. The results showed that in the control conditions, the activity of the catalase enzyme was 0.76 units per mg of protein and the amount of protein was 0.51 mg/g, which reached 0.97 units per mg of protein and 0.79 mg/g with seed priming.
Conclusion: Based on the results obtained from this research, aging led to a reduction in germination indices, the activity of antioxidant enzymes, and seed protein content. The best treatment applied was cytokinin hormone priming for aged Nigella seeds at a concentration of 10 mg/l for 12 h. According to the results, the application of cytokinin at its optimal concentration (10 mg/l) improved the catalase enzyme activity and protein content. Therefore, it can be suggested that hormonal priming with cytokinin helps mitigate the adverse effects of aging in Nigella plants.

Highlights:

1. The impact of hormonal priming with cytokinin at concentrations of 10, 20, 40, and 80 mg/L on aged Nigella seeds was investigated.
2. The use of a concentration of 10 mg/l of cytokinin hormone for 12 hours was introduced as the best treatment.
3. Cytokinin was introduced as a significant hormone that enhances the activity of antioxidant enzymes and physiological traits in aged Nigella seeds.