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Effects of Seed Priming Methods on Germination Parameters of Ajowan (Carum copticum) Seed
Somayeh Malekzade, Seyfollah Fallah2,
Volume 1, Issue 2 (1-2015)
Abstract
In order to investigate the effect of priming techniques on germination parameters of ajowan (Carum copticum L.) seed, an experiment was conducted in completely randomized design with four replications. The experiment treatments included a control (no priming), three hydropriming levels with distilled water (24, 36, and 48 h), three osmopriming levels with PEG (solutions with osmotic potential of -4, -8 and -12 bar), three hormone priming levels with GA3 (50, 100 and 150 ppm), three halopriming levels with KNO3 solution (2, 3, and 4%) and three zinc sulfate levels (0.1, 0.2 and 0.3 %). The results showed that priming treatments had a significant effect on all traits. The rate and percentage of germination were declined in some priming treatments compared to control. Radicle length and root dry weight were decreased in polyethylene glycol -8 bar. Polyethylene glycol -4 bar and 24h hydropriming treatments significantly decreased shoot length and allometry coefficient. However, the treatment of 100 ppm hormone priming significantly increased these traits. Hydropriming 24 h treatment significantly increased germination rate, percentage and seed vigor, but hydropriming 48 h significantly increased radicle and shoot length compared to control. In conclusion, according to the priority of germination or radicle, shoot growth and seed priming cost as well, the hydropriming 24 or 48 h can be recommended as most appropriate priming type for ajowan seeds.

Effect of Stratification and Its Combination with Gibberellic Acid on Seed Dormancy Breaking of Echinophora platyloba
Ali Abbasi Sourki, Zahra Hosseni, Sina Fallah,
Volume 5, Issue 2 (3-2019)
Abstract



Extended Abstract
Introduction: Seeds are a good option for propagation and protection of medicinal plants. Although Seed dormancy is an adaptive strategy for wild medicinal plants, but it is considered as an undesirable trait in domestication and cultivation of them, need to be solved. Echinophora platyloba seed has dormancy despite its remarkable medicinal properties.
Materials and Methods: In order to break seed dormancy, three separate experiment including stratification, hormonal treatment and combination of both were performed. For stratification 10 samples of were placed in a wet bed at 5 ° C for 2, 4, 6, 8, 10, 12, 14 and 16 Week and were compared using a completely randomized design with three replications. For hormonal treatment, the seeds were placed in GA concentrations of 0, 500 and 1000 ppm for 24 hours and then transferred to germination conditions. However, since the breaking of dormancy did not occur, this experiment was not discussed any more. For combined application of hormone and stratification, seeds were placed at mentioned concentrations of gibberellin for 24 hours at 20 ° C and then gibberellin solutions were removed and the seed transmitted to 5 ° C and compared for 2, 4, 6, 8 weeks with a CRD factorial experiment with three replications. The first factor was concentration of gibberellin in three levels and the second factor was the duration of stratification in 4 levels.
Results: Stratification had a positive effect on seed dormancy breaking and 16 week chilling lead to highest germination percentage and rate and vigor indices. The combined application of hormonal treatments accelerated dormancy release and improved seed germination characteristics, which peaked at 8 weeks. 8-week stratification treatment at 5 ° C with 1000 ppm gibberellic acid was the best treatment to overcoming of dormancy in Echinophora-platyloba seeds.
Conclusion: It seems that seed dormancy of Echinophora seeds is physiological, which broke down by moist chilling and simultaneous application of stratification and gibberellin successfully. Although Gibberellin had no effect on dormancy break, it reduced the need for stratification. Combined application of them showed synergistic effects on dormancy release.
 
 
Highlights:

  1. Echinophora seed’s dormancy was broken under stratification conditions, but GA had no effect on it lonely.
  2. The application of gibberellin reduced the chilling demands of Echinophora seeds and the combined application of them had a synergistic effect on dormancy break

Germination indices and morphological properties of Catharanthus roseus Seedlings affected by hormone-priming technique under polyethylene glycol drought stress
Marziyeh Ababaf, Heshmat Omidi, Abdolmehdi Bakhshandeh,
Volume 10, Issue 1 (9-2023)
Abstract
Extended Abstract
Introduction: Various strategies have been used to improve growth and productivity of crops through genetic approach, genetic engineering, and breeding. However, economic feasibility and ease of use can pave the way for the application of priming techniques as "stress relievers" in agricultural production. The aim of this study was to evaluate the ability of priming Catharanthus roseus seed with phytohormones of salicylic acid and Jasmonic acid under drought stress to reduce the effect of water limitation during the germination.
Materials and Methods: Two separate 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 the first experiment, treatments included priming in two levels of SA (0.5 and 1mM) and priming duration in two levels (24 and 48 hours), and drought stress with polyethylene glycol 6000 in 6 levels (0, 0.1, 0.5, 1, 1.5 and 2 Mpa). In the second experiment, treatments included JA (10 µM), priming duration in two levels (12, and 24 hours) and drought stress in levels six (0, 0.1, 0.5, 1, 1.5, and 2 Mpa). Dry seeds (without pretreatment) were considered as control.
Results: In this study, drought stress treatments -1.5 and -2 Mpa in the first experiment and -1, -1.5 and -2 Mpa in the second one had no germination. Seed priming with SA and JA improved the percentage of seed germination so that in the first experiment, the highest percentage of germination (97.33) was observed under stress-free conditions with the application of 0.5 mM salicylic acid for 48 hours, which was 12.2% higher than the control treatment. 0.5 Mm of SA treatment with 24 hours of priming showed the highest percentage of germination under drought stresses of -0.1 and -0.5 Mpa. However, under drought stress conditions of -1 Mpa, 0.5 mM SA+48 hours treatment was superior compared to other treatments of salicylic acid and time. In the second experiment, the highest percentage of germination (98.3) was in the concentration of 10 μM jasmonic acid during 24 hours of priming under stress-free conditions, which showed an increase of 40.4% compared to the control treatment.
Conclusion: The results of the present study showed the importance of salicylic acid and jasmonic acid during seed germination stage under drought stress. Seed priming with salicylic acid alleviated the damages caused by drought stress on germination and growth. The process of adaptation to stress started by jasmonic acid can be attributed to pretreatment with jasmonic acid before applying drought stress.

Highlights:
  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.

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