stimulation of seed germination, seedling growth and changes in biochemical traits kelussia odoratissma mozaff. by scarification treatment

Introduction: among the types of medicinal and aromatic plants, the celery plant (kelussia oderatassima mozaff.) with the local name keluss as a new species of the genus kelussia from the apiaceae family, is one of the native plants of iran (mozaffarian, 2007). unlike cultivated species, most medicinal plants are wild species that are dormant and therefore require special environmental conditions for germination. knowing how to germinate seeds is essential for successful seedling establishment. medicinal plants that are harvested from natural areas need more time for germination than cultivated and modified plants (lee et al., 2020). most plants of the apiaceae family have morph physiological dormancy (mpd). umbrella seeds are characterized by different categories of seed crushing, embryo development and seed maturity in each inflorescence, which is why they have immature embryos and non-uniform germination (lee et al., 2020). scratching the seed coat is a common and efficient method for seeds whose thickness prevents the absorption of water and oxygen or prevents the seedling from exiting, and for this purpose different concentrations of acid, hot water, sandpaper, drilling and sand are used. these physical treatments facilitate the moisture and gas exchanges of the seed with the surrounding space by creating a hole in the seed shell and reducing the resistance of the seed shell to exit from the seed (dewir et al., 2011). the duration of seed contact with acid is important because these compounds may damage the embryo in addition to creating a hole in the seed coat and causing abnormal sprouts and even decreasing the germination percentage (abbasi et al., 2014). considering the wide variety of species of the apiaceae family as well as the variety of the type and depth of dormancy, various treatments have been proposed to break dormancy and stimulate the germination of seeds of this family. the purpose of this research was to investigate different solutions, including pretreatment of scratching with sandpaper and sulfuric acid, as well as piercing the seeds, on the characteristics of seed germination and keluss seedling growth. materials and methods: keluss seeds were collected from their natural habitat in the fall of 2019 in the klousseh area of fereydoun city, isfahan province, with a longitude of 49 °c and 53 minutes and a latitude of 32 °c and 43 minutes at an altitude of 2500 m. this study was conducted in the laboratories of crop physiology and seed technology, faculty of agricultural sciences, shahed university, between 22 may 2022 and 30 may 2022. cultivation was carried out in a petri dish with a constant germination temperature of 2 °c after pre-treatment. there were scratching and riding techniques. the experiment was conducted as a factorial in the form of a completely random basic design in four replications. for cultivation, 25 keluss seeds were placed in each petri dish. the test factors included scratching with sandpaper (20, 40 and 60 s), piercing the seed with a surgical needle (near the embryo, the middle part of the seed and the end part of the seed) and scratching with 98% sulfuric acid (30, 60, 90, 120 and 150 s). the act of counting seeds until the end of germination (for 25 days) was done regularly and continuously. in the end, the characteristics of seedling length, fresh and dry weight of the seedling, and weight and length index of the seedling stem were calculated. germination percentage traits were calculated using equations (1 and 2) (omidi et al., 2015). to analyze the data variance, the sas 9.1 statistical software was used. the comparison of means of traits was performed using the lsd test at a 5% probability level. results and discussion: according to the results of the present experiment, the treatment of mechanical and chemical scratching of seed dormancy had a positive and significant effect on the characteristics of seed germination and callus seedlings (table 1). scratching the seeds with sandpaper had the highest germination percentage in all three scratching times compared to other treatments. scratching the seeds in 20 seconds had the highest percentage of seed germination with an average of 97%. also, scratching the seed with sulfuric acid for 30 seconds germination was observed to be 61%, with the increase in the duration, there was a sharp decrease in germination (6%). the seed piercing treatment, especially piercing in the middle and end of the seed, had 82 and 77% germination, respectively (fig. 1). the germination rate of celery seeds was subjected to seed dormancy treatments, in the treatment of piercing the middle part of the seed, the highest germination rate was obtained with 3.95 seeds per day, followed by the treatment of scratching with sandpaper for 20 seconds after in the treatment of seed piercing, the germination rate was observed with 2.23 seeds per day. scratching the seeds with sulfuric acid had the lowest germination rate, and the germination rate decreased sharply as the duration increased from 30 seconds to 90 seconds (fig. 1). the average germination time of celery seeds was affected by the experimental treatments. in scratching with sandpaper, the germination time lasted for 13.62 days, while in the treatment of scratching with sulfuric acid with a duration of 90 seconds, the average germination time was the lowest. the duration was 2.01 days. in the treatment of scraping with sandpaper and drilling, it took longer due to the high germination percentage and the number of germinated seeds (fig. 2). the rate of germination in the treatment scratched with sulfuric acid was the highest in 90 seconds. scratching with sandpaper was the highest in different periods, and increasing the period resulted in a decrease in the rate of germination. in the treatment of piercing the seed with a needle, piercing the middle part of the seed had a higher germination rate than the other two levels of this treatment (fig. 2). increasing the duration of scraping with sandpaper and sulfuric acid decreased the number of normal seedlings and increased the number of abnormal seedlings. in the seed piercing treatment, the number of normal seedlings increased by piercing the end of the seed, and the number of abnormal seedlings decreased at this level. the highest and lowest normal seedlings were related to scratching with sandpaper for 20 seconds and sulfuric acid for 60 and 90 seconds, respectively. the most abnormal seedlings were related to scratching with sulfuric acid for 30 seconds (fig. 3). recently, the improvement of seed quality has become the main priority of the agricultural market. seed dormancy-breaking techniques are also used to achieve rapid and uniform seed germination and seedling emergence to increase crop yield. these findings show that dormancy pre-treatment dramatically increases the growth of keluss seedlings. according to the wind cheese medicinal plant (withania coagulans) was affected by seed dormancy treatments, the increase in germination characteristics was achieved by scraping treatment with soft sandpaper along with potassium nitrate pretreatment. scratching the seed shell by destroying the seed coat and sclerotized cells allows water to penetrate for the water absorption process and removes seed dormancy caused by the lack of water penetration into the shell (ghanbari et al., 2021). conclusion: the treatment of scraping with sandpaper and piercing the seeds improved the germination of the seeds and the growth of keluss seedlings. choosing the best and most effective treatment is necessary to break seed dormancy in keluss medicinal plant species to increase the germination percentage and establish normal seedlings. wild species like keluss need to germinate to survive and reproduce. among the effective treatments to break keluss seed dormancy, scratching for 20 seconds and piercing the middle part of the seed obtained the highest percentage of germination. this study can be a basic guide for the cultivation and protection programs of the native and endangered keluss medicinal plant.