Optimization of Seed Germination, Growth Index and Photosynthetic Pigments Content of Kelussia odoratissima Mozaff Seedlings under Laboratory Conditions

 Kelussia odoratissima Mozaff is a native species of Iran which is a rare and endangered species. It grows as a wild in cold and mountainous bioclimatic and is used in traditional medicine to treat various diseases such as cardiovascular disease, gastric ulcer, respiratory and intestinal inflammation. The change of status from dormancy to germination can be eliminated by using some treatments in accordance with the natural conditions of the mother base habitat. However, some physiological needs of dormant seeds can be met by scratching (mechanical and chemical), washing in running water, dry storage, cold and humid conditions, light, smoke, and plant growth regulators. The aim of this study was to investigate different strategies including pretreatment, leaching and constant germination temperature on seed germination characteristics and Kelussia seedling growth.

 The experiment was conducted in Petri dishes at Seed Technology Laboratory of Agricultural Sciences Faculty of Shahed University. K. odoratissima Mozaff seeds were collected from their natural habitat in Fereydounshahr, Isfahan province in 2019.This study was performed in the Crop Physiology and Seed Technology Laboratories of Shahed University, Faculty of Agricultural Sciences, from 23.09.2019 to 22.11.2019. The cultivation was in Petridish at constant germination temperatures after priming and leaching. The experiment was performed as a factorial experiment in a completely randomized design with three replications. Each replication included 36 Petridish and 20 Kelussia seeds were planted in each petri dish. Experimental factors include constant germination temperatures (1, 5, 10 and 15°C), duration of rinsing with running water at 15°C (24, 48 and 72 h) and hormone pretreatment with gibberellin (0, 250 and 500 ppm). Before applying the hormonal pretreatment and temperature, the seeds were washed in running water in such a way that seeds were placed in a strainer that was not immersed and water flowed on the seeds for the specified periods of time for this treatment. In this case, germination inhibitors were washed from the seed surface. According to the test period and laboratory conditions, the laboratory temperature could be controlled at 15 °C with a thermometer and cooling devices. Then, for hormonal pretreatment, the seeds were placed in containers containing gibberellin solution with concentrations of 0, 250 and 500 ppm and refrigerated at 4°C for 72 h. After washing the seeds, 20 seeds were placed in Petridish with a diameter of 10 cm and a height of 2 cm on Whatman filter paper No. 1 and at temperatures of 1, 5, 10 and 15°C with 16 h of light and 8 h of darkness passed. Due to the fact that germination in seeds grown at this temperature at 15°C was zero in all treatment compositions, it was excluded from statistical analysis. To analyze the data variance, the SAS 9.1 statistical software was used. The comparison of means of traits was performed using the Duncan test at 5% probability level.

 Germination traits, growth indices and physiological parameters of seedling photosynthetic pigments under the influence of leaching, temperature, gibberellin and the interactions of leaching in temperature, leaching in gibberellin, temperature in gibberellin and the combination of leaching treatment × temperature × gibberellin showed significant differences. The results showed that the optimum germination temperature was 1°C and about 54% of seeds were able to germinate at this temperature without using any pretreatment. However, pretreatment of seeds at a temperature of 1°C with gibberellin at 250 ppm and washing for 72 h increased the germination rate to 65%. It has also been shown that treatment with gibberellin at 250 ppm seedling length and gibberellin at 500 ppm improves seedling fresh and dry weight in three leaching treatments at 10°C. Chlorophyll and carotenoid content of seedlings was observed in the combination of 24 hours leaching treatment, temperature of 5°C and gibberellin priming of 500 ppm. Due to the wide variety of species of Apiaceae and also the variety of type and depth of sleep, various treatments to break dormancy and stimulate seed germination of plants of this genus have been proposed, the most important of which are wet and gibberellin. It should be noted that the germination ecology and appropriate treatments to break dormancy in different plant species, plants of the same family, same species and different ecotypes of the same species can be completely different.

 According to the results of this study, seed treatment with 72 hours of cold water washing, 1°C and gibberellin pretreatment with a concentration of 250 ppm was able to show the highest germination percentage to achieve High germination is recommended. In addition, at 5°C under gibberellin pretreatment and leaching showed a relatively high germination percentage. Accordingly, gibberellin hormonal pretreatment at low temperatures was effective in achieving more germination under priming conditions. Is. On the other hand, a concentration of 500 ppm gibberellin increased seedling weight and photosynthetic pigments. In general, a temperature of 1°C followed by a temperature of 5°C was effective in increasing the germination of celery seeds and was able to record better results. Also, the suitable seedling growth temperature for mountain celery is 10°C and the application of Gibberellin hormonal pretreatment improved the growth characteristics of Kelussia seedlings.