The influence of graft type and age on juvenile period of medicinal plant Barijeh in the North Khorasan landrace

Barijeh is a monocarpic perennial plant belonging to the Umbellifers family. It is one of the most valuable native plants of Iran, and its extracts is a significant export item of Iram. The propagation of plants is one of the most essential processes for the plant sustaining life. In situations where plant propagation via seeds is impossible or problematic, asexual propagation techniques, such as transplantation, can be used. Due to the preservation of genetic characteristics and the absence of somaclone diversity in plants, transplanting is an appropriate technique for large-scale plant production. Increasing the growth rate of young seedlings can frequently shorten the seedling period and advance the plant to the fruiting stage. Type of transplant and age at the time of transplant appear to be influential in this regard. This experiment was conducted in the greenhouse and research farm of the Shirvan Branch of Islamic Azad University in 2018-2019 using a randomized complete block design with three replications and two factors in a factorial arrangement. The first factor was the type of grafting performed on the Barijeh, which was examined at four levels: control (no grafting), tuber grafting, leaf grafting, and crown grafting. The second factor was the age of the grafts, which was examined at four levels: annual, biennial, triple, and four-year-old grafts. Mid-May 2018 saw the preparation of basic plants (aged five years) and tested scions from the botanical garden of the North Khorasan Research Center in Bojnourd. End of May of the same year, three types of transplantation were performed on basic plants: tuber, stem, and leaf transplantation. Midwinter saw the transfer of seedlings to the main land, where they began vegetative growth in early March. At the end of May 2019, three months after the transfer of seedlings to the main land, graft yield, stem height, leaf number, leaf inclination, and tuber length were measured. In addition, once the plant entered its reproductive phase (early July), the number of flowers per plant was measured on June 1 and the number of seeds per plant was measured in late June. Data analysis were performed by Mini tab statistical software version 17 and comparison of means were performed using LSD test at a 1% probability level. The results indicated that the interaction effect of graft type and age was significant for all investigated traits. Tubular and four-year-old grafts had the highest graft success, leaf length, and stem height, at 80%, 3.56 cm, and 4.47 cm, respectively. The greatest number of leaves was observed on four-year-old grafts in the control and tuber graft treatments, and only in these two treatments the number of leaves reached more than 11 leaves per plant. The longest tuber length was observed in three-year-old and four-year-old control and tuber graft treatments, and only in these four treatments the tuber length was observed at more than 24 cm. The success of the grafting is contingent on a number of factors, including the type of base, the physiological condition of the base, the type of graft, the origin of the graft, the age and duration of the graft, and the compatibility of the base and the graft. Because the crown diameters of one- to four-year-old plants used as grafts on five-year-old mature plants as grafting bases were smaller in the present study and in the study of barijeh, crown grafting was less successful. Due to insufficient contact between the rootstock and the graft, leaf grafting was not particularly successful. This experiment revealed that the optimal transplantation method for barijeh is tuber grafting, while the optimal age for graft selection is a four-year-old plant.