Study on development and morphological change rules of root tuber of Ophiopogon japonicus / 中草药

ABSTRACT

Objective To investigate the rules of root tuberenlargement and medicinal materials formation, and lay the foundation for breeding a new Ophiopogon japonicus variety. Method The study was carried out with field cultivation. Samples were collected continuously for every interval 7-10 d. The rules of dry matter distribution and accumulation in each parts of O. japonicus was calculated based on the mean value of 15 plant samples. The number and size of root tuber were calculated based on the mean value of 15 samples. The fiber characteristics of root tuber of O. japonicus were observed by optical microscope. Characters of O. japonicus were observed according to the Chinese Pharmacopoeia 2015 edition and recorded the changes of medicinal characteristics. Results The root tuber of O. japonicus inflated starting from October to April in the next year in Sichuan province. Adventitious roots were initially formed into nutritive roots around caudex, and able to form into root tuber around caudex later. Tuber number of per plant is basic from 5 to 20, most in 8-10, very few more than 20. Adventitious roots expanded gradually into a fusiform root from one end of root tip, root tip can continue to grow to form adventitious roots after the formation of root tuber, the newly formed adventitious roots could be expanded for the second time, very few might appear swollen three times to form beads. Microscopic observation showed that root tubers were inflated primarily by the enlargement of cortical cells and the increase of cell layers, in which cortical cells enlargement played a leading role. While tubers started expanding, the accumulation of dry matter in fibrous roots and stem leaves quickly slowed to stop eventually, and the accumulation of root dry matter increased rapidly in the early stage, and it kept basically dynamic balance in mid and late March, and the whole behavior of medicinal materials was in the process from dry to full. Conclusion The results show the apparent change rules of O. japonicus root tuber in the expanding process, which proves the direction and goal for research on the mechanism of root tuber development of O. japonicus.