麦冬块根发育及其形态变化规律研究

目的探讨麦冬块根膨大及药材形成规律,为麦冬新品种选育奠定基础。方法大田栽培,间隔7~10 d连续采样。以测定15株均值计算麦冬各部分干物质分配和积累规律,以测定15粒均值计算块根数量、大小变化,采用光学显微镜对麦冬块根纤维特征进行观察,并参照《中国药典》2015年版麦冬项下性状描述对麦冬药材性状变化进行观测记录。结果在四川地区麦冬块根从10月份开始膨大至次年4月结束。最初形成的生长于麦冬茎基的不定根多为营养根,可膨大形成块根的不定根多为后期茎基部四周生长出的不定根。麦冬单株块根基本在5~20个,多数在8~10个,极个别超过20个。不定根一般从根尖一端开始膨大逐渐延长形成纺锤形块根,块根形成后根尖可继续生长形成不定根,新形成的不定根可进行2次膨大,极个别不定根可出现3次膨大,形成串珠状。显微观察结果显示麦冬块根膨大主要是由皮层细胞体积增大和细胞层数增加形成,其中皮层细胞体积增大起主导作用。麦冬块根开始膨大,须根和茎叶部分干物质积累快速减缓至最终停止,块根干物质积累在前期增长速率快至3月中下旬基本呈动态平衡,药材性状整体表现为从干瘪向饱满变化的过程。结论研究结果全面反映了麦冬块根膨大过程的表观变化规律,为麦冬块根发育机制的研究探明了方向。

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

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.