Embolization formation and repair of Phyllostachys vivax f. aureocaulis in winter and the role of non-structural carbohydrates in this process

Juan Li^1*Jinge Wang²Lei Chen¹Chongyang Wu¹He Li¹Zhanchao Cheng¹Jian Gao^1*

• ¹International Center for Bamboo and Rattan, Beijing, China
• ²Beijing Botanical Garden, Beijing, China

Phyllostachys vivax f. aureocaulis is an important ornamental plant in Beijing, mainly introduced from Henan, Zhejiang and Jiangsu provinces of China. Low temperature in winter leads to xylem embolism and plant death, but there is few studies on bamboo. At present, the abnormal climates in Beijing in winter were occured, it is of great significance to study the embolism change trend and recovery process of bamboo in Beijing. This experiment was conducted between December 2021 and March 2022 to measure the embolization curve as well as variations in embolization sites in different organs. This study also explored the relationship between hydraulic structural characteristics and embolization regulation by combining physiological water indices and anatomical modifications. The results revealed that the embolization ratios of vascular conduits in the culm, twig, and petiole were 99.44%–62.9%, 96.45%–69.44%, and 97.32%–42.42%, respectively, from December to March. The vulnerability to culm embolization was greater in January and February than in December and March, with the highest vulnerability observed in February. Non-structural carbohydrates (NSCs) in 15, 30cm rhizomes away from the culm were significantly higher in March than in December (P < 0.05); with an significantly increased in starch content, the NSCs and starch content in 10th and 15th inernodes were significantly higher in March than in January and February. The net photosynthetic rates (Pn) were higher in December and March, lower in January and February, and negative throughout February. The diameters of the short and long axes, the number of parenchyma cell pits, and the area of parenchyma cell pits were significantly lower in January and February than in December and March (P < 0.05). In December and January, vascular bundles and cells were intact, whereas in February, signs of fragmentation with invasion body filling were observed. By March, the vascular bundles and cells had returned to normal, with a large number of starch granules in the parenchyma cells. These findings provide a basis for introducing bamboo species to cope with climate change and abnormal climate changes in winter and adopt scientific management methods.