勃氏甜龙竹不同部位根的解剖结构比较

该研究选择勃氏甜龙竹7月份(雨季)和11月份(干季)地面以下10 cm处土壤中秆基处生的根,秆下部节内(地上部分3~4节)和秆上部枝条基部在空气中自然生的根,以及7月份枝条高空压条产生的伸长阶段和成熟阶段的根作为实验材料,采用树脂切片和徒手切片法,对不同部位根的根尖和根毛区进行横切,甲苯胺蓝O和苏丹红7B染色,研究不同起源根的形态解剖结构,为竹子根解剖学研究提供新的理论信息。结果显示:(1)不同来源根的皮层宽度占根直径的比例、周缘纤维组织宽度及其细胞层数、内皮层细胞壁厚度均随生长时间延长而增加。(2)所有起源根的外皮层和内皮层细胞壁均有显著的木栓质沉积,但环内皮层木栓化程度存在显著差别。(3)测量不同来源根的后生木质部导管数目和直径发现,7月份采集的根导管数目更多、直径更大。(4)枝条基部自然生根的根尖与其他起源部位的根相比更为钝平,但根冠面积较小;秆下部节内自然生根非常硬,所以未能成功观察其根尖结构特点。研究认为,勃氏甜龙竹4种不同起源根的基本结构一致,但在各自的具体结构上还存在显著差别,可能与其生长的环境以及发育状况密切相关。

Comparison on the Anatomical Structures of the Roots Generated from Different Parts of Dendrocalamus brandisii

Our works focused on the anatomical structure of roots generated from different parts of Dendrocalamus brandisii. New theoretical information was supplemented for the root anatomy of bamboos by exploring the anatomical structure of these roots. Resin slicing and free hand cross sections were cut from the root hair zone, and were stained by Toluidine blue O and Sudan red 7B. The results showed: (1) the ratio of cortical width to root diameter, the width and number of cell layers of sclerenchyma, and the thickness of endodermis cell walls increased with time. (2) Significant suberization occurred in the exodermis and endodermis of all the roots, but with significant difference in the suberization degree of periendodermis. (3) After measuring the number and diameter of the xylem vessels of all the roots, we noticed that the number and diameter of xylem vessels were higher in July as compared to those in other months. (4) The tips of roots generated at the base of branches were more blunt and flat, with smaller area of root caps, as compared with those generated in other parts. The tips of those roots generated in the culm underpart were so hard that their anatomical characteristics were unsuccessfully observed. The conclusion is that the roots of four originations had the same basic structure, but with significant differences in their specific structures. The structural differences may be closely related to their living environment and development status.