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本文报导了甜菜根尖的结构与初生组织分化的过程.实验观察表明,甜菜根尖的原分生组织有三层原始细胞.中柱和皮层分别起源于最内层和中间一层原始细胞;而表皮和根冠共同起源于最外一层原始细胞.故甜菜根端组织结构属于“封闭型”.根尖的初生分生组织可扩大到伸长区下方一段距离.甜菜根的初生组织在伸长区下方已开始逐渐分化.根冠在胚胎时期已初步形成.在伸长区下方,中柱的外围,表皮和内皮层的分化形成比皮层细胞早一些;但表皮和皮层细胞直到根毛区才高度液泡化.在中柱内部,最早由原形成层分裂衍生的是中柱鞘;其次是原生韧皮部和原生木质部;最后成熟的是后生木质部.最早成熟的初生韧皮部靠近顶端分生组织.初生木质部到根毛区上方才分化成熟.甜菜根的初生组织从它发生的部位起向上一直延续到距子叶节0.6厘米(位置)为止的全部下胚轴.
This paper reports the structure of beetroot tips and the process of primary tissue differentiation.Experimental observations show that the primary meristem of beetroot tips has three primary cells.The middle column and the cortex originate from the innermost and middle layer of primitive cells respectively, The epidermis and root crown originated in the outermost layer of primitive cells .Therefore, the root tissue structure of beetroot belongs to the “closed type.” The primary meristematic tissue of apical meristem can be extended to a distance below the extensional zone.The primary tissue of beetroot The area below the long zone has begun to gradually differentiate, and the root crown has been initially formed during the embryonic period. Below the elongation zone, the periphery of the central column, the epidermis and the endoderm differentiate earlier than the cortical cells; however, the epidermis and cortical cells Highly vacuolated.In the middle of the column, the earliest primordial dissection derived from the pericycle; followed by the native phloem and native xylem; and finally the mature posterior xylem.The earliest mature phloem near the apical meristem.New xylem The root tissues of the beetroots differentiate and mature, and the primary tissue of beetroot extends from its site up to all hypocotyls up to 0.6 cm away from the cotyledonary node.