The formation of nodal adventitious roots in Salix cordata
The formation of nodal adventitious roots in Salix cordata
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DOI：
10.2307/2436930
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发表时间：
1938-11-01
影响因子：
3
通讯作者：
Carlson, MC
中科院分区：
文献类型：
--
作者：
Carlson, MC
根是从节上或节附近的特定位置切下的茎条上长出来的。节根是由原基发育而成的，原基在茎从树上脱落之前就存在于茎中。原基由薄壁次生细胞形成，位于叶或分支间隙上方。维管射线外部的细胞在这一区域扩大并成为分生组织。相邻的细胞也经历类似的变化，直到形成层外的次生细胞，包括几条射线，参与原基的形成。形成层将细胞添加到原基的内表面。原基附近的次生木质部细胞膨大形成半球形突起，将原基中心向外推，使原基呈圆顶状。原基在6月初出现在较低的，但不是在最低的3或4，节点的发展分支。在夏季，它们在生长的枝条的节上逐渐向上形成。到了秋天，除了最年轻的节点，它们已经达到了最大的发展。它们保持休眠状态，除非将树枝从树上移走，并放置在有利于原基生长成根的条件下。
Roots arise on stem-cuttings from definite places at and near the nodes. The nodal roots develop from primordia which are present in the stems before their removal from the tree. A primordium is formed from parenchymatous secondary cells, above a leaf or branch gap. The cells in the outer part of a vascular ray in this region enlarge and become meristematic. Neighboring cells undergo similar changes until the secondary cells outside the cambium, including several rays, are involved in the formation of a primordium. The cambium adds cells to the inner surface of the primordium. A hemispherical protuberance, formed by the enlargement of cells of secondary xylem adjacent to the primordium, pushes the center of the primordium outward, making it dome-shaped. The primordia appear in early June in the lower, but not in the 3 or 4 lowermost, nodes of the developing branches. They are formed progressively upward in the nodes of the growing branches during the summer. By autumn they have reached their maximum development except in the youngest nodes. They remain dormant unless the branches are removed from the tree and placed in conditions favoring the growth of the primordia into roots.