資料來源:
2.http://onlinelibrary.wiley.com/doi/10.1111/j.1399-3054.1978.tb01560.x/abstract
看了兩篇有關於扦插時枝條留葉子有助於生根的文章摘要。其論點大概為:
1.光合作用產生的碳水化合物有助生根，扦插於暗室無法生根，光照於枝條葉子有利生根，但照射於枝條下方盆底則不利生根。
2.低光照情況下，於扦插介質中添加"蔗糖"有利生根。
3.扦插時保留葉子的好處，能經由添加糖類與氮物質於介質的方式達到相同效果。
4.土中礦物質多寡與能否生根無關，但是於出根後，礦物質鈣會增加根生長長度。
其試驗對象非九重葛，但是其結論與我之前見聞一致。扦插介質中不要添加肥料是常識，因此唯一不放心的是"氮"。之前曾聽/見到枝條先泡蔗糖或維生素B1，及扦插前先環剝皮約一週，以累積更多碳水化合物有利生根的論述，與文章論點一致，因只能看到文章摘要無法看到完整內容，細節不知，僅供參考。
註:(1)
雖日光有利發根，扦插初中期均不適合日光直射，應置於遮蔭明亮處，並適當保濕，文中所提添加糖類與氮肥或礦物質，可能是在液態或霧化栽培下，能否直接加在土中或其他介質中及其數量/濃度/頻率...，我不知道
(2)
光合作用：植物透過光合作用，製造植物成長所需的養分－葡萄糖。通過氣孔進入葉肉的二氧化碳，與自水分解得來的氫，在葉子這間精密的綠色工廠，以日光為能源，於葉綠體中製造出葡萄糖與氧氣。葡萄糖透過篩管送達植物的其它器官，供利用或再合成為蔗糖、澱粉等大分子的醣類儲存；氧氣則經由氣孔釋出植物體外。
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An Analysis of the Function of the Leaf in the Process of Root Formation in Cuttings
J. van Overbeek, Solon A. Gordon and Luis E. Gregory
American Journal of Botany
Abstract:
The combined action of auxin and factors coming from the leaves is essential for root formation in cuttings (fig. 1, 2, 3, 4). The leaves exert their influence in the dark as well as in the light (fig. 5). In red hibiscus the root-forming factors of the leaves can be entirely replaced by sucrose and nitrogenous substances (fig. 3, 6, 8). Quantitative chemical analyses show that these substances are actually contributed to the cuttings by the leaves (fig. 9, 10, 11). It is, therefore, concluded that the main function of leaves in the process of root initiation is to supply the cutting with sugars and nitrogenous substances, factors which may be termed nutritional. There is no a priori reason to postulate the production of a special root-forming substance such as "rhizocaline" in the leaves of red hibiscus. In red hibiscus cuttings, after treatment with auxin in conjunction with leaves or with suitable carbohydrate and nitrogen sources, roots were found to originate in the secondary phloem in the ray parenchyma.
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Effects of Nutrients and Light on Growth and Root Formation in Pisum sativum Cuttings
LENNART ELIASSON
Abstract
Cuttings obtained from seedlings of Pisum sativum L. were rooted in water solution. Shoot growth continued after excision and shoot length increased considerably before roots emerged. Increase in dry weight was strongly dependent on light supply. Continued growth was dependent on supply of mineral nutrients to the rooting solution.
Mineral nutrients had no or slight influence on the number of roots formed on cuttings from stock plants grown in fertilized soil, but the growth in length of the roots was dependent on the presence of calcium in the solution. Root formation was dependent on photosynthetic products formed after excision. No roots were formed on cuttings kept in the dark. The number of roots increased with increasing irradiance given to the leafy part of the cutting. At a low level of irradiance sucrose supply through the rooting medium increased the number of roots. Light given to the basal part of the cuttings had a strongly inhibitory effect on the number of roots formed. It is concluded that the carbohydrate level easily becomes a limiting factor for root formation in growing pea cuttings. Availability of mineral nutrients influences in the first place the growth of the shoots.
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