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|Title:||A Physiological Investigation of Adventitious Root Initiation in the Genus Acer|
|Author(s):||Kling, Gary John|
|Department / Program:||Horticulture|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Biology, Plant Physiology|
|Abstract:||Differences in adventitious root initiation among species in the genus Acer were investigated. Acer ginnala, A. rubrum and A. saccharinum were easily rooted from softwood stem cuttings. Acer saccharum was moderately difficult to root from cuttings. Acer griseum was the most difficult-to-root species in this study. Optimum IBA treatments for root initiation were determined for these five species.
The total free phenolic content of these five Acer species varied among species, plant parts and dates sampled. Leaves accounted for the largest share of the total phenolic content followed by young stems and old stems. Easy-to-root species, Acer ginnala, A. rubrum and A. saccharinum, had a higher content of total phenols than difficult-to-root species, A. griseum and A. saccharum. These experiments suggest that differences and changes in total phenolic content may help to explain some of the differences in ease of propagation of plants from cuttings.
The role of phenolic compounds in root initiation and their relationship to extracted rooting promoters and inhibitors was studied. Combinations of catechol and IAA stimulated root initiation in cuttings of Acer griseum and A. saccharinum. Treatment of Acer griseum cuttings with a combination of IAA and catechol for 24 hours resulted in 100% rooting and increased numbers of roots per cutting.
Crude methanolic extracts from leaves, young stems and old stems of Acer ginnala, A. rubrum and A. saccharinum contain substances that stimulate root initiation. Crude extracts from leaves, young stems and old stems of Acer griseum and A. saccharum appeared to contain the same substances at lower concentrations. The higher concentrations of these stimulatory substances in tissues of Acer ginnala, A. rubrum and A. saccharinum may account for the relative ease of propagating these species from cuttings compared to cuttings of A. griseum and A. saccharum.
Fractionation of crude extracts from leaves of Acer ginnala in 80% isopropanol with descending paper chromatography revealed the presence of stimulatory compounds with R(,f) values of 0.7 (compound 0.7) and 0.9 (compound 0.9). Compound 0.7 occurred in the highest concentration in leaves of easy-to-root species, but may occur at lower concentrations in all plant parts of the five species tested. Compound 0.7, extracted from leaves of Acer ginnala, was first observed as an inhibitor of root initiation in the mung bean bioassay. However, this compound was strongly stimulatory to root initiation when tested at lower concentrations. Therefore, a single concentration of an extract cannot be used to assess the presence of inhibitors of root initiation.
Compound 0.7 applied in combination with IAA stimulated root initiation in softwood tip cuttings of Acer saccharinum and A. griseum. The results obtained with Acer griseum indicate that compound 0.7 may hold promise in rooting other difficult-to-root species. Several experiments indicated that the compounds at R(,f) 0.7 were phenols.
Stimulatory compounds with an R(,f) of 0.9 occurred in all plant parts of all species studied. These compounds stimulated adventitious root initiation in the mung bean bioassay, but did not stimulate root initiation in softwood stem cuttings of Acer saccharinum or A. griseum.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.
|Date Available in IDEALS:||2014-12-16|