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Asexual Propagation of Hickories and Pecan Using a Modified-Stool-Bed-Layering Technique
Background and Objectives: Hickories and pecans have long been admired by horticulturists for their superior ornamental features, ability to produce desirable nut crops in northern climates, and resilience to
abiotic and biotic stresses. However, their potential as nursery crops is limited by a lack of asexual propagation protocols and a propensity for being difficult to transplant. As a result, the availability of clonal
varieties and further development of these crops remains minimal. The modified-stool-bed-layering technique involving etiolated shoots, developed by the Urban Horticulture Institute at Cornell University, may
have potential for use as a reliable means of asexually producing hickories and pecan. The objectives of this study were to:
•determine the viability of the modified-stool-bed-layering technique on rooting layers of species belonging to the genus Carya.
•assess the influence of auxin concentration on rooting capacity of Carya illinoinensis (northern pecan), Carya laciniosa (kingnut hickory), and Carya ovata (shagbark hickory).
Methods:
•Species studied: Carya illinoinensis
(northern pecan), C. laciniosa (kingnut
hickory), and C. ovata (shagbark hickory).
•Treatments: 0, 4,000, or 8,000 ppm IBA
dissolved in 95% ETOH
•Nine-single-stock-plant
replicates/species/treatment (N=81)
•Stock plants were stooled in spring before
bud break.
•Layers were harvested in fall after leaf
senescence.
Results: The modified-stool-bed-layering
technique resulted in rooting of each species
tested. Auxin (IBA) applied after etiolation
was necessary for rooting to take place.
Species appear to respond differently to
auxin concentration in both overall rooting
percentage and the number of roots per layer.
Adventitious roots were fibrous and well-
branched.
Acknowledgements: This work is supported by the USDA National Institute of Food and Agriculture, McIntire Stennis/Smith-Lever project 1020775 and the Horticultural Research Institute.
Brandon Miller and Dr. Nina Bassuk
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Procedure (A-L right): A)
established stock plants in field,
B) stock plants stooled in spring,
C) buds emerging from stooled
stock plants ready to be covered,
D) foil-wrapped container for
covering stock plants, E) light-
excluding covers placed on stock
plants, F) etiolated shoots
(~10cm tall), G) application of
auxin dissolved in ETOH or
ETOH alone (control), H) after
treatment, etiolated shoots are
mounded with soilless substrate
(~7.5cm), I) etiolated shoots are
transitioned to light exposure by
shading (two weeks), J) soilless
substrate is removed from
mounded layers in fall, K)
rooted layers are severed , L)
rooted layers are removed.
Next Steps: Additional studies are underway to determine how auxin concentration influences rooting and explant survival as well as broadening the investigation to explore how this technique influences other
desirable hickory species. Further experimentation is in progress to determine if rooted layers exhibit traits that could overcome other limitations typically associated with hickories and pecans grown from seed
such as slow shoot development and the purported side effects of a prominent taproot.
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Conclusions: The modified-stool-bed-layering
technique in tandem with the application of auxin
has potential as a new technique for asexual
propagation of hickories and pecan. New
methods for asexual propagation create greater
opportunity for selection and development of
hickories and pecans as nursery crops for
ornamental and nut-production applications.
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School of Integrative Plant Science