Research ArticleArticles

Cytokinin Phytohormonal Effects on Crown Structure

Alisha M. Autio and Michael E. Day
Arboriculture & Urban Forestry (AUF) January 2016, 42 (1) 1-20; DOI: https://doi.org/10.48044/jauf.2016.001

Article Figures & Data

Figures

  • Figure 1.
    Figure 1.

    Differential effects on foliage and shoot growth of cytokinin application related to tree age in red spruce (Picea rubens Sarg.). The x-axis gives tree age as (S) sapling mean 25 years and old-growth (O) mean 160 years and 0 to 500 mg L−1 exogenous B-6-P application. Both species exhibit maximum treatment effects at 50–100 mg L−1 (Autio 2013), and age differentials consistent with those previously reported for red spruce (Greenwood et al. 2008). Bars indicate standard errors.

Tables

  • Table 1.

    Cytokinin formulations and trade names. See text for further information on group components.

    Cytokinin groupCommon names
    BA2iP, BA, BA 0.1%, BAP, BA 0.2, BA 0.5, Verdan, BA + TIBA®, BA + Alar®, BA + TIBA® + Alar, 6-CP, Cytex®, BA + IBA®, GA + BA + IBA, ProShear®, and other BA/GA mixes
    BA + KinetinBA + Kinetin®—also contains GA and auxin or IBA
    BPABPA, Accel, SD8339®
    KinetinKinetin® 2–500 ppm, Kinetin (270 ppm) with or without GA3 90, GA + Kinetin 100 ppm + 100 ppm
    BA + GABA or BA + GA, Promalin®, PBA, Thidiazuron®, Fascination®, Lanolin®
  • Table 2.

    Cytokinin PGR mixtures, application procedures, results, and commonly treated woody plants. Results of individual application trials are listed in the Appendix.

    Woody plant groupApplicationsEffects on growth
    Cytokinin formulation BA
    Conifer

    • BA 0.01 to 225 ppm/scions dipped prior to grafting or single foliar spray

    • 400 ppm/1 foliar spray; BA 400 ppm reduced height but trees were deformed with poor root growth

    • BA 450 ppm/six foliar sprays at five-day intervals in May and again when weather warmed

    • BA 500 to 1000 ppm/foliar spray applied four times at two-week intervals or whole tree foliar spray application 6 weeks after budbreak

    • BA 2000 ppm/Lanolin paste applied in late summer and autumn

    • 0.1% 9-BA Vasoline paste applied to cut roots (worked best)

    • Growth inhibition

    • Phytotoxicity

    • Branching agent

    • Propagation

    Deciduous

    • BA 11 to 34 ppm/solution applied to the base of a stem via an absorbent wick in mid-summer

    • BA 10 ppm/soak of four-year-old dormant seedlings

    • 50–200 ppm ± Promalin 1000 ppm/foliar sprays

    • BA 100 ppm/stem dip

    • BA 225 ppm/droplet applied daily to a lateral bud

    • Branching agent

    • Propagation

    Fruit Trees

    • BA 200 ppm/drops placed onto buds of cut branches in January

    • BA 300 ppm/single foliar spray in summer at various times

    • BA 150 to 600 ppm/single foliar sprays in autumn

    • Dormancy release

    • Flower enhancer

    • Branching agent

    Shrub

    • BA 1 to 100 ppm/continuous dip of dormant cut stems

    • BA 1 to 100 ppm, Thidiazuron 1 to 50 ppm/continuous dip of cut stems or BA added at various times

    • 10 to 100 ppm/foliar spray every three days 2–32 times

    • BA 200 ppm and 2iP 100 ppm most effective/single foliar sprays onto unpinched plants

    • BA 100 to 1000 ppm/1–2 foliar sprays in summer

    • BA 2500–5000 ppm/1–5 foliar sprays one week apart in April

    • Dormancy release

    • Flower enhancer

    • Branching agent

    Cytokinin formulation BA + GA
    Deciduous

    • BA + GA (Promalin) 1500 ppm/foliar spray applied 10 weeks after the end of spring

    • BA + GA (BAP-10) 1250 ppm/two to four weekly foliar spray applications

    • BA + GA 400 ppm of BA & 2iP and 450 ppm of Promalin/single foliar sprays

    • BA + GA 200 ppm, Promalin 1000 ppm/single foliar spray or three foliar sprays onto rooted cuttings

    • Branching agent

    • Dormancy release

    Fruit Tree

    • BA + GA 500 ppm each/three applications at one week intervals to one-year-old plants; very effective when followed by injection and Lanolin

    • BA + GA (Promalin) 1500 ppm/single foliar spray in June to one-year-old plants

    • BA 1 to 900 ppm, BA + GA (Promalin) 1000 ppm/one to two applications worked best

    • Branching agent

    Shrub

    • BA + GA (Fascination) 125 to 500 ppm/two foliar spray applications at day 0 and day 21

    • BA + GA 200 ppm, Promalin 1000 ppm/single foliar spray or three foliar sprays

    • 450 ppm of Promalin/single foliar sprays

    • BA + GA 200 ppm, Promalin 1000 ppm/single foliar spray or three foliar sprays onto rooted cuttings

    • BA+ GA, PBA, Thidiazuron all at 200 ppm/single foliar spray

    • BA + GA (BAP-10) 1250 ppm/two to four weekly foliar spray applications

    • Promalin 5000 ppm in April was better than pruning

    • Branching agent

    Cytokinin formulation Kinetin
    Conifer

    • Kinetin 100 to 500 ppm

    • Growth inhibitor

    Deciduous

    • Kinetin 50 ppm/applied to seeds

    • Kinetin 100 to 500 ppm; Kinetin 500 ppm worked best

    • Growth inhibitor

    • Dormancy release

    Fruit Tree

    • Kinetin 2 ppm/apply in late autumn for best results

    • Kinetin 65 to 130 ppm/monthly foliar spray applications

    • Kinetin 100 to 500 ppm

    • Branching agent

    • Dormancy release

    Shrub

    • Kinetin 80 ppm/released shoots from dormancy when applied to them

    • Kinetin 100 to 500 ppm

    • Growth inhibitor

    • GA + Kinetin 100 ppm + 100 ppm/applied every four days to the flower bud

    • Kinetin 270 ppm with GA 90 ppm/increased branching more than either chemical alone

    • Dormancy release

    • Branching agent

    • Bud break and formation

    Cytokinin formulation BA + Kinetin
    Conifer

    • BA + Kinetin 1.17 ppm + 1.17 ppm Kinetin in 1125 ml water/apply in early harvest

    • Kinetin 1.17 ppm + BA 1.17 ppm/45 ml soil drenches every two weeks from June to September

    • Branching agent-no effect

    • Stress tolerant

    Shrub

    • 1.17 ppm BA + 1.17 ppm Kinetin/45 ml soil drenches every two weeks from June to September; the low 1.5 ml rate increased plant quality; the 3.0 ml rate increased growth

    • BA 100 ppm/foliar spray 2 to 32 times with no effect on growth

    • Stress tolerant

    • Branching agent

    • Dormancy release

  • TREECYTOKININ: BARATE (PPM)CYTOKININPURPOSE OF EXPERIMENTCITATION
    Acanthopanax sieboldianus (5-leaf Aralia)1–100 ppm/continuous dip of dormant cut stems1–100BAPropagation-delayed budbreak but increased the % of breaks(Yang and Read 1997)
    Aralia elata (Japanese angelica tree)50–200 ppm/one spray onto trees; 50 ppm was best50BABranching agent/propagation(Sugiura and Azuma 2005)
    Camellia × williamsii10–100 ppm/foliar spray every three days, 2–32 times10–100BABranching agent-no effect on branching(Richards and Wilkinson 1984)
    Castanea dentate (chestnut)BA (1–100 ppm)/stem dip; BA 100 ppm100BAPropagation-delayed budbreak but increased the % of buds that broke(Yang and Read 1997)
    Chamaecyparis lawsoniana (Port Orford cedar Christmas trees)500–1000 ppm/foliar spray applied four times at two-week intervals500–1000BAGrowth inhibitor/Branching agent-caused severe phytotoxicity and did not increase bud formation(Duck et al. 2004)
    Chrysobalanus icaco (coco plum)400 ppm of BA and 2iP and 450 ppm of Promalin/single foliar sprays400 and 450BABranching agent(Rudniki and Rejman 1982)
    Forsythia × intermediaBA 200 ppm, Promalin 1000 ppm/single foliar spray or three foliar sprays onto rooted cuttings200BABranching agent(Grzesik and Rudnicki 1985)
    HydrangeaBA 1750–3500 ppm/three foliar sprays one week apart; BA 100–600 ppm/two foliar sprays in summer1750–3500 and 100–600BASenescence inhibitor-no effect on senescence but flowering was delayed(Shanks and Link 1964)
    Ilex crenata (Japanese holly)BA 100–600 ppm/two foliar sprays in summer; BA 125-1000 ppm/one spray; best results from 450 ppm and 1000 ppm100–600BABranching agent-increased branching, increased the number of shoots, reduced shoot length and leaf size(Wright 1975; Wright 1976; Gilliam and Wright 1977; Keever and Foster 1990)
    Ilex glabra (inkberry holly)BA 1750–3500 ppm/three foliar sprays one week apart; the best time to apply BA is when the leaves start to harden off1750–3500BABranching agent(Oates et al. 2005b)
    Ilex opaca (American holly)BA 10–1000 ppm10–100BAFlower enhancer-inconsistent effects on sex of flowers(Milbocker 1967)
    Ilex paraguariensis (Yerba mate)BA 495–2973 ppm/single foliar spray early summer; 1980 ppm was most effective495–2973BABranching agent-stimulated lateral branching(Sansberro et. al. 2006)
    Ilex vomitoria (yaupon holly)BA 125–1000 ppm/single foliar spray; BA 1000 was most effective1000BABranching agent-increased budbreak(Keever and Foster 1990)
    Nandina domestica (heavenly bamboo)BA 1000–5000 ppm/1–5 foliar sprays one week apart; BA 2500–5000 in April was most effective2500–5000BABranching agent-induced lateral branching(Keever and Foster 1990; Keever and Morrison 2003; Oates et al. 2005b)
    Photinia × fraseri (Fraser’s Photinia)BA 500–2500 ppm/single foliar spray; BA 1000 ppm in March greatly increased budbreak overpruning1000BABranching agent(Keever and Foster 1990; Owings and Newman 1993)
    Picea glauca (black spruce)BA 500–1000 ppm/foliar spray applied four times at two-week intervals500–1000BAGrowth inhibitor/branching agent-increased lateral bud formation and caused phytotoxicity and deformities(Duck et al. 2004)
    Picea glehnii (Sakhalin spruce)BA 0.01–10 ppm0.01–10BAGrowth inhibitor(Shibakus 1980)
    Picea omorika, (Serbian spruce Christmas trees)BA 500 to 1000 ppm/foliar spray applied four times at two-week intervals500–1000BAGrowth inhibitor/branching agent(Duck et al. 2004)
    Picea pungens (Colorado blue spruce Christmas trees)BA 500–1000 ppm/foliar spray applied four times at two-week intervals or whole tree single foliar spray application six weeks after budbreak; BA 2.25–225 ppm/scions dipped prior to grafting or single foliar spray2.25–225 ppm and 500–100BABranching agent/growth inhibitor/propagation-BA at 22.5 ppm increased graft success, BA at 225 ppm is best applied at budbreak to stimulate new bud formation(Mulgrew and Williams 1985; Mazzola and Costante 1987; Beeson and Proebsting 1989; Duck et al. 2004)
    Pinus banksiana (Jack pine)BA 50–400 ppm/one foliar spray; BA 400 ppm reduced height but trees were deformed with poor root growth400BAGrowth inhibitor-BA was rejected as appropriate for this use(Schnurr et al. 1996)
    Pinus densiflora (Japanese red pine)BA 2000 ppm/Lanolin paste applied in late summer and autumn2000BAFlower enhancer/yield enhancer-seed yield was decreased and the seed had a slightly lower germination rate than controls(Wakushima 2004)
    Pinus mugo var. mughus (Mugo pine)BA 225–900 ppm/six foliar sprays at five-day intervals in May and again when weather warmed; 450 ppm is best450BABranching agent(Stiff and Boe 1985)
    Pinus nigra (Austrian pine)BA 2000–6000 ppm/1–2 foliar sprays 30–90 days after sowing seed2000–6000BABranching agent/growth enhancer-reduced height and branching(Boe 1990)
    Pinus palustris (long leaf pine)BA 2000–5000 ppm, PBA, Kinetin, 6-CP, Cytex (5% solutions)/applied to the terminal bud biweekly in May three times2000–5000BAGrowth enhancer-BA, PBA, Kinetin and 6-CP caused too many buds to form, all promoted height growth(Hare 1984)
    Pinus ponderosa (Ponderosa pine)BA 10–1000 ppm10–1000BABranching agent/plant propagation(Cohen and Shanks 1975)
    Pinus strobes (white pine)BA 300 ppm/single foliar spray on the terminal leader in June300BABranching agent(Hinesley and Wright 1988)
    Pinus sylvestris (Scots pine)BA 2000 to 6000 ppm/1–2 foliar sprays 30 to 90 days after sowing seed; BA 2000 ppm increased branching but plants were slightly shorter2000BABranching agent/growth enhancer/propagation-BA mixed with other PGRs greatly increased fascicular branch development(Whitehill and Schwab 1975; Boe 1990)
    Pinus thunbergii (Japanese black pine)0.1% 9-BA Vasoline paste applied to cut roots (worked best) or BA 2000 ppm/Lanolin paste applied to the bud2000BABranching agent(Yamaji and Tomioka 1980; Wakushima 2004)
    Pittosporum tobira (Japanese pittosporum)2iP, BA/single foliar spray onto unpinched plants; BA 200 ppm and 2iP 100 ppm most effective300BABranching agent(Rudniki and Rejman 1982)
    Populus hybrids (poplar)BA 225 ppm/droplet applied daily to a lateral bud225BABranching agent(Cline and Dong-Il 2002)
    Prunus persica (peach)BA 100 to 200 ppm/drops placed onto dormant buds of cut branches; applications of 200 ppm were best in January200BADormancy release(Weinberger 1969)
    Prunus × keio-zakura (flowering cherry)BA 300 ppm/single foliar spray in summer at various times300BAFlower enhancer(Yamasaki 2003)
    Pseudotsuga menziesii (Douglas-fir)BA 112 ppm and 1000 ppm/whole-tree single foliar spray application in spring112 and 1000BABranching agent(Mazzola and Costante 1987; Cline et al. 2006)
    Pyrus calleryana (Callery pear)BA 150–600 ppm, Promalin 300–1200 ppm/single foliar spray in autumn150–600BABranching agent-Promalin 1200 ppm was slightly better than BA 600 ppm at increasing shoots and crotch angles significantly(Keever et al. 1993)
    Quercus alba (white oak)BA 1–100 ppm/continuous dip of dormant cut stems; 100 ppm worked best100BAPropagation(Yang and Read 1997)
    Quercus robur (English oak)BA 10 ppm/24 soak of four-year-old dormant seedlings10BAStress tolerance/branching agent-increased branches and leaves(Smith and Schwab 1980)
    Rhapheolepis indica (Indian hawthorn)BA 1750–5000 ppm/three foliar sprays in spring at 1- to 3-week intervals; BA(BAP-10) 1250–5000 ppm/2–4 weekly foliar spray applications; 1250 ppm is most effective and rates above 2500 ppm caused phytotoxicity1250BABranching agent(Oates et al. 2004; Oates et al. 2005a; Oates et al. 2005b)
    Rhododendron (Azalea, florist)BA 2000 ppm in April increased branching but not as much as pruning; Promalin 5000 ppm in April was better than pruning2000BABranching agent(Keever and Foster 1990; Bell et al. 1997)
    Salix alba (white willow)BA 200 ppm, Promalin 1000 ppm/single foliar spray or three foliar sprays200BABranching agent(Grzesik and Rudnicki 1985)
    Sophora microphylla (Kowhai)BA 11–34 ppm/solution applied to the base of a stem via an absorbent wick in midsummer11–34BABranching agent(Carswell et al. 1996)
    Spiraea japonica (Japanese spiraea)BA 200 ppm, Promalin 1000 ppm/single foliar spray or three foliar sprays; BA applied three times increased branching but was not as good as Ethrel; Promalin reduced branching at all application methods as did BA applied only once200BABranching agent(Grzesik and Rudnicki 1985)
    Spiraea × vanhoutteii (Van Houtte’s spiraea)BA 1–100 ppm, Thidiazuron 1–50 ppm/continuous dip of cut stems or BA added at various times1–100BAPropagation/budbreak(Yang and and Read 1991)
    Viburnum odoratissimum (sweet Viburnum)BA 1–900 ppm, BA + GA (Promalin) 250–1000 ppm/1–2 applications worked best; Promalin 1000 ppm was effective in greatly increasing branching1–300BABranching agent-BA 300 ppm and above caused severe phytotoxicity(Schoene and and Yeager 2005)
    Weigela florida (Weigela)BA (200 ppm), Promalin (1000 ppm)/single foliar spray or three foliar sprays onto rooted cuttings200BABranching agent(Grzesik and 1985)
    TREECYTOKININ: BA + GARATE (PPM)CYTOKININPURPOSE OF EXPERIMENTCITATION
    Astilbe taquetiiBA + GA (Fascination) 125–500 ppm/two foliar spray applications at day 0 and day 21125–500BA + GABranching agent-significant phytotoxicity(Lieth and Dodge 2004)
    Buxus sempervirens, B. sinica (boxwood)BA + GA (Promalin) 1500 ppm/foliar spray applied 10 weeks after the end of spring growth was best at increasing lateral shoots1500BA + GABranching agent/remove Dormancy(Musselwhite et al. 2004)
    Carica papaya (papaya)BA + GA 500 ppm each/three applications at one week intervals to one-year-old plants; foliar sprays were most effective followed by injection, then Lanolin1000BA + GABranching agent(Giampan et al. 2005)
    Hibiscus moscheutos (rose mallow)BA + GA (Fascination) 125–500 ppm/two foliar spray applications at day 0 and day 21; but wasn’t very effective125–500BA + GABranching agent(Lieth and and Dodge 2004)
    Pyrus calleryana (Callery pear)BA + GA (Promalin) 1500 ppm/single foliar spray in June to one-year-old plants1500BA + GABranching agent(Jacyna et al. and Dodge 2004)
    Rhaphiolepis indica (Indian hawthorn)BA or BA + GA (Promalin)/single foliar spray application—BA + GABranching agent(Keever and Foster 1990)
    Rhododendron (Azalea, Vireya)BA, PBA, Thidiazuron all 200 at 200 ppm/single foliar spray; PBA was most effective, Thidiazuron was a close secondBA + GABranching agent(Criley 2000)
    Ternstroemia gymnanthera (Japanese cleyera)BA or BA + GA (Promalin)/single foliar spray application—BA + GABranching agent(Keever and Foster 1990)
    TREECYTOKININ: KINETINRATE (PPM)CYTOKININPURPOSE OF EXPERIMENTCITATION
    Berberis thunbergii (Japanese barberry)Kinetin 100–500 ppm100–500KinetinGrowth inhibitor(McCarthy and Bünemann 1981b)
    Camellia sinensis (tea)Kinetin 80 ppm released shoots from dormancy when applied to them80KinetinDormancy release(Kulasegaram 1969)
    Carica papaya (papaya)Kinetin 65–130 ppm, BA 250–500 ppm/monthly foliar spray applications65–130, 250–500KinetinBranching agent(Morales-Payan and Stall 2003)
    Cornus alba (Siberian dogwood)Kinetin 270 ppm; Kinetin + GA increased branching more than either chemical alone270KinetinBranching agent(Loach and Whalley 1975)
    Elaeagnus angustifolia (tea olive)Kinetin 50 ppm/applied to seeds50KinetinGermination promoter(Hamilton and Carpenter 1976)
    Lonicera xylosteum (dwarf honeysuckle)Kinetin 100–500 ppm; applications had no effect—KinetinGrowth inhibitor(McCarthy and Bünemann 1981b)
    Picea abies (Norway spruce)Kinetin 100–500 ppm100–500KinetinGrowth inhibitor(McCarthy and Bünemann 1981a)
    Rhododendron (Azalea)GA + Kinetin 100 ppm +100 ppm/applied every four days to the flower bud100KinetinBudbreak and formation(Furuta and Straiton 1965)
    Ribes (black currant)Kinetin 2 ppm/apply in late autumn for best results2KinetinDormancy release(Lenz and Karnatz 1969)
    Salix purpurea (purple willow)Kinetin 100–500 ppm; Kinetin 500 ppm worked best500KinetinGrowth inhibitor(McCarthy and Bünemann 1981b)
    Syringa spp. (lilac)Kinetin and BA rates and application method not listed—KinetinDormancy release-BA inhibited germination of seeds that were not dormant(Junttila 1970)
    Tsuga canadensis (Canadian hemlock)Kinetin 100–500 ppm100–500KinetinGrowth inhibitor(McCarthy and Bünemann 1981a)
    Viburnum opulus (American cranberrybush)Kinetin 100–500 ppm100–500KinetinBranching agent(McCarthy and Bünemann 1981b)
    Weigela florida (Weigela)Kinetin 270 ppm with GA 90 ppm270KinetinBranching agent(Loach and Whalley 1975)
    TREECYTOKININ: BA+ KINETINRATE (PPM)CYTOKININPURPOSE OF EXPERIMENTCITATION
    Cotoneaster dammeri (bearberry cotoneaster)BA + Kinetin (Early Harvest PGR-also contains GA and auxin) 1.5–3.0 ml in 1125 ml water; (1.17 ppm BA + 1.17 ppm Kinetin)/45 ml soil drenches every two weeks from June to September2.34BA + KinetinStress tolerance/branching agent-no effect on growth(Ruter 2000)
    Cotoneaster salicifolius (willowleaf cotoneaster)BA + Kinetin (Early Harvest PGR-also contains GA and auxin) 1.5–3.0 ml in 1125 ml water; (1.17 ppm BA + 1.17 ppm Kinetin)/45 ml soil drenches every two weeks from June to September2.34BA + KinetinStress tolerance/branching agent-no effect on growth(Ruter 2000)
    RhododendronBA 100 ppm/foliar spray 2–32 times with no effect on growth100BA + KinetinBranching agent(Richards and Wilkinson 1984)
    Spiraea japonica (Japanese spiraea)BA + Kinetin (Early Harvest PGR-also contains GA and auxin) 1.5–3.0 ml in 1125 ml water (1.17 ppm BA + 1.17 ppm Kinetin)/45 ml soil drenches every two weeks from June to September; the low 1.5 ml rate increased plant quality; the 3.0 ml rate increased growth2.34BA + KinetinStress tolerance/branching agent(Ruter 2000)
    Thuja occidentalis (Arborvitae)BA + Kinetin (Early Harvest PGR-also contains GA and auxin) 1.5–3.0 ml in 1125 ml water; (1.17 ppm BA + 1.17 ppm Kinetin)/45 ml soil drenches every two weeks from June to September2.34BA + KinetinStress tolerance/branching agent-no effect on growth(Ruter 2000)
    Weigela florida (Weigela)BA + Kinetin (Early Harvest PGR-also contains GA and auxin) 1.5–3.0 ml in 1125 ml water (1.17 ppm BA + 1.17 ppm Kinetin)/45 ml soil drenches every two weeks from June to September2.34BA + KinetinStress tolerance/branching agent-no effect on growth(Ruter 2000)
    Rhododendron (Azalea)PBA (200 ppm) + GA (200 to 100 ppm)/six foliar sprays during the winter200, 300, 400BA + KinetinBudbreak dormancy(Nell and Larson 1974)
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Cytokinin Phytohormonal Effects on Crown Structure
Alisha M. Autio, Michael E. Day
Arboriculture & Urban Forestry (AUF) Jan 2016, 42 (1) 1-20; DOI: 10.48044/jauf.2016.001
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