Branching Inducers on Plumeria

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Branching Inducers on Plumeria

By Milton Pierson, Suggested by Dr. Richard A. Criley, Univ. of Hawaii
Purpose:

To produce more branches per cut from a pruned plumeria limb. UH experiments suggest that lanolin pastes of cytokinins can improve the number of buds which break following pruning. It is desirable to increase lateral shoot production after pruning for cultural control both in commercial flower production and landscapes as well as for plants grown in containers (Kwon and Criley, 1991).

Procedure:

Apply 6-benzylaminopurine (BA) in a lanolin paste to pruned tips. Kwon and Criley (1991) used single stemmed 2 year old plants of P. rubra in 35 x 22 cm pots containing a medium of equal parts soil, peat, and perlite. The plants were decapitated at 30 cm above the soil line 3 weeks after repotting. Various concentrations of the growth regulator solution was then applied to be absorbed into the cut surface. We will use 2 mg/g and 4 mg/g (BA/lanolin) solutions (2000 and 4000ppm). Four plants should be used for each treatment plus 4 control plants. Data to collect are; (a)number of days to bud break for each plant, (b)number of shoots initiated and (c)surviving and (d)the length of these at 4 months after treatment.

The following passage is quoted from a letter from Dr. Richard A. Criley, dated September 16, 1994. It outlines where BA and lanolin may be obtained, how to mix them, how to apply the paste to plumeria, and addresses the question of the shelf life of the mixture.

“The application of chemical branch inducing substances in lanolin would be an interesting set of studies for PSA members to try. You can get plain old lanolin at many pharmacies or order it through chemical supply houses. It comes as a yellow, very sticky fatty substance. You can melt it in a double boiler and dissolve or suspend substances in it. My recommendation is to weigh out the stuff in the same container you want to melt it in – then you are sure of concentrations.

The benzyladenine is not water soluble to any great extent. I usually dissolve it in a small amount of acetone or alcohol or DMSO. You can also use 0.5 N HCL (small amount) to dissolve it, then dilute in water and add to the melted lanolin. Stir well to make a uniform mixture. Allow to cool. I use it by smearing a glob on the cut stump of a plumeria branch using a finger covered with a latex glove finger. Rates to try: 2 or 4 mg BA in 1 gram of lanolin. I have a mixture from 4 – 5 years ago that still has activity.

You can also pour the BA-lanolin paste mix while still liquid into plastic film canisters. This might be one way to share it around easily. (Maybe you could charge a few dollars per unit and recover the costs.)

The N-6-benzyladenine (BA) is also known as 6-benzylaminopurine.”

Summary:

  • Use 6-benzylaminopurine (BA) in a lanolin paste.
  • Apply paste to pruned tips. (1) 2 mg BA per gram lanolin. (2) 4 mg BA per gram lanolin.
  • These experiments would need control plants which receive a no N-6-benzyladenine . Both the experimental subject and control plant would have to be of the same cultivar to avoid inconsistencies in growth habit and flowering.

References:

Eunoh Kwon and Richard A. Criley (1991), Cytokinin and Ethephon Induce Greater Branching of Pruned Plumeria, Horticulture Digest; Hawaii Cooperative Extension Service, No. 93, March 1991, p. 6-8.

6-benzylaminopurine from Sigma Chemical Company; catalog # B 3408: 1 g, $10.65 + shipping. Lanolin from Sigma Chemical Company; catalog # L 7387: 1 kg, $32.80 + shipping.