Source: UNIV OF WISCONSIN submitted to
DETERMINATION OF PROPER PROPAGATION METHODS FOR POTENTIAL NEW WISCONSIN PLUM CULTIVARS
Sponsoring Institution
State Agricultural Experiment Station
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0192529
Grant No.
(N/A)
Project No.
WIS0M200
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jul 1, 2002
Project End Date
Jun 30, 2005
Grant Year
(N/A)
Project Director
McCown, B.
Recipient Organization
UNIV OF WISCONSIN
(N/A)
MADISON,WI 53706
Performing Department
HORTICULTURE
Non Technical Summary
New, high quality and hardy selections of tree plums offer the potential to become a new alternative crop to fruit producers in the northcentral region of the U.S. but the most appropriate means to clonal propagate them is unknown. This project will determine the best commercially-applicable methods to clonally propagated ten unique hybrid plum selections
Animal Health Component
60%
Research Effort Categories
Basic
10%
Applied
60%
Developmental
30%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2041116102050%
2041116108050%
Goals / Objectives
1. To determine which method(s) will be suitable for the clonal propagation of new elite hybrid plum selections. 2. To determine which rootstock genotypes will be compatible with new elite hybrid plum selections.
Project Methods
During the past decade, a hybridization program in Wisconsin has generated ten hybrid plum clones that possess both the high quality of current commercial cultivars and have potential for commercial production under northcentral U.S. growing conditions. However, a limited amount of propagation material of these selections is available to be used in further testing or commercial plantings. This project will explore the use of cuttings, budding, and micropropagation as alternative cloning methods for these plum hybrids. Softwood cuttings will be taken in June from current plantings. Semi-hardwood cuttings will be taken in July/August. All cuttings will receive a quick-dip of auxin and will be stuck under mist in the greenhouse. Rooted cuttings will be outplanted in field trials and their growth followed for two seasons. This hybrid germplasm is sufficiently diverse to initially warrant a broad range of rootstock testing to accompany the budding propagation research, although ultimately for the Midwest only winter hardy rootstocks can be used. Therefore, the selection of potential rootstocks to test will include P. besseyi, P. americana, an open pollinated population of 'Waneta', Myrobalan 29C (P. cerasifera), P. mandshurica, and Marianna 2624 (P. cerasifera x P. munsoniana). Fall T-budding will be utilized and each of the 10 elite plum selections will be budded on each rootstock. In the spring, rootstocks will be planted in a replicated field trial in a randomized complete block design with four replications. Data collection will include bud take, initial growth rate and winter hardiness, depending on the winter. Starting in summer of 2002, rapidly-growing new shoots will be placed into microculture using Woody Plant Medium supplemented with benzyladenine. After stabilization of each selection, hormone response curves will be determined for each genotype. Microcuttings will be rooted under fog and the resulting plants outplanted in the cutting propagation field trials.

Progress 07/01/02 to 06/30/05

Outputs
Research focused on (1) defining the protocols for successful cloning by softwood cuttings, (2) documenting growth characteristics of trees propagated by budding in 2003/4, and (3) protocols for the generation of stock plants by micropropagation. Softwood cuttings of eight plum fruit selections and three rootstock selections were collected in July, left unwounded and treated with 3,000 ppm auxin (all selections) or 8,000 ppm (rootstocks). Rooting percentage varied by plum fruit genotype and ranged from 30% to 95%; the 8,000 ppm auxin treatment produced superior rooting (73%) than the 3,000 ppm treatment (53%) for the rootstocks. Growth measurements of field-grown trees budded the previous season consisted of caliper @ 10 cm above the bud union, height, and volume estimates. Fruit yields of field-grown trees budded two seasons previously were also taken. This data has not yet been fully processed. Four plum fruit genotypes were propagated by shoot culture, microcuttings harvested and rooted (100%), and planted in tree-pot containers. For comparison, one plum fruit genotype was propagated by softwood cuttings taken from field-grown plants. After going through a normal dormancy, plants were repotted in 2 liter containers and forced under greenhouse conditions. Stock plants derived from micropropagation branched heavily and produced high quality softwood cuttings over 2 generations of harvesting cuttings. Rooting percentages varied with genotype with percentages as high as 83% being readily achieved after treatment with a 10% liquid commercial rooting preparation. The overall conclusion from this project is that the new plum selections generated from the UW-River Falls breeding program can be cloned by budding or softwood cuttings. Because of the low vigor of the shoot cultures of these genotypes, micropropagation can be used only to generate vigorous and juvenile stock plants that provide a convenient, disease-free source of softwood cuttings.

Impacts
New selections of hybrid plums generated in a breeding program at University of Wisconsin-River Falls can be sucessfully cloned. This will allow both the release of selections for evaluation in nurseries as well as the commericial propagation for orchard establishment.

Publications

  • No publications reported this period


Progress 07/01/02 to 06/30/04

Outputs
Propagation and scale-up strategies for 10 advanced plum selections were studied using cuttings, budding, and micropropagation. Five of the selections were t-budded on 6 genotypes of rootstocks and on hybrid seedlings. Budding success varied by plum selection with an overall take of 46%. The successfully budded trees were out-planted in a trial plot. A second round of budding was performed and included four genotypes of rootstocks. Softwood cuttings of two plum genotypes rooted at 87% when treated with 500ppm water-soluble IBA and stuck in a fog house. Twelve plum selections were placed in microculture using standard protocols. Although all plum genotypes initially established in culture, eight of the genotypes continued to grow and only 3 showed acceptable multiplication rates and quality microcuttings. Microcuttings from these genotypes rooted at a 100% rate without hormone treatments. The use of microculture to provide high quality stock plants from which softwood cuttings can be taken and rooted at a high percentage will be explored.

Impacts
The determination of the appropriate clonal propagation methodologies for novel plum selections bred for Wisconsin and upper-Midwest growing conditions will allow their wider distribution and further evaluation for potential commercial use.

Publications

  • No publications reported this period


Progress 01/01/03 to 12/31/03

Outputs
A hybridization program in Wisconsin has generated more than a dozen hybrid plum (Prunus) genotypes worthy of further testing and evaluation in regional trials. Before such larger scale evaluation can begin, propagation protocols for these plums need to be determined. This project has that goal and is exploring three methods of cloning: budding onto rootstocks, softwood cuttings, and micropropagation. Ten plum selections were budded at various times onto seedling and clonal rootstocks. Even though severe weather conditions followed the budding in the fall, an average 46% success rate was observed. Success varied from 0 to 11% depending on the selection utilized. One trial using softwood cuttings generated from field plantings was conducted with two hybrid selections. Untreated softwood cuttings placed in a fog house rooted at 100%. Rooting was strongly reduced after auxin treatment. Eight of the 12 genotypes were successfully established in microculture as shoot cultures. Microcuttings harvested from two of these selections rooted at 100% in the fog house. Subsequent growth on the micropropagated plants appeared normal and vigorous. New hybrid plum selections appear to be readily cloned using multiple methods, however the success rate is dependent on the specific genotype. Further refining of these protocols will be pursued.

Impacts
The determination of the appropriate clonal propagation methodologies for novel plum selections bred for Wisconsin and upper-Midwest growing conditions will allow their wider distribution and further evaluation for potential commercial use.

Publications

  • McCown, Brent H. 2003. Biotechnology in horticulture: 100 years of application. HortScience 38:1026-1030.


Progress 01/01/02 to 12/31/02

Outputs
During the past decade, a hybridization program in Wisconsin has generated ten hybrid plum clones that possess both the high quality of current commercial cultivars and have potential for commercial production under Northcentral U.S. growing conditions. However, a limited amount of propagation material of these selections is available to be used in further testing or commercial plantings. This project is exploring the use of cuttings, budding, and micropropagation as alternative cloning methods for these plum hybrids. Utilizing summer shoots taken from field test plots, nodal and terminal tissue was surface-sterilized using hypochlorite soaks, and following rinsing, was placed on a WPM basal medium supplemented with the cytokinins benzyladenine (BA at 1 and 4 micromolar) or dimethylallylaminopurine (2iP at 10 micromolar). After screening for contamination, explants were subcultured within two weeks to avoid phenolic exudate build-up in the medium. As new shoot growth emerged, it was subcultured. Explants on BA-supplemented medium showed minimal growth and often had yellowing and distorted leaves. Hyperhydricity was more prevalent with explants growing on BA medium. With 6 of the 10 genotypes originally placed into culture, explants on 2iP-supplemented medium showed normal shoot growth and responded to subculturing with a gradual improvement of growth (stabilization). Four of the genotypes have stabilized and are ready for rapid scale-up to provide microcuttings for rooting. The 4 genotypes that did not isolate in microculture will be re-isolated using forced shoots from plants grown in a greenhouse. In the fall of 2002, field T-budding onto one-year old rootstocks was performed. Rootstocks being tested included P. besseyi, P. americana, an open pollinated population of 'Waneta', Myrobalan 29C (P. cerasifera), P. mandshurica, and Marianna 2624 (P. cerasifera x P. munsoniana). Many of the grafts showed healing before winter. These grafts will be forced into growth this spring to determine budding success and winter survival. Potted plants of each genotype will be forced into growth in the spring and used as stock plants for softwood and semi-softwood cuttings placed in rooting benches during the summer.

Impacts
The determination of appropriate clonal propagation methodologies for novel plum cultivars bred for the Wisconsin and upper-Midwest growing conditions will allow their wider distribution and further evaluation for potential commercial release.

Publications

  • No publications reported this period