2012 Annual Report
1a.Objectives (from AD-416):
Objectives over three years:
1. Identify the most easily multiplied/propagated of 24 cold-hardy quince clones.
2. Optimize in vitro propagation of selected clones.
3. Multiply enough quince clones, with and without interstems, to be grafted for multi-site field trials.
4. Field test ungrafted quince selections for fire blight resistance.
5. Establish replicated grafted field trials in Hood River and Wenatchee to determine tree vigor and productivity.
1b.Approach (from AD-416):
The USDA-ARS germplasm repository for quince is located in Corvallis, Oregon, and houses a wide representation of the world's diversity of quince. In our recent study, 24 cold hardy quince genotypes were identified and these plants are now available for evaluating ease of propagation so as to identify the best clones for use in field trials. We are proposing to evaluate ease of propagation by hard and softwood cuttings and by tissue culture. The 10 most easily propagated clones will be increased for a field trial to be grafted with Bartlett and Anjou, with or without interstems of Beurre Hardy. We will also explore the use of micrografting of interstems onto tissue culture plants to produce a ready-to-graft interstem tree in one year. Two fire blight resistant quince clones recently imported from Bulgaria will also be included in the trials.
During the second year a commercial nursery will be employed to graft Anjou and Bartlett onto the most promising quince clones for replicated field trials. Also in year 2, field trials will be planted in West Virginia to examine how ungrafted quince clones stand up to natural fire blight exposure.
In the third year replicated field trials using Anjou and Bartlett, with and without a quince-compatible interstem will be established in Hood River, OR and Wenatchee, WA to assess dwarfing, graft compatibility and fruit production using the 8 or 10 most cold hardy, easily propagated and fire blight resistant quince rootstock selections.
This project relates to objective 3b of the parent project. The objective of this project is to evaluate hard and softwood cutting propagation, as well as the ability to rapidly multiply quince accessions in tissue-culture. Fire blight susceptibility will be determined in year 2 by our ARS collaborator in West Virginia. The propagation technology will be transferred to commercial nurseries, and up to a dozen of the most cold hardy and easily propagated quince selections will be multiplied and grafted in year 3 to two commercial pear cultivars for replicated field trials in Hood River, OR, and Wenatchee, WA, to assess dwarfing, graft compatibility and fruit production. In January, 2012, dormant hardwood cuttings were collected from 24 accessions. Half were treated with rooting hormone and half were untreated. Six accessions had greater than 20% rooting success with hormone, and only two accessions rooted at > 20% with no hormone. In June, 2012 the propagation trial was repeated using softwood cuttings from 33 accessions. After 6 weeks, twelve accessions had greater than 25% rooting success with hormone, and four accessions rooted successfully with no hormone. Plants resulting from the winter hardwood cuttings were used as source material for collecting shoot tips for initiating in vitro cultures. To date, about 24 quince clones are established in tissue culture and will be used for multiplication and media trials. Rooted cold-hardy quince cuttings were also sent to a nursery in South Haven, MN, to test for field hardiness, and to a nursery in Carlton, OR, to begin establishing layer beds.