Location: Fruit and Tree Nut Research
2023 Annual Report
Objectives
1. Develop new high-chill stone fruit cultivars for main season production areas with improved adaptability, cropping reliability, disease resistance, handling ability, and eating quality.
2. Develop new moderate-chill stone fruit cultivars for early season production areas in the lower coastal plain with improved adaptability, cropping reliability, tree architecture, disease resistance, handling ability, and eating quality.
3. Develop new stone fruit rootstocks with improved disease resistance and a range of vigor control to manage tree size.
4. Determine how the individual genetic components of the pecan genome function collectively to determine priority traits for pecan production such as host-plant resistance to scab disease and floral and fruit development that control alternate-bearing. Expected benefits include more effective pecan genetics research coordinated with the ARS breeding program in College Station, Texas and accelerated release of new scion varieties.
Approach
Elite breeding lines and select varieties with appropriate traits will be hybridized and the best hybrid seedlings selected. These selections will be tested for multiple years in several locations to identify those truly superior to existing commercial varieties in terms of cropping reliability, productivity, fruit size, appearance, firmness and eating quality. These superior selections will then be named and released for use by the commercial peach industry.
Parental root-stock lines with superior resistance to peach-tree short life, Armillaria root rot and commercially important root-knot nematode species will be intercrossed to produce hybrid seedlings with the desired characteristics. Extensive field testing will be utilized to identify those hybrids which have the requisite combination of disease resistance and horticultural traits for successful commercial utilization the southeastern U.S. peach industry. Best selections will be released for commercial utilization.
Progress Report
This is the final report for the project 6042-21000-005-000D which terminated in May 2023. Under Objective 1. In the past five years, hybridizations, seedling planting, evaluations, and selections were made every year for the high-chill peach cultivar development program. Progress has been made in the field with advanced selections and breeding lines that appear less prone to chill inadequacy and spring freeze. Promising advanced selections nearing completion of evaluations have been scaled up in anticipation of impending releases. In terms of direct impact to stakeholders, five new high-chill main season peach cultivars have been released by this program and licensed to several nurseries and propagated for commercial use. New cultivar trials of the recent releases have been established in Georgia, Alabama, and Michigan under Plant Material Transfer and Evaluation Agreements to test the performance of these materials against standard commercial cultivars in these regions with different climates and management programs.
Under Objective 2. In the past five years, hybridizations and downstream breeding activities, including variety trials of recent releases, were made for the moderate-chill peach variety development program at a reduced effort due to retirement of incumbent in 2019, short retention of a new replacement in 2021, and critical vacancy of the position in 2019-2020 and 2022-2023. New selections were made and propagated for further development in 2019 and 2021. Breeding materials are being maintained by project lead scientist, program technician, collaborator, and retired scientist.
Under Objective 3. In the past five years, hybridizations and downstream breeding activities, including rootstock trials, were made for the rootstock development program at a reduced effort due to retirement of incumbent in 2019, short retention of a new replacement in 2021, and critical vacancy of the position in 2019-2020 and 2022-2023. New rootstock selections were made and propagated for further development in 2019 and 2021. Rootstock trials of MP-29 (released in 2011) and advanced selections established with collaborators in Georgia, Alabama, South Carolina, Texas, and Michigan under Plant Material Transfer and Evaluation Agreements continued at reduced scales, for example, in Georgia to assess the utility of MP-29 in high-density plantings and evaluate novel management approaches to rootstock sucker suppression and response to differential fertilization and irrigation regimes. Advanced rootstocks selections nearing completion of evaluations were scaled up in anticipation of impending releases. In terms of direct impact to stakeholder, commercial use of disease resistant dwarf MP-29 rootstock has expanded, and a new peach seedling rootstock P-22 has been approved for pending release. Seeds of P-22 have been collected for continuing rootstock trials. Rootstock breeding materials are being maintained by project lead scientist, program technician, collaborator, and retired scientist.
Accomplishments
1. Patents of two new early-season peach cultivars. New and improved peach cultivars remain in high demand by the Southeastern peach industry. Two early-season peach cultivars, intent for commercial use, have been developed through conventional breeding by ARS scientists at the Southeastern Fruit and Nut Research Laboratory in Byron, Georgia. The two new early-season cultivars provide the peach industry with substantially improved alternatives.
2. New licesnsing of three new peach cultivars. New and improved peach cultivars remain in high demand by the Southeastern peach industry. Licensing of three new peach cultivars, developed via conventional breeding by ARS scientists at the Southeastern Fruit and Nut Research Laboratory in Byron, Georgia, have been issued by the agency to a second commercial nursery and undisclosed number of trees have been propagated for commercial growers. Planting trees of the new cultivars with improved characteristics greatly benefit the industry.
3. Marker analysis of stone fruit rootstock accessions. A large collection of stone fruit rootstock accessions maintained in the USDA-ARS Byron Georgia breeding program have never been analyzed using DNA markers. ARS scientists at Southeastern Fruit and Nut Research Laboratory in Byron, Georgia have genotyped these stone fruit materials and revealed their relatedness using optimally selected DNA markers that were able to distinguish these accessions. The new knowledge facilitates understanding of the rootstock accessions and optimization of parents in future rootstock breeding.
Review Publications
Chen, C. 2023. Fruit characteristics of the joy peach cultivars. HortScience. 58(4): 428-432. https://doi.org/10.21273/HORTSCI17056-22.
Chen, C. 2022. Retrospection of century-long peach chill, yield and other production data and implications for breeding programs. Acta Horticulture Proceedings. 1352(1):385-389. https://doi.org/10.17660/ActaHortic.2022.1352.54.
Chen, C., Okie, W. 2022. Inheritance of the rough skin character in peach. Acta Horticulture Proceedings. 1352: 385-389. https://doi.org/10.17660/ActaHortic.2022.1352.53.
