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United States Department of Agriculture

Agricultural Research Service

Research Project: Improvement of Prunus and Vitis Scions for Fruit Quality and Pest Resistance

Location: Crop Diseases, Pests and Genetics Research

2008 Annual Report

1a. Objectives (from AD-416)
Develop and introduce new high quality and disease-resistant cultivars of almonds, grapes and stone fruits that will sustain American agriculture and supply high quality, nutritious fruits and almonds to U.S. consumers and international markets. 1. Continue evaluation of existing high-quality scion selections of stone fruit (apricots, nectarines, peaches, and plums) from the breeding program to identify those having desirable traits such as enhanced sugar content, novel peento flat shape and expanded ripening season, and table and raisin grapes with large seedless fresh fruit that stores and ships well, natural ‘dried on the vine’ raisin trait, economic production levels with spur pruning, and enhanced anthocyanin content for fresh and processing markets. 2. Identify Vitis accessions resistant to powdery mildew and evaluate existing table grape and raisin breeding populations and selections for high fruit quality with host-plant disease resistance. 3. Evaluate existing self-compatible almond accessions adapted to California.

1b. Approach (from AD-416)
Classical breeding techniques have been used to create segregating populations where the expression of quantitative traits has been concentrated and newly availale characters have been transferred into adapted Prunus and Vitis germplasm. Plant materials in existing segregating populations of Prunus and Vitis will be selected and propagated for new cultivar development. Greenhouse and field screening will proceed to select Vitis seedlings with resistant to powdery mildew. The genetic control of raisins that dry on the vine and red flesh color in grapes will be determined through the evaluation of appropriate segregating progenies. Apricots will be selected for white flesh, for drying ability and for late muturity season from numerous segregating progenies. New self-compatible almonds will be selected having kernel qualities similar to Nonpareil, and four high kernel quality self-compatible almond selections will be trialed in isolated orchard conditions to evaluate the yield potential of self-compatible almonds in the absence of bee pollination. Formerly 5302-21220-004-00D (7/08).

3. Progress Report
The progress reported here relates specifically to Component 3 (Genetic Improvement of Crops) of National Program 301 (Plant Genetic Resources, Genomics, and Genetics Improvement) in the evaluation of stone fruits (apricot, peach, nectarine and plum), almonds and grapes for potential introductions as new cultivars. This project, approved on 2 July 2008, continues work accomplished throughout the life of Project No. 5302-21220-004. Seedlings from hybridizations performed in 2007 were field planted during February – April 2008. Grape and apricot seedlings have been trained and cultivated to achieve maximum vegetative growth during the early juvenile period. Hull split in almond began in mid-July, with both self-compatible selections and self-incompatible comparison cultivars being scored weekly for hull split progression throughout the summer. In grapes, field populations having segregation for powdery mildew resistance were left in a natural condition (no fungicides) so that infection levels on specific plant organs could be evaluated systematically. Dry-on-vine (DOV) raisin selections were netted to prevent bird depredation and in anticipation of raisin quality evaluations later in the fall.

4. Accomplishments
1. New Project, continuance of old project No. 5302-21220-004-00D. Please refer to that report.

5. Significant Activities that Support Special Target Populations

Last Modified: 10/20/2017
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