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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

2012 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 available 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 resistantance 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 maturity 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.


3.Progress Report:
Nine new apricot selections were evaluated for floral self-(in)compatibility during the 2012 bloom period. Yield and fruit quality data were obtained from nine apricot accessions grown on two rootstocks to examine differences in fruit size and ripening date. Twelve apricot selections for fresh and industrial markets were propagated on Nemaguard rootstock for advanced trialing. An apricot variety trial in a low-chill environment began the third year of growth with first bloom period scored for timing and duration. Scion vigor differences are beginning to be evident in the low-chill plot. A late-ripening dual purpose (fresh market and dry) apricot selection, three nectarines and two plums were sent to the National Research Support Project 5, Washington State University, Prosser, Washington for virus indexing.

Over 2,000 table grape seedlings were evaluated overall, with 550 advanced seedless selections evaluated in the field and laboratory. Nine promising table grape selections were added to the 27 vine test plot. Sixty-three advanced dry-on-the-vine (DOV) raisin selections fruited. Fifteen of these were harvested during the first week of October. The best DOV selection was harvested October 19, averaging 4.6 tons/acre with 12.2% moisture and a raisin grade of 89.8% B or better. Five seedless DOV raisins with red flesh from mBC1 family for red flesh were selected for propagation to determine production levels and raisin quality.

The 252 table grape and 135 raisin advanced selections grown in no spray plots, were evaluated in August for powdery mildew (PM) resistance. Eighty-six table and 43 raisin selections have remained free of PM for three years. Twenty new table grape selections were made and added to the advanced no spray plot for use as parents, representing three sources of PM resistance. Five tray dry PM resistant raisin selections were propagated into production trials. Modified backcrosses combining high fruit quality with PM resistant were made. A total of 27 seedless x seedless table grape and 18 seedless x seedless raisin crosses using a total of 49,714, and 42,793 emasculations, respectively, were made.

A total of 52 almond selections (36 self-compatible, 16 self-incompatible) as well as Nonpareil, Padre, Carmel (self-incompatible) and self-compatible Tuono were evaluated for bloom and hull split periods as well as shell and kernel characters.

Almond shell granular activated carbon is being challenged with a DBCP-contaminated municipal water stream to examine filter longevity and extent of carbon breakdown in flow rates matched to standard GAC water treatment vessels.

Multivariate analyses are being used to discriminate Nonpareil Marketing Group almond kernels from those of different marketing groups. Five new self-compatible almond selections have been propagated to Nemaguard rootstock to examine cropping efficiency, harvest timing and kernel quality.


4.Accomplishments
1. New molecular markers for powdery mildew resistance in grape. Powdery mildew is the most important disease attacking grapes around the world. ARS researchers at Parlier, California and Geneva, New York identified single nucleotide polymorphism (SNP) markers linked with Ren4 powdery mildew resistance and seedlessness on chromosome 18. Molecular markers allow pyramiding of resistant genes to provide more durable resistance to powdery mildew.

2. Release of new table grape cultivar Valley Pearl. Seedless table grape cultivars with large berry size, productivity and good storage capability are needed for commercial production in California. ARS researchers in Parlier, CA developed and tested grape selection F10 (now known as Valley Pearl) and found it produced large round attractive berries that were productive on spurs with good storability. Valley Pearl was released for commercial production and will provide growers with a white seedless, high yielding, good storage table grape for the early to mid-season.

3. Release of nematode resistant grape rootstock Demko 10-17A. Nematodes are a major pest for grape production, reducing yields and plant vigor making vineyards uneconomical. ARS researchers in Parlier, California tested grape rootstock selection 10-17A (now known as Demko 10-17A) and found it resistant to most nematodes found in California. Demko 10-17A was released as a grape rootstock and will provide growers with a moderately vigorous rootstock that provides protection against many nematodes as well as phylloxera.

4. Release of large red seedless table grape C51-63. Late ripening seedless table grapes with good production and storage ability are needed for commercial production in California. ARS researchers in Parlier, California developed and tested grape selection C51-63 and found it to be very productive with large red seedless fruit that store well. C51-63 was released for commercial production and will provide growers with a late ripening red seedless grape that is very productive with good berry size and storage ability.


Review Publications
Ramming, D.W., Gabler, F., Smilanick, J.L., Cadle Davidson, M., Paola, B., Siraprapa, M., Omer, F., Milgroom, M.G., Cadle Davidson, L.E. 2011. Identification of race-specific resistance in North American Vitis species limiting Erysiphe necator hyphal growth. Phytopathology. 102(1):83-93.

Mahanil, S., Ramming, D.W., Cadle-Davidson, M., Owens, C.L., Garris, A., Myles, S., Cadle Davidson, L.E. 2012. Development of marker sets useful in the early selection of Ren4 powdery mildew resistance and seedlessness for table and raisin grape breeding. Journal of Theoretical and Applied Genetics. 124:23-33.

Ledbetter, C.A. 2012. Register of new fruit and nut varieties list 46. HortScience. 47(5):536-562.

Last Modified: 8/19/2014
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