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Y. M. Moreno, A. A. Gardea and A. N. Azarenko

`Lovell' peach seeds were stratified for 0 to 13 weeks at 4C under moist conditions. Heat of metabolism and CO2 evolution, measured by Differential Scanning Calorimetry, increased with stratification time. The calorespirometric ratio increased between 0 and 6 weeks and then remained constant until 13 weeks. Germination percentages paralleled this ratio and reached 80% only after 6 weeks of stratification.

After radicle emergence, seedlings from different stratification treatments were grown for 3 weeks. Increasing stratification time resulted in taller seedling growth. Calorimetrically measured CO2, evolution and the calorespirometric ratio of the apex (one cm) of the seedling increased with longer stratification time. Contrary to the observations of the seeds, metabolic heat rates decreased as stratification time increased. Yet, seedling sustained higher growth rates. These data suggest that the stratification treatment resulted in an improvement in metabolic efficiency.

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J.L. Olsen, S.A. Mehlenbacher and A.N. Azarenko

Hazelnuts, (Corylus avellana L.), are wind-pollinated, monoecious, mostly dichogamous, and self-incompatible. About 90% of the cultivars studied are protandrous. Anthesis of the pistillate flower is temperature-dependent and occurs December through February, peaking in January. Stigmatic surfaces may remain receptive for up to 3 months. Four to 5 months separate pollination and fertilization of the ovule; the latter usually occurring between mid-May and the end of June in Oregon. A 10% pollinizer density has been the standard, with a recommended distance of 66 ft (20 m) or less between the main cultivar and the nearest pollinizer. Two or three different pollinizer cultivars, with different times of pollen shed, are recommended. The Oregon hazelnut industry is presently combating the fungal disease, eastern filbert blight, caused by Anisogramma anomala (Peck). Current management recommendations suggest reducing risk of infection are to reduce the most susceptible pollinizer cultivars to a density 5%, then gradually replace those left with immune or more resistant genotypes.

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Habib Khemira, T. L. Righetti, David Sugar and A. N. Azarenko

Current N fertilization practices, where high spring applications are utilized, may lead to excessive vegetative growth. However, high rates may not be required to maximize fruit yield and quality. Therefore, alternative strategies to minimize shoot growth while still providing the N needs of the tree were investigated. Mature `Comice' and `Bosc' pear trees were given one of the following treatments: a spring soil (SS) application of NH4NO3 nitrate at 112.5 kg/ha rate, a similar application in the fall after harvest (FS), a fall foliar (FF) spray of a 7.5% urea solution after harvest (FF), or no N (Control). Trees that received a FF application had the same leaf and fruit N content as control trees, but they yielded more fruit The SS application gave more vigorous trees than FF application. Yield, however, was not different.

A 15N enriched urea solution was applied at harvest as either a foliar spray, soil application, or combination of both treatments to mature `Comice' trees. Flower buds from trees that previously received a foliar treatment had 37% of their N derived from the foliar N application. No labeled N was detected in buds from the soil treatment These results indicate that vegetative and reproductive N requirements of fruit trees may be managed separately.

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Haibib Khemira, T.L. Righetti and A.N. Azarenko

Seven-year-old `Royal Ann' cherry trees were given a total of 244 g of actual N as ammonium nitrate depleted in 15N (0.01 atom % 15N) either in March (M), June (J), or both in March and June (Split). The fertilizer was soil-applied to eight single-replicate trees. The following August, leaves from the trees that had the M treatment had 15.3% of their N from the fertilizer compared to 9.6% for the split treatment. Trees that had a J application were not different from the control trees. Even though cherry trees are physiologically active during the late summer months, little N is translocated to the leaves once the crop is fully developed. The percentage of newly acquired N in the fruit is similar to that in the spur leaves. Leaves from the different treatments had similar N contents; therefore, labeled N is the tool of choice to assess the performance of different fertilization practices.

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A. Plotto, A. N. Azarenko, M. R. McDaniel and J.P. Mattheis

`Gala' apples were harvested at weekly intervals for 6 weeks, refrigerated at 0C, and evaluated by a consumer panel monthly over a 6 month period for overall liking, firmness, sweetness, tartness and flavor intensities. Firmness, titratable acidity and soluble solids concentration were also measured. Initial analysis of sensory data revealed multicollinearity for overall liking, sweetness, and flavor. The five descriptors explained 75 % of the dataset variation in the first two factors. An orthogonal rotation separated overall liking, flavor and sweetness, and firmness and tartness into two independent factors. The distribution of mean scores along these independent factors showed that panelists could perceive changes due to ripening and maturation. The multivariate factor analysis was better than univariate ANOVA at illustrating how apple maturity stages were apparent to untrained panelists. Firmness was the only instrumental variable correlated to firmness ratings in the sensory tests. None of the analytical measurements could explain overall liking.

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Anita N. Azarenko, Annie Chozinski, Sarah F. McDonald*, Thomas A. Forge and Timothy Righetti

Information about the use of alternative management practices (AOFMP) in perennial systems to manage soil biota and influence the uptake of nutrients is limited. The objectives of this study are to evaluate AOFMP on soil quality, focussing on soil biology, and on nitrogen uptake efficiency. Research plots are located in Lewis-Brown Farm (LB), Corvallis, OR (`Fuji' apple trees) and Mid-Columbia Ag. Research & Extension Cent. (HR), Hood River, OR (`Red Delicious' apple trees). Main plot treatments were weed control methods: herbicide or cultivation. Sub plot treatments were soil amendments: no amendment, bark mulch (BM), compost, and green vetch/barley mulch (VB). A split-plot completely randomized design with 3 replications was used. Depleted NH3 SO4 was applied to single-tree replicates at bud break in 2001, 2002, and 2003. Compost amended plots contained more fungivorous nematodes than other treatments, although this difference was not significant at LB. At both sites there was a significant interaction between main and sub plot treatments in the number of bacterivores. At LB, the interaction between main and sub plot treatments affected the number of enrichment opportunists and the F-ratio was affected by amendment. At HR, the structural index was also affected by amendment. Compost resulted in the most diverse populations. Soil respiration rates in compost and BM plots were consistently higher than in unamended and VB treated plots. Soil P, pH, and organic matter content were increased by compost amendment and bulk density was decreased. At HR mid-season leaves, fruit, and first year growth from compost treated plots contained the least nitrogen derived from fertilizer, followed by bark mulch. The highest nitrogen derived from fertilizer was in unamended plots.

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M. Ngouajio, K. Delate, E. Carey, A.N. Azarenko, J.J. Ferguson and W.J. Sciarappa

As organic agriculture continues to grow, pressure from students and the public to develop novel curricula to address specific needs of this sector of agriculture also will increase. More students from the cities and with limited background in production agriculture are enrolling in agricultural programs with special interest in organic production. This new student population is demanding new curricula based on a better understanding of agroecology principles and more experiential training. Several universities throughout the nation have engaged in a profound curriculum transformation to satisfy the emerging need of students in organic production. This workshop was organized to bring together experts that are working on different organic and sustainable agriculture curricula throughout the country to share their experiences and lessons learned. Most of these curricula include a traditional classroom teaching component, a major experiential component, a student farm for hands-on experience and internships, and in some cases a marketing—typically a community supported agriculture (CSA)—component. Others programs are more extension oriented, providing applied training to growers outside of the university teaching curriculum.

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Shawn A. Mehlenbacher, Anita N. Azarenko, David C. Smith and Rebecca McCluskey

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Shawn A. Mehlenbacher, Anita N. Azarenko, David C. Smith and Rebecca McCluskey

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Kirk W. Pomper, Anita N. Azarenko, Joel W. Davis and Shawn A. Mehlenbacher

Random amplified polymorphic DNA (RAPD) markers were identified for self-incompatibility (SI) alleles that will allow marker-assisted selection of desired S-alleles and assist in cloning the locus responsible for the sporophytic SI displayed in hazelnut (Corylus avellana L.). DNA was extracted from young leaves collected from field-planted parents and 27 progeny of the cross OSU 23.017 (S1 S12) × VR6-28 (S2 S26). Screening of 10-base oligonucleotide RAPD primers was performed using bulked segregant analysis. DNA samples from six trees each were pooled into four “bulks,” one for each of the following: S1 S2, S1 S26, S2 S12, and S12 S26. “Super bulks” of twelve trees each for S1, S2, S12, and S26 then were created for each allele by combining the appropriate bulks. The DNA from these four super bulks and also the parents was used as a template in the PCR assays. Amplification products were electrophoresed on 2% agarose gels and photographed under UV light after ethidium bromide staining. 200 primers were screened and one RAPD marker each was identified for alleles S2 (OPI-07700) and S1 (OPJ-141700).