Location: Horticultural Crops Research Unit
2019 Annual Report
Objectives
Objective 1. Determine the water and nutrient requirements needed to produce high-quality temperate fruit and nursery crops in the Pacific Northwest.
• Sub-objective 1.1. Develop water and nutrient guidelines to improve fruit and wine quality in Pinot noir.
• Sub-objective 1.2. Characterize the interactions between water and nutrient use efficiency and plant quality in container-grown nursery plants.
• Sub-objective 1.3. Identify salinity thresholds associated with compost and fertilizer use in highbush blueberry and basil.
• Sub-objective 1.4. Determine temperature thresholds for sprinkler frost protection in cranberry.
Objective 2. Evaluate the impact of soil microbes on crop water and nutrient use in grape and other specialty crop production systems.
• Sub-objective 2.1. Characterize taxonomic and functional diversity of indigenous arbuscular mycorrhizal fungi (AMF) in vineyards.
• Sub-objective 2.2. Determine the effects of AMF on interactions among plant development, resource allocation, and product quality in specialty crops.
Objective 3. Develop irrigation and nutrient management practices and strategies that enhance crop productivity and quality with efficient use of water and fertilizers in berry and woody nursery crop production systems.
• Sub-objective 3.1. Identify cover crop practices that enhance vineyard establishment and improve fruit quality in cool-climate wine grapes.
• Sub-objective 3.2. Evaluate the potential benefits of using organic mulches under weed mat and identify the right source(s), time (fall vs. spring), and place (surface vs. incorporation) for organic compost application in highbush blueberry.
• Sub-objective 3.3. Develop irrigation practices to reduce heat-related fruit damage in highbush blueberry.
• Sub-objective 3.4. Develop nutrient management methods to increase cold tolerance in container-grown nursery crops.
Approach
Experiments will be conducted in the greenhouse and field on small fruit and nursery crops, including Pinot noir wine grape, highbush blueberry, cranberry, and container-grown Rhododendron, Vaccinium, Salix, Euonymous, floral geophytes (e.g., lily), and basil. For objective 1, relationships among soil N, P, and K availability, vine growth, and fruit quality will be determined in wine grape and used to develop leaf and petiole nutrient standards for production of Pinot noir and cool-climate cultivars in the Pacific Northwest. The extent to which berry quality of Pinot noir is altered by soil water deficits will also be investigated to provide benchmarks that relate specific indicators of vine water status such as leaf water potential and stomatal conductance to fruit quality. Greenhouse studies will be designed to test whether excess N availability reduces plant quality and water use efficiency in container-grown nursery plants and to identify salinity levels that limit shoot and root growth and function and lead to leaf necrosis in blueberry and basil. Critical temperatures for freeze damage in the region will be likewise determined for cranberry using combination of laboratory measurements on excised plant tissues and temperature-control units on the plants in the field. For objective 2, root and soil samples will be collected from plants grown in both field and greenhouse experiments to test if diversity of arbuscular mycorrhizal fungi (AMF) is a function of sampling location, soil depth, and cover crop use in grape roots; and to ascertain whether AMF improve quality of floral geophytes by enhancing P uptake and allocation. For objective 3, field studies will be designed to determine whether alleyway cover crops and residue placement in vine rows increases root production, AMF colonization, and plant growth and nutrient uptake in young grapevines; if using organic mulches (sawdust or compost) under weed mat will enhance soil conditions, including availability of water and nutrients, and result in more growth and production in highbush blueberry; and whether overhead cooling with sprinklers or misters reduce heat damage in blueberry fruit when applied correctly at the proper temperature, rate, and frequency. Can-yard studies will likewise be designed to test whether increased N availability reduces cold tolerance or, alternatively, if application of cation fertilizers (K, Ca, Mg) increase cold tolerance in container-grown nursery plants. Measurements in the studies will include standard techniques for measuring plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), photosynthetic efficiency (fluorometer), fruit quality (refractometry, acid titratation, colorimetry, HPLC), root production and turnover (minirhizotrons, soil cores), mycorrhizal colonization (microscopy), DNA sequencing (PCR), soil pH and EC, soil water content (TDR, tensiometers), and plant and soil nutrients (CNS analyzer, ICP). Data will be analyzed using ANOVA, ANCOVA, nonparametric, and regression techniques. In some cases, studies may need to be repeated due to poor weather conditions or the need for a wider range of treatments.
Progress Report
This is the final report for project 2072-21000-048-00D, which terminated in December 2018. Research continues under bridging project 2072-21000-053-00D. With the exception of one project that could not be completed due to the presence of a new virus disease in the experimental vineyard, all planned experiments were completed prior to the start of fiscal year 2019.
Significant advances to determine the water and nutrient requirements needed to produce high quality fruit and nursery crops were accomplished under Objective 1. The nitrogen and phosphorus requirements needed to maintain productivity and enhance fruit and wine composition were determined for Pinot noir, and new tissue test guidelines for these nutrients were developed to achieve different goals. Irrigation and nutrient management that optimizes perennial plant growth and storage of reserves for the following year were determined in nursery plants, and new guidelines to improve quality of the plants after transplanting into the landscape were developed. Thresholds to salinity were developed and used to revise extension publications on soil and nutrient management for conventional and organic blueberry production. Critical temperatures for freeze damage were identified and used to develop new guidelines for sprinkler frost protection in cranberry. The overall impact of the research from this objective was that nutrient and water requirements for numerous temperate fruit and nursery crops grown in the Pacific Northwest were quantified for the first time to give producers clear targets to manage inputs more efficiently and meet or exceed end-product quality goals.
Substantial results evaluating the impact of soil microbes on crop water and nutrient use were realized under Objective 2. In grapevines, applications of mulch and nitrogen fertilizer were found to alter the community of beneficial fungi (arbuscular mycorrhizal fungi) engaged in nutrient exchange in roots, and the activity of these fungi was shown to be more sensitive to plant photosynthesis than to high shoot nutrient status. In medicinal and culinary nursery crops, phosphorus fertilizer application rates and inoculation with mycorrhizal fungi were found to enhance production of antioxidant compounds, providing growers with new tools to optimize specific antioxidants that have potential human health benefits. These findings identified practices that positively or negatively altered the function or impact of symbiotic fungi on plants, which allows growers to optimize the benefits derived from mycorrhizal fungi and improve efficiency of production or end-product quality.
Progress was made towards developing irrigation and nutrient management strategies to enhance productivity and quality in berry and woody nursery crops under Objective 3. Growing winter cover crops between the rows of grapevines was found to have little impact on the establishment of new vineyard plantings, although the application of cover crop residue as a mulch layer under the vine row enhanced growth and nitrogen status in young vines by increasing surface soil moisture and reducing soil compaction. Levels of salts in the root environment that have little impact on productivity of nursery and small fruit crops were found to reduce product quality, and threshold salinity levels for different salt sources were developed based on both productivity and quality. Peat and coir were found to be better soilless substrates than bark in blueberry. Addition of sawdust under weed mat mulch was found to produce more growth and fruit production in blueberry than the conventional practices of using either mulch alone. Critical temperatures for heat damage were also identified and used to develop evaporative cooling practices for blueberry. These practices are being used by producers to improve production and quality of their plants and fruit in the Pacific Northwest and to prevent millions of dollars of crop loss each year.
Accomplishments
1. Phosphorus requirements and tissue test guidelines identified for Pinot noir. Information on optimal phosphorus requirements for Pinot noir wine grapes and the impact of phosphorus on must fermentations is needed by wine grape growers. An ARS scientist in Corvallis, Oregon, and collaborators from Oregon State University, identified phosphorus needs and tissue test guidelines for optimal phosphorus status based on productivity and must fermentation kinetics. Phosphorus supply had the greatest impact on must phosphorus levels, but the lowest level obtained was still ample for healthy fermentations. Phosphorus limitation reduced canopy size and crop yield simultaneously when vine phosphorus status was below levels identified in prior studies. Phosphorus did not alter flower development in Pinot noir, in contrast to previous research in other wine grape cultivars. The new tissue test guidelines will be used by wine grape growers to better manage phosphorus to avoid losses in vine productivity and protect the environment.
2. Nitrogen supply alters yeast-derived aromas in Pinot noir wine. Information on the impacts of vine nitrogen, phosphorus, and potassium status in Pinot noir grapevines on wine quality is needed. An ARS scientist in Corvallis, Oregon, and collaborators from Oregon State University, examined how these nutrients influenced wine volatile aromas important for wine quality. Nitrogen was shown to affect wine aroma to a far greater extent than phosphorus or potassium, and nitrogen primarily altered aroma compounds that are produced by the yeast during fermentation. Wines produced from vines with lower nitrogen status had lower levels of straight-chain esters and alcohols, higher levels of branched-chain esters and alcohols, and lower levels of volatile sulfur compounds that impart unpleasant odors in wine. These findings show that Pinot noir producers need to consider the positive impact of low nitrogen status on wine aroma and the negative impact on vine productivity to better manage nitrogen in the vineyard.
3. New insights into how apple tree roots respond to fruit thinning and fertilizers. Upwards of 80 percent of the annual biomass in apple trees is partitioned to fruit, while only about 1 percent to 2 percent is partitioned to roots. As a result, over cropping can lead to severe problems in an orchard, particularly during replant or under poor soil conditions. An ARS scientist in Corvallis, Oregon, and collaborators from The Pennsylvania State University, Ohio University, and Hebei Agricultural University (China), examined how fruit removal affected root and mycorrhizal fungal proliferation in nutrient-rich “hot spots” in the soil of a high-density Golden Delicious apple orchard. Fruit removal increased root growth but had no effect on production of fungal hyphae in the soil. In general, roots proliferated primarily in inorganic nutrient “hot spots” (i.e., where the fertilizer was applied), while fungal hyphae were mostly found in organic nutrient “hot spots” (i.e., decomposing leaf litter). This information is useful to growers for developing new practices to improve root and soil health in apple orchards.
Review Publications
Schreiner, R.P., Osborne, J. 2018. Defining phosphorus requirements for Pinot noir grapevines. American Journal of Enology and Viticulture. 69(4):351-359. https://doi.org/10.5344/ajev.2018.18016.
Lavely, E.K., Zhang, J., Adams, T.S., Bryla, D.R., Deforest, J.L., Marini, R.P., Crassweller, R., Eissenstat, D.M. 2018. Root and mycorrhizal fungal foraging responses to fruit removal in apple trees. Plant and Soil. 146(1-2):401-416. https://doi.org/10.1007/s11104-018-3773-8.
Yuan, F., Schreiner, R.P., Osborne, J., Qian, M. 2018. Effects of soil NPK supply on Pinot Noir wine phenolics and aroma composition. American Journal of Enology and Viticulture. 69(4):371-385. https://doi.org/10.5344/ajev.2018.17077.
