Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Determining Impact of Soil Environment and Root Function on Horticultural Crop Productivity and Quality
2013 Annual Report


1a.Objectives (from AD-416):
Objective 1: Determine nutrient requirements to enhance product quality in woody perennial crops such as grapevine and rhododendron. Objective 2: Characterize the role of mycorrhizal taxonomic diversity and identify important root-mycorrhizal interactions in cropping systems. Objective 3: Enhance product quality by optimizing crop management practices that promote overall root function to satisfy nutrient requirements in woody perennial crops. Objective 4: Integrate new and existing small fruit cultivars into efficient, environmentally accepatble production systems.


1b.Approach (from AD-416):
Determine the relationships between nutrient uptake, plant performance, and fruit quality of Pinor noir grapevines. Characterize the interactions between N use efficiency and plant quality and performance in container-grown nursery plants. Characterize the role of taxonomic and functional diversity of mycorrhizal fungi in grapevine cropping systems. Determine the interactions between plant resource allocation patterns, plant development, and production quality of geophyte nursery crops as affected by mycorrhizal fungi. Determine optimal methods for water application to improve efficiency of nutrient use and plant performance of grapevines and container-grown ericaceous plants. Characterize the influence of management practices on mycorrhizal fungi wthin winegrape and nursery crop production systems. Replacing 5358-12210-002-00D (02/2006). Replacing 5358-12210-003-00D (2/2011).


3.Progress Report:
Two long-term studies were conducted with grower input and in cooperation with researchers at Oregon State University to develop organic production systems for highbush blueberry and processing blackberry that maximize plant growth and yield; facilitate weed, water and nutrient management; and provide economic benefit to growers. We have developed organic production systems with similar yield and production costs to conventional systems. Oregon and Washington blueberry growers have readily adopted our findings in the use of landscape fabric in new plantings. Implementation of the practice has increased from less than 10% of the newly planted acres in 2006 to more than 80% of the new acreage in 2010. We will see whether blackberry growers likewise adopt this practice. Should similar positive effects of landscape fabric on plant growth and yield be noted, increased use of landscape fabric will likely lead to reduced herbicide application in organic and conventional plantings.

Interactions between plants and mycorrhizal fungi alter the physiology and nutrient uptake of small fruit and nursery crops, but plant benefits from mycorrhizas are a function of fungal diversity, plant growth habit, and soil conditions. With grapevines we are assessing how various management practices (cover crops, irrigation, and tillage) influence arbuscular mycorrhizal fungi (AMF) and root function and nutrient use. We are also identifying the major AMF that inhabit roots of grapevines under field conditions and developing single species cultures of these fungi to further test symbiotic function in helping plants obtain nutrients from soil and cope with drought stress. This information will be used to determine how benefits from mycorrhizal fungi can be enhanced to increase production efficiency and product quality in nursery crops and vineyards. We are also determining how N, P, and K supply alters the growth, physiology, and fruit quality attributes in Pinot noir using a controlled pot-in-pot system where nutrient supply can be carefully controlled. This information will be used to refine leaf and petiole nutrient standards for premium quality fruit.


4.Accomplishments
1. Organic blueberry production systems. Organic blueberry production continues to grow in the United States with new growers requiring basic information and existing growers struggling to remain economically viable in a global market. In cooperation with researchers at Oregon State University, an ARS scientist in Corvallis, Oregon, has developed organic production systems with similar yield and production costs to conventional systems. Growers in Oregon and Washington have readily adopted our findings in the use of landscape fabric in new plantings. Implementation of the practice has increased from less than 10% of the newly planted acres in 2006 to more than 80% of the new acreage in 2010. The positive effects of landscape fabric on plant growth and yield will likely lead to reduced herbicide application in both organic and conventional plantings.

2. Defining salinity thresholds for plant function and visual of symptoms in strawberry. Fertilizer application, particularly of N, alters the salinity of soils and soilless growing substrates. In some cases, levels to detrimental to plant production; however, threshold levels of salinity (ECe) have not been well documented in the literature for small fruit and nursery crops. We evaluated the effects of salinity in strawberry and determined that root growth and leaf color were decreased at EC levels > 2.5 dS·m-1, production of daughter stolons and stomatal conductance declined at levels > 3.5 dS·m-1, but levels as high as 4.5 dS·m-1 had no impact on leaf area or stem water potential. Defining salinity thresholds for small fruit and nursery plants will enable growers to identify levels that limit plant function that ultimately result in visual symptoms (e.g., leaf tissue necrosis) and a decline in production.

3. Nitrogen standards for Pinot noir grapevines identified. Management of grapevine nutrition requires better knowledge of how specific nutrients impact growth, yield, and fruit composition. ARS researchers in Corvallis, Oregon, and collaborators at Oregon State University developed leaf nitrogen guidelines by growing grapevines in a sand-culture vineyard where nutrient inputs were precisely controlled. Leaf blade nitrogen concentrations of 25 g kg-1 (or 2.5%) at bloom and 1.8 g kg-1 (or 1.8%) at véraison were required to maintain yields and provide adequate yeast assimilable nitrogen concentrations in berries. Leaf blades were better indicators than petioles for nitrogen and phosphorus status, while petioles were a better indicator for potassium status. Viticulturists can use this information to manage nitrogen inputs for Pinot noir to ensure that nitrogen status is maintained above the aforementioned critical values.

4. Weed, water, and nutrient management practices for organic blackberry production. Organic blackberry production has increased to more than 6200 acres worldwide but due to limited information on how to grow the crop organically, only 500 acres as of 2008 was in the United States. In cooperation with researchers at Oregon State University, an ARS scientist in Corvallis, Oregon, has identified the best practices to establish and transition to organic blackberry for machine harvest and processing. The information was transferred by eOrganic and is currently being adopted by blackberry growers throughout the Pacific Northwest where over 90% of the fruit is processed and more than have the U.S. total is produced. The information will lead to more availability of organic blackberries for consumers in the marketplace.


Review Publications
Schreiner, R.P., Lee, J., Skinkis, P.A. 2013. N, P, and K supply to Pinot noir grapevines:Impact on vine nutrient status, growth, physiology, and yield. American Journal of Enology and Viticulture. 64(1):26-38.

Last Modified: 12/20/2014
Footer Content Back to Top of Page