Location:2015 Annual Report
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.
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.
We are continuing to assess how various management practices (cover crops, irrigation, and tillage) influence production and fruit quality, arbuscular mycorrhizal fungi (AMF) development, and root function and nutrient use in wine grape. 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 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. In addition, a new project was begun in 2015 with a commercial partner and colleagues at Oregon State University to extend findings from our pot-in-pot research trial to further test the impact of N management practices in the vineyard versus in the winery to achieve the highest quality fruit. A new vineyard was also planted in 2015 at Oregon State University’s Woodhall Research Vineyard to assess the effects of canopy architecture, vine density, and crop load on Pinot noir production and fruit quality. This project will provide a large-scale test of whether opening up the canopy to better capture mid-day solar radiation can improve fruit quality and sustainable production goals simultaneously, or whether our current canopy management system, which reduces mid-day solar capture, is beneficial because it reduces water use and/or heat stress. Multiple studies are underway to identify the critical temperatures at which overhead cooling is needed for heat protection in highbush blueberries and to develop strategies for reducing heat damage with and without overhead cooling. Results indicate that cooling is required at 90-95 degrees F in blueberry and that damage can occur in both green and blue fruit. Most of the damage happens when high temperatures are immediately preceded by cooler weather conditions in the previous day or so. Next, we are evaluating different cooling frequencies to determine the amount of water required with either sprinklers or microsprinklers and to develop a model with guidelines for evaporative cooling. Fruit from various cultivars are also being examined microscopically to identify traits such as a thicker culticle that may enhance resistance to heat damage. A study was completed to quantify the effects of temperature on root respiratory energy costs associated with growth and maintenance in northern highbush blueberry roots. Data is being analyzed and will be used to plan follow-up studies that will assess how N availability alters root respiratory costs. The effects of salinity on growth and physiology of young highbush blueberry was assessed. Using three different rates of calcium chloride, growth and water stress of plants were measured and tissue samples were analyzed for nutrients. A second study was completed to determine how different rates of calcium and potassium chloride affect growth and physiology of southern highbush blueberry. A new study was initiated in cooperation with Oregon State University to develop a process for enriching low N compost using biofilters filled with wood chips and shavings to capture ammonia gas emissions from existing animal composting facilities and incorporating the spent biofilter material into low N yard debris compost. We are currently developing a prototype for the biofilters and will begin testing it for use on dairy compost piles. The effects of cultural practices on root health of nursery crops was assessed as part of an agreement to improve plant health for Pacific Northwest nursery production. Frequently occurring root pathogens were isolated from Rhododendron and Ribes plants in several Pacific Northwest nurseries. Isolates were tentatively identified and 3 were selected to evaluate their effects on plant health. A greenhouse trial with Rhododendron and 4 field trials with Rhododendron and Ribes were initiated to determine pathogenicity of isolates and the effects of pathogen population size, irrigation management, and fungicide applications on disease development and plant growth. We are continuing on-going studies that manipulate nutrient supply to determine how different nutrients alter physiology important for quality in container-grown nursery crops and how nutrient availability alters cold tolerance. This information will be used to optimize nutrient management strategies mitigate losses from cold damage. In 2015, a field trial was initiated to assess different methods of nitrogen, calcium, and magnesium fertilizer application alter development of cold hardiness in Rhododendron. Methodology was refined for measurement of cold damage and will be implemented this winter. With geophyte crops used in floral crop production systems, we completed a study investigating how resource allocation patterns altered by AMF influence product quality and determined whether the effects of AMF on plant nutrition result in significant impacts on product quality. Using dwarf lilies we manipulated N-availability and mycorrhizal status in a 2 season study. Samples are being analyzed for nutrients and polyphenolic composition. Additionally, we are assessing how AMF alter end-product qualities (polyphenolic profiles) of medicinal and culinary herbs. We are analyzing samples from a study that assessed how salinity alters growth and secondary metabolites of basil. This information will be used during to determine how benefits from mycorrhizal fungi can be enhanced to increase production efficiency and product quality in nursery crops.
1. Late-season water deficits have little impact on nutrient accumulation and fruit composition of Pinot noir grapevines. ARS researchers in Corvallis, Oregon, examined the effect of late-season water stress on vine growth, yield, and nutrient composition of whole clusters and grape juice in Pinot noir grapevines grown under controlled conditions. Periodic drought stress applied after the onset of color change (veraison) had no impact on vine growth and yield, nutrient status of the leaves, or berry chemical composition. Each of these vine characters were altered by the growing year. This research suggests that new Pinot noir vineyards that are planted on rootstocks and managed with drip irrigation are tolerant of short periods of moderate to severe drought stress with little impact on fruit quality.
2. The majority of plant damaging nematodes are concentrated directly beneath drip irrigation emitters in arid vineyards of the Pacific Northwest. The spatial distribution of plant parasitic nematodes, roots, and mycorrhizal fungal colonization was studied by ARS researchers in Corvallis, Oregon, and collaborators from Oregon State University, to better understand the management zone needed to target control for the key nematode pests in established vineyards and the resulting impact on roots and mycorrhizal mutualists. The northern root knot nematode and ring nematode were aggregated under irrigation emitters within the vine row and decreased with soil depth. Colonization of fine roots by mycorrhizal fungi decreased directly under irrigation emitters and galled roots had lower levels of arbuscular mycorrhizal fungi (AMF) colonization compared with healthy roots. Possible nematode management strategies could include off-set planting (replanting grapevines in the old alleyways as opposed to the old vine rows) when replanting a vineyard, or altering the emitter spacing. Results also indicate that the use of specific cover crops known to suppress plant-parasitic nematodes populations as a means of control would be ineffective.
3. Drip irrigation helps to improve the health benefits of blueberries. Drip irrigation has rapidly become the most popular method to irrigate blueberries in most countries, including the United States. An ARS scientist in Corvallis, Oregon, determined previously that young blueberry plants often grow better with drip than with conventional sprinkler systems, but little information was available on the use of drip in mature plantings. In cooperative work with Agriculture and Agri-Food Canada, researchers found that blueberry plants became more sensitive to soil water limitations with age and required more irrigation for profitable production. Antioxidants in the fruit were also higher with than without drip irrigation, and therefore, drip irrigation, if properly managed, could help to improve the health benefits of blueberries. The information was used to develop new irrigation guidelines for highbush blueberry, which have been adopted by the industry to improve production and quality in the Pacific Northwest.
4. Production benefits of fertigation in highbush blueberry. Many blueberry fields in North America are irrigated by drip. In addition to efficient water use, drip irrigation also offers the opportunity to inject fertilizers through the irrigation system, often referred to as fertigation. ARS scientists in Corvallis, Oregon, cooperated with researchers at Oregon State University and Agriculture and Agri-Food Canada to compare the effects of fertigation with liquid nitrogen (N) fertilizer to standard surface applications of granular N fertilizer on fruit production in highbush blueberry and identified the optimum amount of N needed with each method. Over a five-year period, fertigation resulted in more yield each year than granular applications of N fertilizer and required 30-40% less N than what is currently recommended for highbush blueberry. Fertigation also produced higher anthocyanin concentrations in the fruit. These results have been transferred to the industry and indicate that fertigation can be efficiently and cost effectively utilized to increase fruit production and quality of highbush blueberry with less N than required with conventional granular fertilizers.
5. Organic fertilizer sources for processed and fresh market blackberries. Guidelines for fertilizer and nutrient management in organic blackberry production are presently limited to overarching recommendations and do not address different sources of fertilizers. ARS researchers from Corvallis, Oregon, and researchers at Oregon State University, evaluated the impact of using different organic fertilizer sources, including processed poultry litter, pelletized soybean meal, corn steep liquor, and a fish hydrolysate and emulsion blend with added molasses, on yield and fruit quality of different blackberry cultivars. Each fertilizer was suitable to maintain adequate nutrition in three trailing types (Black Diamond, Marion, and Obsidian) and one semi-erect type (Triple Crown) of blackberry, but the cost per pound of nitrogen (N) was higher for the liquid products than for the poultry litter and soybean meal. These results are helping the industry identify suitable cultivars and cost-effective fertilizers for organic production of processed and fresh market blackberries.
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