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Research Project: Integrated Water and Nutrient Management Systems for Sustainable and High-Quality Production of Temperate Fruit and Nursery Crops

Location: Horticultural Crops Research Unit

2017 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.

Progress Report
The second year of a new study to address the fundamental issue of whether fruit and wine quality in both red and white grape cultivars can best be obtained through nitrogen fertilization in the vineyard or by reducing nitrogen (N) in the vineyard but adding it in various forms in the winery was completed (sub-Objective 1.1). This on-farm project involves collaborators from Oregon State University and industry and will be continued for the next two years. Based on recent work from a highly controlled pot-in-pot system, we expect that condensed tannins, wine color, and fruity/floral aromas will be improved by lower nitrogen status in the vineyard thus improving quality, but we do not yet know how such effects will interact with nitrogen additions in the winery. We are assessing the effects of nitrogen fertilization on numerous aspects of vine growth and yield, nutrient status for all key plant nutrients, water status of vines, berry development and berry composition. Wine quality differences are being determined via a sensory-driven approach to guide further sophisticated chemometric analysis of wines (aroma chemistry, phenolics, etc.). We are continuing our on-going studies to examine how cultural practices alter root health of nursery crops as part of a non-assistance cooperative agreement with Oregon State University [project 2072-22000-041-01S, “Improving Plant Health for Nursery Production in the Pacific Northwest”, funded by Floriculture and Nursery Research Initiative (FNRI) and Northwest Center for Small Fruits Research (NCSFR)] to improve plant health for Pacific Northwest nursery production (Objective 1). We expanded the number of nurseries in our survey to identify frequently occurring root pathogens in Rhododendron in different production systems. Isolates of three pathogens recovered from our survey are being evaluated for their effects on plant health. Three greenhouse trials were completed to evaluate pathogenicity of most prevalent root rot pathogen isolated and how population size alters disease; one greenhouse trial was initiated to evaluate how water availability alters disease; two field trials were completed and a third trial was initiated to determine effects of irrigation management on disease development and plant health; and two field trials were completed and a third trial was initiated to determine effects of fungicide applications on disease development and plant growth. This information will be used to develop cultural management practices to decrease disease. We are continuing our on-going studies to examine how irrigation management alters nutrient uptake and performance of nursery stock (Objective 1). A study was conducted to investigate how altering irrigation frequency or volume during nursery production affected performance of one deciduous and two evergreen cultivars of Rhododendron the following year. A manuscript reporting this research is in preparation. Results will be used to modify irrigation management in nursery production to optimize landscape performance. We are continuing our on-going studies to determine the effects of salinity on growth, nutrient uptake, and secondary metabolism in basil (Objective 1). A study was completed that investigated how arbuscular mycorrhizal fungi (AMF) mitigate the effects of different levels salinity from sodium chloride (NaCl) or calcium chloride (CaCl2). Biomass and nutrient uptake results have been completed. The effects of AMF on secondary metabolites are currently being determined. Results to-date suggest that differences in basil tolerance to NaCl and CaCl2 are not solely a function of electrical conductivity (EC). This highlights the importance of understanding the source of salinity in irrigation waters and soil for predicting damage. We initiated a follow-up study to determine how AMF alter root respiratory function under salinity stress. Results from these studies will be used to develop salinity thresholds for crop production and strategies for enhancing benefits from AMF. Experiments were performed to determine how growing substrate composition and fertilizer source alters growth and nutrient uptake in blueberry plants (Objective 1 and 3). In two greenhouse studies using one northern highbush and two southern highbush blueberry cultivars, we assessed nutrient uptake efficiency and biomass accumulation in young blueberry plants grown in media containing different ratios of perlite, bark, peat, and coir. In a field study under a high tunnel we investigated how potassium (potassium sulfate, potassium acetate, or potassium thiosulfate) and nitrogen (ammonium sulfate or urea) altered growth and yield of one northern highbush and one southern highbush blueberry cultivars. Results will be used to optimize media composition and nutrient management for soilless cultivation of blueberry. 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 (Objective 1). Over two seasons, we manipulated N-availability and mycorrhizal status in dwarf lilies used for floral, potted plant, and field production. Biomass and nutrient uptake results have been completed. We are initiating a new study to determine effects of AMF on bulb storage reserves because samples taken from previous studies were degraded due to equipment malfunction (freezer breakdown). 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. The first study to assess the impacts of taxonomically diverse AMF isolated from vineyards on grapevine growth and nutrient uptake was completed (sub-Objective 2.1). We are presently examining how these different fungi affected production of the soil glycoprotein, glomalin, and how this may relate to soil hyphal production among species with a collaborator from University of Miami. We are also following up with a smaller study to address why one of the species performed so poorly in colonizing roots prior to beginning the next iterations of this research. One of the fungi examined was clearly superior to all others in promoting phosphorus uptake and shoot dry matter, even though root colonization levels and root dry matter were similar to other AMF. We will further evaluate these AMF taxa under more diverse soil conditions. The third year of a new study to examine how canopy architecture, vine density and crop load in Pinot noir interact to alter productivity and fruit quality was developed with collaborators at Oregon State University (sub-Objective 3.1). The focus next year will be to collect all plant and soil baseline data in the year when vines will carry their first half crop. 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. We are continuing to characterize heat-related fruit damage in blueberries (sub-Objective 3.3). Heat damage to blueberries is typically observed a few days after a warm weather event. The most prevalent symptom, which is commonly known as sunburn, is fruit necrosis. Necrosis can occur in both green and blue fruit and usually happens on the upper portion of a berry, which usually receives most of the heat load. An initial cooling study conducted in Salem, Oregon in 2014 showed that micro-sprinklers could effectively reduce berry temperature. It also indicated that it took more time to bring berry temperature down when the cooling was started late in the day. However, once cooling began, berry temperatures stayed below air temperature until the micro-sprinklers were finally turned off. The question of whether cyclic cooling can be as effective as continuous cooling was also tested in both Salem, Oregon and Prosser, Washington. We found cycling was as effective as continuous cooling but used 50% less water. We set up a replicated trial in Corvallis, Oregon in 2016 to examine the effects of cooling on fruit quality. The trial included ‘Aurora’ and ‘Elliott’, each either cooled or not with 20-min cooling cycles. Cooling increased the average berry size in both cultivars, particularly in ‘Aurora’. Cooling also increased fruit firmness of ‘Aurora’ and reduced soluble solids in both cultivars at the first harvest, but it had no effect on titratable acidity or sugar-acid ratio at the first harvest or on any of these quality traits in the two subsequent harvests. The berries that ripen first were prone to more sun exposure and, hence, more likely to have heat-related damage. 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 (sub-Objective 3.4). In 2015, a field trial was initiated to assess different methods of calcium fertilizer application altering development of cold hardiness in Rhododendron and blueberry. Cold tolerance and damage was assessed on plants from autumn 2015 through spring 2016. A repeat trial was initiated in 2016 and data was collected through 2017. A third trial was initiated in 2017 and data will be collected through 2018. This information will be used to optimize nutrient management strategies to mitigate losses from cold damage.

1. Water-saving strategies for highbush blueberries. Many blueberry growers are facing serious water limitations due to warmer and drier weather conditions, increased regulations, and greater demand by other sectors. An ARS scientist at Corvallis, Oregon evaluated the potential of using water-saving management strategies, including deficit irrigation, early and late-season irrigation cut-offs, and crop thinning, to maintain yield and fruit quality with less water in northern highbush blueberry. Fruit production was unaffected by deficit irrigation and, by the second year, was actually greater with crop thinning than with no thinning in the early cutoff treatment. Late cutoffs, on the other hand, reduced yield but increased several fruit quality characteristics, including firmness, storability, and sugar content of the berries. Compared to using full irrigation, deficit irrigation saved nearly 270,000 gallons/acre of water per year, while early and late irrigation cutoffs saved approximately 140,000 and 250,000 gallons/acre of water per year, respectively.

2. Nutrient requirements and timing of uptake of young grapevines were measured. The timing of macro- and micro-nutrient uptake and the quantities of nutrients required by young grapevines was determined by ARS researchers in Corvallis, Oregon. Nitrogen uptake was maximal early in the season with most uptake occurring before bloom. Uptake of phosphorus and sulfur were also early compared to other nutrients with similar quantities of these elements taken up between budbreak and bloom, and between bloom and véraison. All other nutrients had peak uptake between bloom and véraison. Even in these young vines, about 35% of the nitrogen required by the canopy by the time fruit coloration began was remobilized from reserves in the roots and trunks. These findings provide grape growers better guidelines for when to fertilize young vines and how much of different nutrients to apply.

3. Leaf blades are superior to petioles for diagnosing nitrogen status of grapevines. ARS researchers in Corvallis, Oregon compared nutrient concentrations in both leaf blades and petioles (leaf stem) to vine growth, yield, and nutrients in fruit juice to determine which tissue is better for diagnosing the nutrient status of vines. The data were collected from a pot-in-pot vineyard over four years where Pinot noir grapevines were grown with different levels of each nitrogen, phosphorus, and potassium. Leaf blades were clearly superior to petioles in predicting vine growth, yield, and must nitrogen levels in vines receiving different levels of nitrogen. Both leaf blades and petioles were about equal in predicting vine responses to varying phosphorus and potassium levels. Based on these findings, using leaf blades as opposed to petioles is recommended for diagnosing the nutrient status of Pinot noir grapevines.

4. Basil tolerance to salinity differs with salt type. Saline ground water, recycled irrigation water from agricultural runoff, and waste water captured from municipal and industrial effluents are being used more frequently to irrigate crops worldwide. Since information is lacking on how plants respond to different salts, experiments were performed to determine the effects of salinity from sodium chloride (NaCl) and calcium chloride (CaCl2) on growth and nutrient uptake in basil. Results indicate that basil may be more sensitive to salinity from NaCl and CaCl2. While short-term exposure to salinity with an electrical conductivity of 4 to 8 deciSiemens per meter (dS/m) may not alter growth of basil, the effects of salinity on plant physiology may influence crop quality even when productivity is not significantly impacted. Differences in basil tolerance to NaCl and CaCl2 indicate plants may have different mechanisms for dealing with salinity and sensitivity are not solely a function of electrical conductivity (EC). This highlights the importance of understanding the source of salinity in irrigation waters and soil for predicting damage.

5. Substrates were evaluated for soilless production of spinach. The use of substrates and soilless culture systems for production of horticultural crops is increasing worldwide. Substrates often increase plant growth and yield in many crops, reduce the incidence of soil-borne diseases, and, when combined with collection of drainage water, increase the efficiency of water and nutrient use. Despite these many benefits, there is currently very little information available concerning the influence of substrate type on plant growth and nutrient uptake in many crops, including leafy vegetables. In cooperation with scientists at the University of Evora, Portugal, an ARS researcher in Corvallis, Oregon evaluated the influence of different substrate types on plant growth and nutrition of spinach. The substrates included peat, a composted peat mix, and coir. Black peat produced the most growth and the greenest plants among the substrates and, therefore, was the best option for growing spinach in soilless culture.

6. Ploidy level does not alter propagation efficiency in cherrylaurel (Prunus laurocerasus). Cultivar improvement through breeding polypoid plants may be useful for decreasing invasiveness and disease susceptibility of an important nursery crop, cherrylaurel (Prunus laurocerasus). Grower adoption of new cultivars and breeding programs can be limited by ability of cuttings to form adventitious roots. In collaboration with the nursery crop breeding program at Oregon State University (OSU), experiments were conducted to determine whether newly developed polyploid plant selections by OSU differed in their ability to root. Results indicated that there are no apparent detrimental effects to rooting cuttings following inducing higher level polyploids of ‘Schipkaensis’ cherrylaurel. This indicates that this polyploidy will not alter the efficiency of vegetative propagation during nursery production and will improve efficiency of cultivar development in breeding programs.

Review Publications
Schreiner, R.P. 2016. Nutrient uptake and distribution in young Pinot noir grapevines over two seasons. American Journal of Enology and Viticulture. 67:436-448. doi: 10.5344/ajev.2016.16019.
Scagel, C.F., Bryla, D.R., Lee, J. 2017. Salt exclusion and mycorrhizal symbiosis increase tolerance to NaCl and CaCl2 salinity in ‘Siam Queen’ basil. HortScience. 52(2):278-287. doi: 10.21273/HORTSCI11256-16.
Barcelos, C., Machado, R.M., Alves-Pereira, I., Ferreira, R., Bryla, D.R. 2016. Effects of substrate type on plant growth and nitrogen and nitrate concentration in spinach. International Journal of Plant Biology. 7(1):44-47. doi: 10.4081/pb.2016.6325.
Schreiner, R.P., Scagel, C.F. 2017. Leaf blade versus petiole nutrient tests as predictors of nitrogen, phosphorus, and potassium status of ‘Pinot noir’ grapevines. HortScience. 52(1):174–184. doi: 10.21273/HORTSCI11405-16.
Schulze, J.A., Contreras, R.N., Scagel, C.F. 2017. Comparing vegetative propagation of two ‘Schipkaensis’ common cherrylaurel ploidy levels. HortTechnology. 27(1):69-72. doi: 10.21273/HORTTECH03600-16.
Houston, L.L., Capalbo, S., Seavert, C., Dalton, M., Bryla, D.R., Sagili, R. 2018. Specialty fruit production in the Pacific Northwest: Adaptation strategies for a changing climate. Climatic Change. 146(1-2):159-171.
Alumtairi, K., Bryla, D.R., Strik, B.C. 2017. Potential of deficit irrigation, irrigation cut-offs, and crop thinning to maintain yield and fruit quality with less water in northern highbush blueberry. HortScience. 52(4):625-633. doi: 10.21273/HORTSCI11533-16.
Yeo, J.R., Weiland, G.E., Sullivan, D.M., Bryla, D.R. 2017. Nonchemical, cultural management strategies to suppress phytophthora root rot in northern highbush blueberry. HortScience. 52(5):725-731. doi: 10.21273/HORTSCI11437-16.
Howland, A., Skinkis, P.A., Wilson, J.H., Riga, E., Pinkerton, J.N., Schreiner, R.P., Zasada, I.A. 2015. Host status of own-rooted Vitis vinifera varieties to Meloidogyne hapla. Journal of Nematology. 47:141-147.